Physiological and Biochemical Effects of Mono-, Di-and Polyphenolic Compounds on Groundnut

Three phenolic compounds-salicylic, caffeic and tannic acids (mono, di and polyphenolic compounds, respectively), were sprayed at two stages (anthesis and pod filling) in two doses. Best results were obtained in response to tannic acid spray @ 100 ppm; groundnut pod yield being 47 Qha^-1 and 100 kernels weight 68.7 g. This dose significantly improved oil content (2.7%), oil yield (43.8%) and protein content (5.2%). Maximum linoleic acid (23.4%) was obtained with salicylic acid (40 + 40 ppm) spray, while tannic acid spray @ 100 ppm gave 63.7% oleic acid and 2.8% arachidic acid. However, there was no significant effect on the saturated fatty acids. O/L ratio to the tune 3 was obtained as a result of this treatment thus enhancing the keeping quality of the oil.     

Mut-Test to detect substances suppressing spontaneous mutation due to oxidative damage

Since it has been considered that suppression of spontaneous mutation in cells is related to suppression of spontaneous carcinogenesis, it is significant to detect substances which suppress spontaneous mutation in bacterial cells such as Escherichia coli and Salmonella typhimurium in the environment. However, since the frequency of spontaneous mutation in bacteria is usually very low, generally 10(-8)-10(-10),it is difficult to determine significant suppressive ability of such substances on spontaneous mutation. A new method, Mut-Test, was developed by us, applying Luria & Delbruck fluctuation test, to detect substances which suppress spontaneous mutation using E. coli mutT mutant in which spontaneous mutation frequency due to oxidative damage is enhanced to approximately 500-1000 times of the wild type strain. Suppressive abilities of two hydroxyl radical scavengers: D(-)-mannitol and thiourea, were examined and clear positive results were obtained, suggesting that the radical scavengers are suitable as the positive control for the test. Using Mut-Test, suppressive abilities of four vitamins: L-ascorbic acid, beta-carotene, folic acid and riboflavin; 10 polyphenols: caffeic acid, ellagic acid, (-)-epicatechin, (-)-epicatechin gallate, (-)-epigallocatechin, gallic acid, pyrocatechol, pyrogallol, quercetin and tannic acid which are recognized as antimutagens, were examined. Furthermore, the concentrations for 50% of suppressive abilities of five positive samples, L-ascorbic acid, folic acid, caffeic acid, pyrocatechol and pyrogallol were compared. Negative results were obtained in nine samples, riboflavin, tannic acid, etc. suggesting that their antimutagenic effect on cells may not be related to oxidative damage in cells.     

A reevaluation of the peroxynitrite scavenging activity of some dietary phenolics

Peroxynitrite is implicated in many diseases. Hence, there is considerable interest in potential therapeutic peroxynitrite scavengers. Diet-derived phenolics have been claimed to be powerful peroxynitrite scavengers. However, the reactivity of peroxynitrite can be significantly modified by bicarbonate and this has not been considered in evaluations of the scavenging activity of phenols. Bicarbonate (25 mM) significantly decreased the ability of several phenolic compounds (caffeic acid, o- and p-coumaric acid, gallic acid, ferulic acid) but not others (catechin and epicatechin) to inhibit peroxynitrite-mediated tyrosine nitration. Bicarbonate (25 mM) also decreased the ability of catechin, epicatechin, quercetin and ferulic acid but not chlorogenic acid, gallic acid, caffeic acid and o-coumaric acid to inhibit peroxynitrite-mediated alpha(1)-antiproteinase inactivation. These results show that physiological concentrations of bicarbonate substantially modify the ability of dietary phenolics to prevent peroxynitrite-mediated reactions. When assessing compounds for peroxynitrite scavenging, experiments should be conducted in the presence of bicarbonate to avoid misleading results.     

