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PubMed1998

Induction of p34cdc2 in mouse parotid glands upon activation of beta1-adrenergic receptors.

Dramatic morphological, biochemical and cytological changes occur in parotid glands of rats and mice which have been treated with the beta-adrenergic receptor agonist isoproterenol (Ipr). Changes include glandular hypertrophy, induction of tissue-specific proline-rich proteins (PRPs), increases in cAMP, and occurrence of polyploidy. Similar changes also occur after feeding mice polyphenolic compounds commonly referred to as tannins. Data are presented which show that changes in cell cycle proteins are due to stimulation of the beta-adrenergic receptor by either isoproterenol or tannin treatment of mice. Both p34cdc2 mRNA and protein levels were elevated dramatically after mice were treated. Induction of p34cdc2 occurred within 24 hrs. and was transient during treatment. The beta1-adrenergic receptor antagonist atenolol blocked both tissue-specific expression of proline-rich proteins and induction of p34cdc2. Coincident with the increase in p34cdc2, cyclin-dependent kinase complexes containing cyclins A and B increased forty- and ten-fold, respectively. These results show that in mouse parotid glands activation of the beta1-adrenergic receptor by either the administration of isoproterenol or ingestion of dietary tannins induces synthesis of p34cdc2 and most likely contributes to the occurrence of polyploidy.

Adrenergic beta-Agonists↗

PubMed1997

[Antiphysiological and nutritional factor changes in sorghum (Sorghum bicolor (L.) Moench) seeds during germination].

The purpose of this work was to evaluate the effects of germination on the nutritional quality of two commercial varieties of low tannin content Sorghum: brown sorghum without testa (ICSY-CM89513) and white sorghum (ISIAP Dorado). After 24 hours of germination the condensed tannin concentration (catechin equivalent) was reduced 60% and 40% for brown and white sorghum respectively. However, tannin levels increased up 100% at 96 h germination. Phytic acid concentration decreased about 90% in 96 hours for both varieties. The lysine concentration increased up 110% (72 h germination) and 129% (48 h) for white and brown sorghum respectively. The thiamine, niacin and riboflavin contents increased 73, 200 and 353% respectively for brown sorghum in 72 h and 15, 44 and 93% respectively for white sorghum in 48 h. The "in vitro" enzymatic digestibility was increased 39.3% (72 h) for brown sorghum and 100% for white sorghum. The albumin concentration increased 80% and 74% (72 h) for brown and white sorghum respectively. The Calculated Protein Efficiency Ratio indicated nutritional improvements with germination. The sprouting was a practical and simple process for providing better nutritional properties in sorghum seeds to be used as human food.

Amino Acids↗

PubMed2001

Investigations on antimycobacterial activity of some Ethiopian medicinal plants.

Fifteen crude extracts prepared from seven Ethiopian medicinal plants used to treat various infectious diseases were assessed for their ability to inhibit the growth of Mycobacterium tuberculosis. A preliminary screening of the crude extracts against M. tuberculosis typus humanus (ATCC 27294) was done by dilution assay using Löwenstein-Jensen medium. None of the tested extracts except the acetone fraction obtained from the stem bark of Combretum molle (R. Br. ex G. Don.) Engl & Diels (Combretaceae) showed significant inhibitory action against this strain. The acetone fraction of the stem bark of C. molle caused complete inhibition at concentrations higher than 1 mg/mL. Phytochemical analysis of the bioactive fraction led to the isolation of a major tannin and two oleanane-type pentacyclic triterpene glycosides. The tannin was identified as the ellagitannin, punicalagin, whilst the saponins were characterized as arjunglucoside (also called 4-epi-sericoside) and sericoside. All the pure compounds were further tested against the ATCC strain. Punicalagin was found to inhibit totally growth of the ATCC and also of a patient strain, which was fully sensitive to the standard antituberculosis drugs, at concentrations higher than 600 microg/mL and 1.2 mg/mL, respectively. On the other hand, the saponins failed to show any action on the ATCC strain. It appears that our findings are the first report of tannins exhibiting antimycobacterial activity.

Antitubercular Agents↗

PubMed1998

Analysis of parotid and mixed saliva in Roe deer (Capreolus capreolus L.).

