Voacangine

Voacangine is an indole alkaloid that has been found in T. citrifolia, V. africana, V. obtusa, and T. iboga with diverse biological activities. It inhibits the growth of M. tuberculosis, M. avium, and M. kansasii with MIC values of 50, >200, and 100 μg/mL, respectively. Voacangine (0.01-100 μM) dose-dependently reduces membrane currents in HEK293 cells expressing the hERG potassium channel and displaces the hERG ligand dofetilide with a Ki value of 3.9 μM. Voacangine suppresses agonist-induced activation of transient receptor potential (TRP) channels with IC50 values of 50 and 9 μM for activation induced by the TRPV1 agonist capsaicin and the TRPM8 agonist menthol, respectively. It also activates TRPA1 channels and stimulates calcium influx (IC50 = 8 μM in HEK293 cells expressing TRPA1), an effect that is blocked by the TRPA1 blocker HC-030031 . In vivo, voacangine (2 and 4 μg per egg) inhibits angiogenesis in chick embryo chorioallantoic membranes without apparent cytotoxicity.