Phytochemical screening, antibacterial and allelopathic effects of few invasive plants of Kerala.
Invasive species are often regarded as a threat to native flora. Many of them curtail the normal physiological functioning abilities of the native plants by growing over them, or by producing certain metabolites which control their growth potentials and seed germination abilities. The present study aims to find out the different bioactive compounds like alkaloids and terpenoids responsible for the vast spread of Eupatorium odoratum, Vernonia cinerea, Mikania micrantha, Tridax procumbens, Pilea microphylla and Cuscuta reflexa which are some of the major invasive plants of Kerala. Apart from these negative roles attributed to invasive plants, whether they possessed any beneficial roles was the prime concern of this study. Our study brings to light the allelopathic effects of invasive plants upon legume seeds. Different phytochemicals which are known to produce such effect were present in all these plants. Greatest allelopathic effects were exhibited by C. reflexa and E. odoratum. Against Escherichia coli bacteria, E. odoratum and M. micrantha showed highest zone of inhibition (20 mm, 15 mm) while against Proteus vulgaris bacteria, C. reflexa, M. micrantha and T. procumbens produced inhibition zones of 21 mm, 15 mm and 12 mm. Against Pseudomonas aeruginosa bacteria, C. reflexa, M. micrantha and E. odoratum produced inhibition zones of 16 mm, 13 mm and 12 mm. Alcoholic extract of V. cinerea showed comparatively high inhibition against Staphylococcus aureus bacteria (10 mm). V. cinerea showed inhibitiory effects against E. coli, S. aureus and P. vulgaris (11 mm, 10 mm and 9 mm). Similarly, P. microphylla showed inhibition only against P. vulgaris and P. aeruginosa (10 mm and 8 mm).