In ruminants, different functions have been ascribed to the different salivary glands according to the feeding type. In this context, possible adaptations of salivary functions were investigated regarding the secretion of various proteins by different types of salivary glands. To yield uncontaminated parotid saliva in large quantities, a non-surgical method has been developed. Parotid gland secretions were collected via endoscopic placement of guide wires into each parotid duct, which were subsequently used for placement of collection catheters. Salivary flow was stimulated by intra-glandular administration of the parasympathomimetic compound pilocarpine-hydrochloride into the parotid gland. Mixed saliva (excluding parotid saliva) was collected into sterile tubes by normal outflow during the sampling of parotid saliva. The total flow volume, flow rate and the content of proteins as well as of several ions (Na+, K+, Ca2+, inorganic phosphate) of both types of saliva were measured in sheep, fallow deer and roe deer. Roe deer secreted the highest amount of total salivary proteins relative to body mass [mg/kg body mass] and the highest relative volume [ml/10 min/kg body mass], both in parotid and mixed saliva, of all ruminant species examined. Additionally, the protein profile and the tannin-binding properties of parotid and mixed saliva in roe deer were investigated. Parotid saliva bound almost twice as much tannin as mixed saliva, underlining the importance of yielding uncontaminated parotid saliva for tannin-binding studies.

Adaptation, Physiological↗

PubMed2002

Recovery of Bacillus sphaericus 2362 spores from growth medium by flocculation/sedimentation.

Bacillus sphaericus 2362 spore sedimentation was evaluated through batch settling experiments, using tannin as the flocculating agent. The flocculation was demonstrated to be efficient up to the tannin concentration of 150 ppm. The floc diameter averaged 208 micro m, and its density was found to be 1.09 g/mL. The sedimentation process using tannin as a flocculating agent is promising, and a spore concentrate was obtained without loss of biological activity, presenting a LC(50) equal to 0.22 ppm. The result indicates that the larvicide activity is appropriate for controlling populations of Culex quinquefasciatus.

Journal Article↗

PubMed1991

High-resolution electron crystallography of light-harvesting chlorophyll a/b-protein complex in three different media.

Large two-dimensional crystals of the light-harvesting chlorophyll a/b-protein complex (LHC-II) from the photosynthetic membrane of pea chloroplasts were grown by a new method from detergent solution. The structure of these crystals was examined by electron crystallography, using three different media to preserve high-resolution detail: vitrified water, glucose and tannin. The crystals diffracted electrons to at least 3.2 A resolution in all three media. R-factors between the three data sets of electron diffraction amplitudes ranged from 6.4% to 14.3%. Fourier difference maps were generated and compared to a projection map of the complex at 3.4 A resolution. No significant differences were found, proving that all three media preserved the native structure of LHC-II at high resolution. The probability of recording high-quality electron diffraction patterns with tannin was 90%. With glucose and water this probability was lower by a factor of 10 to 20, suggesting that tannin may be preferable as a preserving medium for sensitive biological specimens.

Chlorophyll↗

PubMed2005

Phytochemical and pharmacological screening of Sterculiaceae species and isolation of antibacterial compounds.

Little previous phytochemical investigation has been conducted on South African Sterculiaceae species used in traditional medicine. In this study, five species, varying in growth type (small herbs, shrubs and large trees) and traditional usage were investigated. The species screened were Cola greenwayi Brenan, Cola natalensis Oliv., Dombeya burgessiae Gerr. ex Harv., Dombeya cymosa Harv. and Hermannia depressa N.E.Br. Extracts were screened for alkaloids, cardiac glycosides, cyanogenic glycosides, saponins and tannins. The probable presence of bufadienolides in the leaf material of Dombeya burgessiae and Dombeya cymosa was determined. Alkaloids, cyanogenic glycosides and saponins were absent in all the plant material investigated. Tannins were detected in the leaf extract of Cola greenwayi and in the leaves, stems and roots of Hermannia depressa. Extracts were screened for anti-inflammatory and antibacterial activity using the cyclooxygenase-1 (COX-1) inhibition assay and the microdilution antibacterial assay. The ethanol and dichloromethane extracts of Cola greenwayi, Dombeya burgessiae and Dombeya cymosa, and the dichloromethane extracts of Hermannia depressa showed the highest levels of COX-1 inhibition. It is possible that the high levels observed may be due to the presence of tannins in some of the extracts. Generally, all the aqueous extracts exhibited low activity. Similarly, no antibacterial activity was observed with the aqueous extracts, although some mild activity was exhibited with some of the ethanol and ethyl acetate extracts. Following the general phytochemical and pharmacological screening, extracts showing antibacterial activity were further purified using bioassay-guided fractionation. Dombeya rotundifolia (Hochst.) Planch., which was screened in a previous study, was also included in the isolation of active compounds. A bioautographic assay, using Staphylococcus aureus, was used to detect the presence of the antibacterial compounds. These were isolated and identified as fatty acids.

