Diversité Chimique et Activité Cytotoxique de Stipularia africana (Rubiaceae)

Abstract

The present study focuses on studying the chemical diversity and evaluating the cytotoxic activity of Stipularia africana, a Cameroonian medicinal plant belonging to the Rubiaceae family. The leaves of this plant are widely used in traditional medicine to treat chronic diseases such as diabetes, hypertension and cancers.The crude extract and fractions obtained after alkaloid treatment were evaluated for their cytotoxic activities against three glioblastoma cell lines, U251-MG, U87-MG, and LN229, using the MTT assay. The results revealed that the alkaloid and non-alkaloid fractions exhibited moderate cytotoxic activity against these cell lines, with IC50 values ranging from 23.14 to 139.90 µg/mL, compared to oxaliplatin, used as a reference.From the dichloromethane alkaloid fraction, which demonstrated the strongest cytotoxic activity, three compounds (SA.11 to SA.13) were isolated using classical chromatographic techniques. These compounds were fully characterised and identified as two aporphine-type alkaloids, lirioferine (SA.12) and N-acetylcatalpifoline (SA.13), and a sterol, β-sitosterol (SA.11).The structural elucidation of these compounds was achieved using standard spectroscopic methods, including one-dimensional NMR ( H and C), two-dimensional NMR (HSQC, HMBC, and COSY), mass spectrometry, and by comparing their spectroscopic data with those reported in the literature.