Determination Of Persimmon Tannin And Its Metabolism By Rats’ Intestinal Flora

Persimmon tannins arehighly polymerized polyphenolic compounds with complex chemical structure. Previous studies had proved that persimmon tannin exerted many physiological activities such as antioxidant activity, anti-inflammatory activity and atherosclerosis prevention, et al. It’s important for accurate quantification of tannin to evaluate its health benefits and potential risk in persimmon pμLp and related products. However, previous studies found that quantification of polyphenols in persimmon related products using the widely employed colorimetric methods is inaccurate and problematic. In our study, Folin-Ciocalteu method, vanillin assay, butanol hydrochloride method and4-(Dimethylamino)cinnamaldehyde assay were chosen to measure the contents of tannin and the most suitable standards in all four methods were determined. Meanwhile, comparison of intestinal metabolism of four persimmon characteristic units, i.e. B-type EC dimer, A-type EC dimer, A-type ECG dimer and A-type EGCG dimer was made. And the metabolism of persimmon tannin in rats was also included. The main resμLts were as follows:1Develop a suitable standard for accurate determination of total phenol in persimmon productsThe main fractions of persimmon tannin, i.e. PT20, PT40, PT60were prepared and the polyphenol contents were determined as91.40%,94.40%,92.21%, respectively, using formaldehyde precipitation method. In Folin-Ciocalteu assay, PT40was recommended as the most suitable standard in determining the phenol content of persimmon extracts. In the vanillin assay, A-type EGCG dimer or A-type ECG dimer were superior to the commonly used C as standards and ECG was also an alternative. In butanol hydrochloride method, PT40was also the most suitable standard. The ability of color manifestation of all the standards was so bad that it was unsutibale of DMAC assay as the method to determine the contents of persimmon products.2Intestinal metabolism of four dimersMetabolism in different extent of four dimers accrued by the action of rat intestinal bacteria. The rates of metabolism were different, and A-type EC dimer was least susceptible to intestinal flora. A-type ECG dimer and A-type EGCG dimer were metabolism fastest.There were both similarities and differences of four different dimers’ metabolites. Hydroxyphenyl acetic acid was generated by both A-type EC dimer and B-type EC dimer. Transformation from A-type EC dimer to B-type EC dimer was also detected. Both monomeric compounds catechin and EGCG were found after the metabolism of B-type EC dimer and A-type EGCG dimer, respectively.Total antioxidant capacity, ABTS+· scavenging ability, DPPH· scavenging ability were used to evaluation of antioxidant capacity of intestinal flora metabolites of procyanidin dimers. The resμLts showed that6hours later, the antioxidant activity of metabolites increased at different extent in the antioxidant system of T-AOC and ABTS+·. And the antioxidant ability decreased obviously in the following12h until24h. In DPPH· scavenging ability experiment, no decline in antioxidant ability was found, which indicated that the antioxidant capacity of proanthocyanidins will increase with the intestinal flora’ metabolism.3Metabolism of persimmon tannin in ratsRats were administrated persimmon tannin after fasting18h. The resμLts indicated there was little difference in metabolites in the urine of rats administrated with or without persimmon tannin. Persimmon tannin was detected in the fecal. It was worth noting that many peaks were found in the hump, which is much different from the HPLC fingerprint spectrum graph of persimmon tannin. Somepeaks were detected by mass spectrometry in the comparison between control group and the experimental group. It meant that metabolism tookplace of tannin by rats’ intestinal flora to some extent.