~ 4228 ~ Journal of Pharmacognosy and Phytochemistry 2019; 8(3): 4228-4244 E-ISSN: 2278-4136 P-ISSN: 2349-8234 JPP 2019; 8(3): 4228-4244 Received: 10-03-2019 Accepted: 12-04-2019 Legesse Adane Department of Chemistry, College of Natural and Computational Sciences, Hawassa University, Hawassa, Ethiopia Mulugeta Teshome Department of Chemistry, Bonga Teachers’ Training College, Bonga, Ethiopia Yinebeb Tariku Department of Chemistry, College of Natural Sciences, Jimma University, Jimma, Ethiopia Correspondence Legesse Adane Department of Chemistry, College of Natural and Computational Sciences, Hawassa University, Hawassa, Ethiopia Isolation of compounds from root bark extracts of Moringa stenopetala and evaluation of their antibacterial activities Legesse Adane, Mulugeta Teshome and Yinebeb Tariku Abstract This study was conducted to isolate compounds from root bark extracts of M. stenopetala and evaluating its antibacterial activity. The root bark was extracted with different solvent systems (Petroleum ether, chloroform, and acetone) using maceration technique. The acetone crude extract was subjected to column chromatographic separation. Four compounds (labeled as MOST-1, MOST-2, MOST-3, and MOST-5) were obtained in the process. The compounds were found to be stigmastereol, ursolic acid, tasnemoxide and oleic acid respectively, based on their spectral analyses (IR, 1 H-NMR, 13 C-NMR and DEPT-135) data and comparison with data reported in literatures. The antibacterial activity of the compounds reveled that they show good antibacterial activities against the four bacterial strains used in the experiment. However, further tests (on more bacterial strains) are recommended in order to make decision on potential of the isolated compound as lead compounds and also to support the claims made by traditional healers on medicinal use of the plant used in the study. Keywords: Moringa stenopetala, Ursolic acid, stigasterol, Oleic acid, disc diffusion, Tasnemoxide Introduction Moringa stenopetala (M. stenopetala) is one the 14 species of moringa. M. stenopetala is one of the well-known trees in southern part of Ethiopia (especially in Konso, Arbamicnh and Wolayta areas). The tree (locally known as Haleko or Shiferaw) is well known for its medicinal uses and nutritional value [1] . Some of the medicinal uses of its different parts to treat malaria, hypertension, stomach pain, leishmaniasis and also to expel retained placenta in women who have just given birth [1-4] . This made it imperative to conduct scientific investigations in search of lead compounds that could be used in drug discovery programs of pharmaceutical companies and academic institutes. This involves isolation of compounds, and subsequent test of their biological activities. There are several literature reports in this regard. For instance, a compound with antimicrobial (antibacterial and antifungal) activities 4-(α-L- rhamnosyloxy) benzyl isothiocyanate (1) (Figure 1) was isolated from seeds of M. stenopetala [5] . Isolation of other compounds such as benzyl isothiocyanate (2), isobutyl isothiocyanate (3), benzene-1-isocyano-2-methyl (4), cycloprpane pentyl (5), methyl 9-octadecenoat (6), methyl palmitate (7), nonanoic acid (8), δ-cadinene (9), 5,5-dimethyloxazolidine-2-thione (10) (Figure 1) were reported from seed extract of the plant [5, 6] . Reports also showed isolation of diverse group of unsaturated fatty acids such as oleic acid (11), and saturated acids such as behenic acid (12) and palmitic acid (13) as well as high levels of β-sitosterol (14), stigmasterol (15), and campesterol (16) from n-hexane and chloroform: methanol (1:1) extracts of seed oils of the plant [7] . Moreover, defatted and shell-free seeds of were found to contain the glucosinolates such as 4-(α-L-rhamnopyranosyloxy)-benzylglucosinolate (17) [8] . Similar reports showed isolation several compounds from the leaves and roots of M. stenopetala. Compounds such as 4-(α-l-rhamnopyranosyloxy)-benzylglucosinolate (17), 4-(4'-O-acetyl-L- rhamnosyloxy)-benzylisothiocyanate (18), 4-(4'-O-acetyl-L-rhamnosyloxy)-benzaldehyde (19), rutin (20), quercetin 3-O-rhamnoglucoside (21) and 5-caffeoylquinic acid (22) have been isolated from the leaves [9] whereas benzyl glucosinolate (23), cholest-5-en-3-ol (cholesterol) (24), palmitic acid (13), n-octacosane (25), Oleic acid (26), 1, 3-dilinoleoyl-2-olein (27) and 1, 3-dioleoyl-2-linolein (28) (Figure 1) are some of the compounds isolated from roots and root wood of the plant [9, 10] . Biological activity tests of the isolated compounds showed promising potentials to be used as drug candidates in the development of drugs for treatment human diseases such as antitrypanosomasis [11, 12] , hypertension [6] , bacterial infection [7] and leishmaniasis [10] . In continuation of our previous effort to explore potential drug candidate for antibacterial activity from M. stenopetala [7, 10] , we carried out isolation of compounds from root bark of this