In vitro antioxidant activities of the methanol extracts of four Helichrysum species from Turkey
This study was designed to examine the in vitro antioxidant activities of the methanol extracts of four Helichrysum species (Helichrysum noeanum Boiss., H. chionophilum Boiss. & Bal., H. plicatum DC. subsp. plicatum, H. arenarium (L.) Moench. subsp. aucheri (Boiss.) Davis & Kuphicha). The extracts were screened for their possible antioxidant activitiy by two complementary test systems, namely DPPH free radical-scavenging and beta-carotene/linoleic acid systems. In the first case, non-polar subfractions of the methanol extracts of Helichrysum species studied did not show any antioxidam activity, while the most active one was H. chionophilum (IC50 = 40.5 mug/ml) among the polar subfractions. In the beta-carotene/linoleic acid test system, inhibition rates of the oxidation of linoleic acid of H. noeanum and H. arenarium were very close to each other. The inhibition rate of the synthetic antioxidant BHT was determined to be 96%. Since the polar extracts of Helichrysum species dealt with here exhibited interesting antioxidant activities when compared to BHT, we believe that it would be useful to take the results into consideration as an alternative for food processing industries. (C) 2004 Elsevier Ltd. All rights reserved.