Lawrence Onyango Arot Manguro

Phenolics of Moringa oleifera leaves.

Five flavonol glycosides characterised as kaempferide 3-O-(2″,3″-diacetylglucoside), kaempferide 3-O-(2″-O-galloylrhamnoside), kaempferide 3-O-(2″-O-galloylrutinoside)-7-O-α-rhamnoside, kaempferol 3-O-[β-glucosyl-(1 → 2)]-[α-rhamnosyl-(1 → 6)]-β-glucoside-7-O-α-rhamnoside and kaempferol 3-O-[α-rhamnosyl-(1 → 2)]-[α-rhamnosyl-(1 → 4)]-β-glucoside-7-O-α-rhamnoside together with benzoic acid 4-O-β-glucoside, benzoic acid 4-O-α-rhamnosyl-(1 → 2)-β-glucoside and benzaldehyde 4-O-β-glucoside have been isolated from methanolic extract of Moringa oleifera leaves. Also obtained from the same extract were known compounds, kaempferol 3-O-α-rhamnoside, kaempferol, syringic acid, gallic acid, rutin and quercetin 3-O-β-glucoside. Their structures were determined using spectroscopic methods as well as comparison with data from known compounds.

Benzoquinone derivatives of Myrsine africana and Maesa lanceolata.

The fruits of Myrsine africana afforded two new benzoquinone derivatives, methylvilangin and methylanhydrovilangin. On the other hand, from the fruits of Maesa lanceolata two more novel compounds; 2,5-dihydroxy-3-(nonadec-14-enyl)-benzoquinone and lanciaquinone were isolated. Their structural elucidation was achieved by spectroscopic measurements including 2D NMR experiments.

Further flavonol and iridoid glycosides from Ajuga remota aerial parts

Five new iridoid glycosides characterised as 6-keto-8-acetylharpagide (1), 6,7-dehydro-8-acetylharpagide (2), 7,8-dehydroharpagide (3), 8-acetylharpagide-6-O-β-glucoside (4), harpagide-6-O-β-glucoside (5) together with three flavonol glycosides, myricetin 3-O-rutinoside-4′-O-rutinoside (6), myricetin 3-O-rutinoside-3′-O-rutinoside (7) and isorhamnetin 3-O-rutinoside-7-O-rutinoside-4′-O-β-glucoside (8) have been isolated from the aerial parts of Ajuga remota. Also isolated were two known compounds ajugarin IV and ajugarin V. Their structures were established using spectroscopic methods including UV, IR, FAB-MS, HR-MS, 1D and 2D NMR techniques.

Triterpenes of Commiphora holtziana oleo-gum resin

Chemical analysis of the acetone extract of Commiphora holtziana gum resin has led to the isolation of triterpenes characterized as methyl 3-oxo-1α,19α,28-trihydroxyurs-12-en-24-oate (1), methyl 3β...

Isolation of a new β-carboline alkaloid from aerial parts of Triclisia sacleuxii and its antibacterial and cytotoxicity effects

Abstract A new β-carboline alkaloid named sacleuximine A (1) together with known compounds palmatine (2), isotetrandrine (3), trans-N-feruloyltyramine (4), trans-N-caffeoyltyramine (5), yangambin (6), syringaresinol (7), sesamin (8), (+) epi-quercitol (9), 4-hydroxybenzaldehyde (10), β-sitosterol (11), quercetin 3-O-rutinoside (12) and myricetin 3-O-β-glucose (1→6) α-rhamnoside (13) have been isolated from methanol extract of Triclisia sacleuxii aerial parts. Compounds 1–10 were evaluated for their cytotoxicity against human adenocarcinoma (HeLa), human hepatocarcinoma (Hep3B) and human breast carcinoma (MCF-7) cells lines and also for antibacterial activities against both Gram-positive and Gram-negative bacteria. The cytotoxicity (IC50) values ranged between 0.15 and 36.7 μM while the minimum inhibitory concentrations were found to be in the range of 3.9 and 125 μM, respectively. This is the first report of antibacterial compounds and the isolation of lignans together with a β-carboline alkaloid from T. sacleuxii.

Ursane and tirucallane-type triterpenes of Boswellia rivae oleo-gum resin.

Abstract Two new ursane-type triterpenes characterized as 3-oxo-24-acetoxy-11α-hydroxy-urs-12-ene (1) and methyl 3α-acetoxy-11α-methoxy-urs-12-en-24-oate (2), together with known compounds 3–11, were isolated from Boswellia rivae oleo-gum resin exudate. Their structural elucidation was accomplished using physical, chemical, and spectroscopic methods. The compounds exhibited weak to moderate antibacterial activities against some Gram-positive and Gram-negative bacteria.

