Background: Ocimum gratissimum leaf is used in managing rheumatism and other inflammatory conditions. In this study, we investigated the antioxidant and anti-inflammatory effects of phenolic extract obtained by sequential methanol extraction of O. gratissimum leaves (MEOg).
Methods: The methanol extract (MEOg) was obtained after sequential maceration (n-hexane, chloroform and methanol) of dried O. gratissimum leaves. The fingerprint of the extract was obtained using a high-performance liquid chromatrographic method. In vitro effects were tested by 1,1-Diphenyl-2-picryl-hydrazyl (DPPH), nitric oxide (NO) free radical scavenging, lipoxygenase, and xanthine oxidase inhibitory assays. MEOg was studied for anti-inflammatory activity in carrageenan-induced paw edema and air pouch inflammation in rats.
Results: HPLC fingerprint of the extract shows the presence of caffeic acid, rutin, ferulic acid, apigenin, and quercetin. Antioxidant activity of MEOg revealed an IC50 value in DPPH (31.5±0.03 μg/mL) and NO assay (201.6±0.01 μg/mL), respectively. The extract demonstrated strong xanthine oxidase inhibitory and weak antilipoxygenase activities. MEOg (100 mg/kg) significantly inhibited carrageenan-induced paw edema by 43.2%. Furthermore, MEOg (50 and 100 mg/kg) significantly reduced exudate volume, leucocyte count, neutrophil infiltration, TNF-α, nitrites, myeloperoxidase, and malondialdehyde in carrageenan-induced air pouch inflammation. MEOg also elevated the glutathione levels in the inflammatory exudates.
Conclusions: MEOg shows potential therapeutic benefits in slowing down inflammation and oxidative stress in chronic diseases, such as arthritis.
Keywords: anti-inflammatory; antioxidant; apigenin; carrageenan; phenolic; xanthine oxidase.