Publications (4)10.04 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: The in vitro oxidative hemolysis of human red blood cells (RBCs) was used as a model to study the free radical-induced damage of biological membranes and the protective effect of resveratrol (3,5,4′-trihydroxy-trans-stilbene, 1) and its analogues, i. e., 4-hydroxy-trans-stilbene (2), 3, 5-dihydroxytrans-stilbene (3), 3,4-dihydroxy-trans-stilbene (4), 4,4′-dihydroxy-trans-stilbene (5) and 2, 4, 4′-trihydroxy-trans-stilbene (6). The hemolysis of RBCs was induced by a water-soluble free radical initiator 2, 2′-azobis (2-amidinopropane hydrochloride) (AAPH). It was found that addition of AAPH at 37 °C to the suspension of RBCs caused fast hemolysis after a short period of inhibition period, and addition of 1–6 significantly suppressed the hemolysis. Compound 4 which bears an ortho-dihydroxyl functionality showed much more effective anti-hemolysis activity than that of resveratrol and the other analogues.
- [Show abstract] [Hide abstract] ABSTRACT: Resveratrol (3,5,4'-trans-trihydroxystilbene) is a natural phytoalexin present in grapes and red wine, which possesses a variety of biological activities including antioxidative activity. To find more efficient antioxidants by structural modification, resveratrol analogues, that is, 3,4-dihydroxy-trans-stilbene (3,4-DHS), 4,4'-dihydroxy-trans-stilbene (4,4'-DHS), 4-hydroxy-trans-stilbene (4-HS) and 3,5-dihydroxy-trans-stilbene (3,5-DHS), were synthesized and their antioxidant activity studied for the free radical-induced peroxidation of rat liver microsomes in vitro. The peroxidation was initiated by either a water-soluble azo compound 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) or Fe(2+)/ascorbate, and monitored by oxygen uptake and formation of thiobarbituric acid reactive substances (TBARS). It was found that all of these trans-stilbene derivatives are effective antioxidants against both AAPH- and iron-induced peroxidation of rat liver microsomes with an activity sequence of 3,4-DHS>4,4'-DHS>resveratrol>4-HS>3,5-DHS. The remarkably higher antioxidant activity of 3,4-DHS is discussed.
- [Show abstract] [Hide abstract] ABSTRACT: Antioxidative effects of the principal polyphenolic components extracted from green tea leaves, i.e. (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), and gallic acid (GA), against free radical initiated peroxidation of rat liver microsomes were studied. The peroxidation was initiated by a water-soluble azo compound 2,2'-azobis(2-amidinopropane hydrochloride (AAPH). The reaction kinetics was monitored by oxygen uptake and formation of malondialdehyde (MDA). Kinetic analysis of the antioxidation process demonstrates that these green tea polyphenols (GOHs), especially EC and ECG which bear ortho-dihydroxyl functionality, are good antioxidants for microsomal peroxidation. The antioxidant synergism of these GOHs with the endogenous alpha-tocopherol (TOH) (vitamin E) is also discussed.
- [Show abstract] [Hide abstract] ABSTRACT: Peroxidation of linoleic acid was initiated by azobis(isobutyronitrile) in tert-butyl alcohol and inhibited by -tocopherol, β-carotene and retinal, either alone or in combination. Significant antioxidant synergism and a novel mutual protection of -tocopherol and β-carotene were found and the possible involvement of retinal in the process is discussed.
Kao-lan-hsien, Gansu Sheng, China
- State Key Laboratory of Applied and Organic Chemistry