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Tannic acid
About: Tannic acid is a research topic. Over the lifetime, 2862 publications have been published within this topic receiving 67766 citations.
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TL;DR: Treatment of sheep erythrocytes with suitable concentrations of tannic acid render them capable of adsorbing certain protein molecules from solution in saline, and small amounts of the antigens can be detected through their power to inhibit hemagglutination of the treated cells.
Abstract: Treatment of sheep erythrocytes with suitable concentrations of tannic acid render them capable of adsorbing certain protein molecules from solution in saline. Red cells which have adsorbed proteins in this way are agglutinated after washing by the homologous antiprotein sera, even by high dilutions. Through hemagglutination sera can be titrated for antibodies against antigens adsorbed on the cells exposed to tannic acid. Furthermore, small amounts of the antigens can be detected through their power to inhibit hemagglutination of the treated cells.
1,209 citations
TL;DR: In this paper, a method for gravimetric determination of tannins based on binding with insoluble polyvinylpyrrolidone (PVP) is presented.
Abstract: . A method for gravimetric determination of tannins based on binding with insoluble polyvinylpyrrolidone (PVP) is presented. The gravimetric method gives the absolute amount of tannins and avoids problems of standards associated with spectrophotometric methods. The method was applied to nine browse and tree leaves. The values obtained correlate significantly with tannins determined spectrophotometrically, protein precipitation capacities and protein precipitable phenotics. This method together with other tannin assays will be useful in nutritional studies. The present study also demonstrates the different behaviour of tannic acids from different commercial sources towards PVP suggesting the presence of different moieties in tannic acids from different commercial sources and even among batches from the same source thereby affecting the results obtained using the spectrophotometric methods. Use of well-defined tannic acid as a standard in spectrophotometric methods is suggested which will allow meaningful comparison of values obtained from different laboratories.
1,091 citations
TL;DR: The tannin content of crude plant exts. was detd. by adding the sample to a std. soln. as discussed by the authors, and measuring the absorbance at 510 nm after adding FeCl3.
Abstract: The tannin content of crude plant exts. or of purified prepns. was detd. by adding the sample to a std. soln. of protein, isolating the insol. tannin-protein complex, dissolving it in alk. soln., and measuring the absorbance at 510 nm after adding FeCl3. Plots of absorbance as a function of the amt. of tannin are linear for 0.20-1.0 mg tannic acid and partially purified sorghum tannins. Nontannin components of crude MeOH exts. of sorghum and cowpeas do not interfere with the assay. The results of the pptn. method are qual. similar to those obtained by vanillin assay. The pptn. assay can be used to study the effects of pH and other parameters on tannin-protein interactions
921 citations
TL;DR: Tannic acid merits further investigation as a possible adjuvant agent against S. aureus skin infections treated with beta-lactam antibiotics.
Abstract: We examined the antibacterial action of several tannins on plasma coagulation by Staphylococcus aureus and the effect of conventional chemotherapy combined with tannic acid below the MIC. Coagulation was inhibited in plasma containing tannic acid (100 mg/L), gallic acid (5000 mg/L), ellagic acid (5000 mg/L), (-)-epicatechin (1500 mg/L), (-)-epicatechin gallate (500 mg/L) or (-)-epigallocatechin gallate (200 mg/L) after incubation for 24 h. All tannins inhibited coagulation at a concentration below the MIC. The MICs of oxacillin and cefdinir for S. aureus were reduced to < or = 0.06 mg/L in Mueller-Hinton agar plates with tannic acid (100 mg/L) at a concentration below the MIC. The antistaphylococcal activity of tannic acid was reduced in plates with 10% rabbit blood, but not in those with 10% rabbit plasma. Membranous structures formed in a culture medium containing equal proportions of plasma and tryptic soy broth after incubation for 24 h. The colony counts of S. aureus in membranous structures in the medium containing oxacillin (40 mg/L) and tannic acid (100 mg/L) were c. 10-fold lower than those in medium containing oxacillin (40 mg/L) alone (P < 0.01). Tannic acid merits further investigation as a possible adjuvant agent against S. aureus skin infections treated with beta-lactam antibiotics.
780 citations
TL;DR: The methodology associated with the Folin-Ciocalteau phenol reagent was investigated and the performance characteristics of a method using sodium carbonate as the supporting medium were determined as discussed by the authors.
736 citations