Antibacterial activity of Physalis angulata L., Merremia umbellata L., and Cryptostegia grandiflora Roxb. Ex R.Br. - medicinal plants of the Colombian Northern Coast

Abstract

Among the great Colombian biodiversity are several vegetal species that represent a wide source of potentially bioactive substances; these are commonly used in the folk medicine for the treatment of various infectious diseases. In this work we evaluated the antibacterial activity of the total ethanolic extracts obtained from the calyces of Physalis angulata L. and the leaves of Merremia umbellata L. and Cryptostegia grandiflora Roxb. ex R. Br., against ATCC strains of Staphylococcus aureus (25923), Klebsiella pneumoniae (13883) and Pseudomonas aeruginosa (27853). Bacterial sensitivity tests were performed using the broth microdilution method. Based on the results, the most active extract was fractionated and its bacterial sensitivity and minimum inhibitory concentration was calculated. All extracts proved to be active against the bacterial strains used. Physalis angulata L. was the most active extract, showing total inhibition of the bacterial growth of all microorganisms used at 1000 μg/mL. This activity was maintained by its dichloromethane fraction, which showed a potent antibacterial activity with a minimum inhibitory concentration ≤128 μg/mL against all the strains, without cytotoxic activity against normal human dermal fibroblasts. In conclusion, the total ethanolic extracts of the leaves of M. umbellata, C. grandiflora and the calyces of P. angulata were active against known pathogenic bacteria. The dichloromethane fraction of P. angulata showed a potent activity at low concentrations, without toxic effects on human cells, becoming a promissory source in the search for new therapeutic alternatives.