Chemical composition and antibacterial action of Stryphnodendron pulcherrimum bark extract, “barbatimão” species: Evaluation of its use as a topical agent

Abstract

Stryphnodendron pulcherrimum (Willd.) Hochr. (Fabaceae) is a native Amazonian tree, popularly known as “barbatimão”. The stem barks of this tree are widely used in folk medicine to treat infections, cutaneous and ulcerative wounds, under the form of a suspension of the bark-derived powder. The present study aimed to investigate the in vitro antibacterial and cytotoxic activities of the ethanolic extract of S. pulcherrimum (SPEE). Likewise, to putatively identify the active compounds of the extract by ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS). Therefore, we aimed to rationalize this observation by turning the bark powder-derived suspension into an ointment (SPEEO) incorporating SPEE (20% w/v). Both the antibacterial action and the acute dermal toxicity were evaluated in rats as animal model. Mortality, body weight changes, feed and water intake, organ weights, histological and biochemical parameters were measured for 14 days post-treatment with no major sign of toxicity. The SPEE showed excellent in vitro antibacterial activity (Minimum Inhibitory Concentration = 100 µg/mL) against Staphylococcus aureus and no in vivo acute dermal toxicity. The SPEEO inhibited up to 85% bacterial growth in a petri dish, with better results than the control standard ointment (Kollagenase®). We putatively identified 13 compounds present in the SPEE, belonging to the class of tannins, including one trimer and two dimers of catechin. Thereby, the data showed SPEEO as a potent antibacterial candidate for herbal medicine preparation.