1. Introduction
According to the European Regulation [
1], spirit beverages are classified into 44 categories; some of which are marketed without ageing while others undergo an ageing stage during their production process and are marketed as aged spirits. Among them, wine spirit, brandy, whiskey, sugar cane spirits (rum and cachaça) and grape marc spirit are traditionally aged in wooden barrels, and have great importance worldwide in terms of production, trade and consumption [
2,
3,
4] -
Figure 1. The spirit beverages accounts for c.a. 37% of the global alcoholic drinks market, the market's largest segment with a value of 408.8 billion USD in 2023 [
4]. In addition, the latter is projected to grow c.a. 23% in the 2023-2028 period, reaching 1,373.9 billion USD; specifically, the spirits segment is expected to grow by 2.2% in 2024 and keep up this trend until 2029 [
4,
5]. Evidence supports the notion that premium spirit beverages have a favourable impact on driving market expansion. This helps mitigate market constraints caused by the adverse effects of excessive alcohol intake on consumer health [
5,
6]. Indeed, moderate alcohol consumption behaves as a stimulant, due to the direct absorption into the bloodstream from the stomach, while excessive consumption (≥ 15 drinks per week) can affect the central nervous system and cause chronic diseases [
7,
8]. In almost every world's cultures, spirit beverages have been appreciated due to their composition and sensory properties, and because they can be stored for long periods; their consumption is socially acceptable and they play an important role in the diet [
9,
10]. Therefore, the six types of aged spirit beverages aforementioned, enriched in wood compounds that enhance the distillates quality through the sensory and nutraceutical features imparted, can have a prominent role, contributing to the development of the related value chains, meeting consumer preferences, and driving market growth.
The freshly distilled spirits have high ethanol content (80-96%) and are rich in volatile compounds derived from the raw materials and/or formed during the operations composing their production process up to distillation (described in
Section 2), but are devoid of phenolic compounds other than some volatile phenols, and of some furanic aldehydes [
11,
12,
13,
14,
15,
16,
17,
18,
19,
20]. Thus, contact with wood during the ageing stage is a core aspect in the manufacture of these beverages, as it confers them unique physicochemical and sensory characteristics, resulting from many phenomena involving the distillate and wood compounds, as well as the oxygen that enters the barrel by diffusion or is applied by micro-oxygenation [
14,
18,
19,
21,
22,
23,
24].
Specifically, phenolic compounds (detailed in
Section 3), released from the wood into the distillate, play a notable role in the distinctive characteristics acquired by these spirits - colour, aroma, flavour (including bitterness) and mouthfeel sensations (such as astringency) [
22,
25,
26,
27,
28,
29,
30] - which are not significantly modified during storage in bottle [
31], and can therefore be perceived by the consumer.
Although many studies have been carried out to gain knowledge on the phenolics involved and their relationship with the factors that govern ageing, as well as their repercussions, the information available in the literature on coumarins is limited. The main sources of coumarins are examined in
Section 4. According to our knowledge, research on coumarins began in the 1960s-1970s with the works of Baldwin et al. [
32] in whiskey, Bricout [
33] and Joseph and Marche [
34] in wine spirit, and Otsuka and Zenibayashi [
35] in brandy, rum and whiskey. However, it wasn't until the late 1980s that new studies were conducted, particularly in wine spirit [
36,
37,
38]. Recently, this topic has been addressed for wine spirit [
39,
40,
41,
42], cachaça [
43,
44,
45], whiskey [
22,
46,
47], brandy [
48], grape marc spirit [
22] and rum [
22]. This chronology can be ascribed to:
i) the evolution of analytical methods supported by new technologies (described in
Section 5);
ii) growing attention paid by the consumer and the scientific community to nutraceutical quality, even in alcoholic beverages, because there is greater awareness that the presence of bioactive compounds, such as coumarins, can partially mitigate the harmful effects of alcohol [
49]. From this perspective, scientific outcomes are mainly related to wine [
50,
51], and only a few works have been devoted to whiskey [
52], wine spirit [
53,
54,
55], brandy [
54,
56], and rum [
57] (described in
Section 7). This could be an important driver for the six related industries (wine spirit, brandy, whiskey, rum, cachaça, and grape marc spirit);
iii) health concerns on the part of the consumer, industries and food science researchers, leading to an interest in food safety. However, little is known about the relationship between coumarins and the food safety of spirits (disclosed in
Section 8);
iv) the importance of chemical markers for authenticity purposes, which is a key aspect in the production and trade of spirits, in order to protect crucial players in each value chain: the producers (the Designations of Origin, if applicable) and the consumers [
58,
59]. Coumarins are potential chemical markers - for example, they are associated with oak wood
versus chestnut wood in the ageing of wine spirits [
38,
40] - but this requires knowledge on their contents and their variation with the ageing conditions for the different spirit beverages (discussed in
Section 6 and
Section 9).
Despite coumarins are minority phenolic compounds in these matrices [
19], a thorough understanding of the above-mentioned topics is imperative to understand their importance, to explore/manipulate and control the ageing stage, and consequently the production process, in order to shape the final product profile according to the target consumer, while guaranteeing quality, sustainability, authenticity and food safety. This review aims to summarise, for the first time, the existing knowledge on coumarins in the most relevant spirit beverages, focusing on the issues highlighted above.
3. Coumarins in the context of phenolic composition
The name “coumarin” derives from the French term “coumarou” for the tonka bean that are the seeds of
Dipteryx odorata (Aubl.) Forsyth f. (or
Coumarouna odorata Aubl.), in which coumarin was first isolated by Vogel [
85,
86]. This compound has a sweet odour that is easily identified as the aroma of freshly mown hay; as a result, it has been used in perfumes since the late 19
th century [
87,
88].
Coumarins are important secondary metabolites that can be found abundantly in the plants (detailed in
Section 4). Numerous studies have been conducted on the isolation, structural characterization, synthesis, and biological activity of an extensive variety of natural coumarins, derived from trees and plants, including some used in the production of beverages [
89,
90,
91,
92,
93], as well as coumarins obtained by chemical synthesis [
94]. Regarding its chemical structure, natural coumarins are unsaturated lactones that belong to the C6C3 chemical class, that is, a class of benzopyrones (1,2-benzopyrones or 2H-1-benzopyran-2-ones; consisting of a benzene ring fused to an α-pyrone ring), which can be thought of structurally as
ortho-hydroxy-cinnamic acid derivatives (
Figure 8). The majority of natural coumarins, including umbelliferone, scopoletin, aesculetin, among others, include an oxygenated substituent at position 7 [
95]. This substituent can exist either in its free form, as seen in hydroxylated umbelliferone, or in combination with other compounds (methyl, ethyl, saccharides, etc.) in different derivatives. These compounds exhibit a conjugated system that is rich in electrons, resulting in favourable charge-transport features [
91,
96].
