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A mycelial culture of the Kenyan basidiomycete Fomitiporia aethiopica was fermented on rice and the cultures were extracted with methanol. Subsequent HPLC profiling and preparative chromatography of its crude extract led to the isolation of five previously undescribed pregnenolone type triterpenes 1–5, for which we propose the trivial name aethiopinolones A–E. The chemical structures of the aethiopinolones were determined by extensive 1D- and 2D-NMR, and HRMS data analysis. The compounds exhibited moderate cytotoxic effects against various human cancer cell lines, but they were found devoid of significant nematicidal and antimicrobial activities. View Full-Text

The essential oil from leaves of Coriandrum sativum L. (Apiaceae), obtained by hydro-distillation was analysed by gas chromatography–mass spectrometry (GC–MS) and also evaluated for in vitro antimicrobial activity. Out of 27 peaks, 24 components, which constitute 92.7%, were identified in the oil. The oil was dominated by aldehydes and alcohols which accounted for 56.1% and 46.3% of the oil, respectively. The major constituents were 2E-decenal (15.9%), decanal (14.3%), 2E-decen-1-ol (14.2%) and n-decanol (13.6%). Other constituents present in fairly good amounts are 2E-tridecen-1-al (6.75%), 2E-dodecenal (6.23%), dodecanal (4.36%), undecanol (3.37%), and undecanal (3.23%). The oil was screened for antimicrobial activity against both Gram positive (Staphylococcus aureus, Bacillus spp.) and Gram negative (Escherichia coli, Salmonella typhi, Klebsiella pneumonia, Proteus mirabilis, Pseudomonas aeruginosae) bacteria and a pathogenic fungus, Candida albicans. The oil showed pronounced antibacterial and antifungal activity against all of the microbes tested, except for P. aeruginosae, which showed resistance.

The fumigant and repellent effects of Ocimum gratissimum L. oil and its constituents, β-(Z)-ocimene and eugenol, were evaluated against adults of Sitophilus oryzae (L.), Tribolium castaneum (Herbst), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (F.) and Callosobruchus chinensis (L.). The fumigant toxicities of the oil and two of its constituents were assessed at four rates (0, 1, 5 and10 μL/L air) in space fumigation, whereas repellence of the oil and eugenol in acetone was evaluated in choice bioassays at five rates (0, 1.0, 2.0, 3.0 and 4.0 μL oil/2 g grain). Results showed that fumigant toxicity and repellence of the oil and its constituents were significantly (P

Chiral GC–MS analyses of natural and synthetic trans- and cis-piperitone oxide were performed on an Rt-βDEX-sm capillary column in order to clarify the stereochemistry of their enantiomeric forms. Only enantiomerically pure laevo-rotatory piperitone oxides, (1S,2S,4S)-trans-piperitone oxide and (1S,2S,4R)-cis-piperitone oxide, were detected by chiral analyses of Micromeria fruticosa (L.) Druce and Mentha longifolia L. The occurrence of the cis- and trans-piperitone oxides was dependent on the population of the species. In all cases (1S,2S,4S)-trans-piperitone oxide was detected together with (4S)-piperitone, while (1S,2S,4R)-cis-piperitone oxide was detected together with (4R)-piperitone in the plants analysed. The four stereoisomers of trans- and cis-piperitone oxide were obtained by alkaline epoxidation of both (4R)- and (4S)-piperitone. The formation of the 1,2-epoxide can take place on either side of the 1,4-substituted six-membered ring. Racemization at C4 was observed under alkaline epoxidation reaction conditions due to keto-enol tautomerism. Copyright © 2007 John Wiley & Sons, Ltd.

