Isolation, Chemical Identification and Pharmacological Evaluation of Eucryphin, Astilbin and Engelitin Obtained from the Bark of Hymenaea martiana

Abstract

This study was designed to isolate, chemically characterize, and pharmacologically evaluate the active principles present in a crude extract from the bark of Hymenaea martiana. β-Sitosterol-3-O-glycoside and three rhamnosides (eucryphin, engelitin and astilbin) were identified. As demonstrated previously with an alcohol extract from H. martiana, the glycoside eucryphin (29.5-236 μM) caused a concentration-dependent rightward displacement of the bradykinin (BK) concentration response curve in the isolated rat uterus. In contrast, astilbin (22-176 μM) and engeletin (21-92 μM) caused only a discrete displacement to the right of BK-induced contractions. Acetylated astilbin (18-72 μM) and eucryphin (13-53 μM) caused a parallel and concentration-dependent displacement to the right of BK concentration-response curves associated with slight depression of the maximal contraction. However, the antagonistic actions of these glycosides were found to be non-selective against BK, since at the same concentration range they antagonized acetylcholine-induced uterine contractions. These results further extend our previous studies carried out with the crude extract of H. martiana and furnish strong evidence that astilbin, eucryphin and to a lesser extent engelitin seem to be the active principles present in the bark of this plant. Whether these compounds demonstrate in vivo pharmacological activity remains to be determined.