Several methodologies for classifying coumarins can be found in the literature. Among them, the most comprehensive, which includes coumarins with the greatest complexity and substituted coumarins, often found in combination with other heterocycles [
88], categorises these compounds into the following groups: simple coumarins, furanocoumarins, dihydrofuranocoumarins, pyranocoumarins (both linear and angular), phenylcoumarins, bicoumarins, and coumarin glycosides, as depicted in
Figure 9 [
97].
Simple hydroxycoumarins, furanocoumarins and isofuracoumarins, pyranocoumarins, bicoumarins, and dihydroisocoumarins are the most important compounds of this chemical family isolated from plants. In plants, coumarins often exist in the free form due to their polar nature, and a significant number of these compounds have the ability to undergo sublimation. Additionally, they can also be present in the form of glycosides, including psoralen-correlated compounds. These entities exhibit a distinct blue fluorescence owing to their absorption of UV light, and they possess a high degree of photosensitivity, making them susceptible to modification by natural light. These properties are exploited for separation and analysis purposes, as well as in unconventional therapeutic approaches such as photochemotherapy and the chemical sensor industry (detailed in
Section 5 and
Section 7).
Simple coumarins are synthesised biogenetically by the transformation of shikimic acid into cinnamic acid. The underlying primary enzymatic transformation is the C-2 hydroxylation, which results in the cleavage (
β-oxidation) of the side chain, or alternatively, chain isomerization followed by lactonization, leading to the formation of umbelliferone (
Figure 10). Shikimate dehydrogenase (AroE) promotes the transformation of shikimate and NADP
+ into 3-dehydroshikimate, NADPH, and H
+. The shikimate pathway is a metabolic system consisting of seven steps and it is involved in the synthesis of phenylalanine, tyrosine, and tryptophan.
Shikimic acid is also the source of furanocoumarins and pyranocoumarins, which have a wide range of biological activity and are present in many natural products and synthetic drugs [
98].
Furanocoumarins consist of a furan (or dihydrofuran) ring fused with the coumarin skeleton and can be classified as linear or angular; a good example can be seen in the structure of psoralen [
99]. These structures are derived from umbelliferone by the addition of a prenyl group [
100]. In general, furanocoumarins are biosynthesized involving two pathways, the phenylpropanoid and the mevalonic acid ones, by a coupling of dimethylallyl pyrophosphate (DMAPP) with umbelliferone, as well as through the formation of a prenylated simple coumarin intermediate [
99].
Pyranocoumarins typically consist of a pyran (or dihydropyran) ring that is usually fused with the aromatic ring of the coumarin skeleton, as in xanthyletin [
99]. Based on where the isopentenyl pyrophosphate is condensed to further cyclize and produce the heterocycle, these coumarins can be classified as linear or angular. The synthesis of these complex coumarins might possibly be the outcome of the cyclization of a prenylated simple coumarin [
101]. Phenylalanine, a compound generated by the shikimate biosynthetic pathway, undergoes conversion by phenylalanine ammonia lyase (PAL) into
trans-cinnamic acid, which gives rise to the core metabolite 4’-coumaroyl-S-CoA. This intermediate can subsequently be converted into a variety of phenylpropanoids via 6’-hydroxylation,
trans >
cis isomerization of the exocyclic double bond, and the final lactonization/cyclization step (
Figure 11). The initial and crucial step in biosynthesis is 6'-
ortho-hydroxylation, which is carried out by the 2-oxoglutarate-dependent dioxygenase F6'H1.
Some works have been devoted to clarify the biosynthesis pathways of scopoletin at a molecular level. Scopoletin, like umbelliferone, undergoes benzene ring alterations, and studies conducted on
Arabidopsis thaliana demonstrated that scopoletin is produced through the phenylpropanoid pathway via
ortho-hydroxylation of cinnamate,
p-coumarate, caffeate, and ferulate [
102,
103]. Similarly, these coumarins, as well as esculetin, can be produced via the phenylpropanoid route (
Figure 12), specifically generated from
trans-cinnamic acid, but instead of undergoing through the lactonization process of the caffeic acid derivative, 2’-hydroxy-caffeic acid, they can be synthesised via umbelliferone [
104]. Cinnamic acid also plays a role in the synthesis of scopoletin, as an intermediate, but this time through caffeic acid ester derivatives. Besides the synthesis of coumarins, the phenylpropanoid route is responsible for the synthesis of other phenolic compounds, such as flavonoids and phenolic acids.
Furthermore, bicoumarins deserve attention as they are a category of great interest for pharmaceutical applications, particularly as anticoagulants. Bicoumarin connects two coumarin moieties by an orthoester structure, being the dicoumarol the first isolated compound [
105]. Dicoumarol, in particular, consists of two cyclic
β-ketoesters linked by a methylenic bridge, and was isolated from plant sources, in which the two coumarin units are linked at C3-C3’ via methylene group [
106] (
Figure 13). One possible route for the biogenesis of this compound might be the hydroxylation of the carbon atom at 4-position of coumarin framework, which then captures a molecule of formaldehyde, and is condensed with another molecule of 4-hydroxycoumarin, and finally enolises the keto group that forms dicoumarol [
107,
108].
Dicoumarol, and related compounds with substituent groups (R) on carbon atoms at 3, 5, 6, 7 and 8-positions, are often addressed due to their unique molecular structures, which may include two intramolecular O–H···O hydrogen bonds (
Figure 13b) and different biological features depending on type of substituents on the central methylene linkage (3-position). The parent molecule, the 4-hydroxycoumarin, which may be represented as one of three tautomeric structures (
Figure 14), effectively depicts the structural changes occurring in dicoumarol. Some studies have shown that coumarin form A (
Figure 14) is the primary tautomer in both the solid state and in solution in polar solvents [
109,
110], which is relevant in the context of spirit beverages.
In general, nature exhibits a certain degree of creativity; given the proper building blocks, it is capable of producing the most varied compounds; bicoumarins are an example of this matter. A wide variety of bicoumarins are available, each of which is composed of coumarins connected by carbon-carbon bonds or an ether linkage. Nevertheless, these links are located on different carbon atoms, such as C3-C3', C3-C6', C3- C7, C3-C8', C4-C4', C8-C8', C5-C6', C6-C6 C6-C8', C5-C8', C7-C7', C7-C8', C8-C8', or C6-C6'-linked bicoumarins. Spirobicoumarins, monoterpene-unit linked bicoumarins, and C3-C3'-linked with methylene and methine group-linked bicoumarins are further examples of bicoumarin sets [
105].