Anti-Bacterial Agents↗

PubMed2005

Influence of extracts of Stryphnodendron polyphyllum Mart. and Stryphnodendron obovatum Benth. on the cicatrisation of cutaneous wounds in rats.

Stem bark of the two species Stryphnodendron polyphyllum Mart. and Stryphnodendron obovatum Benth., Leguminosae, was investigated for wound healing, antibacterial and antioxidant activity. These plants contain 12 and 19% tannins in their stem bark, respectively, and are widely used in traditional medicine in Brazil. The total content of phenolics of the crude extract (CE) of Stryphnodendron obovatum was 76.95 +/- 2.98% (CV = 3.87%) and of the ethyl-acetate fraction (EAF) was 89.13 +/- 0.34% (CV = 0.38%); whereas in Stryphnodendron polyphyllum the CE phenolics content was 51.62+/-1.53% (CV = 2.96%) and the EAF phenolics content was 59.00 +/- 1.91% (CV = 3.24%). The tannin content of CE from Stryphnodendron obovatum [36.58 +/- 0.35% (CV = 0.98%)] was about 11% higher than in CE from Stryphnodendron polyphyllum [25.43 +/- 0.96% (CV = 3.77%)]. The difference between the species was even greater in the EAF: in Stryphnodendron obovatum the EAF phenolics content was 55.01 +/- 0.36% (CV = 0.65%), whereas in Stryphnodendron polyphyllum the content was 36.16 +/- 0.42% (CV = 1.16%). The healing effect of ointments containing 2.5% crude lyophilised extract (PCE) and 2.5% ethyl-acetate lyophilised fraction (PEA) of the stem bark of Stryphnodendron polyphyllum and Stryphnodendron obovatum was studied in cutaneous wounds of Wistar rats after 4, 7 and 10 days of treatment. Epithelial cell proliferation in the area of re-epithelialisation of the wounds was evaluated by counting the metaphases blocked by vincristine sulfate. With PCE an increase in epidermal growth was observed after 4 and 7 days of treatment with Stryphnodendron polyphyllum, and after 7 and 10 days of treatment with Stryphnodendron obovatum. Wounds treated with PEA of Stryphnodendron obovatum showed increased epidermal growth only 4 days after the treatment; for Stryphnodendron polyphyllum, epidermal growth was observed after 4 and 7 days of treatment. Both the CE and the EAF fractions of Stryphnodendron polyphyllum and Stryphnodendron obovatum showed antibacterial activity against Staphylococcus aureus with MIC values of 125 and 250 microg/ml, respectively. Gram-negative bacteria tested were not inhibited by extracts and fractions at concentrations > 1000 microg/ml. The antioxidant activity through reduction of the DPPH radical in TLC, confirmed the anti-radical properties of these extracts in both species. CE and EAF of both species showed a radical scavenging activity (RSA) and protected DPPH from discolouration, already at 0.032 microg/ml. The extract from Stryphnodendron polyphyllum were more effective than those Stryphnodendron obovatum, although the former had a lower tannin content.

Animals↗

PubMed2005

Use patterns and knowledge of medicinal species among two rural communities in Brazil's semi-arid northeastern region.

