Studies on component analysis and antioxidant charactersization and inhibition of tyrosinase activity of persimmon peel extracts

• Main Authors: Ya- Wun Jhuang, 莊雅雯
• Other Authors: Jan-Jeng Huang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/35505013283161594167

碩士 === 國立嘉義大學 === 食品科學系研究所 === 95 === In this study, persimmon (Bull Heart persimmon, Diospyrous kaki L.) was harvested subject to the process of removing astringency from October to Novermber (2005-2006) and was peeled from persimmon fruits process. The persimmon peels was employed as the raw material. The persimmon peel was pulverized after different drying methods. The peel was extracted with water/ethanol extraction, lyophilized and pulverized. Content of total phenolic and flavonoids and the inhibitory effect on linoleic acid autoxidation for the extractions was determined. Results indicated that the highest content of extraction yield and total phenolic is the persimmon peel extracts (PPE) by lyophilizing from 30% ethanol concentration extraction. In the case of purification polyphenolic, Amberlite XAD-7 and XAD-16 adsorbent resins were chosen followed by column chromatography. The persimmon peel extracts were eluted by four solvents from XAD-7 and XAD-16 column chromatogram on extracts from persimmon peel(PPE). The persimmon peel extracts (PPE) by XAD-7 and XAD-16 column chromatogram was to separate into thirdteen, twelve fractions respectively. The highest recovery of fractions was eluted by H2O/MeOH=7/3(v/v), but its phenolic content is the lowest. In contrast, the other fractions had lower recovery but much higher phenolic content. As for the phenolic recovery, most polyphenolic compounds could be recovered from XAD-7 adsorbent resin, however, partial polyphenolic compounds were retained in XAD-16 adsorbent resin.The highest total phenolic and flavonoids content of fractions was eluted by H2O/MeOH=3.5/6.5(v/v). Results indicated polyphenolic of persimmon peel extracts are gathered up in 65% methanol between 30% and 80% methanol polarity. The effective fractions in linoleic acid autooxidation were d-I, d-II, D-I and D-II. The scavenging effect on DPPH radical of fraction c-II, c-III, B-III and C-III were effective. Fraction d-I, d-II, C-V, D-I and D-II had stronger chelating activity than other fractions. The 50% chelating ability of fraction D-I is 20 ppm total phenolic concentration and its ability was higher than that of 20 ppm EDTA (33.6%), however, the total phenolic concentration in 200 ppm for fraction D-I, d-I and d-II had chelating Fe2+ ability up to 80%. Fractions c-II, c-III, B-II and B-III had stronger reducing power. The reducing power in 80 ppm total phenolic concentration were higher than catechin and vitamin C, and their reducing power increased linearly with phenolic concentration. All the above results suggested that the more effective antioxidant fractions separated by both XAD-7 and XAD-16 column chromatography were mainly contributed by the chelating effect of Fe2+, followed by the scavenging effect of DPPH radical. In inhibition of tyrosinase activity test. Fraction d-II, C-I and D-I had effective tyrosinase activity inhibition. Fractions of c-IV, d-I, C-III, C-IV and C-V in high phenolic concentration (500 ppm) showed tyrosinase enhancing activity. According to analysis of antioxidant properties, its polarity fractions and HPLC profile, the antioxidant activity of fraction d-I, d-II, D-I and D-II are quercetin, rutin (flavones) compounds. Nevertheless, lower antioxidant activity but higher reducing power and scavenging effect on DPPH radical of fraction c-II, c-III, B-II and B-III, their constituents are the phenolic acid. The constituents of tyroinase inhibiting activity are likely quercetin. Even so the constituents of tyroinase enhancing activity are similar to caffeic acid in phenolic acid. To sum up, the polyphenolic in persimmon peel had both antioxidant activity and tyrosinase inhibiting activity, and its constituents are mainly quercetin and rutin.