Being aware of the metabolic pathways of compounds such as coumarins is useful for a variety of reasons, including nutraceutical and safety evaluations (detailed in
Section 7 and
Section 8). Determining how coumarins are metabolised can be useful for identifying the risks associated with their consumption and defining safe levels of exposure. In terms of coumarin metabolism, two major processes have been identified: 7-hydroxylation (umbelliferone) and the opening of the lactone ring with the loss of carbon dioxide (
Figure 15). This reaction takes place on the intermediate coumarin 3,4-epoxide produced in the phase I of the metabolic process. Under aqueous conditions, this epoxide releases carbon dioxide to create
ortho-hydroxyphenyl acetaldehyde (
o-HPA), which can subsequently be metabolised to the corresponding acid (
o-HPAA) and alcohol (
o-HPE). A series of intermediates can be formed when glutathione nucleophilically attacks the 3,4-epoxide, including the 4-HDHC-GSH (4-hydroxy-3,4-dihydrocoumarin-3-mercapturic acid) or 3-hydroxycoumarin.
Understanding coumarins’ metabolic pathways is crucial for determining the toxicity of the metabolites generated through excretion, as well as for extrapolating the formation of coumarins in spirit beverages through various chemical processes such as oxidation, reduction, hydroxylation, radical reactions, electrophilic or nucleophilic additions, and metal-catalysed additions (mainly copper and iron) [
28,
114,
115,
116]. These processes may occur during the prolonged ageing of beverages in wooden barrels and may cause changes in the coumarins profile.
4. Sources of coumarins
Coumarins have been isolated from hundreds of plant species belonging to more than 40 families [
117], and in several parts/tissues: leaves [
118], flowers [
119], fruits [
117,
120], seeds [
121], stems [
122], wood [
38,
123,
124], inner bark [
112] and roots [
125,
126]. Indeed, phenolic compounds play a significant role in the intricate defence mechanism of plants, and their biosynthesis is triggered by abiotic stress, such as UV radiation and ozone [
108,
127,
128,
129], and biotic stresses such as infections and wounding [
108,
130,
131]. For these reasons, coumarins are considered phytoalexins; some of these compounds have been found in high concentrations, while others, as is usually the case with coumarins, even in low concentrations are involved in the plant's defence [
104,
132].
Coumarins are found in the raw materials used in the production of spirit beverages addressed in this work: i) grapes [
133] and wine [
22,
134] in grape marc spirit, wine spirit and brandy manufacture; ii) cereal seeds [
135,
136] in whiskey manufacture; iii) sugar cane [
137] in rum and cachaça manufacture. However, they are not released from the wine, the grape marc or the
wash into the steam during distillation, and consequently, they are not present in the corresponding distillates. Thus, the only source of coumarins is the wood used in their ageing. According to the literature, among the many coumarins found in plants, those present in wood used for the ageing of spirit beverages are shown in
Table 1, and their structures are elucidated in
Figure 16.
The results attained for coumarins in these studies clearly reveal the differences imparted by the botanical species. Moreover, variation in their concentrations within each kind of wood is observed. It reflects the influence of some well-known factors, such as the geographical origin and the single-tree [
124,
139,
143,
144,
145,
146,
147,
148], the wood age [
149,
150,
151], as well as the analytical methods used in their quantification. Details on the last topic are addressed in
Section 5.
Nevertheless, scopoletin was the most plentiful compound in the majority of the wood types examined, followed by umbelliferone, aesculetin and aesculin in the oak wood, and coumarin in the Brazilian kinds of wood. On the other hand, among the oaks, higher levels of scopoletin were found in American oak wood, followed by
Q. robur wood, and lower levels were exhibited by
Q. pyrenaica wood. Regarding the other species, cherry wood presented an intermediate scopoletin content, while very low concentrations were observed in Portuguese chestnut, amendoim, cabreúva-parda and canela-sassafrás, and it was not detected in the remaining species. Umbelliferone was also more abundant in American oak wood, its levels were similar in the other kinds of oak wood, and it was not detected in the other species. Scopoletin and umbelliferone have been reported as chemical markers of oak wood [
19,
152]. Aesculetin contents in different oak wood were quite similar, except in
Q. faginea which was richer in this compound, and higher contents were associated with cherry wood and mulberry wood from Serbia. Aesculin was quantified in
Q. robur and
Q. sessiliflora wood, which presented lower contents than mulberry and myrobalan plum wood. Finally, the wood from Brazilian species can be classified into three groups according to the coumarin content: jatobá, with the highest amount; pequi, amendoim and cabreúva-parda, with intermediate levels; canela-sassafrás and castanheira, with the lowest content.
The effect of the wood type on the concentration of coumarins in the spirit beverages under study is therefore predictable, and will be discussed in
Section 6.
Additionally, it is noteworthy the potential use of waste from these kinds of wood resulting from the barrel making or production of fragments in the cooperage industry (closely associated to the aged beverages industries) as sources of coumarins for other purposes, such as natural preservatives and fortifying agents in the food industries [
153,
154] and as bioactive compounds for the pharmaceutical industry [
97,
155,
156,
157,
158,
159,
160].
7. The role of coumarins in the nutraceutical quality of spirit beverages
Besides the contribution of coumarins to the sensory properties of spirit beverages according to the ageing conditions, they are involved in the nutraceutical component of these beverages' quality. Nutraceutical quality is related to the health benefits of foods and beverages [
49,
221,
222,
223]. Indeed, moderate consumption of alcoholic beverages as part of a healthy lifestyle has been associated with lower cardiovascular risk compared to abstinence or heavy drinking [
224]. The health benefits of moderate consumption of aged spirits can be assigned to their phenolic composition, which has remarkable biological functions, such as free radical scavenging, inhibiting lipid peroxidation, and reducing platelet aggregation and thrombosis [
225], in opposition to the ethanol-induced damage [
6].
Concerning specifically the spirit beverages covered by this review, evidence exists on the relationship between the in vitro antioxidant properties and lignin-derived phenolic compounds extracted from wooden barrels to wine spirits [
31,
53,
54,
55,
226], brandy [
54,
56], whiskey [
52] and rum [
57]. In addition, consumption of whiskey (100 mL/day) transiently increases the total phenolic content and enhances the plasma antioxidant capacity, thus potentially lowering the risk of coronary heart disease [
227]. The work of Suzuki et al. [
228] revealed that compounds extracted from wooden barrels during the ageing of whiskey increased the cytoprotective protein, the enzyme heme oxygenase-1 (HO-1), in human endothelial cells, demonstrating that upregulation of HO-1 protein level might possibly contribute to the maintenance of blood vessel function.
The health effects of phenolic compounds, and particularly those found in aged spirit beverages, depend on their chemical composition, their potential interactions with ethanol and the presence of other bioactive compounds [
8]. Among them, phenolic aldehydes (such as sinapaldehyde, coniferaldehyde and vanillin), phenolic acids (such as vanillic acid and ellagic acid) and coumarins (such as esculetin) identified in whiskey play an important role as antioxidants, and may partly contribute to the protection of blood vessels by triggering the activation of HO-1 gene [
228,
229,
230]. Similar effects have been reported for wine spirit by Duriez et al. [
231] and Umar et al. [
232].
