Synthesis and antibacterial activities of cyclodimers of styrene oxides

A simple synthetic procedure for preparation of 1,4-dioxanes or 1,3-dioxolanes from styrene oxides is described. Electron-donating groups on the aromatic ring of the styrene oxides were found to favour formation of 1,4-dioxanes while electron-withdrawing groups favoured formation of 1,3-dioxolanes. Antibacterial activities of the prepared cyclodimers are reported. KEY WORDS: Dioxanes, Dioxolanes, Styrene, Epoxidation, Cyclodimerization, Antibacterial activities Bull. Chem. Soc. Ethiop. 2011, 25(2), 299-304

FACILE ENANTIOSELECTIVE PALLADIUM CATALYSED TRANSFER HYDROGENATION OF α-METHYLCINNAMIC ACID IN THE PRESENCE OF OPTICAL PURE ORGANIC ACIDS

An efficient and enantioselective method for catalytic transfer hydrogenation of the C=C double bond of α-methylcinnamic acid with the aid of chiral organic acids as the hydrogen donors and palladium(II) chloride as the catalyst is reported. Enantiomeric excess was assayed using optical rotation measurements. The best stereoselectivity was achieved when L-(+)-tartaric acid was used as the hydrogen donor and acetonitrile as the solvent. KEYWORDS: Enantioselective, Chiral, α-Methylcinnamic acid, Transfer hydrogenation, Palladium(II) chloride Bull. Chem. Soc. Ethiop. 2007, 21(3), 457-460

Two new isoflavanoids from <i>bolusanthus speciosus</i>

The structures of two new isoflavonoids from the combined ethyl acetate/methanolic extracts of the stem bark of Bolusanthus speciosus have been established as 4,7,2' -trihydroxy-4' -methoxyisoflavanol (1) and 5,7,3',4' -tetrahydroxy-5' -(2-epoxy-3-methylbutyl)isoflavanone (2). Five other known isoflavonoids, 5,7,3' -trihydroxy-4' -methoxy-5' -γγ; -dimethylallylisoflavanone, 5,7,2' -trihydroxy-4' -methoxy-6,5' -di)(γγ -dimethylallyl)isoflavanone, 5,7,2' ,4'-tetrahydroxy-8,5'2; -di(γγ -dimethylallyl)flavanone, 5,7,2',4' -tetrahydroxy-8,3' -di(γγ -dimethylallyl)-isoflavanone, and derrone were also isolated. Compound 2 showed moderate activity against gram positive bacteria and weak activity against gram negative bacteria, while compound 1 was weakly active against both organisms in a TLC bioautography assay

Chemical constituents of the root wood of Erythrina sacleuxii and determination of the absolute configuration of suberectin

Phytochemical investigation on the root wood of Erythrina sacleuxii (Leguminosae) led to the isolation of nine secondary metabolites (1-9). Compound 1 was isolated from the genus Erythrina for the first time. The pure compounds were identified on the basis of comprehensive spectroscopic and spectrometric analyses, while their absolute configurations were determined based on chiroptical measurements. Compounds 5 and 6 showed weak antifungal activity against Pyricularia oryzae with MIC values of 20&nbsp;µg/mL. &nbsp; Bull. Chem. Soc. Ethiop. 2020, 34(1), 135-140. DOI: https://dx.doi.org/10.4314/bcse.v34i1.1

GC-MS Analysis and Preliminary Antimicrobial Activity of Albizia adianthifolia (Schumach) and Pterocarpus angolensis (DC)

The non-polar components of two leguminoceae species Albizia adianthifolia (Schumach), and Pterocarpus angolensis (DC) were investigated. GC-MS analysis of the crude n-hexane and chloroform extracts together with several chromatographic separation techniques led to the identification and characterization (using NMR) of sixteen known compounds from the heartwood and stem bark of Albizia adianthifolia and Pterocarpus angolensis respectively. These constituents include, n-hexadecanoic acid (palmitic acid) 1, oleic acid 2, chondrillasterol 3, stigmasterol 4, 24S 5α-stigmast-7-en-3β-ol 5, 9,12-octadecadienoic acid (Z,Z)-, methyl ester 6, trans-13-octadecanoic acid, methyl ester 7, tetradecanoic acid 8, hexadecanoic acid, methyl ester 9, octadecanoic acid 10, tetratriacontane 11, 7-dehydrodiosgenin 12, lupeol 13, stigmasta-3,5-diene-7-one 14, friedelan-3-one (friedelin) 15, and 1-octacosanol 16. Using agar over lay method, the preliminary antimicrobial assay for the extracts was carried out against bacterial (E. coli, P. aeruginosa, B. subtilis, S. aueus) and a fungus/yeast (C. albicans) strains. The n-hexane and chloroform extracts of A. adianthifolia showed the best activity against E. coli with minimum inhibition quantity (MIQ) of 1 µg each while the remaining exhibited moderate-to-weak activity against the test microorganisms

New flavonoids from the stem bark of Erythrina caffra Thunb.