The present work seeks to quantify the knowledge of two rural communities in the semi-arid region of the state of Pernambuco (northeastern Brazil) concerning two species of native medicinal plants: "aroeira do sertão", Myracrodruon urundeuva (Engl.) Fr. All. (Anacardiaceae) and "angico", Anadenanthera colubrina (Vell.) Brenan (Mimosaceae). Semi-structured interviews were carried out, combined with a checklist/inventory method, which yielded different indexes for quantifying knowledge and use of these species. In addition, the reliability of local knowledge was tested using analytical techniques to determine actual tannin concentrations. Although both communities possess knowledge concerning these two species, one of them stood out in terms of the diversity of information presented (P < 0.05), a difference that may be related to its lower degree of modernization. In general, older people had a greater variety of information about these plants, although both men and women demonstrated similar knowledge. Of the 101 people interviewed in Riachão, 85% stated that they knew of uses for both species studied; in Ameixas, of the 55 interviewees, 63% responded that they knew of uses for Myracrodruon urundeuva, and 45% knew of uses for Anadenanthera colubrina. A total of 97 different uses were reported by all informants for the two species studied. Of these, 62 were mentioned in only a single community, confirming our hypothesis of differences in knowledge between them. Informants from both communities knew of a great variety of uses for these plants as well as a number of different collection techniques. We expected that knowledge about the two species would differ in relation to both gender and age, but this was only true for one of the communities. Greater concentrations of tannins were expected to be found consistently in the tree bark, but experimental data demonstrated that tannin concentrations can vary among plant parts during the year.

Brazil↗

PubMed2000

Extraction and filtering in ultrasonic field: finite element modelling and simulation of the processes

In this research, the use of powerful sonification is studied in making the extraction of tannins more efficient. A combined extraction-filtration system using sonification was designed and modelled. Preliminary extraction studies were carried out to show the effect of ultrasound in extraction. In these experiments high-intensity ultrasound was utilised in extraction of tannins of Salix phylicifolia. Different solvents were used in extraction experiments. Pickled sheepskin was tanned with the extracts and with some other vegetable tannins for comparisons.

Journal Article↗

PubMed2000

Biological detoxification of coffee husk by filamentous fungi using a solid state fermentation system.

Studies were carried out on detoxification of coffee husk in solid state fermentation using three different strains of Rhizopus, Phanerochaete, and Aspergillus sp. Fungal strains were selected by their ability to grow on a coffee husk extract-agar medium. Using R. arrizus LPB-79, the best results on the degradation of caffeine (87%) and tannins (65%) were obtained with pH 6.0 and moisture 60% in 6 days. When P. chrysosporium BK was used, maximum degradation of caffeine and tannins were 70.8 and 45%, respectively, with coffee husk having 65% moisture and pH 5.5 in 14 days. The Aspergillus strain, isolated from the coffee husk, showed best biomass formation on coffee husk extract-agar medium. Optimization assays were conducted using factorial design, and surface response experiments with Aspergillus sp. The best detoxification rates achieved were 92% for caffeine and 65% for tannins. The results showed good prospects of using these fungal strains, in particular Aspergillus sp., for the detoxification of coffee husk.

Journal Article↗

PubMed2000

Antioxidant activity of pomegranate juice and its relationship with phenolic composition and processing.

The antioxidant activity of pomegranate juices was evaluated by four different methods (ABTS, DPPH, DMPD, and FRAP) and compared to those of red wine and a green tea infusion. Commercial pomegranate juices showed an antioxidant activity (18-20 TEAC) three times higher than those of red wine and green tea (6-8 TEAC). The activity was higher in commercial juices extracted from whole pomegranates than in experimental juices obtained from the arils only (12-14 TEAC). HPLC-DAD and HPLC-MS analyses of the juices revealed that commercial juices contained the pomegranate tannin punicalagin (1500-1900 mg/L) while only traces of this compound were detected in the experimental juice obtained from arils in the laboratory. This shows that pomegranate industrial processing extracts some of the hydrolyzable tannins present in the fruit rind. This could account for the higher antioxidant activity of commercial juices compared to the experimental ones. In addition, anthocyanins, ellagic acid derivatives, and hydrolyzable tannins were detected and quantified in the pomegranate juices.

Antioxidants↗

PubMed2001

Nutrient distribution and phenolic antioxidants in air-classified fractions of beach pea (Lathyrus maritimus L.).