Coumarins are nutraceutical compounds due to their ability to exert non-covalent interactions with protein structures and free radical scavenging activity [
233,
234]; in general, they scavenge reactive oxygen species (ROS) via hydrogen atom transfer mechanism or electron transfer to peroxyl radical [
235]. The health effects of simple coumarins, the most plentiful in wood and aged spirit beverages (as specified in
Section 4 and
Section 6), have been thoroughly investigated
in vitro and
in vivo studies, as shown in
Table 8.
Apart from the activities identified, the high bioavailability of coumarins [
117] is an essential feature to guarantee their biological effectiveness. Actually, the oral intake does not result in complete uptake of bioactive compounds into the gastrointestinal tract, and a certain percentage is not absorbed [
223]. Bioavailability includes bioaccessibility and bioactivity: i) bioaccessibility corresponds to the fraction of a compound released from the food matrix during digestion process in the luminal content, being accessible for absorption in the small intestine or biotransformed by the gut microbiota; ii) bioactivity contemplates the phenomena involving the absorbed compounds or their metabolites in the target tissue, resulting in biological activity on the body [
275,
276]. However, in the light of current knowledge, compound concentrations cannot usually be determined directly at the site of action or target tissue. Thus, bioavailability assessment consists of determining the concentration of the bioactive compound in the blood (how fast and how much of a compound appears in the blood after a specific dose is administered) or urine [
277].
Interestingly, strategies have been widely investigated to enhance the bioavailability and transport of pharmaceuticals by conjugating with coumarins. In a pharmacological study, bioavailability evaluation of the prodrug system showed that coumarin-based prodrug meptazinol produced a fourfold increase in oral bioavailability over the parent drug meptazinol in rats [
278]. The pharmaceutical sertraline, an antidepressant drug, replaced the chloride anion for coumarin 3-carboxylate (bioactive compound), revealing that its antidepressant action was improved compared to the native drug [
279]. Coumarins can also be used to minimise the permeability glycoprotein-mediated efflux (P-glycoprotein) and enhance bioavailability of some drugs, such as placlitaxel (anticancer drug), which inhibits breast cancer stem cell growth [
280]. The P-glycoprotein is known to cause multidrug resistance phenotype in cancer cells, being a major obstacle in cancer treatment [
281]. In an experimental study, the introduction of a sulfamide moiety into coumarin derivatives provided greater RAF/MEK (rapidly accelerated fibrosarcoma/mitogen-activated protein kinase) inhibitory activity concomitantly with an acceptable pharmacokinetic profile (51% bioavailability in mouse) [
282].
In summary, coumarins are one of the most important groups of natural compounds with diverse pharmacological properties, and therefore they have been extensively studied in the field of medicinal chemistry and as therapeutic agents. However, studies involving beverages, and especially spirit beverages, have received less attention.
8. Do coumarins have impact on food safety?
As aforementioned, simple coumarins are the most plentiful in wood and aged spirits. The majority of these coumarins are considered not hazardous to human health at the concentrations detected in beverages and edible plants [
283]. Nevertheless, studies dealing with higher dosage of coumarin extracted from natural sources revealed chronic toxic effects, particularly hepatotoxicity [
234]. As a result, it is necessary to quantify coumarins, specifically the coumarin, in spirit beverages using precise and accurate analytical methods (described in
Section 5).
Clinical studies have shown that coumarin is probably not a carcinogen to humans, which have led to its classification as a Group 3 chemical with only limited toxicity [
284]. Previously, coumarin was used in flavours and as a chrome plating brightener until 1954, when the FDA classified it as a carcinogen and banned its use in foodstuffs [
284]. In 1956,
in vivo studies revealed that the coumarin incorporated in the diet of rats and dogs caused the initial damage to their liver tissue [
285]. Contrary to these findings, the
in vivo studies for mutagenic and genotoxic potential suggest that coumarin is not a genotoxic agent, because the dose–response relationships for coumarin-induced toxicity and carcinogenicity are non-linear, with tumour formation occurring only at high doses (> 280 mg/kg/day) which are associated with pulmonary and hepatic toxicity [
112,
286].
Although the majority of coumarins are not intrinsically toxic, with the exception of coumarin, some derivatives and higher doses may raise concerns related to food safety. Regarding data on food toxicology, which is focused on the study of compounds present in food that can potentially cause adverse effects on consumer health, the Chemical Safety Data Sheets (SDS) and PubChem data available confirm that the most common coumarins found in wood raw material and aged spirit beverages have little harmful effect on human beings (
Table 9).
Table 16 have a notable impact, and even minor differences in structure lead to different actions and varied affinities for biological targets: hydroxyl, methoxy, and glycosidic groups in various positions on the coumarin skeleton. Certain structural modifications during metabolic degradation can result in more toxic metabolites, the reason why it is critical to identify and understand the metabolites that can be generated in the human system. Umbelliferone, for example, is a coumarin degradation metabolite that is also a known human metabolite of 7-methoxycoumarin and coumarin.
Specific tissues or organs may be highly susceptible to the impacts of particular substances due to their physiological activities, high metabolic activity, or exposure. As in the instance of coumarin, which is predominantly metabolised in the liver through cytochrome P-450. In phase I, metabolic events such as oxidation, reduction, and hydrolysis are used to modify functional groups in order to prepare the substrate for subsequent conjugation reactions in phase II. The cytochrome P-450 enzyme in the liver hydroxylates coumarin and similar compounds [
298], and the most prevalent hydroxylation pathways happens at 3 and 7-positions to produce 3-hydroxycoumarin (3-OHC) and 7-hydroxycoumarin (7-OHC), respectively and for coumarin [
299,
300]. The presence of a significant amount of 3-OHC is thought to facilitate the formation of the cytotoxic byproduct
o-HPA (
Figure 15), which could potentially contribute to or be accountable for coumarin-induced toxicity.
Coumarin demands extra attention when compared to other naturally occurring coumarins, not only because its lower LD50 (more toxic), but also because it is commonly found in cinnamon-containing food and drinks, which is not applicable to the spirit beverages addressed in this review. It is noteworthy that the influence on food safety mainly depends on the coumarins concentrations in specific food products and their compliance with regulatory criteria than to the presence of coumarins in general. To ensure food safety, as with any food component, moderation is key, and it is advised to follow dietary guidelines and limits set by local authorities for this purpose.
9. Coumarins and spirit beverages’ authenticity
Assuring authenticity is a pivotal aspect in spirit beverages value chains, and has therefore been a major concern and challenge for all their players, including the regulatory/governmental agencies and researchers worldwide. It allows protecting producers, producing regions and countries, as well as consumers, from inauthentic spirit beverages. This type of beverages has become a target for adulteration and fraud through practices that include supplementing with ingredients or aromas to boost the product at a lower price, and adding of non-specified additives to increase volume [
58]. According to Popping [
301], there are two types of inauthenticity events: i) misrepresentation that a beverage is within the contractual arrangement between trading partners, namely breach of contract; ii) misrepresentation that a beverage is within the legal obligations of the region of intended trade, namely noncompliance (
Figure 20).