The essential oil of Tarchonanthus camphoratus (Asteraceae), obtained by hydro-distillation, was analysed by gas chromatography–mass spectrometry (GC–MS) and also evaluated for antimicrobial activity. Out of 45 peaks representing 99.8% of the oil, 38 components which constitute 95.8% of the total oil were identified. The oil was dominated by monoterpenes, which accounted for 80.9% of the oil. This study indicates the presence of a high percentage of oxygenated monoterpenes (62.3%), of which the main constituents were fenchol (15.9%), 1,8-cineole (14.3%) and α-terpineol (13.2%). Other monoterpenes present in fairly good amounts were α-pinene (6.87%), trans-pinene hydrate (6.51%), terpinen-4-ol (4.74%) and camphene (3.76%). The oil was screened for antimicrobial activity against both Gram positive (Staphylococcus aureus, Bacillus ssp.) and Gram negative (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Klebsiella pneumoniae, Proteus mirabilis) bacteria and a pathogenic fungus Candida albicans. Except for P. aeruginosa, which showed resistance, the oil had pronounced antibacterial and antifungal activities.

Two coumarins were isolated from the plant Acokanthera schimperi (Apocynaceae), and the in vitro larvicidal activities of these compounds against East Coast Fever vector Rhipicephalus appendiculatus was investigated. The mortalities of the larvae were determined after 48 h post treatment. The finding demonstrated that Compound 1 and 2 as amixture registered LC50/LC90 values of 2.96/6.09 mg/ ml. These findings could be useful as lead compounds for the development of acaricides. Additionally, these findings underscore the fact that this plant is used ethnomedicinally as an acaricide. The discovery of plant compounds that may control ticks could be of great value to the agricultural sector.

Sleeping sickness or human African trypanosomiasis (HAT) is a neglected tropical disease (NTD) threatening millions of peoples’ lives with thousands infected. The disease is endemic in poorly developed regions of sub-Saharan Africa and is caused by the kinetoplastid “protozoan” parasite Trypanosoma brucei. The parasites are transmitted to humans through bites of infected tsetse flies of the genus Glossina. The few available drugs for treatment of this disease are highly toxic, difficult to administer, costly and unavailable to poor rural communities bearing the major burden of this infection. Therefore, the search for new efficacious, safe and affordable drugs is of high importance. Vernonia lasiopus O. Hoffm., an indigenous African plant of the Asteraceae family, has been extensively reported to be used ethno-medicinally as a treatment for malaria. Its crude extracts obtained with solvents of different polarity were screened in vitro for anti-protozoal activity and the dichloromethane extract was found to be particularly active against Trypanosoma brucei rhodesiense (IC50 = 0.17 µg/mL). Bioassay-guided chromatographic fractionation of the dichloromethane extract led to the isolation and identification of six elemanolide type sesquiterpene lactones: 8-desacylvernolide, vernolepin, vernomenin, vernodalol, vernodalin and 11,13-dihydrovernodalin. All these elemanolide sesquiterpene lactones showed in vitro anti-trypanosomal activity. They were also tested for cytotoxicity against mammalian cells (L6 cell line). Vernolepin, the main component in the extract, was also the most potent with an IC50 value of 0.05 µg/mL against T.b. rhodesiense trypomastigotes. This compound showed a selectivity index of 14.5, which makes it an interesting candidate for in vivo tests and determination of its mechanism of action.

Hydro-distilled essential oil from Kenyan Piper capense (Piperaceae) was analysed by gas chromatography mass spectrometry (GC?MS) and evaluated for larvicidal activity against the malaria vector, Anopheles gambiae. The oil consisted mainly of sesquiterpene hydrocarbons which accounted for 43.9% of the oil. The major sesquiterpenes were δ-cadinene (16.82%), β-bisabolene (5.65%), and bicyclogermacrene (3.30%). The oil also had appreciable amounts of monoterpene hydrocarbons (30.64%), including β-pinene (7.24%) and α-phellandrene (4.76%), and arylpropanoids (8.64%), including myristicin (4.26%). The oil showed larvicidal activity against third instar larvae of A. gambiae, with LC 50 and LC 90 values of 34.9 and 85.0 ppm, respectively. Most of the larvae died within the first few hours. The high larvicidal activity of this oil was indicated by the fact that over 80% mortality was observed at a concentration of 100 ppm after 24 h. These results compared favourably with the commercial larvicide pylarvex® which had LC 50 and LC 90 values of 3.7 and 7.8 ppm, respectively. Application of this oil or of products derived from it to larval habitats may lead to promising results in malaria and mosquito management programmes.

