Prenylated pterocarpans as bacterial neuraminidase inhibitors

During the course of a neuraminidase inhibitor screening program on natural products, four new (6, 8, 11, and 12) and eleven known (1–5, 7, 9–10, and 13–15) pterocarpan derivatives were isolated as active principles from the EtOAc extract of the stem bark of Erythrina abyssinica. Their structures were identified by spectroscopic data analyses. All isolates exhibited significant inhibitory effects on the neuraminidases from Clostridium perfringens and Vibrio cholerae with IC50 values ranging from 1.32 to 77.10 μM and 0.35 to 77.73 μM, respectively. The isolates (1–3, 5–8, 10, and 13–15), which possessed noncompetitive inhibition modes in kinetic studies, showed stronger activity against C. perfringens neuraminidase (IC50 1.32–19.82 μM) than quercetin (IC50 25.34 μM), which was used as the positive control. In contrast, compounds 4 and 9 behaved as competitive inhibitors and were displayed less effective (IC50 26.39–33.55 μM). Furthermore, calopocarpine, as a neuraminidase inhibitor, produced a decrease of V. cholerae adhesion to the host cell. Overall, these results suggest that neuraminidase inhibitors can be used in the development of new treatments to combat infectious diseases.

Four new pterocarpenoid derivatives (6, 8, 11, and 12) and eleven known ones (1–5, 7, 9, 10, and 13–15) were isolated from the stem bark of Erythrina abyssinica. All compounds exhibited strong inhibitory effects on the neuraminidase from Clostridium perfringens and Vibrio cholerae with IC50 values ranging from 1.32 ± 0.2 to 77.10 ± 2.2 μM and 0.35 ± 0.02 to 77.73 ± 11.01 μM, respectively. This finding suggests that E. abyssinica and its constituents, pterocarpanoids, can be considered as promising therapeutic agent in the treatment of bacterial infections.Figure optionsDownload as PowerPoint slide