RESUMEN
The aim of this work was to explore in an active, fractioned, and chemically characterized Tamarindus indica L. (TIL) leaves extract, the influence of flavonoids and polyphenol compounds on the antimicrobial activity. A spectrophotometric quantification of the total phenols and flavonoids content was determinate to the TIL leaves extract, as well as, to the four fractions in which was fractioned (n-hexane, chloroform, ethyl acetate and n-butanol). The extracts and their fractions were microbiologically tested against six ATCC bacteria and Candida albicans, being determined their minimum inhibitory and bactericidal concentrations (MIC and MBC). Additionally, the extracts were evaluated in their influence on human complement system (classical and alternative pathways). Fractions with high content of flavonoids and polyphenols (ethyl acetate and n-butanol) are active against Bacillus subtilis and inhibit the human complement system (direct pathway, IC50 31.05 and 33.65 ug/mL respectively), but are not active over Staphylococcus aureus. However, this bacterium was susceptible to fractions with low or null concentration of flavonoid or polyphenol compounds. No fractions neither the fluid extract were active against Salmonella typhimurium and Candida albicans. Experimental data suggest that phenols and flavonoids are not the only components involved in the antimicrobial activity of TIL leaves as has been previously suggested by other authors. Complement activity tests did not support a putative role on the antimicrobial activity.
El objetivo de este trabajo fue explorar en un extracto activo de hojas de Tamarindus indica L. (TIL), fraccionado y caracterizado químicamente, la influencia de los polifenoles y flavonoides en su actividad antimicrobiana. Se cuantificaron por espectroscopia UV-visible los contenidos de fenoles totales y flavonoides en el extracto de TIL así como de las cuatro fracciones obtenidas (n-hexano, cloroformo, acetato de etilo y n-butanol). Se evaluó la actividad microbiológica del extracto y sus fracciones contra seis bacterias ATCC y Candida albicans, determinándose sus concentraciones mínimas inhibitorias y bactericidas (MIC y MBC). Adicionalmente, se evaluó la influencia de los extractos en el sistema de complemento humano (vía clásica y alternativa). Las fracciones con altas concentraciones de polifenoles y flavonoides (acetato de etilo y n-butanol) fueron activas contra el Bacillus subtilis e inhibieron el sistema de complemento humano (vía directa, IC50 31.05 y 33.65 g/mL, respectivamente), pero no fueron activas contra Staphylococcus aureus. Sin embargo, esta bacteria fue susceptible a fracciones con baja o nula concentración de polifenoles y flavonoides. El extracto fluido y todas sus fracciones resultaron inactivos frente a Salmonella typhimurium y Candida albicans. Los datos experimentales sugieren que los fenoles y flavonoides no son los únicos compuestos involucrados en la actividad antimicrobiana de hojas de TIL, como había sugerido por otros autores. La actividad medida sobre el sistema de complemento, no aporta relevancia a la actividad antimicrobiana de las hojas de TIL.
Asunto(s)
Antibacterianos/farmacología , Extractos Vegetales/farmacología , Tamarindus/química , Bacillus subtilis , Activación de Complemento , Candida albicans , Etanol , Fenoles/análisis , Flavonoides/análisis , Hojas de la Planta/química , Pruebas de Sensibilidad Microbiana , Salmonella typhimurium , Staphylococcus aureusRESUMEN
Tamarindus indica L. leaves are reported worldwide as antibacterial and antifungal agents; however, this observation is not completely accurate in the case of Cuba. In this article, decoctions from fresh and sun dried leaves, as well as fluid extracts prepared with 30 and 70% ethanol-water and the pure essential oil from tamarind leaves were microbiologically tested against Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Pseudomona aeruginosa and Candida albicans. Aqueous and fluid extracts were previously characterized by spectrophotometric determination of their total phenols and flavonoids, while the essential oil was chemically evaluated by gas chromatography/mass spectroscopy (GC/MS). Experimental data suggest phenols as active compounds against B. subtilis cultures, but not against other microorganisms. On the other hand, the essential oil exhibited a good antimicrobial spectrum when pure, but its relative low concentrations in common folk preparations do not allow for any good activity in these extracts.