Isolation, Purification And Bioactivity Of Polyphenol From

In this study, the Nephelium lappaceum Linn peels was selected as research material, and the Nephelium lappaceum Linn peels polyphenols (NP) were purified using a macroporous adsorption resins method. Analyses the composition and content of NP before and after purification.The antioxidant activity of NP was evaluated by three kinds of antioxidant system (DPPH·, ABTS·+ and FRAP) and investigate the protective effect of the purification NP on AAPH-induced pET23b plasmid DNA. Also studied the protective effect of the purification NP on H2O2 induced oxidative stress in HepG2 cells. The inhibitory effects NP on the non-enzymatic glycosylation of proteins were studied in an in vitro model non-enzymatic glycosylation reaction system consisting of bovine serum albumin and glucose. In the hope of providing a theoretical basis for the rational utilization of Nephelium lappaceum Linn peels. The major findings were presented as follows:1. By comparing the NP separation effect of five different types (S-8, NKA-9, AB-8, D4020, and HPD 600) of macroporous resin, NKA-9 was selected as the ideal adsorbent as it had a strong adsorption ability and a high desorption rate, which was a better resin to enrichment the NP. Through a nonlinear curve fitting with adsorption models, it was found that the adsorption of NP by NKA-9 resin was not ideal monolayer adsorption, but with part of the multilayer adsorption. Static and dynamic adsorption, and desorption experiment results indicated that the ideal technological parameters keeping the temperature for 30℃, the concentration for 4.37 mg/mL, the original pH value, sample volume 350 mL, flow velocity 1.0 mL/min and the adsorption rate was 93.92%. Until reaching adsorption balance, dynamically elute with 120 mL 60% ethanol, and the desorption flow velocity was 1.0 mL/min. The desorption rate was 90.45% and the elution peak relatively was concentrated, symmetry, no trailing phenomenon.2. The results demonstrated that there were 14 kinds of polyphenols before purification. After purification, in addition to caffeic acid, the content of the other four acids (5-sulfosalicylic acid, syringic acid, ellagic acid and 3,4-dimethoxybenzoic acid) have different degrees of increase, the content of ellagic acid was four times as large as before purification.3. The NP exhibited strong antioxidant activities in the three in vitro assaying models of reducing power, ABTS-+and DPPH-scavenging activities. The values of EC50 and IC50 for the three assaying models were 1.56,1.72 and 2.67 μg/mL (before purification) and 0.87,1.14 and 1.67 μg/mL (after purification), compared with the previous purification, purified antioxidant activity increased significantly. Gel electrophoresis experiment indicated that the optimal concentration of AAPH-induced pET23b plasmid DNA was 100 mmol/L. And found that NP had a significant protective effect on DNA strand breaks induced by AAPH, showing a concentration dependent velationship.4. Compared with the blank control group, the treatment of HepG2 cells with purification NP (5～80 μg/mL) for 24 h was without significant effect on cell viability (p>0.05). The results showed that the optimal H2O2 concentration determined was 0.9 mmol/L. The purification NP can effectively restrain H2O2 induced damage of HepG2 cells, when the concentration of NP was 20μg/mL, SOD activity relative level rose to 113.39%, the relative level of ROS dropped to 88.44% and reduce apoptosis proportion to 19.56%.5. The inhibitory effects NP on the non-enzymatic glycosylation of proteins showed that NP has a certain inhibitory effect on the Amadori products, dicarbonyl compounds and advanced glycation end products (AGEs), and its effect was stronger than the positive control amino guanidine. At 7 days, the inhibition rates for the three assaying models were 30.8%n 32.79%and 32.52%(beforepurification) and 37.87%、43.26%and 44.07%(after purification).