Auxin Synergists in Rooting of Cuttings

Leafy cuttings of Eranthemum tricolor were treated with tannic acid, gallic acid, p-hydroxybenzoic acid and salicylic acid at the concentrations of 1000, 100, 10 and 1 nig/1 for 24 hours, whereafter they were dipped quickly in a 1000 mg/l solution of IAA, IBA and NAA for ten seconds. None of the phenolics showed any root promoting effect when used singly. In combination with NAA and IBA tannic acid promoted rooting, however, with IAA there was no effect to be seen. Gallic acid also markedly increased the number of roots of cuttings treated with NAA and IBA. Even in this case there was no effect with IAA. Synergism was also recorded between p-hydroxybenzoic acid and IAA or NAA but not with IBA. Salicylic acid greatly promoted rooting in combination with both IAA, IBA and NAA.     

Tannase activity from the marine cyanobacterium Phormidium valderianum BDU140441

The marine cyanobacterium Phormidium valderianum BDU 140441 exhibited the ability to grow at 0.25?mM tannic acid, a known hindering chemical for microbial growth. The tannic acid-degrading ability of the organism is evident from the UV–visible absorption spectrum. In addition, the existence of tannase has been localized by activity staining, and its induction in activity upon tannic acid exposure was confirmed in native gel. The critical tannic acid metabolization enzymes tested for are polyphenol oxidase and esterases; both are well known for tannic acid degradation. Upon tannic acid exposure, increased activity of polyphenol oxidase and expression of few new isoforms of esterase were identified by activity staining.     

Interactions of dextransucrase purified from Streptococcus mutans 890 with plant polyphenols

Plant polyphenols have been extensively studied for their chemopreventive properties for human health. Dextransucrase plays an essential role in synthesizing exopolysaccharides from its exclusive substrate sucrose in Streptococcus mutans. In the present study, the effect of polyphenols gallic acid and tannic acid was investigated on the dextransucrase activity. The enzyme was purified by ethanol precipitation followed by column chromatography by Sephadex G-200 gel chromatography, followed by PEG-400 treatment. The purified enzyme exhibited 52 fold enrichment with 17.5% yield and specific activity of 3.54 Units/mg protein. On SDS-PAGE enzyme protein gave a single band with a molecular weight of 160 kDa. Dextransucrase activity was inhibited 80–90% by 0.04 mM tannic acid (TA) or 0.4 mM gallic acid (GA) suggesting that tannic acid has 10- fold more inhibitory potential than gallic acid on the activity of dextransucrase. CD/ORD studies revealed modifications in the tertiary structure of enzyme protein in presence of tannic acid and gallic acid, which were further confirmed by fluorescence spectra of the protein in presence of tannic acid. These results suggest that inhibition of dextransucrase activity in S. mutans by polyphenols may have potential applications in the prevention and control of dental caries.     

Alkyl esters of hydroxycinnamic acids with improved antioxidant activity and lipophilicity protect PC12 cells against oxidative stress

Hydroxycinnamic acids (HCAs) are phenolic compounds present in dietary plants, which possess considerable antioxidant activity. In order to increase the lipophilicity of HCAs, with the aim of improving their cellular absorption and expansion of their use in lipophilic media, methyl, ethyl, propyl and butyl esters of caffeic acid and ferulic acid have been synthesized. All caffeate esters had a slightly lower DPPH IC(50) (13.5-14.5 μM) and higher ferric reducing antioxidant power (FRAP) values (1490-1588 mM quercetin/mole [mMQ/mole]) compared to caffeic acid (16.6 μM and 1398 mMQ/mole, respectively) in antioxidant assays. In contrast, ferulate esters were less active in DPPH (56.3-74.7 μM) and FRAP assays (193-262 mMQ/mole) compared to ferulic acid (44.6 μM and 324 mMQ/mole, respectively). Redox properties of HCAs were in line with their antioxidant capacities, so that compounds with higher antioxidant activities had lower oxidation potentials. Measurement of partition coefficients disclosed the higher lipophilicity of the esters compared to parent compounds. All esters of caffeic acid significantly inhibited hydrogen peroxide-induced neuronal PC12 cell death assessed by MTT assay at 5 and 25 μM. However, caffeic acid, ferulic acid and ferulate esters were not able to protect the cells. In conclusion, these findings suggest that alkyl esterification of some HCAs augments their antioxidant properties as well as their lipophilicity and as a consequence, improves their cell protective activity against oxidative stress. These compounds could have useful applications in conditions where oxidative stress plays a pathogenic role.     