Beach pea (Lathyrus maritimus L.) cotyledons and hulls were air-classified into different fractions. The crude protein content (%N x 6.25) of samples ranged from 32.8 to 35.3% in cotyledons and 14.7 to 16.8% in hulls. Crude fiber content was higher in hulls fraction 1 (37.13%) and fraction 2 (36.85%) than in cotyledons (2.83, 2.99, and 3.08% in fractions 1, 2, and 3, respectively). Condensed tannins of cotyledons ranged from 5.76 to 6.90% and of hulls ranged from 52.49 to 57.24%, expressed as catechin equivalents. Minerals, namely P, K, and Zn, were higher in cotyledons, but Ca and Mn were more prevalent in hulls. Nonprotein nitrogen was concentrated in hulls, whereas phytic acid was more abundant in the cotyledons. The UV absorption pattern showed that flavonoids were present in fractions (I-III) from hulls separated on Sephadex LH-20. Fraction III from hulls had the highest content of total phenolics and condensed tannins, but no condensed tannins were detected in fractions I and II from hulls. The antioxidant activity of fractions separated on Sephadex LH-20 from hulls and crude extracts in a beta-carotene-linoleate model system was in the order of fraction III > crude extract > fraction II > fraction I. Spots on silica gel TLC plates, sprayed with a solution of beta-carotene and linoleic acid, indicated that many of the individual compounds were antioxidative in nature. Further, separation of fraction III from hulls on a semipreparative HPLC showed the presence of (+) catechin and (-) epicatechin as the main low-molecular-weight phenolic compounds present.

Antioxidants↗

PubMed2006

NMR, ESI/MS, and MALDI-TOF/MS analysis of pear juice polymeric proanthocyanidins with potent free radical scavenging activity.

The structure of a polymeric proanthocyanidin fraction isolated from pear juice was characterized by NMR, ESI/MS, and MALDI-TOF/MS analyses, and its antioxidant activity was investigated using the DPPH free radical scavenging method. The results obtained from 13C NMR analysis showed the predominance of signals representative of procyanidins. Typical signals in the chemical shift region between 70 and 90 ppm demonstrated the exclusive presence of epicatechin units. The results obtained through negative ESI/MS analysis showed singly and doubly charged ions corresponding to the molecular mass of procyanidins with a degree of polymerization up to 22. The spectra obtained through MALDI-TOF/MS analysis revealed the presence of two series of tannin oligomers. Supporting the observations from NMR spectroscopy, the first series consists of well-resolved tannin identified as procyanidin polymers units with chain lengths of up to 25. A second series of monogalloyl flavan-3-ols polymers with polymerization degree up to 25 were also detected. This is the first mass spectrometric evidence confirming the existence of galloylated procyanidin oligomers in pear fruits. Within each of these oligomers, various signals exist suggesting the presence of several oligomeric tannins. The antioxidant properties of the polymeric fraction were investigated through reduction of the DPPH free radical, and the results obtained showed that the polymeric fraction exhibited a higher antioxidant power compared to those of (+)-catechin and B3 procyanidin dimer.

Antioxidants↗

PubMed1999

Role of polyphenols in copper complexation in red wines.

Four monovarietal red wines, Tinta Roriz, Tinta Barroca, Touriga Nacional, and Touriga Francesa, were studied for their complexometric properties toward copper. For the purpose, ion selective electrode potentiometric titrations were carried out, and the data were treated by two methods suitable for heterogeneous ligands: the Scatchard plot, which provided the complexation capacity (CC(total) = maximum number of moles of sites per liter), and the differential equilibrium function (DEF), which provided the conditional stability constants of the sites effectively involved in the metal complexation (K(DEF)) at a given titration point. The different wines displayed similar properties: CC(total) ranged from 4.5x10(-3) (Tinta Barroca) to 4.9x10(-3) M (Touriga Francesa), and log K(DEF) values were between 4.2 and 6.5. The range of log(|Cu|(bound)/CC(total)) = log theta embraced in the titration was between -0.2 and -1.9. With regard to the natural levels of copper, from 4.4x10(-7) (Tinta Roriz) to 1.3x10(-6) M (Touriga Nacional), and ligands (CC(total)) in the wines, it can be expected that copper will be strongly complexed in the studied wines (log K(DEF) > 6). Studies carried out, in parallel, for solutions of isolated seed tannins and skin polyphenols (mainly anthocyans) showed that their contribution to the CC(total) of the wines was <40% for tannins and <2% for skin polyphenols. However, skin polyphenols were shown to be much stronger copper ligands (log K(DEF) = 6.7, log theta = -1.5) than tannins (log K(DEF) = 4.5, log theta = -1.5).

Copper↗

PubMed2003

Resource allocation in different parts of juvenile mountain birch plants: effect of nitrogen supply on seedling phenolics and growth.

