Investigation of the antifungal activity of Pterocarpus erinaceus led to the identification of two new diarylpropanoids from its roots
Résumé
The popular use of Pterocarpus erinaceus as antimicrobial prompted us to study the antifungal properties of its bark, leaves and roots against Candida albicans, Aspergillus fumigatus, and Aspergillus niger. Thus, the broth microdilution method was used to perform the test and only the root extract showed significant antifungal activity against A. fumigatus with value at MIC 16 μg/mL. This root extract was further partitioned by immiscible liquid-liquid extraction into five fractions. Successive chromatographic columns were used for the purification of the organic fractions which led to the isolation and the identification of five compounds including two new (3 and 5) and three known (1, 2, and 4). Their structures were established as muningin 1, the mixture of formononetin and pseudobaptigenin 2, boutotone 3, isoliquiritigenin 4, and boutomycone 5, by the mean of spectroscopic data compared to those reported in the literature. Compounds 1-5 were also tested on A. fumigatus against which 1, 2, and 5 showed antifungal effects with MIC values at 853.3, 28.7, and 452.3 μM, respectively. The obtained results indicated that the traditional use of this plant as antimicrobial could be related to its roots.