Colorimetric assay method for determination of the tannin acyl hydrolase (EC 3.1.1.20) activity

A new colorimetric method of tannase (tannin acyl hydrolase, EC 3.1.1.20) assay has been developed using its specific substrate tannic acid. It is based on the changes in optical density of substrate tannic acid after enzymatic reaction at 530 nm. The residual tannic acid was measured by a modified BSA precipitation method. This assay is very simple, reproducible, and very convenient, and with it tannase activity can be measured in relation to the growth of the organism.     

Inhibition of boar sperm hyaluronidase activity by tannic acid reduces polyspermy during in vitro fertilization of porcine oocytes

The present study was conducted to examine the effects of three polyphenols (tannic acid, apigenin and quercetin) on hyaluronidase activity and in vitro fertilization (IVF) parameters. Among them, tannic acid showed by far the strongest potency for blocking hyaluronidase activity extracted from preincubated boar sperm, causing a dose-dependent inhibition over the range of 2-10 microg/ml. When cumulus-intact and cumulus-free oocytes were inseminated in IVF medium containing tannic acid, the penetration and the polyspermy rates were significantly decreased in the presence of 10 microg/ml tannic acid compared with those in the absence of tannic acid, and the addition of 5 microg/ml tannic acid significantly reduced the polyspermy rate (p < 0.05) compared with that of the control while maintaining the high penetration rate. However, apigenin and quercetin had no effect on the rate of polyspermy. Interestingly, the incidence of polyspermy was significantly reduced in oocytes inseminated with sperm pretreated with 5 microg/ml tannic acid (p < 0.05), although the pretreatment of oocytes had no effect against the polyspermy after insemination with untreated sperm. Treatment with tannic acid caused neither a protective proteolytic modification of the zona pellucida matrix before fertilization, nor a reduction of the proteolytic activity of acrosomal contents or the number of zona-bound spermatozoa. These data suggest that an appropriate concentration of tannic acid prevents polyspermy through the inhibition of sperm hyaluronidase activity during IVF of porcine oocytes.     

Inhibitory activity of pine needle tannin extracts on some agriculturally resourceful microbes

Crude extracts of water and solvent extractable tannin fractions from pine needles were found to contain tannin concentrations of 10.15% and 13.15% tannic acid equivalents respectively. Thin Layer Chromatography revealed the presence of four distinct phenolic compounds, amongst which two were tannic acid like compounds. Both the extracts were found to be inhibitory to several microbes of agricultural importance. Amongst the bacterial strains studied, Azotobacter sp (VL-A2) was able to tolerate upto 1000 ppm of crude tannin concentration without any growth inhibition. While growth of Rhizobium (VL-R1) and Bacillus halodurans (MTCC 7181) was inhibited by crude tannin concentrations of 50 and 100 ppm respectively of both water and solvent extracted tannins. Among the fungal genera, Pleurotus djamor was found to tolerate up to 10000 ppm of crude tannins, while Trichoderma virescens (MTCC 6321) and T. reesii could tolerate up to 3000 ppm of both water extractable and acetone extractable crude tannins without any growth inhibition.     

Evaluation of antiviral activity of different origin compounds by flow cytometry

Against many viral diseases caused for example by HSV, EBV, CMV, HIV, RSV, HCV for which vaccines are not available, chemiotherapeutics seem to have the principal significance. High progress in development of new antiviral compounds is observed. In addition to synthetic compounds a large number of naturally occurring substances have been shown to posses antiviral activity. One of such substance is tannic acid. In this study comparison of antiviral activity of tannic acid, acyclovir (ACV) and ganciclovir (GCV) against cytomegalovirus (CMV) is presented. The MRC5 cells infected with CMV and treated with different compounds were analyzed by flow cytometry and cythopatic effect inhibition test for inhibition of virus replication and by MTT assay for cytotoxity. It has been shown that tannic acid has antiviral activity against cytomegalovirus and that expression of virus antigens measured as median fluorescence intensity (MFI) by flow cytometry can be used for evaluation of virus replication.     

