Phytochemical Studies of Alstonia scholaris, Chemical Transformation and Biological Evaluation against a Breast Cancer Cell Line

Background: Some Alstonia species are used in traditional medicine to treat diseases such as cancer, dysentery, diarrhea, jaundice, malaria, gastrointestinal troubles, and snake-bites. Objective: In this study, we aim to evaluate the ethanol leaf extract of Alstonia scholaris for anticancer constituents and structural modification to introduce a privilege medicinal α,β-unsaturated scaffold. Methods: The relative viability of the MDA-MB-231 breast cancer cell line exposed to isolated compounds at different concentrations was assayed. Chemical analysis was carried out by high resolution mass spectrometry and one and two-dimensional NMR techniques. Results: Structures of purified compounds were determined as betulin 1, α-amyrin acetate 2, mixture of β-sitosterol 3 and stigmasterol 4, tetratriacontyl-trans-p-coumarate 5, ursolic acid 6, β-sitosterol glucoside 7, picralstonine 8 and scholaricine 9. To introduce privilege medicinal scaffold, compounds 1 and 2 under SeO2 oxidation condition afford new acrylaldehye derivatines. Compound 1 afforded Betulin acrylaldehyde 10 while compound 2 afforded lupeolacetate acryl aldehyde 11 in an intriguing mechanism with the conversion of ursane to lupane scafford. Compound 11 equally showed interesting activity against MDA MB 231 breast cancer cell line with an IC50 of 4.63 ± 0.09 μg/ml. Conclusion: From these findings, the medicinal α,β-unsaturated scaffold could have pharmacological effects in treating MDA-MB-231 breast cancer.