The synthesized spin trap 3,5-diphenyl-5-methylpyrroline-1-oxide (3), its derivatives and spin adducts were studied using NMR, ESR and ENDOR spectroscopic methods. The structure of 3 was determined using x-ray analysis. The nitrone 3 was found to have a rigid structure. Two species were observed in the EPR and ENDOR spectra of the spin adducts of 3, but not in the NMR spectra of its diamagnetic derivatives. These two species were attributed to those formed when the addends attack carbon-2 from both the re and si sides, resulting in trans (I) and cis (II) adducts in relation to the phenyl substituent in position 3. Therefore, these two species differ only through the substitution on carbon-2, whereby there are different steric interactions of the substituents within both species. The lack of observation of these two species in NMR spectra could be interpreted in terms of unfavourable relaxation times on the NMR time-scale. These species are observed in EPR and ENDOR spectra mainly because of their different β-C—H dihedral angles, which do not play a role in NMR spectroscopy. Both species have the ability to trap stereoselectively carbon- and oxygen-centred radicals, which occupy pseudo-equatorial and pseudo-axial positions, respectively. The occupation of oxygen-centred addends in the pseudo-axial positions is stabilized by the ‘anomeric effects.’ This nitrone 3 was found to have the ability to scavenge short-lived free radicals in both aqueous and non-aqueous solutions. © 1998 John Wiley & Sons, Ltd.

A chiral spin trap, 5,5-dimethyl-3-phenylpyrroline-1-oxide (5), and several hydroxylamines were synthesized. The structures and conformations of these compounds were investigated mainly by 1H NMR spectroscopy. This spin trap was used to trap carbon- and oxygen-centered radicals. The corresponding hydrogen spin adduct was prepared by oxidizing the hydroxylamine to the nitroxide radical. By the combination of 1H NMR and EPR results, it was shown that the conformation with the phenyl group of C-3 at the equatorial position is exclusively populated and its lifetime is long compared with the EPR time-scale. Addition of carbon-centered radicals to 5 leads to trans adducts whereas oxygen-centered radicals formed cis isomers. These could be confirmed by the investigation of the monovalent oxidation products of the hydroxylamines. The preference for these conformers is explained by the competition between steric and stereoelectronic effects. Despite the racemic nature of 5 and the formation of a new chiral center(s) in the spin adducts, the presence of different diastereomers would not be observed by EPR whereas 1H NMR studies of some of the nitrones showed clear evidence of diastereomeric mixtures. However, the spin adduct of sec-hydroxybutyl radical showed some linewidth effects which could be attributed to the presence of two groups of diastereomers that were resolved by ENDOR spectroscopy. In general, the spin adducts of 5 are closely related to those of the well known DMPO, but the presence of a phenyl substituent at the 3-position results in a variation of the β-H coupling constants. In contrast to DMPO, 5 can scavenge short-lived radicals in aqueous and non-aqueous solutions.

Hydro-distilled volatile oils from the leaves of Ocimum gratissimum L. (Lamiaceae) of 13 populations of different silvicultural zones were evaluated for antimicrobial activity against Gram positive (Staphylococcus aereus, Bacillus spp.) and Gram negative (Escherichia coli, Pseudomonas aeruginosa, Samonella typhi, Klebisiella pneumoniae, Proteus mirabilis) bacteria and a pathogenic fungus, Candida albicans. All the essential oils are active to the tested microbiles with different strength. The highest antimicrobial activity against Gram positive bacteria (Staphylococcus aureus) and Gram negative bacteria (Pseudomonas aeruginosae and Proteus mirabilis) was observed from the eastern Kenya (Meru) oil. Meru oil was the best and its effectiveness was consistent on nearly all the microbes tested. The oil from the plant growing in the coastal region of Kenya (Mombasa) showed the best effect only on Gram negative bacteria (Escherichia coli and Proteus mirabilis). Both oils (Meru and Mombasa) were dominated by monoterpenes accounting for 92.48 % and 81.37 % respectively. The monoterpene fraction was characterized by a high percentage of eugenol (68.8 %) for Meru oil and 74.10 % for Mombasa oil. The other major monoterpene was methyl eugenol (13.21 %). Camphor (0.95 %) was observed only in the Meru oil. (Cis)-Ocimene, (trans)-ocimene and β-pinene were present in both Meru and Mombasa oils. The sesquiterpenes present in fairly good amounts in both oils were germacrene D and (trans)-caryophyllene. The minor sesquiterpenes were α-farnesene (0.85 %) and β-bisabolene (0.74 %) which were present in the Meru oil only.

