Etude chimique de Croton oligandrum Pierre ex Hutch(Euphorbiaceae). Evaluation des activités antiproliférative, antioxydante et antimicrobienne de quelques diterpenes isolés.

Abstract

This work focuses on phytochemical and biological evaluation of the stem barks, roots, leaves and wood of Croton oligandrum, a Cameroonian medicinal plant belonging to the Euphorbiaceae family. From the different parts of Croton oligandrum studied, we have isolated twenty-four compounds by usual chromatographic techniques and characterized them by spectroscopic methods. Five of them are new derivatives thus: crotonoligaketon, crotonoligafuranon A, croton oligafuranon B, ferrulicrutonoate and cis-balanopholin.The nineteen others have been reported before in the literature; they include: Four pentacyclic triterpenes: aleuritolic acetyl acid, lupeol, taraxerol and 3α-acetoxy 15β-hydroxyoleanan-28, 13-olid. Five steroids: β-sitosterol, stigmasterol, β-sitosterol palmitate, β-sitosterol glucoside and sitoindoside I. Nine diterpens: crotozambefuranA, crotozambefuranB, crtozambefuranC, crotocorylifurane, Crotonadiol, kayadiol, 7β-acetoxytrachyloban-18-oic acid, Ent trachylobane-15β, 18-diol and trachinodiol. One phenolic compound: 4-hydroxy-3-méthoxybenzaldéhyde Acetylation was carried out on kayadiol and Ent-trachylobane-15β, 18-diol which enabled us to obtain two acetylated derivatives namely: 15, 18- diacetoxylabda-8(17), 13-diene and 15β, 18-diacetoxy-Ent-trachylobane, respectively. Antimicrobial, antioxidant and antiprolifarative tests on five diterpenes isolated from the stem bark of Croton oligandrum namely: crotozambefuran B, crotonadiol, kayadiol, 7β acetoxy trachyloban-18-oic acid, and crotonoligaketone allowed to show that: All tested compounds showed a weak antibacterial activity. All tested compounds have antiproliferative activity; the largest being observed by crotozambefuran B with IC50 from 10 to 100µM.7β-acetoxy trachyloban-18-oic acid showed the most interesting antioxidant activity, with IC50 of (7,75±0,88) mg/mL .It also showed the highest ferrous iron chelating ability (26,5±0,5)%.