Harvesting the potential of medicinal plant extracts for anti-diarrhoeal treatment and water purification

Methanol extracts from 23 plants were tested for antimicrobial activity against five pathogenic bacteria responsible for diarrhoeal disease: Vibrio cholerae, Escherichia coli, Salmonella enterica, Shigella sonii and Staphylococcus aureus. Among the tested plants, seven plant extract demonstrated antimicrobial activity. Terminalia chebula (Retz) (Hirda) and Terminalia bellirica (Gaertn.) Roxb. (Behada) fruit extracts demonstrated maximum antimicrobial activity. MIC of T. chebula (Retz) and T. bellirica (Gaertn) Roxb. fruit extracts were determined by using agar well diffusion method. It was found that V. cholerae, E. coli, and Salmonella enterica were sensitive to T. chebula (Retz) extract at 60 µg level, while Shigella boydii and S. aureus were sensitive at 240 and 1920 µg levels, respectively. In the case of T. bellirica, V. cholerae was sensitive to the extract at the level of 60 µg, E. coli and Salmonella enterica at 120 µg and Shigella boydii and S. aureus at the level of 960 µg. Phytochemical analyses of the plant extracts revealed the presence of diverse bioactive metabolites like terpenes, carotenoids, cardiac glycosides, saponins, phenolic glycosides, phloroglucides, anthrocenocides, flavonoids, tannins, quinones and coumarins. Methanol extract of T. bellirica (Gaertn.) Roxb. reduced the bacterial load of tap water at a concentration of 0.6% (w/v) pointing to its usefulness in water purification.