Effects of Selected Indeginous Plant’s Extract on Diarrhoeal Diseases in Bangladesh

Abstract

Babla (Acacia nilotica), Neem (Azadirachta indica) and Peyara (Psidium guajava) leaves have been using as a well-known remedy for the treatment of various types of disorders in the ayurvedic, homoeopathic and traditional system of medicine in Bangladesh, India and many other countries. Considering the medicinal importance and availability in Bangladesh, the plant species, A nilotica, A.indica and P.guajava leaves were collected from Rajshahi University campus and extracts were prepared using ethanol, methanol, petroleum ether, chloroform and ethyl acetate as solvents. Seven diarrhoeal bacteria were collected from the Department of Pharmacy and Institute of Biological Science of University of Rajshahi, and ICDDR, B. Dhaka. In this study, we have investigated antibacterial and cytotoxic activities of A.nilotica, A.indica and P.guajava leaves extracts. Antibacterial activity of the different extracts were evaluated at concentrations (100µg/disc) against Escherichia coli, Shigella boydii, Shigella dysenteriae, Shigella flexneri, Shigella shiga, Shigella sonnei and Vibrio cholerae bacteria. Ethanol, methanol, petroleum ether, ethyl acetate and chloroform extracts of A.nilotica leaves exhibited 10.67, 10.00, 9.33, 9.67 & 9.33 mm clear zone of inhibition against E.coli & V.cholerae; E.coli; V.cholerae; S.boydii and V.cholerae, with respect to standard ciprofloxacin disc (10 µg/disc). The same solvent extracts of A.indica leaves demonstrated 10.33, 9.67, 10.00, 9.67 and 9.33 mm clear zone against S.boydi; S.flexneri; S.shiga; V.cholerae and E.coli. Similarly, the extracts of P. guajava leaves indicated 9.33, 9.67, 9.33, 9.67 and 933 mm, the highest clear zone of inhibition against S.shiga; V.cholerae; S.shiga; S.sonnei and S.dysenteriae, respectively. Antibacterial activity was tested on seven diarrhoeal bacteria by the purified ethanol extract of A.nilotica leaves (compound E001). The compound E001 (100 µg/disc) was effective against all types of diarrhoeal bacteria. Extracts of A.nilotica, A.indica and P.guajava leaves showed detectable MIC against diarrhoeal bacteria. The lowest MIC of A.nilotica leaves of ethanol, methanol, petroleum ether, chloroform and ethyl acetate extracts were 16, 16, 32, 16 & 32 µg/ml against S.sonnei; S.flexneri; S.dysenteriae, S.boydii & S.flexneri; S.boydii and E.coli & S.sonnei, respectively. Similarly, the lowest MIC values of the extracts of A. indica leaves demonstrated 32, 32, 16, 32 & 16 µg/ml against S. dysenteriae, S. shiga & S. sonnei; S.shiga & S.sonnei; S.dysenteriae; S.shiga & V.cholerae and S.shiga, respectively. And the lowest MIC of the same solvent extracts of P. guajava leaves 32, 16, 32, 32 & 16 µg/ml against S. shiga, S. sonnei, & Vibrio cholera; S.dysenteriae; E.coli, S.shiga, S.sonnei & V.cholerae; S.dysenteriae & S.shiga and E.coli, respectively. It was observed that ethanolic extract of A.nilotica leaves showed the potent activity than other extracts. Cytotoxicity test was also performed with various extractives of A.nilotica, A.indica and P.guajava leaves through brine shrimp (Artemia salina) lethality bioassay. LC₅₀ values of A.nilotica leaves of ethanol, methanol, chloroform, ethyl acetate and petroleum ether extracts were found to be 395.581, 603.472, 830.236, 702.830 and 651.289 ppm, respectively. Similarly, LC₅₀ values of A. indica leaves extracts were 830.236, 651.289, 682.959, 830.236 and 774.694 ppm. and P. guajava leaves extracts were 651.289, 682.959, 830.236, 682.959 and 651.289 ppm. Among the tested extracts, ethanolic extract of A.nilotica leaves showed the highest cytotoxicity against Artemia salina. As ethanolic extract of A.nilotica leaves showed highest antibacterial and cytotoxicity activities. So, it was purified by PTLC and OCC methods. The purities and bioactivities of single purified compound E001 were reconfirmed by NMR study and further experiment on diarrhoeal bacteria. The isolated compound E001 was a steroid analogue and might be the derivatives of sitosterol. The phytochemical properties of different solvent extracts of A.nilotica leaves were investigated. The extracts showed the presence of saponins, tannins, glycosides, steroids, alkaloids, phenolic compounds, flavonoids and many other bioactive compounds. It has significant reducing power capacity, antioxidant activity and DPPH radical scavenging activity. The main targets of this research have traced out the isolated bioactive potentials from the ethanolic extract of A.nilotica leaves and significant response was found against diarrhoeal bacteria. This investigation of bioactive compound may ultimately find its use for the relief of the human diarrhoea in near future and thereby contribute a lot to the rural poor people of developing countries like Bangladesh.