The effect of capsicum oleoresin on nitric oxide production and nitric oxide synthase gene expression in macrophage cell line

Abstract

Background: Nitric oxide (NO) is an inflammatory agent produced by macrophages. It also acts as a neurotransmitter. However, overproduction of NO results in acute or chronic inflammation. Capsicum is well known for its anti-oxidant, anti–inflammatory, and anticancer properties. Objective: The objective of this study was to evaluate the effect of capsicum oleoresin on NO production and NO synthase gene expression in lipopolysaccharide (LPS) stimulated RAW 264.7 macrophage cell line. Materials and Methods: Macrophage RAW 264.7 cells were obtained from the National Centre for Cell Science, Pune with Passage no 16. RAW macrophages were treated with 12.5 μg/ml, 25 μg/ml, and 50 μg/ml of Capsicum extract with 1 μg/ml of LPS and incubated for 24 h. Results: When capsicum was added at three different doses of 12.5 μg/ml, 25 μg/ml, and 50 μg/ml, the inducible NO synthase (iNOS) levels was significantly suppressed, compared to that of LPS treatment only. The level of NO increased by LPS induction was significantly decreased in a dose-dependent manner when treated with different concentrations of capsicum extract and capsicum had a suppressing effect on iNOS gene expression in LPS – stimulated RAW 264.7 macrophage. Conclusion: This study concludes that capsicum oleoresin is good enough to suppress iNOS gene expression and NO production. Hence, it may be used in inflammatory conditions with excessive NO production. Abbreviations Used: NO: Nitric oxide, LPS: Lipopolysaccharide, iNOS: Inducible nitric oxide synthase, DMEM: Dulbecco's modified Eagle medium, MTT: 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide for, DMSO: Dimethyl sulfoxide, PBS: Phosphate buffer saline, FBS: Fetal bovine serum.