In vitro and in vivo evaluation of the inhibitory effect of Limnophila indica (Linn.) Druce on shigellosis.

Objective: The research aimed to evaluate the anti-Shigella and antacid activities of the methanolic extract of Limnophila indica.

Methods: The whole plant of L. indica was extracted using methanol and then subjected to preliminary chemical screening. The in vitro antibacterial screening on two Gram-positive and two Gram-negative bacteria as well as three Shigella species of which two bacteria were antibiotic-resistant were evaluated by disc diffusion method. Castor oil-induced diarrhoea on Wistar albino rats was performed by using loperamide as a standard control. The in vitro antacid activity was tested by artificial stomach model. The neutralization efficiency, capacity, volume and hydrogen ions consumed were also evaluated.

Results: The preliminary chemical screening on methanolic extract of L.indica showed the presence of phenolic compounds, flavonoids, alkaloids, fats and oils. It was proved to be a potent antibacterial agent against the four bacterial strains. Screening against Shigella species revealed that it was a powerful antibacterial agent towards antibiotic-resistant Shigella species. In the case of in vivo antidiarrheal activity, the plant has shown a dose-dependent activity and the lowest dose at 100 mg/kg gave a much better result than loperamide (P<0.01). The in vitro antacid study showed a mild activity.

Conclusion: As the plant L. indica has been proved to be a competent antibacterial as well as a compelling antidiarrheal agent with mild antacid activity, this plant can be very well suggested to be an eminent substitute for the various synthetic anti-dysentery and antidiarrheal agents available in the market.