The genus Erythrina, Family Fabaceae comprises around one hundred and ten species of orange or red‐flowered trees, shrubs and herbaceous plants. In Southern Africa, it occurs in scrub forest, dry woodland and coastal bush in the northern provinces of South Africa. We isolated a number of alkaloids from Erythrina plants and reported 4 for the first time in nature and five for the first time in this species and the rest having been re‐isolated. We have screened several of them for activity on recombinant caspase‐3, in vitro. Caspase‐3 (Calbiochemas a kit) activity was assayed according to prescribed protocol and incubated for overnight at ambient temperature. Assays were performed in 96‐well plates, incubated overnight at ambient temperature and read at 405nm on a micro plate reader. We report that several of the alkaloids, one of which is new, induced two to four‐fold increases in caspase‐3 activity over the controls. We propose that these alkaloids may be potential lead compounds in therapeutic strategies targeting induction of apoptotic death of cancerous cells. Funded by the MHIRT/NCMHD/NIH Grant #5T37MD001810, Elizabeth City State University and University of Botswana.

Prostate cancer is a leading killer disease among men all over the world. Inducing apoptosis (programmed cell death) is a strategic chemotherapeutic approach. Caspase-3 is a key effector of apoptosis, and its activation promotes apoptosis. It was hypothesized that erythrinaline alkaloids activate caspase-3. The alkaloids were isolated from the flowers and pods of Erythrina lysistemon. Their effect on human recombinant caspase-3 was studied. This study reports that three erythrinaline alkaloids (+)-11α-hydroxyerysotrine N-oxide (1), (+)-11β-hydroxyerysotrine N-oxide (2) and (+)-11β-methoxyerysotrine N-oxide (3) activated human recombinant caspase-3 in a dose-dependent manner. Compound 1 and 2 increased the activity by five-fold while compound 3 increased it by ten-fold. Erythrinaline alkaloids exhibit remarkable ability to activate caspase-3 and may be lead compounds as potential therapeutics for the treatment of cancer as inducers of apoptosis in cancer cells.