Cyclooxygenase, Lipoxygenase, Nitric Oxide Synthase, Myeloperoxidase and Protease Inhibiting Activities of the Leaves and Flowers of Mikania micrantha Kunth

Abstract

Aim: To study in vitro anti-inflammatory activity of the leaves and flowers of the perennial climber Mikania micrantha. Methods: Leaves and flowers of the plant was collected in February 2015. Dried and powdered plant materials was extracted with ethyl acetate at room temperature in an orbital shaker. Cyclooxygenase, 5-lipoxygenase, myeloperoxidase and nitric oxide synthase inhibiting activities of the ethyl acetate extract were tested in human monocytic cell line THP1 after activation with lipopolysaccharide. Protease inhibiting activities were tested using trypsin as the enzyme. Percentage inhibitions of enzyme activities were calculated and IC50 values were determined. Diclofenac sodium was used as the reference drug. Results: Ethyl acetate extract of the leaves as well as flowers exhibited very good myeloperoxidase, nitric oxide synthase, cyclooxygenase and lipoxygenase inhibiting activities and showed moderate effect towards protease inhibition. The IC50 of inducible nitric oxide synthase activity was 5 and 11µg respectively for leaf and flower extracts. IC50 of myeloperoxidase activity was 4µg for flower extract. The inhibition of myeloperoxidase activity by leaf extract was so high that IC50 could not be determined at the tested concentration. IC50 of cyclooxygenase activity was 25 and 89µg and lipoxygenase activity was 98 and 185µg respectively for leaf and flower extracts. The IC50 of leaf and flower extracts towards protease inhibition were 1180 and 1250 µg respectively. Conclusion: This study revealed that Mikania micrantha contains principles which can inhibit diverse enzymes of inflammatory pathway and is a potential target for the development of new anti-inflammatory drug.