In vitro antioxidant activity of the ethanol extracts from the leaves of Calotropis gigantea

Key words: 
• Calotropis gigantea leaves /
• antioxidant activity /
• total polyphenol /
• total flavonoids /

Abstract: The leaves of a medicinal plant Calotropis gigantea were extracted with ethanol, and the chemical constituents of the ethanol extracts of the leaves were identified by gas chromatography-mass spectrometry（GC-MS）spectrometer to evaluate their antioxidant activity. The contents of total polyphenols and total flavonoids in the ethanol extract of the leaves, and the DPPH and hydroxyl free radical scavenging effects and the total reducing capacity of the extract were determined. The results indicated that the ethanol extract of the leaves of C. gigantea had a high anti-oxidant activity and that the alcohols content of the extract was the highest（60.2%）, followed by the esters（24.09%）. Lupeol（26.7%） was the main single component of the extract. The total polyphenols content was（26.22 ± 0.01） mg·g^-1 DW（GAE）, and the total flavonoids content was（0.70 ± 0.02） mg·g^-1 DW（RE）. The IC₅₀ values of the extract in scavenging the activities of DPPH and hydroxyl free radicals were 0.33 g·L^-1 and 0.21 g·L^-1,respectively, which were not significant different from those of the control Lupeol and TBHQ, respectively.Moreover, the total reducing capacity of the extract was increased with the increase of the sample concentration.The ferric reducing antioxidant power was 0.69 mmol·L^-1 FeSO₄·7 H₂O·g^-1 DW. This indicates that the ethanol extract of the leaves of C. gigantea showed excellent antioxidant activity, which provides guidance for the further development and utilization of the extracts.