In vitro antioxidant and anti-inflammatory activities of Costus igneus leaf fractions

Abstract

Costus igneus Nak is an ethnobotanical plant used in the management of several inflammatory and oxidative stress-related disorders. There is a need to scientifically validate its use in ethnomedicine. This study investigated the antioxidant and anti-inflammatory activities of fractions from ethanol extract of C. igneus leaf using in vitro methods. Crude ethanol extract of C. igneus leaf was successively partitioned to obtain hexane, ethyl acetate, butanol and aqueous fractions. The fractions were screened for in vitro anti-inflammatory activity using erythrocyte membrane stabilization and inhibition of protein denaturation assays. In vitro antioxidant activity was carried out using 1-1-diphenyl, 2-picryl hydrazyl (DPPH), nitric oxide and hydrogen peroxide radical scavenging assays. Data were analyzed using GraphPad Prism 6.0 and p value was set at 0.05. The percentage yield of the crude ethanol extract of C. igneus leaf was 25.40%. The aqueous fraction (37.05%) had the highest percentage yield, followed by butanol fraction (34.33%), hexane fraction (16.58%) and the ethyl acetate fraction (12.04%). Anti-inflammatory studies showed that C. igneus butanol fraction (CIBF) had the highest erythrocyte membrane stabilizing effect (IC50 = 140.61 µg/mL) and highest percentage inhibition of protein denaturation (IC50 = 20.40 µg/mL) when compared to the hexane, ethyl acetate and aqueous fractions. Antioxidant study also showed that CIBF had the highest percentage inhibition of DPPH radicals (IC50 = 18.36 µg/mL), highest nitric oxide radical scavenging activity (IC50 = 67.26 µg/mL) and highest hydrogen peroxide radical scavenging activity (IC50 = 160.50 µg/mL) when compared to the hexane, ethyl acetate and aqueous fractions. The findings showed that CIBF demonstrated remarkable anti-inflammatory and antioxidant activities in vitro. Key words: Costus igneus, Antioxidant, Anti-inflammatory, In vitro, Butanol fraction.