Kinetics of urease inhibition by different fractions of Cassia fistula

Abstract

Urease serves as the basis for Helicobacter pylori infection of stomach as well as urinary tract infection by Proteus, Klebsiella, Pseudomonas and Staphylococus species. Ureolytic activity by these pathogens causes various gastric and urinary diseases. Urease inhibitors can be used as potential approach for treatment of these infections. Cassia fistula, an ayurvedic medicinal plant also named as Aragvadha (a disease killer), was explored as source of urease inhibitors. In the present study, we evaluated the five different extracts viz. aqueous, methanol, hexane, chloroform and ethyl acetate for their urease inhibition potential. Except chloroform extract, all four samples exhibited more than 50% urease inhibitory activity. The IC50 of ethyl acetate sample was 0.27 mg/ml lower than standard thiourea. The inhibition kinetics of all four samples was studied. Line weaver Burk plot and Dixon plots revealed the ethyl acetate sub fraction as most potent inhibitor as it exhibited competitive mode of inhibition with Ki of 280 μg/ml. All the other samples exhibited mixed and uncompetitive mode of inhibition. Further characterization of bioactive compounds in the ethyl acetate sample was performed using GC-MS. The analysis identified 26 compounds in the sample. Mome-inositol, a derived sugar was found to be major compound (80.83%). From the present observation it can be concluded that C. fistula plant needs to be explored further for identifying the lead molecule to treat various ureolysis based diseases.