The global market and the growing variability and availability of alcoholic beverages from different countries have made consumers increasingly aware of the importance of consuming certified products (in terms of quality and food safety) [
302]. In this regard, Europe has taken the lead position by creating, in 1992, a robust system of geographical indications to protect the name of a product originating from a specific region and resulting from a traditional production process. Currently, this regime comprises: Protected Designations of Origin - in which all production stages must take place; Protected Geographical Indications (PGI) - at least one of the production, processing or preparation phases must take place in the region. Concerning the spirit beverages, the rules are set by Regulation (EU) [
1]. Other producing countries, such as the USA, Canada and Brazil also have specific regulations for spirit drinks.
For this purpose, more advanced analytical methods, as well as the identification of compounds that act as chemical markers, are required for the certification of spirit drinks and the strengthening of legislation. Several techniques, such as spectrophotometry [
303,
304,
305], synchronous fluorescence spectrometry [
306], GC [
307,
308,
309], HPLC [
310], capillary electrophoresis [
311], nuclear magnetic resonance (NMR) spectroscopy [
312,
313,
314], and electrospray ionisation mass spectrometry (EIS-MS) [
315,
316,
317] have been used to determine the indicators of authenticity in the spirit beverages, such as alcohol strength [
318], sugars [
315], volatile compounds [
319], colouring compounds [
318] and wood-derived compounds [
320].
Regarding the wood-derived compounds of the spirit beverages under analysis, resulting from the ageing stage of the corresponding distillates, some studies pointed out the role of coumarins, phenolic aldehydes and phenolic acids as chemical markers of wine spirits, brandies, whiskeys, rums and cachaças [
41,
167,
192,
306,
311,
321]. Among coumarins, scopoletin has been considered as a possible marker of ageing in oak barrels [
19,
36,
322].
Furthermore, coumarins contribute to antioxidant activity reported among alcoholic beverages, which is also thought to be a marker of authenticity. Ziyatdinova et al. [
307], studying the adulteration of brandies, reported that the antioxidant activity of authentic brandies was 15-fold higher than that of adulterated ones. Hence, the literature suggests that coumarins can be used as authenticity markers of aged spirits, but further research is needed to provide robust outcomes for quality assessment and authenticity control.
10. Concluding Remarks and Perspectives
A comprehensive overview of the state-of-the-art and contemporary approach on coumarins in spirit beverages is presented for the first time. A connection between these findings and crucial aspects of everyday life, particularly in terms of authenticity and food safety concerns, was established. Six renowned types of spirit beverages were chosen (wine spirit, brandy, whiskey, rum, cachaça, and grape marc spirit) due to their enhancement with wood compounds during the ageing process, and were thoroughly discussed. The ageing process improves the quality of the distillate by enhancing its sensory and nutraceutical properties, in which coumarins are involved. Given the dynamic interplay between additive and subtractive processes, the chemical composition of aged spirits undergoes significant changes over time. Consequently, when taking into account differentiated products, consumer health concerns, food science, and food safety in the market's largest segment of the global alcoholic drink market, comparing the effects of different ageing time, wood sources, heat treatment, and ageing technology on specific phenolic composition of spirit beverages is worthwhile. A balance of its phenolic composition and certain coumarins, can play a major role in developing value chains, meeting consumer preferences, and driving market growth.
In order to understand the occurrence of coumarins in the addressed spirit beverages, it was considered essential to elucidate their production processes and the type of wood used in the ageing stage. Furthermore, significant information revealing that different kinds of wood provide considerably different coumarins contents have been collected in this review. Nevertheless, only simple coumarins have been identified in wood and aged spirits: coumarin, scopoletin, umbelliferone, 4-methylumbelliferone, aesculin, aesculetin and fraxetin. Among them, scopoletin was the most plentiful in the majority of wood species, while umbelliferone was more abundant in American oak wood. Though, the concentrations of coumarins in aged beverages are significantly lower in comparison to those reported from wood sources.
This review further looked at coumarin metabolic pathways for nutraceutical and safety purposes. As a prime instance, it was clarified that umbelliferone is metabolised into coumarin, which is then metabolised into 7-hydroxycoumarin and eliminated by the human system, and that all these metabolites exhibit interactions and increased biological activities. Therefore, further research is needed for a comprehensive insight into the metabolites generated after coumarins ingestion. Although the majority of coumarins are generally non-toxic, except coumarin itself, some derivatives and higher amounts may trigger food safety issues. Coumarins' significant bioavailability is an important feature that ensures their biological efficacy; thus, detailed information about how the gastrointestinal system absorbs these compounds and what happens to the other portion of bioactive substances from oral ingestion is required.
A growing demand for more sensitive, selective, and efficient procedures has driven improvements in analytical techniques for molecular structural elucidation, and some of the cutting-edge analytical methods being used for other organic substrates will likely influence the identification of novel coumarins in wood extracts and spirit beverages. Among these novel approaches that are becoming more accessible, democratised, and disseminated in the scientific community, this review highlights Tandem Mass Spectrometry (MS/MS or MSn), Ion Mobility Spectrometry (IMS), liquid chromatography with nuclear magnetic resonance (LC-NMR), as well as computational techniques that may be very useful, along with the use of advanced data processing techniques such as Data Mining and Cheminformatics, along with machine learning algorithms. The authenticity of spirit beverages is of the utmost importance for consumers, producers, governmental authority, and the agrifood sector, the reason why the role of coumarins in this topic was contextualised. Despite their low concentrations, the results support scopoletin and umbelliferone as chemical markers for ensuring authenticity of aged spirit beverages, which has been a major concern and challenge for all players and researchers worldwide. Given the broad biological function exhibited by the coumarins chemical family, further research will be necessary in this matter.
Figure 1.
Global market exchange rates of alcoholic beverages from 2018 to 2023. Adapted from Statista [
4].
Figure 1.
Global market exchange rates of alcoholic beverages from 2018 to 2023. Adapted from Statista [
4].
Figure 2.
Scheme of wine spirit production process.
Figure 2.
Scheme of wine spirit production process.
Figure 3.
Scheme of
Brandy de Jerez ageing process. Adapted from Durán-Guerrero et al. [
70].
Figure 3.
Scheme of
Brandy de Jerez ageing process. Adapted from Durán-Guerrero et al. [
70].
Figure 4.
Scheme of whiskey production process.
Figure 4.
Scheme of whiskey production process.
Figure 5.
Main types of whiskey.
Figure 5.
Main types of whiskey.
Figure 6.
Scheme of rum and cachaça production process.
Figure 6.
Scheme of rum and cachaça production process.
Figure 7.
