Background: Plant Kingdom still constitutes a source for antimicrobials, screening bioassays of plants extracts is one of the first steps in the search of new antimicrobial compounds. Cuba has a rich flora with a high degree of endemism that practically has not been investigated. Method: Twelve acetone extracts (1mg/ml) of seven Cuban plants (four endemic), were tested by agar disc diffusion method against selected strains of bacteria and fungi: Escherichia coli (three strains), Staphylococcus aureus and Candida albicans. Results: In general null or poor antimicrobial effect was observed, except in Caesalpinia bahamensis subs bahamensis heartwood, that showed activity of interest against bacteria even at 0,5mg/ml; while modest antibacterial effects was found in endemics: Hypericum styphelioides (leave, stem), H. limosum (leave, stem), Vaccinium leonis (leave) and V. ramonii (leave, stem); Agdestis clematidea show lowest effect. S. aureus was the most sensitive bacteria (six species and 11 extracts) and only a negligible activity was found against C. albicans in four extract of four species. Discussion: Morphology of Gram positive bacteria, in contrast to Gram negative that have a more resistant outer membrane, seem to be the cause of S. aureus sensitiveness. Starting from these results, further current antimicrobial research approach related virulence factors mechanisms interference can be carried out in these plants. Conclusions: In this experimental conditions, except in one specie, null or poor antimicrobial effect was found in tested plants, studies on these plants have to be continues, since in other conditions maybe could be found some bacteriostatic or bactericide activity.
Key words: Antimicrobial activity, Cuba, medicinal plants, plant extracts
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