Effects of Senna didymobotrya Root Extract and Compounds on Tritoninduced Hyperlipidaemic Rats and Differentiation of 3T3-Li Preadipocytes

The lipid lowering effects of Senna didymobotrya (Leguminoceae) root extract (250 mg/kg) and pure isolates (100 mg/kg) were investigated for hypolipidemic activity on Triton-induced hyperlipidemic rats (in-vivo). The extracts and isolates showed significant (p�0.01) reduction in serum lipid contents, and reactivation of the lipolytic enzymes, relative to the Triton-treated group. Ethyl acetate extract exhibited the highest lipid lowering (p�0.01) compared to other fractions. Seven anthraquinones, obtusifolin (1), 1,6-di-O-methylemodin (2), nataloemodin-8-methyl ether (3), chrysophanol (4), physcion (5), chrysophanol-10,10-bianthrone (6), physcion-10,10-bianthrone (7) and stigmasterol (8) were isolated from the ethyl acetate extract. Compounds 3, 5 and 7 displayed significant (p�0.01) lipid lowering effects. The hypolipidaemic activities prompted the determination of inhibition of differentiation of 3T3-L1 preadipocytes into adipocytes by the compounds 3, 5 and 7. Only compound 7 exhibited potent anti-adipogenic activity without significant cytotoxicity. The result indicated that extracts of S. didymobotrya root extract can provide good antidyslipidaemic and adipocytes maturation inhibitors.

Triterpene saponins of Maesa lanceolata stem wood

Phytochemical analysis of aqueous MeOH extract of Maesa lanceolata stem wood has led to the isolation of four new triterpene saponins characterized as 16α,21β-diacetoxy-22α-angeloyl-28-hydroxyolean-12-ene 3-O-[α-rhamnopyranosyl-(1″″ → 6‴)-β-glucopyranosyl-(1‴ → 3′)][β-glucopyranosyl-(1″ → 2′)]-β-glucuronopyranoside (1), 16α-acetoxy-21β-hydroxy-22α-angeloyl-13β,28-oxydoolean-28α-ol 3-O-[α-rhamnopyranosyl-(1″″ → 6‴)-β-glucopyranosyl-(1‴ → 4′)][β-glucopyranosyl-(1″ → 2′)]-α-arabinopyranoside (2), 16α-acetoxy-21β,22α-diangeloyl-13β,28-epoxyoleanane 3-O-[α-rhamnopyranosyl-(1″″ → 6‴)-β-glucopyranosyl-(1‴ → 4′)][β-glucopyranosyl-(1″ → 2′)]-β-xylopyranoside (3), and 16α,22α-diacetoxy-13β,28-oxydoolean-28α-ol 3-O-[β-glucopyranosyl-(1″ → 2′)][β-glucopyranosyl-(1‴ → 3′)]-β-glucuronopyranoside (4), together with the known compounds β-acetylamyrin, physcion, emodin, chrysophanol, ursolic acid, 16α-hydroxy-12-oleanene 3-O-glucoside, β-amyrin, sitosterol 3-O-β-glucoside, stigmasterol, and 3β,28-dihydroxyolean-12-ene. Their structural elucidation was accomplished by homo- and heteronuclear 2D NMR technique as well as comparison with data from known compounds. The in vitro antibacterial activity of the aqueous MeOH extract was also investigated and zones of inhibition ranging from 32 ± 1.1 to 14 ± 0.2 mm were observed. Among the isolates, compound 1 was the most active with an minimum inhibitory concentration value of 25 μg/ml against Staphylococcus aureus.

Chemical constituents of essential oils from three Eucalyptus species acclimatized in Ethiopia and Kenya.

Abstract Essential oils obtained by steam distillation of three Eucalyptus species acclimatized in Ethiopia and Kenya were analyzed using GC and GC-MS. The species were Eucalyptus citriodora, Eucalyptus globulus and Eucalyptus camaldulensis. Results showed that the oils from E. globulus and E. citriodora from trees grown in the two countries were quite comparable. The major component of the essential oil of E. globulus was 1,8-cineole while that for E. citriodora was citronellal. The oils from E. camaldulensis grown in the two countries, however, were found to differ. While trees from Kenya afforded an oil rich in 1,8-cineole, those from Ethiopia yielded p-cymene and cryptone as major components. Oils from E. camaldulensis grown in two different locations in Ethiopia were also found to vary in their p-cymene content; one had 35 %while the other gave 21.2 %.

New compounds with antimicrobial activities from Elaeodendron buchananii stem bark

Abstract The plant species Elaeodendron buchananii Loes is widely used in folklore medicine to manage microbial infections in Kenya. Previous studies on the plant fruits and root bark revealed the presence of steroids and terpenoids. The present phytochemical analysis of the plant stem bark has led to the isolation of four new triterpenes characterized as methyl 3β-acetoxy-11α, 19α, 28-trihydroxyurs-12-en-23-oic acid (1), 3β, 11α, 19α-trihydroxyurs-12-en-23, 28-dioic acid (2), 3β-acetoxy-19α, 23, 28-trihydroxyurs-12-ene (3) and 3-oxo-19α, 28-dihydroxyurs-12-en-24-oic acid (4), together with ten known ones (5–14), whose structures were elucidated using spectroscopic techniques. The isolate canophyllol (8) showed promising antibacterial activity against N. meningitides with MIC value of 31.25 μg/ml.