Scheme of grape marc spirit production process.
Figure 7.
Scheme of grape marc spirit production process.
Figure 8.
Chemical structure of coumarin and the IUPAC numbering system for its framework.
Figure 8.
Chemical structure of coumarin and the IUPAC numbering system for its framework.
Figure 9.
Classification and generic structures of the main categories of plant-derived coumarins (some examples are given in green).
Figure 9.
Classification and generic structures of the main categories of plant-derived coumarins (some examples are given in green).
Figure 10.
Phenylpropanoids' general biosynthetic route. PAL: l-phenylalanine ammonia-lyase; TAL: tyrosine ammonia lyase.
Figure 10.
Phenylpropanoids' general biosynthetic route. PAL: l-phenylalanine ammonia-lyase; TAL: tyrosine ammonia lyase.
Figure 11.
Proposed radical mechanism for 7-hydroxycoumarin (umbelliferone) biosynthesis from 4'-coumaroyl-S-CoA (adapted from [
102]). F6'H1, a 2-oxoglutarate-dependent dioxygenase, comprises the first step.
Figure 11.
Proposed radical mechanism for 7-hydroxycoumarin (umbelliferone) biosynthesis from 4'-coumaroyl-S-CoA (adapted from [
102]). F6'H1, a 2-oxoglutarate-dependent dioxygenase, comprises the first step.
Figure 12.
Schematic illustration of the phenylpropanoid pathway leading to coumarins (particularly esculetin and scopoletin) and the formation of flavonoids and other phenolic compounds. PAL: l-phenylalanine ammonia-lyase.
Figure 12.
Schematic illustration of the phenylpropanoid pathway leading to coumarins (particularly esculetin and scopoletin) and the formation of flavonoids and other phenolic compounds. PAL: l-phenylalanine ammonia-lyase.
Figure 13.
Structures of dicoumarol.
Figure 13.
Structures of dicoumarol.
Figure 14.
Tautomeric structures of 4-hydroxycoumarin (A, B and C).
Figure 14.
Tautomeric structures of 4-hydroxycoumarin (A, B and C).
Figure 15.
Illustrative routes of coumarin metabolism (adapted from [
111,
112,
113]. GSH: glutathione.
Figure 15.
Illustrative routes of coumarin metabolism (adapted from [
111,
112,
113]. GSH: glutathione.
Figure 16.
Chemical structure of the most prevalent coumarins in wood used for the ageing of spirit beverages.
Figure 16.
Chemical structure of the most prevalent coumarins in wood used for the ageing of spirit beverages.
Figure 17.
Average concentrations of coumarins in aged wine spirits according to the toasting level of the barrels; LT - light toasting, MT - medium toasting, HT - heavy toasting [adapted from Canas 19].
Figure 17.
Average concentrations of coumarins in aged wine spirits according to the toasting level of the barrels; LT - light toasting, MT - medium toasting, HT - heavy toasting [adapted from Canas 19].
Figure 18.
Evolution of coumarins contents in spirit beverages over the ageing time: (a) whiskey [adapted from Otsuka and Zenibayaashi, [
35]]; (b) wine spirit [adapted from Salagoity, [
214]; (c) wine spirit [adapted from Tricard et al. [
37]; (d) cachaça [adapted from Santiago et al. [
44].
Figure 18.
Evolution of coumarins contents in spirit beverages over the ageing time: (a) whiskey [adapted from Otsuka and Zenibayaashi, [
35]]; (b) wine spirit [adapted from Salagoity, [
214]; (c) wine spirit [adapted from Tricard et al. [
37]; (d) cachaça [adapted from Santiago et al. [
44].
Figure 19.
Average contents of coumarins in wine spirits aged in barrels (B), in demijohns with wood staves and micro-oxygenation (O15, O30 and O60) and nitrogen (N, control).
Figure 19.
Average contents of coumarins in wine spirits aged in barrels (B), in demijohns with wood staves and micro-oxygenation (O15, O30 and O60) and nitrogen (N, control).
Figure 20.
Beverages inauthenticity events. Adapted from Popping [
301].
Figure 20.
Beverages inauthenticity events. Adapted from Popping [
301].
Table 1.
Sources of coumarins.
Table 1.
Sources of coumarins.
Source |
Species’ country of origin |
Compound |
Mean content |
References |
Oak Quercus robur L. |
France Limousin |
scopoletin umbelliferone aesculetin |
65 μg/L 4.7 μg/g FW 5.28 μg/g DW 0.006 μg/g DW 1.68 μg/g FW |
[38] [123] [124] [124] [138] |
Bulgaria |
scopoletin |
125 μg/L |
[38] |
Spain |
aesculetin |
2.1 μg/g FW |
[138] |
Croatia |
aesculin |
0.44 μg/g FW |
[139] |
Serbia |
aesculin |
0.22 μg/g FW |
[139] |
Bosnia and Herzegovina |
aesculin |
0.11 μg/g FW |
[139] |
Oak Quercus sessiliflora Salisb. |
France Allier |
scopoletin umbelliferone aesculetin |
55 μg/L 3.6 μg/g FW 3.45 μg/g DW 0.006 μg/g DW 1.97 μg/g FW |
[38] [123] [124] [124] [138] |
Spain |
aesculetin |
4.2 μg/g FW |
[138] |
Serbia |
aesculin |
0.44 μg/g FW |
[139] |
Portugal |
scopoletin umbelliferone |
1.37 μg/g DW 0.006 μg/g DW |
[138]
|
Oak Quercus faginea Lam. |
Spain |
aesculetin |
4.9 μg/g FW |
[138] |
Oak Quercus alba L., Quercus bicolor Willd. Quercus lyrata Walt. Quercus stellata Wanghen. |
North America |
scopoletin umbelliferone aesculetin |
425 ug/L 25.15 ug/g DW 0.007-0.025 μg/g DW 1.45 μg/g FW |
[38] [124] [124] [138] |
Chestnut Castanea sativa Mill. |
Portugal |
scopoletin umbelliferone |
1.07 μg/g DW nd |
[124]
|
France |
scopoletin |
6.73-16.7 μg/g FW |
[141] |
Cherry Prunus avium L. |
Spain |
scopoletin |
18.8 μg/g FW |
[142] |
Serbia |
aesculetin |
102.30 μg/g FW |
[139] |
Myrobalan plum Prunus cerasifera Ehrh. |
Serbia |
aesculin |
1.87 μg/g FW |
[139] |
Mulberry Morus alba L. |
Serbia |
aesculin |
2.31 μg/g FW |
[139] |
aesculetin |
29.15 μg/g FW |
[139] |
Amendoim Pterogyne sp. |
Brazil |
scopoletin coumarin |
0.007 mg/L 0.067 mg/L |
[43] |
Cabreúva-parda Myrocarpus frondosus Allem. |
Brazil |
scopoletin coumarin |
0.018 mg/L 0.050 mg/L |
[43] |
Canela-Sassafrás Ocotea pretiosa (Vell.) Rohwer |
Brazil |
scopoletin coumarin |
0.028 mg/L 0.011 mg/L |
[43] |
Jatobá Hymenaea courbaril L. |
Brazil |
scopoletin coumarin |
nd 9.15 mg/L |
[43] |
Pequi Caryocar brasiliense Cambess. |
Brazil |
scopoletin coumarin |
nd 0.071 mg/L |
[43] |
Castanheira Bertholletia excelsa Humb. & Bonpl. |
Brazil |
scopoletin coumarin |
nd 0.007 mg/L |
[43] |
Table 2.
