tannins and protocatechuic-acid

Legumes are a good source of bioactive phenolic compounds which play significant roles in many physiological as well as metabolic processes. Phenolic acids, flavonoids and condensed tannins are the primary phenolic compounds that are present in legume seeds. Majority of the phenolic compounds are present in the legume seed coats. The seed coat of legume seeds primarily contains phenolic acids and flavonoids (mainly catechins and procyanidins). Gallic and protocatechuic acids are common in kidney bean and mung bean. Catechins and procyanidins represent almost 70% of total phenolic compounds in lentils and cranberry beans (seed coat). The antioxidant activity of phenolic compounds is in direct relation with their chemical structures such as number as well as position of the hydroxyl groups. Processing mostly leads to the reduction of phenolic compounds in legumes owing to chemical rearrangements. Phenolic content also decreases due to leaching of water-soluble phenolic compounds into the cooking water. The health benefits of phenolic compounds include acting as anticarcinogenic, anti-thrombotic, anti-ulcer, anti-artherogenic, anti-allergenic, anti-inflammatory, antioxidant, immunemodulating, anti-microbial, cardioprotective and analgesic agents. This review provides comprehensive information of phenolic compounds identified in grain legume seeds along with discussing their antioxidant and health promoting activities.

Topics: Anthocyanins; Antioxidants; Catechin; Edible Grain; Flavanones; Flavones; Flavonoids; Flavonols; Hydroxybenzoates; Phaseolus; Phenols; Plant Extracts; Proanthocyanidins; Seeds; Tannins; Vaccinium macrocarpon

Antioxidant activities of eight indigenous cyanobacterial strains belonging to the genera Oscillatoria, Chroococcidiopsis, Leptolyngbya, Calothrix, Nostoc and Phormidium were studied in relation with their phenolic and flavonoid contents, ranging 3.9-12.6 mg GAE g(-1) and 1.7-3.44 mg RE g(-1). The highest activities were shown by Leptolyngbya sp. SI-SM (EC50 = 63.45 and 67.49 μg mL(-1)) and Calothrix sp. SI-SV (EC50 = 65.79 and 69.38 μg mL(-1)) calculated with ABTS and DPPH assays. Significant negative correlations were seen between total phenolic and flavonoid contents and the antioxidant activities in terms of EC50 values. Furthermore, HPLC detected 15 phenolic compounds with total concentrations ranging from 277.3 to 829.7 μg g(-1). The prevalent compounds in most of the strains were rutin, tannic acid, orcinol, phloroglucinol and protocatechuic acid. Cyanobacterial strains showed high potential as a good source of phenolic compounds with potent antioxidative potential which could be beneficial for food, cosmetic and pharmaceutical industries.

Topics: Antioxidants; Chromatography, High Pressure Liquid; Cyanobacteria; Flavonoids; Hydroxybenzoates; Phenols; Phloroglucinol; Resorcinols; Rutin; Tannins

Previous studies have shown that naturally occurring phytochemicals, indole-3-carbinol, phenethyl isothiocyanate, protocatechuic acid, and tannic acid increased the activity and protein level of hepatic phase II enzymes in animal models. In order to further explore the mechanism of this activity, we investigated the effect of these compounds on the activation of nuclear factor erythroid-2-related factor 2 (Nrf2)-regulated transcription in human hepatocellular carcinoma HepG2 cells. Treatment with all the tested compounds resulted in the translocation from the cytosol and nuclear accumulation of active phosphorylated Nrf2. Furthermore, phenethyl isothiocyanate and indole-3-carbinol increased the transcript and protein levels of GSTA, GSTP, GSTM, GSTT, and NQO1. On the other hand, protocatechuic and tannic acids enhanced only the expression of GSTA, GSTM, and GSTT. The expression of genes encoding antioxidant enzymes CAT, SOD, GR, and GPx was increased after the treatment with all the tested phytochemicals. These results indicate that isothiocyanates/indoles and protocatechuic and tannic acids induce phase II and antioxidant gene expression in HepG2 cells through the Nrf2-Keap1-ARE signaling pathway. Moreover, the results of this study confirmed that the degradation products of glucosinolates are more effective inducers of phase II and antioxidant enzymes than protocatechuic and tannic acids.

Topics: Antioxidant Response Elements; Antioxidants; Cell Survival; Enzymes; Gene Expression Regulation; Hep G2 Cells; Humans; Hydroxybenzoates; Indoles; Isothiocyanates; NF-E2-Related Factor 2; Phosphorylation; Phytochemicals; Signal Transduction; Tannins

Epidermal growth factor receptor (EGFR) plays an important role in epithelial carcinogenesis and appears to be involved in STATs activation. In this study we investigated the possible interference of naturally occurring phenolic acids with EGFR, activator protein-1 (AP-1), and signal transducers and activators of transcription (STATs) pathways activated by topical application of tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in Balb/c mice epidermis. Pretreatment with tannic or chlorogenic acid resulted in a significant decrease in the phosphorylation of EGFR Y-1068 and Y-1173 tyrosine residues, which was accompanied by reduced activation of AP-1. Tannic acid decreased also the c-Jun AP-1 subunit level and binding to TPA response element (TRE) (3- and 2-fold in comparison with TPA-treated group respectively). Simultaneous reduction of JNK activity might be responsible for reduced activation of AP-1. In contrast to these more complex phenolics, protocatechuic acid increased the activity of JNK and was also the most efficient inhibitor of STATs activation. These results indicate that naturally occurring phenolic acids, by decreasing EGFR, AP-1, and STATs activation, may modulate other elements both upstream and downstream in these pathways and thus inhibit the tumor development. Although more complex phenolics affect mainly the EGFR/AP-1 pathway, STATs seem to be the most important targets for simple compounds, such as protocatechuic acid.

