Hydrolyzable tannins from Poincianella (Caesalpinia) microphylla fruits: Metabolite profiling and anti-Trichomonas vaginalis activity

Poincianella (Caesalpinia) microphylla fractions were analyzed by LC-DAD-MS and by statistical tools to determine the possible bioactive compounds against T. vaginalis. Tannins enriched-fractions toxicity (M5 and M10) were analyzed in in vitro against human red cells and in in vivo model of Galleria mellonella. Twenty-six compounds were detected from the P. microphylla fractions. The main compounds identified were hydrolyzable tannins (gallotanins and ellagitannis), such as O-digalloyl hexoside, O-digalloyl HHDP -hexoside, tri-O-galloyl HHDP-hexoside, O-galloyl HHDP-DHHDP-hexoside and their isomers. In addition, procyanidin dimer, epicatechin, ellagic acid and O-(digalloyl) quinic acid were also identified. Based on univariate statistical analyses, stronger correlations with the anti-T. vaginalis properties were observed for the compounds 7 (O-galloyl HHDP-DHHDP-hexoside - Geraniin isomer), 3 (O-digalloyl HHDP -hexoside - mallotinic acid), 2 (O-digalloyl) quinic acid), 1 (O-digalloyl hexoside) and 9 (unknown). Tannins enriched-fractions (M5 and M10) presented anti-Trichomonas activity (IC50 70.41 mu g/mL and 142.1 mu g/mL, respectively) and no toxicity in the in vivo model of G. mellonella. This innovative approach allowed us to identify likely bioactive compounds in the extracts, although the mechanism(s) underlying anti-trichomonal activity encompass a complex trait.