Excitation and emission wavelengths of prevalent coumarins in wood and aged spirit beverages.
Table 2.
Excitation and emission wavelengths of prevalent coumarins in wood and aged spirit beverages.
Compound |
λex (nm) |
λem (nm) |
4-methylumbelliferone |
218 |
454 |
coumarin |
280 |
393 |
aesculin |
335 - 337 |
409 |
umbelliferone |
340, 380 |
467 |
scopoletin |
345 - 347 |
430, 460 |
aesculetin |
347 - 353, 340 |
467 |
Table 3.
Sample preparations by spirit beverage.
Table 3.
Sample preparations by spirit beverage.
Spirit Beverage |
Sample preparation |
References |
Wine Spirit |
Coumarins should be extracted since this matrix is complex and rich in phenolic compounds. An ether extraction was therefore carried out |
[36] |
Samples directly analysed (without preparation) |
[38] |
Adding an internal standard to the samples, filtering them through a 0.45 µm membrane and analysing them by direct injection |
[39,40,152,164,165] |
De-alcoholised samples (to 8% alcohol) and filtered through a 0.45 µm membrane |
[22] |
Brandy |
Samples directly analysed (without preparation) |
[38] |
Samples filtered at 0.20 µm membrane and directly injected |
[123] |
De-alcoholised samples (to 8% alcohol) and filtered through a 0.45 µm membrane |
[22] |
Whiskey |
Samples extracted with ethyl acetate |
[35] |
Samples directly analysed (without preparation) |
[38] |
De-alcoholised samples (to 8% alcohol) and filtered through a 0.45 µm membrane |
[22] |
Sugar cane spirit |
Samples extracted with ethyl acetate (Rum) |
[35] |
SPE extraction (Cachaça) |
[43] |
Samples filtered at 0.45 µm polyethylene membrane and directly injected |
[166] |
For fluorescence detection, the samples were not prepared; for UV-vis detection, the samples were diluted 30 times with an ethanol/water solution (40:60 % v/v) (Cachaça) |
[167] |
De-alcoholised samples (to 8% alcohol) and filtered through a 0.45 µm membrane (Rum) |
[22] |
Table 4.
Analytical methods used for coumarins determination in spirit beverages.
Table 4.
Analytical methods used for coumarins determination in spirit beverages.
Spirit Beverage |
Analytical methods |
References |
Separation |
Detection |
Wine Spirit |
HPLC |
|
[36,38,39,40,152,164,165] |
HMRS with ESI/ HESI II |
[22] |
Brandy |
HPLC |
FLD |
[38,123] |
HMRS with ESI/ HESI II |
[22] |
Fluorescence Spectrometry |
[48] |
Whiskey |
TLC |
Fluorometer |
[35] |
HPLC |
FLD |
[38] |
HMRS with ESI/ HESI II |
[22] |
Sugar cane spirit |
TLC |
Fluorometer |
[35] |
HPLC |
FLD |
[43] |
HPLC |
DAD |
[166] |
|
UV-Vis spectrophotometry and spectrofluorimetry |
[167] |
HPLC |
HMRS with ESI/ HESI II |
[22] |
Table 5.
Coumarins contents in wine spirits according to the kind of wood used in their ageing.
Table 5.
Coumarins contents in wine spirits according to the kind of wood used in their ageing.
Origin |
Wood species |
Compound |
Mean content (μg/L) |
References |
Armagnac |
Oak |
scopoletin umbelliferone 4-methylumbelliferone aesculetin |
301.1 2.8 2.8 1.9 |
[36] [36] [36] [36] |
Lourinhã |
Oak Q. robur
|
scopoletin umbelliferone |
88.0 37.12 1.0 0.95 |
[39] [19] [39] [19] |
Oak Q. sessiliflora
|
scopoletin umbelliferone |
19.74 0.78 |
[19] [19]
|
Oak Q. pyrenaica
|
scopoletin umbelliferone |
10.33 0.98 |
[19] [19]
|
Oak Q. alba Q. bicolor Q. lyrata Q. stellata |
scopoletin umbelliferone |
164.77 1.48 |
[19] [19] |
Chestnut C. sativa
|
scopoletin umbelliferone |
9.0 8.63 5.0 0.92 |
[39] [19] [39] [19] |
Table 6.
Coumarins contents in brandies according to the kind of wood used in their ageing.
Table 6.
Coumarins contents in brandies according to the kind of wood used in their ageing.
Origin |
Wood species |
Compound |
Mean content (μg/L) |
References |
Italy |
Oak Q. robur
|
scopoletin |
102.1 |
[123] |
Oak Q. sessiliflora
|
scopoletin |
101.5 |
[123] |
Table 7.
Coumarins contents in cachaças according to the kind of wood used in their ageing.
Table 7.
Coumarins contents in cachaças according to the kind of wood used in their ageing.
Origin |
Wood species |
Compound |
Mean content (μg/L) |
References |
Brazil |
European oak |
4-methylumbelliferone coumarin |
nd nd |
[44] |
Amburana Amburana cearensis (Allemão) A.C.Sm. |
4-methylumbelliferone coumarin |
0.014 0.049 |
[44] |
Balsam Myroxylon peruiferum L. f. |
4-methylumbelliferone coumarin |
nd 0.002 |
[44] |
Jatoba Hymenaeae carbouril L. |
4-methylumbelliferone coumarin |
nd nd |
[44] |
Peroba Paratecoma peroba (Record) Kuhlm. |
4-methylumbelliferone coumarin |
nd nd |
[44] |
Table 8.
Coumarins and related pharmacological activities examined in vitro and in vivo studies.
Table 8.
Coumarins and related pharmacological activities examined in vitro and in vivo studies.
