In vitro Antimicrobial Activity of Tropical Medicinal Plants used in Santo Domingo, Dominican Republic: Part 2

Introduction: Medicinal plants of Dominican Republic are used for medicinal purposes, but still very little is known about these uses and very few evidence exist to support such uses. The objective of this study was to evaluate the antimicrobial activity of crude ethanolic extracts of 48 medicinal plants collected at regional or municipal markets in Dominican Republic for the treatment of several types of infections associated diseases. Methods: Crude ethanolic plant extracts were tested against five species of micro-organisms - E. coli, K. pneumoniae, S. aureus, P. aeruginosa and C. albicans using the disc diffusion method. For selected plants, antibacterial activity was also measured for seven (Gram positive and Gram negative) micro-organisms by the standard radial streak method in agar plates. MIC of selected plants was determined against B. subtilis by the broth microdilution method using MTT dye. Results and Discussion: Forty-three of the plants tested showed inhibitory activity against one or more of the micro-organisms at 50 μg of extract. Eleutherine bulbosa, Hymanea courbaril, Ocimum basilicum, Petiveria alliacea, Piper aduncum, Plantago major, Rosmarinus officinalis and Trichilia hirta were effective inhibiting growth of at least three out of the four bacteria strains tested. Moderate MIC values were in the range of 140 µg/mL for A. racemosus to 2920 µg/mL for Chamaesyce hyssopifolia. A few extracts showed antifungal activity against Candida albicans. Conclusion: Several ethanolic crude extracts derived from plants used in traditional medicine in the Dominican Republic possess antimicrobial activity against a variety of the tested micro-organisms. Isolation and/or identification of potential biologically active compounds and elucidation of their mechanism(s) of action will require further study.