In vitro screening and evaluation of some Indian medicinal plants for their potential to inhibit Jack bean and bacterial ureases causing urinary infections

Context: Bacterial ureases play an important role in pathogenesis of urinary infections. Selection of plants was done on the basis of their uses by the local people for the treatment of various bacterial and urinary infections.Objective: Our investigation screens and evaluates 15 Indian medicinal plants for their possible urease inhibitory activity as well as their ability to inhibit bacteria causing urinary infections. Materials and methods: Plant extracts in three different solvents (methanol, aqueous, and cow urine) were screened for their effect on Jack-bean urease using the phenol-hypochlorite method. Subsequently, seven bacterial strains were screened for their ability to release urease and further antimicrobial-linked urease inhibition activity and minimum inhibitory concentration of the tested extracts were evaluated by the agar well diffusion and microdilution method, respectively. Results: Five plants out of 15 crude extracts revealed good urease inhibitory activity (>= 20% at 1 mg/ml conc.) and IC50 values for these extracts ranged from 2.77 to 0.70 mg/ml. Further testing of these extracts on urease-producing bacterial strains (Staphylococcus aureus NCDC 109, S. aureus MTCC 3160, Proteus vulgaris MTCC 426, Klebsiella pneumoniae MTCC 4030, and Pseudomonas aeruginosa MTCC 7453) showed good anti-urease potency with an MIC ranging from 500 to 7.3 mu g/ml. Discussion and conclusion: The results of screening as well as susceptibility assay clearly revealed a strong urease inhibitory effect of Acacia nilotica L. (Fabaceae), Emblica officinalis Gaertn. (Phyllanthaceae), Psidium guajava L. (Myrtaceae), Rosa indica L. (Rosaceae), and Terminalia chebula Retz. (Combretaceae). Our findings may help to explain the beneficial effect of these plants against infections associated with the urease enzyme.