Antimicrobial activity of phenolic acids from some selected medicinal plants of South India

In the search of plants as a source of natural antibiotics, four medicinal plants namely Anisomeles malabarica (L.) R. Br. ex Sims (Lamiaceae), Erythrina variegata L., (Leguminosae) and Merremia gangetica Cufod., (Convolvulaceae) and Operculina turpethum (L.) Silva Manso (Convolvulaceae) were selected for the present investigation. In the present study, four bioactive phenolic acids were isolated from methanolic extract of the selected plants viz., tannic acid (A. malabarica), ferulic acid (E. variegata), chlorogenic acid (M. gangetica), p-coumaric acid (O. turpethum) and their identities were confirmed with previous reports. The isolated molecules were subjected to determine the antimicrobial activity by Agar well diffusion method. The study reveals that all the phenolic acids showed significant antimicrobial activities against tested gram-negative, gram-positive and fungal organisms. Based on this, it is concluded that all the phenolic acids exhibited significant antibiotic activity and thus it proved as a potent antibiotic therapeutic agent to develop a plant based drug from these bioactive molecules against various pathogenic infections.