Effect of phenolic compounds on protein cross-linking and properties of film from fish myofibrillar protein

The effects of several phenolic ocmpounds (caffeic acid, catechin, ferullic acid and tannic acid) at various concentrations (1, 3 and 5% based on protein) on cross-linking and properties of film from myofibrillar proteins of bigeye snapper (Priacanthus tayenus) were investigated. Among all phenolic compounds used, tannic acid exhibited the highest cross-linking ability on myofibrillar protein as evidenced by higher decrease in free amino groups with coincidentally lower band intensity of myosin heavy chain (MHC). In addition, the extent of protein cross-linking increased with increasing concentration of phenolic compounds. Addition of phenolic compounds could enhance mechanical properties of the resulting films. As phenolic compounds content increased, Young's modulus (E) and tensile strength (TS) of the films increased, while their elongation at break (EAB) decreased (P<0.05), suggesting stronger and stiffer film structure. At the same concentration used, tannic acid rendered the film with higher mechanical properties, compared to others. Phenolic compounds decreased film transparency and affected color of the films differently, depending on types and concentrations used. Films from myofibrillar proteins with and without polyphenol generally had the excellent barrier properties to UV light at the wavelength of 200-800nm. Therefore, it could potentially be used as inner packaging material for high-fat foods to prevent the lipid oxidation and thus prolonging the shelf-life of foods during storage.     

Purification and properties of S-adenosyl-L-methionine: caffeic acid O-methyltransferase from leaves of spinach beet (Beta vulgaris L).

1. An enzyme catalysing the methylation of caffeic acid to ferulic acid, using S-adenosyl-L-methionine as methyl donor, has been extracted from leaves of spinach beet and purified 75-fold to obtain a stable preparation. 2. The enzyme showed optimum activity at pH 6.5, and did not require the addition of Mg2+ for maximum activity. 3. It was most active with caffeic acid, but showed some activity with catechol, protocatechuic acid and 3,4-dihydroxybenzaldehyde. The Km for caffeic acid was 68 muM. 4. 4. The Km for S-adenosyl-L-methionine was 12.5 muM. S-Adenosyl-L-homocystein (Ki = 4.4 muM) was a competitive inhibitor of S-adenosyl-L-methionine. 5. The synthesis of S-adenosyl-L-homocysteine from adenosine and L-homocysteine and its consequent effect on caffeic acid methylation were demonstrated with a partially-purified preparation from spinach-beet leaves, which possessed both S-adenosyl-L-homocysteine hydrolase (EC 3.3.1.1) and adenosine nucleosidase (EC 3.2.2.7) activities. This preparation was also able to catalyse the rapid breakdown of S-adenosyl-L-homocysteine to adenosine and adenine; the possible significance of this reaction in relieving the inhibition of caffeic acid methylation by S-adenosyl-L-homocystein is discussed.     

Thiopental Anesthesia and Tannic Acid Diagnostic Enemas

The administration to albino rats of tannic acid as a retention enema (in doses of 0.2 g./kg. body weight and over) prolonged the duration of anesthesia induced by thiopental given immediately before, or 72 hours after, the tannic acid. This dose of tannic acid corresponds, on the basis of body weight, to a radiodiagnostic enema of 2 1. of 0.25% tannic acid in barium sulfate suspension given to a child weighing 25 kg. By excluding certain hypothermic effects of tannic acid, it was concluded that thiopental potentiation was probably due to impairment by the tannic acid of the liver''s ability to detoxify the barbiturate. The results suggest that a drug which is detoxified in the liver should be administered three to five days after a tannic acid-barium sulfate radiodiagnostic enema only with considerable caution.     