Hydro-distilled essential oil from Satureja biflora (Lamiaceae) growing in Kenya was analysed by gas chromatography mass spectrometry (GC-MS) and also evaluated for antimicrobial activity. Twenty two compounds which constitute 99.29 % of the total oil were identified. The oil was dominated by monoterpenes, which accounted for 62.02 % of the oil. This monoterpene fraction was characterized by a high percentage of linalool (50.60 %) such that this Satureja species can be classified as the linalool chemotype. The other major monoterpenes were α-terpineol (2.80 %), β-ocimene (2.25 %), β-pinene (1.96 %) and cis -linalool oxide (1.91 %). Sesquiterpenes present in fairly good amounts are germacrene D (10.63 %), α-cadinol (4.53 %), β-bourbonene (2.33 %), δ-cadinene (2.19 %), τ-cadinol (2.17 %), endo-1-bourbonanol (2.14 %) and β-caryophyllene (1.98 %). Aliphatic alcohols and acids accounted for 7.23 % of the oil, of which the major one was linoleic acid (4.48 %). The oil was screened for antimicrobial activity against both gram-positive ( Staphylococcus aureus, Bacillus ssp. ) and gram-negative ( Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Klebsiella pheumoniae, Proteus mirabilis ) bacteria and a pathogenic fungus ( Candida albicans ). To the best of our knowledge nothing concerning the chemical composition and biological activity of the essential oil of S. biflora has been reported. KEY WORDS : Satureja biflora , Essential oil, Antimicrobial activity Bull. Chem. Soc. Ethiop. 2007 , 21(2), 249-254.

This study evaluated the larvicidal activity of essential oil of Lippia kituiensis leaves against larvae of Rhipicephalus appendiculatus . The oil was obtained by hydro-distillation of fresh leaves and analysed using Gas Chromatography-Mass Spectrometry (GC-MS). Analysis showed that sesquiterpenes were dominant (56.57%), followed by monoterpenes (36.36%), diterpenes (2.59%) and others (5.19%). Major sesquiterpenes were germacrene D, β-bourbonene, gamma cadinene and 2-isopropyl-5-methyl-9-methylene-bicycle (4.4.0)dec-1-ene. Major monoterpenes were (1S, 4S)-(-)-camphor, trans-sabinene hydrate, gamma-terpinene, dl-limonene, alpha-terpinolene, l-Phellandrene, beta-Myrcene, sabinene, camphene, alpha-pinene, 4-terpineol, 4-methyl-1-(1-methylethyl)-3-cyclohexen-1-ol, 14.29 borneol (=endo-borneol), camphore, and neo-alloocimene. At 6, 12, 24, and 48 hrs after larval treatment, the oil showed activity against R. appendiculatus larvae with LC 50 in mg/ml of 3.26(3.14-3.38), 3.21(3.08-3.32), 3.15(3.03-3.26), 3.09(2.97-3.20) while LC 90 in mg/ml were 4.15 (3.95-4.45), 4.03 (3.85-4.30), 3.94 (3.77-4.19), 3.86 (3.69-4.09) respectively. Results of one way ANOVA (Analysis of Variance) showed there was no significant difference in activity of the oil against the larvae, between 6, 12, 24 and 48 hrs in all the concentrations used P = 0.97, 95% confidence. The findings indicatedthat essential oil of L. kituiensis possessed larvicidal properties and can be used to control tick larvae. Keywords : Rhipicephalus appendiculatus; essential oils; acaricidal activity, ticks.