Compound |
Pharmacological activity |
Research Method |
Experimental |
Doses |
References |
umbelliferone
|
neuroprotective effects |
chronic unpredictable mild stress (CUMS) |
male Sprague-Dawley rats |
15 mg/kg 30 mg/kg |
[236] |
anti-inflammatory |
inflammatory cytokines in hippocampus |
male Sprague-Dawley rats |
15 mg/kg 30 mg/kg |
[236] |
lipopolysaccharide (LPS)-induced acute lung injury (ALI) |
BALB/c mice |
40 mg/kg
|
[237] |
antidepressant |
post-traumatic stress disorder model (PTSD) |
male Sprague-Dawley rats |
60 mg/kg |
[238] |
antidiabetic |
streptozotocin (STZ)-induced diabetes |
male Wistar rats |
30 mg/kg |
[239,240] |
anticancer |
cell cycle analysis and apoptosis detection |
HepG2 HCC cells
|
50 μM |
[241] |
antihypertensive
|
vascular activity assay |
male spontaneously hypertensive rats (SHR) |
300 μM |
[242] |
4-methylumbelliferone |
anticancer |
human pancreatic cancer cells (KP1-NL) transplanted into the hypodermis of nude mice |
male nude mice |
3 mg/g |
[243] |
anticancer |
breast cancer xenograft models |
BALB/C nu/nu mice |
0.5 mg/g |
[244] |
antitumor |
inhibition of fibroblast and melanoma cells |
human melanoma cell line, C8161 and MV3 |
0.5 mM |
[245] |
anti-inflammatory |
inflammatory cytokines in astrocytes cultures |
rat astrocytes (glial cells) |
400 μM |
[246] |
antidiabetic |
glucose level and glucose tolerance test in mice fed a high-fat diet
|
male C57BL/6J mice
|
0.2 g/kg
|
[247] |
neuroprotective |
acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition |
in vitro
assay
|
1 mg/mL
|
[248] |
aesculetin
|
antiadipogenic |
PPARg Expression |
3T3-L1 preadipocyte cells |
100 μM
|
[249] |
antidiabetic |
streptozotocin (STZ)-induced diabetes |
male albino rats (Wistar strain) |
40 mg/kg |
[250] |
antithrombotic |
platelet aggregation |
human assay |
50 μM |
[251] |
antitumor |
mitogen-activated protein kinase (MAPK) assay |
HepG2 cells |
100 μM
|
[252] |
anticancer |
trail-induced apoptosis |
oral cancer SAS cells |
10 μg/mL |
[253] |
anti-inflammatory |
colitis induced by trinitrobenzenesulphonic acid (TNBS) |
male Wistar rats |
5 mg/kg |
[254] |
aesculin
|
antidiabetic |
dexamethasone-induced insulin resistance |
male Institute of Cancer Research (ICR) mice |
40 mg/kg |
[255] |
streptozotocin (STZ)-induced diabetes |
male C57BL/6J |
20 mg/kg |
[256] |
renoprotective |
STZ-induced diabetic renal damage |
male ICR mice |
20 mg/kg |
[257] |
gastroprotective |
gastric mucosal injury index |
male Kunming mice |
20 mg/kg |
[258] |
antioxidant |
AAPH-induced erythrocyte hemolysis assay |
erythrocytes |
50 μM |
[259] |
anti-inflammatory |
carrageenan induced paw oedema |
male and female Kunming mice |
20 mg/kg |
[260] |
endotoxin shock induced by lipopolysaccharide (LPS) |
male and female Kunming mice |
20 mg/kg |
[261] |
liver injury induced by lipopolysaccharide/D-Galactosamine (LPS/D-Gal) |
BALB/c mice |
40 mg/kg |
[262] |
coumarin
|
antidiabetic |
animal model of induced type 2 diabetes mellitus (NIDDM) |
male albino Wistar rats |
100 mg/kg |
[263] |
α-glucosidase inhibition assay |
in vitro assay |
20 mM |
[264] |
anticancer |
inhibition of proliferation and induction of apoptosis |
human cervical cancer HeLa cells |
100 μM |
[265] |
inhibition of proliferation |
human lung cancer cell lines, A427 and Calu-1 |
1.0 mM |
[266] |
inhibition of proliferation |
human lung cancer cell lines, A427 and SK-LU-1 |
100 μg/mL |
[267] |
anti-inflammatory |
colonic damage induced by trinitrobenzenesulfonic acid (TNBS) |
Male Wistar rats |
25 mg/kg |
[268] |
scopoletin
|
antibacterial |
minimum inhibitory concentrations (MIC) |
Pseudomonas aeruginosa |
0.66 μg/mL
|
[269] |
antihypertensive |
multiple model of hypertension (blood pressure) |
male Wistar-Kyoto rats |
10 mg/kg |
[270] |
antidiabetic |
streptozotocin (STZ)-induced diabetes |
male ICR mice |
10 mg/kg |
[271] |
α-glucosidase/α-amylase inhibition assay |
in vitro assay |
100 μM |
[271] |
glucose uptake assay |
3T3-L1 preadipocyte cells |
20 μM |
[272] |
anti-inflammatory |
carrageenan induced paw oedema |
female Sprague-Dawley rats |
10 mg/kg |
[273] |
anti-ageing |
autophagy assay |
human lung fibroblast cells (IMR 90) |
16 μM |
[274] |
Table 9.
Bioaccumulative potentiala and toxicological information of most prevalent coumarins in wood and aged spirit beverages.
Table 9.
Bioaccumulative potentiala and toxicological information of most prevalent coumarins in wood and aged spirit beverages.
Compound |
n-octanol/water (log KOW)b
|
Test Type/Routec
|
Organism |
Dose |
References |
Remarks |
coumarin |
1.39 |
LD50 / oral |
rat |
293 mg/kg |
[287] |
May cause irritation; Harmful if swallowed: causes liver injury and somnolence |
LD50 / oral |
mouse |
196 mg/kg |
[288] |
LD50 / intraperitoneal |
mouse |
220 mg/kg |
[289] |
LD50 / subcutaneous |
mouse |
242 mg/kg |
[288] |
LD50 / oral |
guinea pig |
202 mg/kg |
[290] |
umbelliferone |
1.03 (TOXNET) |
LD50 / intravenous |
mouse |
450 mg/kg |
[291] |
Causes liver effects, effects on plasma proteins, hypoglycemia, and changes in clotting factors in 45-day intermittent intraperitoneal studies of rats |
scopoletin |
nd |
LD50 / oral |
rat |
3800 mg/kg |
[292] |
Irritant |
4-methylumbelliferone |
nd |
LD50 / intravenous |
mouse |
350 mg/kg |
[291] |
Irritant |
LD50 / oral |
rat |
3850 mg/kg |
[293] |
LD50 / intraperitoneal |
rat |
2550 mg/kg |
[293] |
LD50 / subcutaneous |
rat |
7200 mg/kg |
[293] |
LD50 / oral |
mouse |
2850 mg/kg |
[293] |
LD50 / intraperitoneal |
mouse |
1250 mg/kg |
[294] |
aesculetin |
0.55 |
LD50 / intraperitoneal |
mouse |
1500 mg/kg |
[295] |
Irritant |
aesculin |
nd |
LD50 / intraperitoneal |
mouse |
1900 mg/kg |
[296] |
Irritant |