单宁酸对棉铃虫谷胱甘肽S转移酶的影响

通过培养基混药法,研究了植物次生物质单宁酸对棉铃虫Helicoverpa armigera（Hübner）谷胱甘肽S-转移酶活性的影响。谷胱甘肽S-转移酶活性随棉铃虫发育期的进程而变化,在卵期最低,5龄、6龄幼虫和成虫期最高。用含0.005%单宁酸的饲料饲喂棉铃虫后,5龄和6龄幼虫的谷胱甘肽S-转移酶活性明显降低,分别为对照的59%和67%。单宁酸低剂量、短时间处理棉铃虫幼虫,可诱导中肠和脂肪体中的谷胱甘肽S-转移酶的活性增加,高剂量或低剂量长时间处理没有诱导增加作用,甚至还有抑制作用。单宁酸连续处理4代,对棉铃虫6龄幼虫中肠谷胱甘肽S 转移酶均有抑制作用,对脂肪体谷胱甘肽S-转移酶活性无明显影响或有抑制作用。单宁酸处理的第4代幼虫对溴氰菊酯的敏感度有增加的趋势,对甲基对硫磷的敏感度没有明显改变。     

Preventive effect of tannic acid on 2-acetylaminofluorene induced antioxidant level, tumor promotion and hepatotoxicity: a chemopreventive study

Tannic acid, present in almost every food derived from plants, has been widely investigated as a chemopreventive agent because, apart from its use as a food additive, pharmacological studies have demonstrated its many health-promoting properties. In this study, we show the modulatory effect of tannic acid on 2-acetylaminofluorene (2-AAF)-mediated hepatic oxidative stress and cell proliferation in rats. 2-AAF (50 mg/kg body weight) caused reduction in hepatic glutathione content and the activities of hepatic anti-oxidant enzymes and phase-II metabolizing enzymes with an enhancement of xanthine oxidase activity, lipid peroxidation and hydrogen peroxide content. 2-AAF treatment also induced serum oxaloacetate and pyruvate transaminase, lactate dehydrogenase and gamma-glutamyl transpeptidase. Treatment of rats orally with tannic acid (125 and 250 mg/kg body weight) resulted in significant recovery of hepatic glutathione content, antioxidant and phase-II metabolizing enzymes. Also, significant decreases in lipid peroxidation, xanthine oxidase, hydrogen peroxide generation and liver damage marker enzymes were observed. The antiproliferative efficacy of the tannic acid was also evaluated. The promotion parameters induced (ornithine decarboxylase activity and DNA synthesis) by 2-AAF administration in the diet with partial hepatectomy (PH) were also significantly suppressed, dose dependently, by tannic acid. Hence, we propose that tannic acid might suppress the promotion stage via inhibition of oxidative stress and polyamine biosynthetic pathway.     

大豆胰蛋白酶抑制剂与棉酚或丹宁混用对棉铃虫中肠蛋白酶和生长率的影响

本文报告了大豆胰蛋白酶抑制剂(STl)与棉酚、丹宁酸单一和协同作用对棉铃虫Helicoverpa armigera(Hubner)幼虫中肠蛋白酶活性和生长速率的影响。在离体条件下,STI、棉酚和丹宁酸均对中肠蛋白酶有抑制作用,以STI的作用最强。活体试验表明,人工饲料中0.84%(干重)的S丁I对强碱性类胰蛋白酶活力有显著抑制作用;0.3%丹宁酸则对弱碱性类胰蛋白酶和总蛋白酶活力有显著抑制作用;0.3%棉酚对几种蛋白酶活力的影响均不显著。三者均能显著抑制幼虫的生长,而Sn与棉酚或丹宁酸的协同作用比三者的单独作用更能有效地抑制幼虫的生长发育和中肠蛋白酶活性。     

Characterization of tannin acylhydrolase activity in the ruminal bacterium Selenomonas ruminantium

