Neonauclea formicaria (Rubiaceae) Leaf Extract Inhibits Vascularization in the Chorioallantoic Membrane of Duck Embryos

Plants are reservoirs of bioactive compounds with the potential for pharmaceutical use. In this study, the secondary metabolites of Neonauclea formicaria leaf crude ethanolic extract were determined using phytochemical screening. The plant's leaf extract was then used to test its angiogenesis activity using the chorioallantoic membrane (CAM) assay. Four concentrations of the extract were prepared—0.1 mg/L, 1.0 mg/L, 10.0 mg/L, and 100.0 mg/L and were topically applied on the CAM. Phytochemical screening revealed that N. formicaria leaves contain heavy amounts of flavonoids and tannins, while alkaloids, saponins, and steroids were present in trace amounts. The crude ethanolic extract was anti-angiogenic, as indicated by the significant decrease of vascular density at higher concentrations (P<0.05).  The 100 mg/L extract concentration showed the highest vascular inhibition (50.93%) among the other concentrations, suggesting its angiopreventive potential (P<0.05). Further investigation on the embryo's gross morphometry revealed no significant effects in the weight, crown-rump length, head-beak length, forelimb length, and hind limb length. Also, these indices were not associated with the angiogenesis activity on the CAM. Further studies exploring the specific metabolites of the different plant parts of N. formicaria and the plant's angiopreventive potential are recommended.