ANTIOXIDANT ACTIVITY OF FLAVONES FROM SCUTELLARIA-BAICALENSIS IN LECITHIN LIPOSOMES

The antioxidant effect of a trihydroxyflavone extract from Scutellaria baicalensis on oxidation induced by ultraviolet light, was studied wi th phosphatidylcholine liposome membrane. Also, as standards, the anti oxidative activity of baicalin, wogonin, baicalein and butylated hydro xytoluene (BHT) was investigated. Comparison of the protective effects of the compounds studied against photoinduced lipid peroxidation in l ecithin liposome membranes showed that: (1) the inhibitory effect of t hose compounds (at 1.2 mol% antioxidant content in liposomes) on TBA r eactive materials from lipid peroxidation decreased in the order of ba icalin > BHT congruent to Scutellaria baicalensis. These were found mu ch greater than wogonin and baicalein: (2) the depressed effect of tho se compounds (at 1.1 mol% compounds content in liposomes) on the produ ction of conjugated dienes (proportional to oxidation index) could hz classified as follows: Scutellaria baicalensis congruent to baicalin > BHT. these three were found more active much greather than baicalein and wogonin. Results obtained by ESR measurer,lent confirm that Scutel laria baicalensis extract and the BHT compound significantly depressed the effect of liposome oxidation. It was found that the new trihydrox yflavones of Scutellaria baicalensis, ensured a very satisfactory conc entration-dependent protection of the liposome membrane against UV-ind uced oxidation. These findings suggest that some of the beneficial eff ects of the extract of the Scutellaria baicalensis can be mediated in certain diseases (for example in skin diseases) by their ability to sc avenge free radicals and by their protective effect on lipid peroxidat ion caused by sunlight irradiation.