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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.

This study investigated the antioxidant and anti-inflammatory activities of g-oryzanol rich extracts from Thai glutinous purple rice bran. Five purple rice bran samples, PAH E-KAW,GAM PEUAK, NIAW DAM, GAM THOR and GAM BOUNG were obtained from local glutinous cultivars in Northern Thailand. The g-oryzanol rich extracts were prepared by soxhlet extraction and semi-purified by column chromatography. The extracts contained g-oryzanol in the range of 1.23 to 9.14% w/w. The extracts containing more than 5% w/w of g-oryzanol (PAH E-KAW, GAM THOR and GAM BOUNG) were selected for investigation of antioxidant and anti-inflammatory activities; and first standardized by adding the equivalent amount of each extract to give 10% w/v g-oryzanol. All of extracts exerted moderate ABTS·+ and superoxide anion scavenging activity. GAM BOUNG exhibited the highest ABTS·+ scavenging activity with VCEAC value of 201.3 ± 1.84 mg L-ascorbic acid/ gram extract, TEAC value of 267.2 ±2.96 mg Trolox/ gram extract and QEAC value of 137.4 ± 3.41 mg Quercetin/ gram extract followed by PAH E-KAW and GAM THOR, respectively. GAM BOUNG also showed the highest activity on superoxide anion scavenging at IC50 = 12.56 ± 0.13 mg/ml followed by GAM THOR and PAH E-KAW. Furthermore, GAM BOUNG exhibited a strong inhibition effect on linoleic acid peroxidation (IC50 = 36.79 ± 2.97 mg/ml). Additionally, all of the extracts showed a strong anti-inflammatory activity through inhibitory effect on nitric oxide (NO) production in combined LPS-IFN-g-activated RAW 264.7 murine macrophage cells. GAM BOUNG exhibited the highest inhibitory effects on NO production (IC50 = 29.32 ± 2.21 mg/ml), without exerting cytotoxicity followed by GAM THOR and PAH E-KAW. These results indicate that g-oryzanol rich extracts from Thai glutinous purple rice bran are acting as a lipophilic radical scavenger better than a hydrophilic radical scavenger. Moreover, these extracts exert a potent anti-inflammatory activity. Key words: Purple rice bran, g-oryzanol, antioxidation, anti-inflammatory.