Steam distilled volatile oils from the leaves of Ocimum americanum L. growing in Western Kenya were analysed by GC and GC-MS. A total of 36 compounds, representing a total of 88.51% of the total oil, were identified. The oil was classified as terpinen-4-ol-type according to the terpinen-4-ol content (43.21%). To the best of our knowledge this chemotype of O. americanum has not yet been reported from the East African region. This chemotype of O. americanum has only been reported from Togo. Other notable components include 1,8-cineole (16.13%), α-terpineol (4.01%), trans -caryophyllene (3.06%), α-bergamotene (2.68%) and cis -sabinene hydrate (2.59%). The oil contains mainly oxygenated monoterpenes which accounted for 71.24% of the total oil. The yield obtained was 4% w/w on a dry weight basis. KEY WORDS : Ocimum americanum , Lamiaceae, Chemotype, Terpinen-4-ol, 1,8-Cineole, µ-Terpineol, trans-Caryophyllene, Kenya Bull. Chem. Soc. Ethiop. 2006 , 20(1), 177-180.

Hydro-distilled essential oil from Piper capense (L. f.) growing in Kenya was analyzed by gas chromatography mass spectrometry (GC-MS) and evaluated for antifungal activity. The oil was dominated by sesquiterpene hydrocarbons (43.9%) with δ-cadinene (16.82%), b-bisabolene (5.65%) and bicyclogermacrene (3.30%). There was appreciable quantity of monoterpene hydrocarbons (30.64%) including b-pinene (7.24%) and α-phellandrene (4.76%). Arylpropanoids (8.64%) was found in reasonable quantity having myristicin (4.26%) as its major constituent. A total of ten, fourteen and sixteen mycotoxigenic species of Aspergillus, Fusarium and Penicillium respectively were assayed. The oil showed strong antifungal activity against these fungi with Minimum Inhibition Concentration (MIC) ranging from 33.1 to 265 mg/ml. These results show that the oil has antifungal activities against fungi that are producers of poisonous mycotoxins found in foods and therefore can be used in food preservation systems to inhibit the growth of moulds and retard subsequent mycotoxin production. Keywords : Essential oil, inhibition zone, moulds, mycotoxigenic fungi.

Five new drimane-type sesquiterpenoids were isolated from cultures of the tropical basidiomycetes, Perenniporia centrali-africana (originating from Kenya) and Cerrena sp. nov. (originating from Thailand). A new pereniporin A derivative (1), a new drimane-type sesquiterpene lactam (2), and the new 6,7-Dehydro-isodrimenediol (3) were isolated from P. centrali-africana. In parallel, the two new drimane-type sesquiterpene lactams 5 and 6 were isolated together with known isodrimenediol (4) from Cerrena sp. This is the first report of drimane-type sesquiterpene lactams from basidiomycetes. The structures were elucidated based on 1D and 2D nuclear magnetic resonance (NMR) spectroscopic data, in combination with high-resolution electrospray mass spectrometric (HR-ESIMS) data. The compounds were devoid of significant antimicrobial and cytotoxic activities.

With heimionones A–E (1–5), five new terpenoids were isolated from submerged cultures of Heimiomyces sp. in addition to the previously described compounds hispidin, hypholomin B, and heimiomycins A and B. Planar structures of the metabolites were elucidated by 1D and 2D NMR in addition to HRESIMS data. While ROESY data assigned relative configurations, absolute configurations were determined by the synthesis of MTPA esters of 1, 3, and 5. The [6.3.0] undecane core structure of compounds 3–5 is of the asteriscane-type, however, the scaffold of 1 and 2 with their bicyclo [5.3.0] decane core and germinal methyl substitution is, to our knowledge, unprecedented. Together with several new compounds that were previously isolated from solid cultures of this strain, Heimiomyces sp. showed an exceptionally high chemical diversity of its secondary metabolite profile.