In Vitro Evaluation of the Anti-Proliferative and Anti-Diabetic Activities of Streptocaulon juventas Leaf Extracts

Streptocaulon juventas, a medicinal plant traditionally used in Vietnam and other Southeast Asian countries, has been previously investigated for certain biological activities of its roots; however, studies on its leaves remain limited. In this study, leaf extracts were evaluated for their in vitro anti-proliferative activity against B16F10 (murine melanoma) and HepG2 (human hepatocellular carcinoma) cell lines, as well as for their α- glucosidase inhibitory potential. MTT assays revealed that the hexane (Sj-Hx) and dichloromethane (Sj-DCM) fractions exhibited the strongest cytotoxic effects on B16F10 cells, with IC₅₀ values of 36.09 µg/mL and 45.91 µg/mL, respectively. The hexane fraction (Sj-Hx) also demonstrated potent activity against HepG2 cells, with an IC₅₀ value of 36.65 µg/mL. Notably, none of the extracts exhibited cytotoxicity toward Hs68 normal human fibroblasts, indicating favorable selectivity. DAPI staining further confirmed that both Sj-Hx and Sj-DCM induced nuclear fragmentation and chromatin condensation, consistent with apoptosis induction. Additionally, in vitro assays of anti-diabetic activity revealed that the hexane (Sj-Hx) and ethyl acetate (Sj-EA) extracts displayed the strongest α-glucosidase inhibition, with IC₅₀ values of 221.59 µg/mL and 265.73 µg/mL, respectively. Collectively, these findings suggest that S. juventas leaf extracts possess selective pro-apoptotic activity against cancer cells and represent a promising natural source for the discovery of anti-diabetic agents.