Isopteropodine (Uncarine E) is an isoyohimbine-type octindole alkaloid isolated from Hamelia patens micropropagated and has antimicrobial activity and stimulates the immune system. Isopteropodine has antimicrobial activity and stimulates the immune system.Isopteropodine is a positive modulator of muscarinic M1 and 5-HT2 receptors and a PXR activator that induces contraction of the rat myometrium.

Here, we investigated for the first time the antiproliferative and apoptotic effects of highly purified oxindole alkaloids, namely Isopteropodine (A1), pteropodine (A2), isomitraphylline (A3), uncarine F (A4) and mitraphylline (A5) obtained from Uncaria tomentosa, a South American Rubiaceae, on human lymphoblastic leukaemia T cells (CCRF-CEM-C7H2). Four of the five tested alkaloids inhibited proliferation of acute lymphoblastic leukaemia cells. Furthermore, the antiproliferative effect of the most potent alkaloids pteropodine (A2) and uncarine F (A4) correlated with induction of apoptosis. After 48 h, 100 micromol/l A2 or A4 increased apoptotic cells by 57%. CEM-C7H2 sublines with tetracycline-regulated expression of bcl-2, p16ink4A or constitutively expressing the cowpox virus protein crm-A were used for further studies of the apoptosis-inducing properties of these alkaloids. Neither overexpression of bcl-2 or crm-A nor cell-cycle arrest in G0/G1 phase by tetracycline-regulated expression of p16INK4A could prevent alkaloid-induced apoptosis[1]