Anti-oxidant properties and anti-hemolytic activity of Psidium guajava, Pandanous odorus and Rhinacanthus nasutus

The ethanolic extracts of leaves of Psidium guajava (PG), Pandanous odorus (PO),Rhinacanthus nasutus (RN) contained polyphenolic compounds in the order of PG > RN > PO. All the extracts exhibited 2,2-diphenyl-1-picryhydrazyl (DPPH) and 2,2’-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radicals scavenging activities. PG showed a marked antioxidant effect whereas PO and RN were comparable. Interestingly, they were able to bind with ferric (Fe3+) and ferrous (Fe2+) ion and completed within 5 min of incubation times. In accordance with previous results, PG extract could effectively protect erythrocytes from iron induced hemolysis with the activity higher than PO and RN. Based on all results, tested leaf extracts of three Thai medicinal plants might be used for alleviating or preventing harmfulness in many oxidative stress disorders. Key words: Psidium guajava, Pandanous odorus, Rhinacanthus nasutus, antioxidant, iron binding capacity, anti-hemolysis activity.