The composition and concentrations of phenolic compounds were studied in the first true leaves, cotyledons, stems and roots of 2.5-week-old seedlings of mountain birch (Betula pubescens ssp. czerepanovii). The differences in secondary compounds among these plant parts were both qualitative and quantitative. In all parts, condensed tannins accounted for more than 50% of the phenolics. In the first true leaves and cotyledons, chlorogenic acid was the most abundant of the HPLC phenolics. The main components in stems were (+)-catechins and rhododendrins whereas in roots, the main components were ellagitannins. The seedlings were grown at three levels of nitrogen supply (very low-N, low-N, moderate-N), and the effect of nitrogen on concentrations of phenolic compounds was studied in all plant parts. The dry weight of all plant parts, except the roots, increased with increased nitrogen. In all parts, the concentration of condensed tannins was higher at lower levels of nitrogen than at moderate-N. The concentrations of total HPLC phenolics and also those of the compound groups of HPLC phenolics were, however, affected only in the first true leaves and roots. The concentrations in the first true leaves were generally higher in seedlings grown at very low-N and low-N than in seedlings grown at moderate-N. The concentrations in roots were highest at low-N. Not all compounds responded to nitrogen supply in the same manner. The changes in concentrations cannot be exclusively interpreted as changes in the accumulation of phenolic compounds, due to dilution caused by the increase in biomass in better nitrogen availability. There were differences in carbon allocation between condensed tannins and HPLC phenolics in seedlings grown at different nitrogen levels.

Journal Article↗

PubMed2003

Degradation of phytic acid in cereal porridges improves iron absorption by human subjects.

BACKGROUND: Phytic acid in cereal-based and legume-based complementary foods inhibits iron absorption. Low iron absorption from cereal porridges contributes to the high prevalence of iron deficiency in infants from developing countries. OBJECTIVE: The objective was to measure the influence of phytic acid degradation on iron absorption from cereal porridges. DESIGN: An exogenous phytase was used to fully degrade phytic acid during the manufacture of 9 roller-dried complementary foods based on rice, wheat, maize, oat, sorghum, and a wheat-soy blend. Iron absorption from the phytate-free and native phytate porridges prepared with water or milk (wheat only) was measured in adult humans with an extrinsic-label radioiron technique. Ascorbic acid was added to some porridges. RESULTS: When the foods were reconstituted with water, dephytinization increased iron absorption from rice porridge from 1.73% to 5.34% (P < 0.001), from oat from 0.33% to 2.79% (P < 0.0001), from maize from 1.80% to 8.92% (P < 0.0001), from wheat from 0.99% to 11.54% (P < 0.0001), from the wheat-soy blend without ascorbic acid from 1.15% to 3.75% (P < 0.005), and from the wheat-soy blend with ascorbic acid from 2.40% to 8.46% (P < 0.005). Reconstituting wheat porridge with milk instead of water markedly decreased or completely removed the enhancing effect of dephytinization on iron absorption in the presence and absence of ascorbic acid. Dephytinization did not increase iron absorption from high-tannin sorghum porridge reconstituted with water but increased iron absorption from low-tannin sorghum porridge by approximately 2-fold (P < 0.01). CONCLUSIONS: Phytate degradation improves iron absorption from cereal porridges prepared with water but not with milk, except from high-tannin sorghum.

6-Phytase↗

PubMed2005

Polyphenols in foods are more complex than often thought.

Dietary polyphenols show a great diversity of structures, ranging from rather simple molecules (monomers and oligomers) to polymers. Higher-molecular-weight structures (with molecular weights of > 500) are usually designated as tannins, which refers to their ability to interact with proteins. Among them, condensed tannins (proanthocyanidins) are particularly important because of their wide distribution in plants and their contributions to major food qualities. All phenolic compounds are highly unstable and rapidly transformed into various reaction products when the plant cells are damaged (for instance, during food processing), thus adding to the complexity of dietary polyphenol composition. The polyphenol composition of plant-derived foods and beverages depends on that of the raw material used but also on the extraction process and subsequent biochemical and chemical reactions of plant polyphenols. The occurrence of specific tannin-like compounds (ie, thearubigins and theaflavins) arising from enzymatic oxidation is well documented in black tea. Various chemical reactions involving anthocyanins and/or flavanols have been demonstrated to occur during red wine aging. Current knowledge regarding the reaction mechanisms involved in some of these processes and the structures of the resulting products is reviewed. Their effects on organoleptic and nutritional quality are also discussed.

Flavonoids↗