Topics: Animals; Carcinogens; Chlorogenic Acid; Epidermis; ErbB Receptors; Female; Hydroxybenzoates; Mice; Mice, Inbred BALB C; Phosphorylation; Signal Transduction; STAT3 Transcription Factor; STAT5 Transcription Factor; Tannins; Tetradecanoylphorbol Acetate; Transcription Factor AP-1

To complete our study on tannin degradation via gallic acid by the biotechnologically interesting yeast Arxula adeninivorans as well as to characterize new degradation pathways of hydroxylated aromatic acids.. With glucose-grown cells of A. adeninivorans, transformation experiments with hydroxylated derivatives of benzoic acid were carried out. The 12 metabolites were analysed and identified by high performance liquid chromatography and GC/MS. The yeast is able to transform the derivatives by oxidative and nonoxidative decarboxylation as well as by methoxylation. The products of nonoxidative decarboxylation of protocatechuate and gallic acid are substrates for further ring fission.. Whereas other organisms use only one route of transformation, A. adeninivorans is able to carry out three different pathways (oxidative, nonoxidative decarboxylation and methoxylation) on one hydroxylated aromatic acid. The determination of the KM-values for protocatechuate and gallic acid in crude extracts of cells of A. adeninivorans cultivated with protocatechuate and gallic acid, respectively, suggests that the decarboxylation of protocatechuate and gallic acid may be catalysed by the same enzyme.. This transformation pathway of protocatechuate and gallic acid via nonoxidative decarboxylation up to ring fission is novel and has not been described so far. This is also the first report of nonoxidative decarboxylation of gallic acid by a eukaryotic micro-organism.

Topics: Decarboxylation; Gallic Acid; Hydroxybenzoates; Oxidation-Reduction; Parabens; Saccharomycetales; Tannins

Protein kinase C (PKC) is thought to be a major intracellular receptor for the mouse skin tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). The diversity of PKC isoforms, and their central role in many signaling pathways, makes them important targets for potential chemopreventive agents. Our earlier studies showed that the plant phenols protocatechuic acid, chlorogenic acid and tannic acid alter the activity of enzymes involved in carcinogen activation, inhibit the formation of polycyclic aromatic hydrocarbon (PAH)-DNA adducts in mouse epidermis and decrease the level of lipid peroxidation in the epidermal microsomes. In the present study the effects of protocatechuic acid, chlorogenic acid and tannic acid on TPA-stimulated PKC isozymes alpha, beta(1), beta(2), gamma and zeta activity, and their distribution in mouse epidermis, was examined. The application of these phenolics 15 min before a single dose (3.4 nmol) of TPA resulted in significant inhibition of PKC translocation and a subsequent decrease in classical and novel/atypical PKC isoforms in comparison to a group of mice treated with TPA alone. The most potent inhibitor of PKC translocation and activity was tannic acid. This compound increased the levels of PKCalpha, beta(1), beta(2) in the cytosolic fraction by between 127% and 492% in comparison with TPA treated group of mice. Tannic acid decreased the activities of all three PKC classes by approximately 94% in the membrane fraction in comparison with the TPA treated group of animals. The effect of protocatechuic and chlorogenic acids on the distribution and activity of PKC isozymes was moderate. These compounds mostly affected translocation of PKCalpha and subsequently the activity of classical PKC. The enzyme activity in the particulate fraction was reduced by 59% and 43% in comparison with the TPA group, respectively. Thus, the results of these studies suggest that the subcellular distribution of PKC isoforms, and the activity of PKCs, can be modulated by plant phenolic acids, particularly tannic acid, and that such actions represent a part of the anti-promotional activity of these substances in mouse epidermis.

Topics: Animals; Anticarcinogenic Agents; Blotting, Western; Chlorogenic Acid; Cytosol; Enzyme Induction; Epidermis; Female; Hydroxybenzoates; Isoenzymes; Mice; Phenols; Phorbol Esters; Plants; Protein Kinase C; Subcellular Fractions; Tannins; Tetradecanoylphorbol Acetate

A facultatively anaerobic, mesophilic, non-motile, non-sporulating bacterium, designated strain B7, was isolated from an anaerobic digester fed with shea cake rich in tannins and aromatic compounds, after enrichment on tannic acid. The coccoid cells (less than 2 microm in diameter) occurred in pairs or short chains and stained gram-positive. Strain B7 fermented a wide range of carbohydrates (cellobiose, fructose, galactose, glucose, lactose, maltose, mannitol, melibiose, raffinose and trehalose), grew optimally at pH 7.0 and had a G+C content of 40.4+/-0.3 mol%. Strain B7 was closely related to Streptococcus gallolyticus ACM 3611T, a member of the Streptococcus bovis rRNA cluster, with a sequence similarity of 98% and a DNA hybridization value of 86 mol%. Isolate B7 hydrolysed tannic acid and decarboxylated gallic acid to pyrogallol, traits also observed in S. gallolyticus ACM 3611T. In addition, both strains decarboxylated protocatechuic acid to catechol, p-coumaric acid to 4-vinylphenol, caffeic acid to 4-vinylcatechol and ferulic acid to 4-vinylguaiacol. An unsubstituted para-hydroxyl group on the benzene ring was required for decarboxylation. Glucose addition markedly increased the conversion rate. As these traits were not described previously, emendation of the description of the species Streptococcus gallolyticus is proposed.

Topics: Anaerobiosis; Bacterial Typing Techniques; Biodegradation, Environmental; Bioreactors; Coumaric Acids; Decarboxylation; DNA, Ribosomal; Hydroxybenzoates; Molecular Sequence Data; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Streptococcus; Tannins; Trees