Antibacterial and antidiarrhoeal effects of alkaloids of Holarrhena antidysenterica WALL.

The alkaloids from the ethanolic extract of H. antidysenterica seeds were evaluated for their antibacterial activity against clinical isolates of enteropathogenic Escherichia coli (EPEC) in vitro, and their antidiarrhoeal activity on castor oil-induced diarrhoea in rats, in vivo. The plasmid DNA, whole cell lysate and outer membrane protein profile of a clinical isolate of EPEC was determined in presence of alkaloids of H. antidysenterica. The disc diffusion and agar well diffusion methods were used to evaluate the antibacterial efficacy. The alkaloids showed strong antibacterial activity against EPEC strains. In castor oil-induced diarrhoea, alkaloids reduced the diarrhoea with decrease in the number of wet faeces in pretreated rats at a dose of 200-800 mg/kg. The loss of plasmid DNA and suppression of high molecular weight proteins were observed on alkaloids treatment. Taking into account the multiple antibiotic resistance of EPEC, the results suggest usefulness of alkaloids of H. antidysenterica seeds as antibacterial and antidiarrhoeal agents.