Effect of lutein from marigold on nitric oxide production and nitric oxide synthase enzyme – An in vitro study

Plants are well known for their versatile pharmacological activity because of the presence of various phytochemicals. Marigold plant is a well-known plant with many traditional uses including anti-inflammatory activity. Plants can produce an anti-inflammatory effect by inhibiting excessive nitric oxide production. The present study aimed to evaluate the effect of lutein extract on nitric oxide production and nitric oxide synthase gene expression in LPS stimulated RAW 264.7 macrophage cell line. Macrophage RAW 264.7 cells were obtained from the NCCS, Pune with Passage no 16. The presence of nitrite, a stable oxidised product of nitric oxide (NO), was determined in cell culture media using Griess reagent. RT-PCR was used to examine the expression of the iNOS gene in activated macrophages. LPS stimulated RAW macrophages strongly upregulated the iNOS gene expression levels. In the presence of lutein at three different doses of 17.5µg/ml, 35µg/ml and 70µg/ml, the iNOS levels were significantly suppressed, compared to that of LPS treatment only. The different concentrations used in the study have significantly suppressed the iNOS levels, compared to that of LPS treatment alone. The Statistical analysis of the difference between the groups was evaluated by Dunnett's following one-way ANOVA Posthoc comparisons in Graph Pad Prism 5.0 software version. P <0.001, p<0.01 and p<0.05 were statistically significant. This study has concluded that lutein has a significant inhibitory effect on iNOS gene expression and nitric oxide production. Hence, it may be used in inflammatory conditions with excessive nitric oxide production.