Gurmeet Singh, Yogita Bansal, Gulshan Bansal and Rajesh Kumar Goel Pages 418 - 425 ( 8 )
Two series of compounds (AB and APB) bearing substituted phenoxy groups at 2-position of benzimidazole nucleus through amino or phenyleneamino were synthesized and evaluated through PASS software for predicting the activity spectrum of each compound. All compounds of both the series were predicted to have potent anthelmintic activity. The activity of each compound was evaluated experimentally at the concentrations of 0.1, 0.2 and 0.5% in terms of mortality time and paralysis time of the helminthes and was found to comply with the PASS predicted activity. In general, all compounds of APB series were more potent than those of AB series probably due to the additional hydrophobic interactions of the spacer phenyl ring in the APB series. The activity of all compounds was found to increase with increasing concentration. The compound with p-chlorophenoxy moiety was the most active from the APB series (mortality time 5.7±0.4 min and paralysis time 3.1±0.3 min) and equipotent to albendazole (mortality time 5.4±0.1 min and paralysis time 2.8±0.2 min) at concentration of 0.2%. The o-chlorophenoxy analogs in both the series were found to be the least active of all. Based on these results, a substituent capable of binding with the receptor through van der Waals and/or electronic interactions at 4-position of the phenoxy ring in the compound is suggested to increase binding interaction leading to potent anthelmintic activity.
Benzimidazole, phenoxyacetic acid, anthelmintic, PASS, pharmacophore, intestinal worms, albendazole.
Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala – 147 002, India.