Isoprenoids and Fatty Acids Derivatives from the Chloroform Fraction of the Antimycobacterial Methanol Extract Ximeniaamericana Lam. (Olacaceae) Stem Bark

Abstract

This study investigated the triterpenoids and fatty acid derivatives, and the in vitro growth inhibitory effect against clinical strains of Mycobacteria tuberculosis of the stem bark of Ximenia Americanaa plant widely used in ethno-medicine for the treatment of bacterial and skin infections, poison, post-partum hemorrhage, anaemia, and dysentery. The macerated methanol extract (XAM) of the stem bark was evaluated for anti-tuberculosis activity using the Lowensten Jensen method against de-contaminated clinical strains of Mycobacterium tuberculosis. The XAM was fractionated by open column chromatography on a normal phase silica gel column with a 25 % stepwise gradient of chloroform-methanol as mobile phase. The constituents of the non-polar column fractions eluted with 100% chloroform were characterized using Gas Chromatography-Mass spectroscopic (GC-MS) techniques and by comparison with reference NIST library compound. The XAM (5 mg/mL) inhibited the growth of the Mycobacterium tuberculosis. GC-MS analysis of the non-polar column fractions afforded Two lupane-type triterpenoids: Lup-20-(29)-en-3-one (15) and lupeol (16), three phytosteroids: campesterol (11), stigmasterol (12) and gamma-sitosterol (14), one fridelane-type triterpenoid: Friedelan-3-one (8), one oleanane-type triterpenoid: 12-oleanen-3-one (13), and the fatty acids: Palmitic acid methyl ester (1), Palmitic acid (2), 11-octadecenoic acid methyl ester (3), Octadecanoic acid methyl ester (4), Cis-13-Octadecenoic acid (5), 10,13-octadecadiynoic acid methyl ester (6), Docosanoic acid (7), Tetracosanoic acid (9), and Hexacosanoic acid methyl ester (10). The presence of these bioactive triterpenoids and fatty acids could offer an explanation for the ethno-medicinal uses of this plant. Further work is on-going to isolate in pure form, and characterized the bioactive constituents in the XAM with the view of discovery lead compounds for the treatment of tuberculosis and associated opportunistic bacterial infections.