From a methanol extract of dried-ground aerial parts of Senecio lyratus, an anti-fungal and anti-bacterial active compound was isolated and identified as β-sitosterol by spectroscopic analysis.

Raman and FT-IR absorption spectra of t-butyl alcohol and t-butylamine pure components have been recorded in the liquid state in the region of 400-4000 cm -1 . The data obtained have been used to propose complete vibrational assignments for each of the liquid component and the structural features are discussed. Additionally, the Raman and infrared spectra of the binary liquid mixtures for the t-butyl alcohol/t-butylamine system have also been recorded. The variations in frequency shifts, intensities and line widths are discussed with a view to understanding the origin of such variations.

Five oleanane-type pentacyclic triterpenoids were isolated by chromatographic separation of a chloroform extract of the stem bark of Embelia schimperi. Three of these compounds have a methyleneoxy bridge. Two compounds, embelinone and schimperinone, are reported here for the first time from a natural source (they have been synthesized previously during chemical transformations). Their structures were determined by spectroscopic techniques, among which 2-D NMR was useful for complete characterization. Three of the triterpenoids exhibited mild antibacterial properties against the gram-positive bacterial strain Rhodococcus sp.

The study focussed on four limonoids (calodendrolide, harrisonin, pedonin and pyroangolensolide) as larvicidal components against mosquito 2 nd instar larvae of the species Aedes aegypti Linn. senso stricto. Since pyroangolensolide is close to calodendrolide in structure, it was synthesized through reduction of calodendrolide with chromium(II) chloride in acetone. Harrisonin and pedonin were extracted with cold methanol from the root bark of Harrisonia abyssinica while calodendrolide was extracted with the same solvent from the root bark of Calodendrum capense. The structure of pyroangolensolide was elucidated using physical and spectroscopic techniques. 25, 50, 75, and 100 μm of each compound were tested against the mosquito larvae. Calodendrolide was the most toxic since 100% mortality was registered at all concentrations, while pyroangolensolide showed 100% mortality up to 50 μm and for contents of 25 μm, a mortality of 70% was registered. As a result of this toxicity, lower concentrations (5, 10 and 15 μm) were tested for both calodendrolide and pyroangolensolide. Toxicity of harrisonin and pedonin was lower. The relative toxicity was in the order: calodendrolide Ͼ pyroangolensolide Ͼ harrisonin Ͼ pedonin with LC 50 values of 13.2, 16.6, 28.1 and 59.2 μm, respectively.

There is an increasing need for innovative drug and prophylaxis discovery against malaria. The aim of the present study was to test in vivo antiplasmodial activity of Croton macrostachyus H. (Euphorbiaceae) stem bark extracts from Kenyan folkloric medicine. Inbred Balb/c mice were inoculated with erythrocytes parasitized with Plasmodium berghei (ANKA). Different doses (500, 250, and 100 mg/kg) of C. macrostachyus ethyl acetate, methanol, aqueous, and isobutanol extracts were administrated either after inoculation (Peters' 4-day suppressive test) or before inoculation (chemoprotective test) of the parasitized erythrocytes. All the extracts showed significant suppression of parasitemia compared to control (p < 0.001): for the ethyl acetate extract in the range of 58–82%, for the methanol extract in the range of 27–68%, for the aqueous extract in the range of 24–72%, and for the isobutanol extract in the range of 61–80%. Chemoprotective effect was significant (p < 0.001) and the suppression caused by the ethyl acetate extract was between 74 and 100%, by the methanol extract between 57 and 83%, and by the isobutanol extract between 86–92%. The study showed that it is possible to inhibit the growth of the parasites by various stem bark extracts of C. macrostachyus in Balb/c mice supporting the folkloric use of the plant against malaria.

Chromatographic separation of an ethyl acetate extract from Embelia schimperi led to the isolation of a new compound identified as 2,5-dihydroxy-3-methyl-1,4-benzoquinone (1) on the basis of spectroscopic and physical data. The plant's crude extract and pure compound 1 were assayed for in vitro antimicrobial activity against clinical strains of Salmonella spp., Proteus spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Cryptococcus neoformans, Shigella dysentriae and Staphylococcus aureus. Disc diffusion method was used and zones of inhibition, after respective incubation periods, were used to quantify antimicrobial activity. Standard antibiotics namely: augmentin, cotrimoxazole, gentamycin, tetracycline and lyncomycin were used as controls.The crude extract was inactive while the pure compound 1 showed significant activities against Salmonella spp., Proteus spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Cryptococcus neoformans, Shigella dysentriae and Staphylococcus aureus with zones of inhibition ranging from 10Ð20 mm. The most sensitive microorganism was P. aeruginosa while C. neoformans was insensitive to both the crude extract and compound 1.

No abstract

Embelia schimperi is a plant belonging to the family of Myrsinaceae. The Myrsinaceae are chemotaxonomically associated with long alkyl side chain benzoquinones with embelin compound (1) being one of the benzoquinones. Isolation, constitution and synthesis of embelin (1) have already been effected but its capacity to form metallic complexes with all metals has not been studied so far. The chromatographic separation of an ethyl acetate extract from Embelia schimperi led to the isolation of a compound identified as 2,5-dihydroxy-3-methyl-1,4-benzoquinone (1) through spectroscopic analyses. Embelin (1) was modified by complexing it with nickel metal and found to form a complex under suitable conditions. The synthesis and structure determination of the metallic complex of embelin (1) have been described. The conductance measurement showed that the metallic complex formed was a non-electrolyte. The nickel metal is a good lewis acid since it has a great affinity for oxygen donors. Embelin (1) on the other hand, has electron donating carbonyl and hydroxyl oxygen atoms hence it reacts with the metal in an acid-base reaction. The Atomic Absorption Spectroscopy, Infrared Spectroscopy and 1 H NMR Spectroscopy were used to determine the structure of the nickel-embelin complex.