A strain of the anaerobe Selenomonas ruminantium subsp. ruminantium that is capable of growing on tannic acid or condensed tannin as a sole energy source has been isolated from ruminal contents of feral goats browsing tannin-rich Acacia sp. Growth on tannic acid was accompanied by release of gallic acid into the culture medium but the bacterium was incapable of using gallic acid as a sole energy source. Tannin acylhydrolase (EC 3.1.1.20) activity was measured in crude cell-free extracts of the bacterium. The enzyme has a pH optimum of 7, a temperature optimum of 30-40 degrees C and a molecular size of 59 kDa. In crude extracts, the maximal rate of gallic acid methyl ester hydrolysis was 6.3 micromol min(-1) mg(-1) of protein and the K(m) for gallic acid methyl ester was 1.6 mM. Enzyme activity was displayed in situ in polyacrylamide and isoelectric focusing gels and was demonstrated to increase 17-fold and 36-fold respectively when cells were grown in the presence of gallic acid methyl ester or tannic acid.     

Production, properties and application to biocatalysis of a novel extracellular alkaline phenol oxidase from the thermophilic fungus Scytalidium thermophilum

Scytalidium thermophilum produces an extracellular phenol oxidase on glucose-containing medium. Certain phenolic acids, specifically gallic acid and tannic acid, induce the expression of the enzyme. Production at 45°C in batch cultures is growth-associated and is enhanced in the presence of 160 μM CuSO₄.5 H₂O and 3 mM gallic acid. The highest enzyme activity is observed at pH 7.5 and 65°C, on catechol. When incubated for 1 h at pH 7 and pH 8, 95% and 86% of the activity is retained. Thermostability decreases gradually from 40°C to 80°C. Estimated molecular mass is c. 83 kDa, and pI is acidic at c. 5.4. Substrate specificity and inhibition analysis in culture supernatants suggest that the enzyme has unique properties showing activity towards catechol; 3,4-dihydroxy-l-phenylalanine (l-DOPA); 4-amino-N, N-diethylaniline (ADA); p-hydroquinone; gallic acid; tannic acid and caffeic acid, and no activity towards l-tyrosine, guaiacol, 2,2′-azino-bis(3-ethyl-benzthiazoline-6-sulphonic acid) (ABTS) and syringaldazine. Inhibition is observed in the presence of salicyl hydroxamic acid (SHAM) and p-coumaric acid. Enzyme activity is enhanced by cetyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP), and the organic solvents dimethyl sulfoxide (DMSO) and ethanol. No inhibition is observed in the presence of carbon monoxide. Benzoin, benzoyl benzoin and hydrobenzoin are converted into benzil, and stereoselective oxidation is observed on hydrobenzoin. The reported enzyme is novel due to its catalytic properties resembling mainly catechol oxidases, but displaying some features of laccases at the same time.     

Tannic acid, a potent inhibitor of epidermal growth factor receptor tyrosine kinase

Increasing evidence supports the hypothesis that tannic acid, a plant polyphenol, exerts anticarcinogenic activity in chemically induced cancers. In the present study, tannic acid was found to strongly inhibit tyrosine kinase activity of epidermal growth factor receptor (EGFr) in vitro (IC50 = 323 nM). In contrast, the inhibition by tannic acid of p60(c-src) tyrosine kinase (IC50 = 14 microM) and insulin receptor tyrosine kinase (IC50 = 5 microM) was much weaker. The inhibition of EGFr tyrosine kinase by tannic acid was competitive with respect to ATP and non-competitive with respect to peptide substrate. In cultured cells, growth factor-induced tyrosine phosphorylation of growth factor receptors, including EGFr, platelet-derived growth factor receptor, and basic fibroblast growth factor receptor, was inhibited by tannic acid. No inhibition of insulin-induced tyrosine phosphorylation of insulin receptor and insulin-receptor substrate-1 was observed. EGF-stimulated growth of HepG2 cells was inhibited in the presence of tannic acid. The inhibition of serine/threonine-specific protein kinases, including cAMP-dependent protein kinase, protein kinase C and mitogen-activated protein kinase, by tannic acid was only detected at relatively high concentration, IC50 being 3, 325 and 142 microM respectively. The molecular modeling study suggested that tannic acid could be docked into the ATP binding pockets of either EGFr or insulin receptor. These results demonstrate that tannic acid is an in vitro potent inhibitor of EGFr tyrosine kinase.