Identification of human cyclooxegenase-2 inhibitors from Cyperus scariosus (R.Br) rhizomes

Cyperus scariosus (R.Br) belongs to the family Cyperaceae and it has a diverse medicinal importance. To identify human cyclooxegenase-2 (COX-2) inhibitors from C. scariosus, the rhizome powder was exhaustively extracted with various solvents based on the increasing polarity. Based on the presence and absence of secondary metabolites, we have selected the methanolic extract to evaluate the anti-oxidant and anti-inflammatory activity. The same extract was further subjected to gas chromatography-mass spectroscopy (GC-MS) analysis to identify the active compounds. Binding affinities of these compounds towards anti-inflammatory protein COX-2 were analyzed using molecular docking interaction studies. Phytochemical analysis showed that methanol extract is positive for all secondary metabolites. The antioxidant activity of the C. scariosus rhizomes methanolic extract (CSRME) is half to that of ascorbic acid at 50 µg/ml. The anti-inflammatory activity of CSRME is higher than that of diclofenac sodium salt at high concentration, which is evident from the dose dependent inhibition of bovine serum albumin denaturation at 40 µg/ml–5 mg/ml. GC-MS analysis showed the presence of nine compounds, among all N-methyl-1-adamantaneacetamide and 1,5,diphenyl-2H-1,2,4- triazine form a hydrogen bond interactions with Ser-530 and Tyr-385 respectively and found similar interactions with crystal structure of diclofenac bound COX-2 protein. Benzene-1, 2-diol, 4-(4-bromo-3 chlorophenyl iminomethyl forms hydrogen bond interactions with Thr-199 and Thr-200 as similar to crystallized COX-2 protein with valdecoxib. Collectively our results suggest that CSRME contains medicinally important anti-inflammatory compounds and this justifies the use of this plant as a folklore medicine for preventing inflammation associated disorders.