Antibacterial and antibiofilm activities of Mayan medicinal plants against Methicillin-susceptible and -resistant strains of Staphylococcus aureus

Ethnopharmacological relevance: Several medicinal plants are used in Mayan Traditional Medicine to treat skin, urinary, respiratory, and gastrointestinal infectious diseases. However, scientific studies that have supported the bioactivity of these Mayan medicinal plants are limited. Aim of the study: To assess the in-vitro anti-Staphylococcus aureus growth and biofilm-formation activities of 15 Mayan medicinal plants that were selected based on their traditional uses for the treatment of infectious diseases. Materials and methods: Mayan medicinal plants used traditionally to treat infectious diseases were preselected. For each part of the plants, four extracts were prepared with different solvents (water, n-hexane, ethyl acetate, and methanol). These were tested against two reference strains: a Methicillin-susceptible and -resistant S. aureus, and two clinical isolates, including a susceptible and multidrug-resistant S. aureus using a Resazurin Microtiter Assay. In addition, the plant extracts were evaluated in biofilm-formation inhibition on S. aureus by means of the Crystal Violet method. Results: A total of 120 extracts from 15 Mayan medicinal plant species belonging to 12 different families were selected according their ethnopharmacological uses to treat infectious diseases. Among the selected plant species, 26 extracts obtained from eight medicinal Mayan plants exhibited significant anti-S. aureus against the four strains tested. The most active extracts were the Aq (aqueous) leaf extract of Krugiodendron ferreum (Minimal Inhibitory Concentration [MIC] = 125-250 mu g/mL), the MeOH bark extracts of Matayba oppositifolia, Clusia flava, Gymnopodium floribundum, the MeOH leaf extract of Spondias purpurea with MIC values of 250 mu g/mL, and the MeOH leaf and Aq bark extracts of K. ferreum (MIC = 250-500 mu g/mL). Among the active extracts, 12 exhibited a bactericidal effect on S. aureus strains (Minimal Bactericidal Concentration [MBC] = 250-1000 mu g/mL). Forty extracts from 13 plants have an effect on the anti-formation of biofilm, the most active were the MeOH leaf extract of M. oppositifolia (one-half Inhibitory Concentration [IC50] = 10.4 mu g/mL) and the MeOH (IC50 = 17.7 mu g/mL) and Hex (18.2 mu g/mL) leaf extracts from S. purpurea. Conclusion: Aqueous and organic extracts from Mayan medicinal plants showed bactericidal and anti-biofilm activities even against drug-resistant S. aureus strains. The present study supports the traditional usage of some plants employed in Mayan medicine for illnesses such as skin, gastrointestinal, and urinary infections and suggest that these plants could be a good source of antibacterial phytochemicals.