Rationale for immunomodulatory and anti-inflammatory effects of Ocimum sanctum: radical scavenging potential and effect on nitric oxide production

Abstract

Antioxidant activity of polar methanolic extract of aerial parts of Ocimum sanctum using multiple screens was studied. Various concentrations of the standardized extract were examined for the free radical scavenging activity, superoxide radical scavenging potential and effect on nitric oxide production in RAW 264.7 mouse monocytes cell line. The results indicated that the O. sanctum extract has strong antioxidant activity. In the assay for free radical scavenging activity measured in terms of scavenging of DPPH (1,1-diphenyl-2-picryl hydrazyl) radical, the extract exhibited the IC50 of 94.51 ± 6.47 µg/ml. NBT reduction assay was used to measure the superoxide reducing capacity of the extract and the extract inhibited the NBT reduction with IC50 of 71.17 µ 8.13 µg/ml. Effect on nitrite production was tested in Lipopolysaccharide (LPS) activated RAW 264.7 mouse monocytes cell line. In this assay, biphasic response was observed for the extract. At lower concentration it stimulated nitrite production while at higher doses the nitrite production was suppressed (EC50 4.89 ± 0.47 µg/ml and IC50 66.67 ± 0.91 µg/ml). These results suggest that the antioxidant activity of O. sanctum may be partly responsible for its reported immunomodulatory and anti-inflammatory effects.