Desta ZY, Sewald N, Majinda RRT. New flavonoids from the stem bark of Erythrina caffra Thunb. Natural Product Research. 2014;28(9):667-673.Three new flavonoids 5,7-dihydroxy-2 ',4 '-dimethoxy-5 '-formylisoflavanone (erycaffra E) (1), 5,7-dihydroxy-3 '-(2 ''-hydroxy-3 ''-methylbut-3-enyl)-5 '-(3"'-hydroxy-3"'-methyl-trans-but-1-enyl)-4 '-methoxyflavanone (erycaffra D) (2) and 5,7-dihydroxy-4 '-methoxy-3 ',5 '-di-(3 ''-hydroxy-3 ''-methyl-trans-but-1-enyl)flavanone (erycaffra F) (3) were isolated from the stem bark of Erythrina caffra along with four known compounds, namely 5,4 '-dihydroxy-6-(3 ''-methylbut-2 ''-enyl)-5"'-hydroxyisopropyldihydrofurano[2"',3"':7,8]isoflavone (isosenegalensein) (4), 5,7-dihydroxy-4 '-methoxy-3 '-(3 ''-methylbut-2-enyl)-5 '-(3"'-hydroxy-3"'-methylbut-1-enyl)flavanone (burttinone) (5), 5,4 '-dihydroxy-5 ''-hydroxyisopropyldihydrofurano[2"',3"':7,6]isoflavone (erythrinin C) (6) and 5,4 '-dihydroxy-6 ''-hydroxymethyl-6 ''-methylpyrano[2 '',3 '':6,7]isoflavone (erysubin B) (7). The structures were determined on the basis of spectroscopic data (1D, 2D NMR and MS) and by comparison with literature values

CYTOTOXIC FLAVONOIDS FROM ERYTHRINA CAFFRA THUNB

Desta ZY, Sewald N, Majinda RRT. CYTOTOXIC FLAVONOIDS FROM ERYTHRINA CAFFRA THUNB. BULLETIN OF THE CHEMICAL SOCIETY OF ETHIOPIA. 2016;30(3):427-435.Erythrina caffra is an important medicinal plant native to South Africa. Its stem bark was investigated for the flavonoid constituents and biological activity. Some isolated flavonoids, 3, 5, 6, 8, 9, 10, 11, 12, 13, 15 and 16 were found to be active against the human cervix carcinoma KB-3-1 cells with IC50 values in the micromolar range. Compounds 8, 9, 11, 13 and 15 also showed weak to moderate antibacterial activity against some organisms using the disc diffusion assay at loadings of 62.5 mu g/disc (8, 11) and 125 mu g/disc (9, 13, 15)

Anti-Oxidant and Hepatoprotective Activities of Ziziphus mucronata Fruit Extract Against Dimethoate-Induced Toxicity

Objective: The study was carried out to evaluate the hepatoprotective and antioxidant potential of Ziziphus mucronata (ZM) fruit extract. Methods: The different types of fruit extract were prepared by soaking the dry powdered fruit in different solvents followed by rotary evaporation. Each extract was tested for its phenol content and antioxidant activities. An in vivo study was performed in Sprague- Dawley (SD) rats. Thirty adult male SD rats (aged 21 weeks) were divided into six groups of five rats each and treated as follows: The normal control (NC) received distilled water while the dimethoate control (DC) received 6 mg/kg.bw.day-1 dimethoate dissolved in distilled water. The experimental groups E1, E2, E3, and E0 received dimethoate (6 mg/kg.bw) + ZMFM (100 mg/kg.bw-1), dimethoate (6 mg/kg.bw) + ZMFM (200 mg/kg.bw-1), dimethoate (6 mg/kg.bw) + ZMFM (300 mg/kg.bw-1), and ZMFM (300 mg/kg.bw-1) only. Both the normal control and the dimethoate control groups were used to compare the results. After 90 days, rats were sacrificed, blood was collected for biochemical assays, and livers were harvested for histological study. Results: High phenol content was estimated, and 2, 2- diphenyl-1-picryl hydrazyl radical (DPPH) spectrophotometric, thin layer chromatography (TLC) and 2, 2-Azobis-3-ethyl benzothiazoline-6-sulphonic acid (ABTS) assays showed a high antioxidant activity among the extracts. The preventive effects observed in the E1, E2 and E3 groups proved that the extract could prevent dimethoate toxicity by maintaining normal reduced glutathione (GSH), vitamin C and E, superoxide dismutase, catalase, cholineasterase and lipid profiles. The preventive effect was observed to be dose dependent. The EO group showed no extractinduced toxicity. Histological observations agreed with the results obtained in the biochemical studies. Conclusion: The study demonstrated that ZM methanol fruit extract is capable of attenuating dimethoate-induced toxicity because of its high antioxidant activity