Screening of Selected Medicinal Plants of Bangladesh for Biological

Abstract

In the current study three plants namely Cassia sophera (L.) Roxb, Cassia fistula (L.) and Cassia tora (L.) Roxb. were evaluated for their bioactivities. For these antibacterial, antitumor, phytotoxic and phytochemical properties of leaves extracts of plants were evaluated. In case of antibacterial activity test, methanol leaves extracts were screened against five gram positive (Staphylococcus aureus, Bacillus cereus, Streptococcus haemolytica, Bacillus subtilis and Sarcina lutea) and five gram negative (Escherichia coli-B, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi and Shigella dysenteriae) bacteria using agar disc diffusion method compared with antibiotics (tetracycline). Plants extracts were very efficient against all tested bacteria, whereas C. tora was more effective followed by C. sophera and C. fistula. Furthermore the extract of C. tora showed the highest zone of inhibition (15.67 mm) against gram positive S. lutea at 300 mgml-1. In case of MIC and MBC, C. sophera extracts showed MIC values ranged from 100 (S. lutea) to 350 mgml-1 (S. haemolytica) and MBC were ranged from 250 (S. lutea) to 450 mgml-1 (S. haemolytica and K. pneumoniae) where C. fistula MIC were ranged from 150 (S. lutea and S. dysenteriae) to 350 mgml-1 (B. cereus, S. haemolytica and K. pneumoniae) and MBC were ranged from 250 (S. dysenteriae) to 500 mgml-1 (K. pneumoniae). Followed by C. tora MIC values were ranged from 25 (S. lutea) to 100 mgml-1 (B. cereus, S. haemolytica, E. coli-B and S. dysenteriae) and MBC were ranged from 100 (S. lutea) to 250 mgml-1 (B. cereus E. coli and S. dysenteriae) against all tested strains. The lowest MIC (25 mgml-1) and MBC (100 mgml-1) values were observed by C. tora against S. lutea is a good indication of high efficacy. For antitumor activity test, studied three plants extracts were used by potato disc bioassay through Agrobacterium tumefaciens infection. Before this, antibacterial assay was performed on three A. tumefaciens strains (AtTa0112, AtAc0114 and AtSl0105) to check whether extracts are lethal for bacteria or are inhibiting at any level that is necessary for the genetic transfer mechanism and finally induction of tumor. It confirmed that extracts has no effect on the viability of Agrobacterium strains. Although no significant differences were observed in tumor inhibition by three extracts but C. tora (57.14%) was more effective for tumor inhibition followed by C. fistula (47.70%) and C. sophera (47.66%) respectively at 1000ppm on AtSl0105. It was also observed that out of three concentrations (10, 100 and 1000 ppm), tumor inhibitions were only observed at 100 and 1000 ppm concentrations, while AtSl0105 was more prominent for producing tumor followed by AtAc0114 and AtTa0112. Preliminary phytochemical studies showed that C. tora leaves contain maximum occurrence of phytoconstituents like alkaloids, flavonoids, saponins, tannins, glycosides and sterols, and absence of phenols and terpenoids. Followed by C. fistula showed presence of alkaloids (moderately), flavonoids, saponins, tannins, phenols and terpenoids, and absence of glycosides and sterols, whereas C. sophera showed presence of alkaloids, flavonoids, saponins, tannins, glycosides and steroids, and absence of phenols and tannins. For phytotoxicity test, radish seeds germination and root lengths were significantly inhibited by the studied extracts at 10000 ppm concentration. All extracts exhibited significant phytotoxicity on radish seeds and maximum seed germination inhibition (57%) was observed by methanol extract of C. sophera after 5th day of incubation followed by C. tora (23%) and C. fistula (16%) respectively. Also minimum root length (1.39 mm) was observed when radish seeds were grown in the presence of C. sophera. In summary the above studies indicate that many of the species of Cassia, used in traditional medicine, are powerful inhibitors of both microbial and cancer cell growth, meaning there is high chance to develop plant based drugs for treating infectious and cancer type diseases from the studied plants.