Antioxidant and heme oxygenase-1 (HO-1)-induced effects of selected Taiwanese plants

Recent studies have shown biological effects of heme oxygenase-1 (HO-1) induction and antioxidation in cardiovascular disorders. The ethanol extracts of leaves of 12 selected indigenous Taiwanese plants were investigated for their antioxidant activities, evaluated using assays of 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl, and superoxide radicals scavenging and reducing power activities as well as the induction of heme oxygenase-1 (HO-1). Acer alboputpurascens. Cinnamomum kanehirai, Diospyros discolor, Excoecaria kawakamii, Koelreuteria henryi, and Syzygiun formosanum showed better DPPH-scavenging activities than the other plants. IC50 values ranged from 1.7 to 8.7 mu g/mL. Excepting Millettia pulchra var. microphylla and Pittosporum moluccanum, the extracts displayed hydroxyl-scavenging activities (IC50 of 0.16-0.67 mu g/mL). A. albopurpurascens, D. discolor, K. henryi, and S.formosanum also showed good superoxide anion radical scavenging activities and IC50 values ranged from 12.9 to 28.5 mu g/mL. D. discolor, K. henryi, and S. formosanum showed potent reducing power and M. pulchra var. microphylla and S. formosanum exhibited potent HO-1 induced activity. These active plant extracts also contained abundant phenolic constituents. The present results provide candidates to isolate the active constituents and develop natural antioxidants. (c) 2005 Elsevier B.V. All rights reserved.