Study On Inhibition Of LDL And HDL Oxidation By Five Flavoniods

Lipoprotein oxidation, including Ox-LDL, Ox-HDL and Ox-VLDL, is one of the most important induce mechanism of atherosclerosis (As). Therefore, it is an important anti-atherogenic means to resort to preventing lipoprotein from being oxidized.Flavoniods, as natural antioxidants, can get rid of superoxide anions, hydroxyl radicals and lipid peroxyl radicals. Some have been used in prevention and cure of atherosclerosis. In order to study more flavoniods' effects on LDL and HDL oxidation induced by Cu²⁺ in vitro, five flavonoids were incubated with LDL or HDL respectively beforehand, which were Quercetin, Isorhamnetin, Rutin, Hesperidin and Puerarin; the agarose gel relative electrophoretic mobility (REM), absorbance at 234nm (A_234nm), fluorescence of thiobarbituric acid reaction substance (TBARS) and protein carbonyls content of LDL and HDL were observed.The result indicated what is as below:1. All the five flavoniods are inhibitor of LDL and HDL oxidation. Inthe LDL oxidation induced induced by Cu2+ for 2, 4, 6, 8, 12 and 24 hours and incubated with Quercetin, Isorhamnetin, Rutin, Hesperidin and Puerarin of 5 umol/L, the kinetic changes of A234nni, REM, TBARS and protein carbonyls formation showed lag phases of 2—4 h> 2—6 h, 2h and 2—4 h respectively; and reduced by 27.7—49.6 °/11.1 —21.2% and 3.3—19.2 % (PO.001) ;24.1-38.6%> 23.3—37.7%, 15.7-32.0 %(P<0.001) and 9.20-28.3 %, 7.0-22.5 %(P<0.01); 19.8-34.3 %, 18.6-30.3 %, 19.0-28.1 %, 13.7-21.3 % and 19.5-22.8 % (PO.001) ; and 36.4-56.8 %, 20.1-52.4%, 12.8-50.3% (PO.001 X5.0—43.8% (PO.05) and 5.0-47.0% (PO.01) .As the same, In the HDL oxidation induced by Cu2+ for 2, 4, 6, 8, 12 and 24 hours and incubated with Quercetin, Isorhamnetin, Rutin and Hesperidin of 5 umol/L, the kinetic changes of A234nm, REM, TBARS and protein carbonyls formation showed lag phases of 2—4h, 2—6lu 2—4hand 2—4h respectively; and reduced by 24.2—49.0 %> 16.3—46.9 %(P<0.001 )> 9.4—42.0 % (.PO.01) and 1.5—30.0 % (PO.001) ; 3.0—25.0 %, 9.2-25.2 %, 4.0—20.7 % and 1.4—13.3 % (PO.05) ; 7.9—34.1 % (P<0.05)> 9.2—28.4 % (PO.01 X 1.2—26.8 % and 6.6—18.8 % (P<0.05); and 31.9—50.4 %> 11.6-45.2 %, 18.6-64.6% and 14.4-59.9% (PO.001) .Only protein carbonyls formation of Puerarin group reduced by 14.1 — 52.1%(P<0.001), its A234nni, REM, TBARS reduced in small range.2. Isorhamnetin and Hesperidin dose-dependent experiments showed that the two flavonionds began inhibited LDL and HDL oxidation at the concentration of 2.5 umol/L. and their inhibition capability grew with the concentration correspondingly, and reach to maximum at the concentration of5-15umol/L.3. During LDL and HDL oxidation induced by Cu2+ and incubated with Quercetin, Isorhamnetin, Rutin, Hesperidin and Puerarin, A234nm, REM, TBARS and protein carbonyls formation showed lag phases of 2—4 h> 2—6 h> 2 h and 2—4 h; and 2 h, 2—6 h, 2—4 h and 2—4 h; and reduced by 5.7— 45.9%, 7.0-26.0%, 19.5-31.5 % and 13.7—42.2 %; and 4.4—32.1 %, 2.61-9.8 %, 3.2-22.4 % and 11.6—45.0 % respectively.Quercetin, Isorhamnetin, Rutin, Hesperidin and Puerarin are in descending order of antioxidative capability. Puerarin showed no inhibition of HDL oxidation.