ANTIOXIDANT ACTIVITIES OF SOME EXTRACTS OF THYMUS-ZYGIS

The antioxidant activities of methanol and ethyl ether extracts obtain ed from Thymus zygis, collected during the flowering or non-flowering period, were evaluated and compared. To investigate this potential, ex tracts were tested on their capacity to react with diphenylpicrylhydra zyl (DPPH) in a homogeneous medium, and to inhibit Fe2+/ascorbate-indu ced membrane Lipid peroxidation, as estimated by the formation of thio barbituric acid-reactive substances (TEARS). Although methanol extract s reduce DPPH radicals more efficiently than ethyl ether extracts, sug gesting a potent radical scavenger activity, the ethyl ether extracts were found to be most active in inhibiting lipid peroxidation in sarco plasmic reticulum (SR) membranes. In addition, both extracts present p eroxyl and superoxide radical scavenging activities. Peroxyl radicals were generated by the water soluble 2,2'-azobis(2-amidinopropane) dihy drochloride (AAPH) azoinitiator, and the scavenging activities of the extracts were measured by the inhibition of cis-parinaric acid (PnA) f luorescence decay in SR. Superoxide radicals were generated either by an enzymatic or a non-enzymatic system, and the scavenger ability was evaluated by the inhibition of nitroblue tetrazolium reduction. Methan olic extracts are more potent as scavengers of peroxyl and superoxide radicals than the ethyl ether extracts. Apparently, there is a relatio nship between antioxidant potency and the total phenolic groups conten t in each extract.