Phytochemical and antimicrobial properties of leaf extracts of Calliandra calothyrsus, Leucaena diversifolia and Sesbania sesban

Abstract

Phytochemical compounds are secondary metabolites of plants useful as antimicrobial agents. Botanicals are being explored for bioactive compounds with antimicrobial properties against phytopathogens. Little information is available on the phytochemical and antimicrobial activity of Calliandra calothyrsus, Leucaena diversifolia and Sesbania sesban against Cercospora zeae-maydis and Xanthomonas campestris pv. musacearum. The aim of the study was to determine the phytochemical and antimicrobial properties of leaf extracts of C. calothyrsus, L. diversifolia and S. sesban against C. zeae-maydis and Xc. pv. musacearum. Dried leaves were extracted in methanol and aqueous solvents and screened for phytochemical and antimicrobial activity using Kirby-Bauer’s disk diffusion and poisoned food technique methods. Sesbania sesban extracts contained all the phytochemical tested; tannins, terpenoids, steroids, saponins, flavonoids, and alkaloids, Leucaena diversifolia lacked alkaloids while Calliandra calothyrsus lacked steroids and alkaloids. The extracts were active against Cercospora zeae-maydis and Xc.pv. musacearum with Sesbania sesban having greater radial inhibition activity. There was no significant difference in the antimicrobial activity between the lowest concentrations (25% and 25mg/ml) and highest concentrations (75% and 75mg/ml) in all the three plant extracts. Growth inhibition observed could be as a result of the different chemical compound observed in the extracts. Presence of alkaloids in Sesbania sesban could explain the greater growth inhibition of the pathogens under study. The results form the basis for further research that could lead to isolation and development of antimicrobial agents. Therefore, these plants can be used as an alternative to synthetic chemicals to control Cercospora zeae-maydis and Xanthomonas campestris pv. Musacearum