RP-Department of Chemistry

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Suppression of interfering ions in the analysis of plants to determine fluoride using the fluoride ion selective electrode
(Royal Society of Chemistry, 197) Brian, Vickery; Vickery, M. L.
Plant ashes may contain sufficient aluminium and/or iron to interfere seriously in the determination of fluoride ions when using the fluoride ion selective electrode. In the presence of these metals the known additions method gave erroneous results, as did that involving the attempted formation of complexes with ethylenediaminetetraacetic acid, disodium salt, or 1,2-cyclohexylenedinitrilotetraacetic acid. Good recoveries of fluoride ion were obtained in the presence of aluminium, iron, magnesium or silicate, using sodium citrate as the complexing agent. The application of the citrate complex method to ashes of commercial tea, high in aluminium and iron, gave recoveries of fluoride ion of greater than 90%.
Characterization of heart plaque in by‐passed and non‐bypassed heart arteries
(Taylor & Francis, 199) Murungi, J. I.; Robinson, J. W.
Patients who have undergone bypass surgery often find the bypasses fill up again with plaque ("new plaque") whereas the heart arteries not bypassed contain plaque deposited since childhood ("old plaque"). A preliminary study was undertaken to characterize and contrast the chemical compositions of these “new”; and “old”; plaques. The samples were obtained from a particular surgeon. His patients had had bypass surgery but the bypasses had refilled over a period of a few years. In the surgery both bypassed and non‐bypassed arteries were reopened as necessary to improve circulation by surgically drilling out some plaque. This plaque was analyzed. Each particular sample was divided into two portions. One portion was used for lipid analysis using High Pressure Liquid Chromatography (HPLC) and Thin Layer Chromatography (TLC) while the other portion was used for the determination of selected metals using Inductively Coupled Plasma (ICP). The results are summarized below. The analytical procedures (HPLC and ICP) were fast and reliable techniques for plaque characterization and provided extensive information. Phospholipids, lipids, and triglycerides were found in the plaque but the types of phospholipids, lipids and triglycerides varied from one patient to the next. Cholesterol and/or cholesterol esters such as oleate, linoleate and arachidonate were found in both old and newly deposited plaque but not all samples contained cholesterol. The results of metal analyses indicated there was increased deposition of Cu, Zn, Mn, Ca, Mg and P in the newly deposited plaque compared to the old plaque, but Na, Cr, Fe and K decreased in concentration in the new material. The concentrations of calcium and phosphorus were almost sixteen times higher in the new plaque compared to the old deposits. Ca/Mg and Ca/Na ratios was much higher in the new material than the old plaque and the ratio in both the old and the new was much higher than in normal blood. For example the average Ca/Mg ratio in the new plaque was found to be about 77/1 while in the old plaque it was found to be 28/1 in matched samples. The normal ratio in the blood plasma is around 3/1. The Cu/Zn ratios were less than 1/1 in all samples. The ratio in the new material was lower than in the old. Results suggest a change in body metabolism in later life leading to the formation of a different plaque from that deposited in earlier life.
Fabrication of Rh-doped TiO2 nanofibers for Visible Light Degradation of Rhodamine B
(Materials Research Society: Volume 1352,, 201) Obuya, E. A.
The synthesis and application of environmentally benign, efficient and low cost heterogeneous catalysts is increasingly important for affordable and clean chemical technologies. Nanomaterials have been proposed to have new and exciting properties relative to their bulk counterparts due to the quantum level interactions that exist at nanoscale. These materials also offer enormous surface to volume ratios that would be invaluable in heterogeneous catalysis. Recent studies point at titanium dioxide nanomaterials as having strong potential to be applied in heterogeneous photocatalysis for environmental remediation and pollution control. This work reports the use of surface modified anatase TiO2 nanofibers with rhodium (Rh) nanoparticles in the photodegradation of rhodamine B (RH-B), an organic pollutant. The dimensions of TiO2 nanofibers were 150±50 nm in diameter and the size of the Rh nanoparticles was ~5 nm. The Rh-doped TiO2 catalyst exhibited an enhanced photocatalytic activity in photodegradation of rhodamine B under visible light irradiation, with 95 % degradation within 180 minutes reaction time. Undoped TiO2 did not show any notable phocatalytic activity under visible light.
Anti-protozoal activity of aporphine and protoberberine alkaloids from Annickia kummeriae (Engl. & Diels) Setten & Maas (Annonaceae)"
(BMC Complementary and Alternative Medicine, 201) Malebo, H. M.; Wenzler, Tanja; Cal, Monical; Swaleh, Sauda M.; Omolo, Maurice O; Hassanali, Ahmed; Séquin, Urs; Häussinger, Daniel; Dalsgaard, P.; Hamburger, Matthias; Brun, Reto; Ndiege, I. O.
Background: Malaria, trypanosomiasis and leishmaniasis have an overwhelming impact in the poorest countries in the world due to their prevalence, virulence and drug resistance ability. Currently, there is inadequate armory of drugs for the treatment of malaria, trypanosomiasis and leishmaniasis. This underscores the continuing need for the discovery and development of new anti-protozoal drugs. Consequently, there is an urgent need for research aimed at the discovery and development of new effective and safe anti-plasmodial, anti-trypanosomal and anti-leishmanial drugs. Methods: Bioassay-guided chromatographic fractionation was employed for the isolation and purification of antiprotozoal alkaloids. Results: The methanol extract from the leaves of Annickia kummeriae from Tanzania exhibited a strong anti-plasmodial activity against the multi-drug resistant Plasmodium falciparum K1 strain (IC50 0.12 ± 0.01 µg/ml, selectivity index (SI) of 250, moderate activity against Trypanosoma brucei rhodesiense STIB 900 strain (IC50 2.50 ± 0.19 µg/ml, SI 12) and mild activity against Leishmania donovani axenic MHOM-ET-67/82 strain (IC50 9.25 ± 0.54 µg/ml, SI 3.2). Bioassay-guided chromatographic fractionation led to the isolation of four pure alkaloids, lysicamine (1), trivalvone (2), palmatine (3), jatrorrhizine (4) and two sets of mixtures of jatrorrhizine (4) with columbamine (5) and palmatine (3) with (-)-tetrahydropalmatine (6). The alkaloids showed low cytotoxicity activity (CC50 30 - >90 µg/ml), strong to moderate anti-plasmodial activity (IC50 0.08 ± 0.001 - 2.4 ± 0.642 µg/ml, SI 1.5-1,154), moderate to weak anti-trypanosomal (IC50 2.80 ± 0.001 - 14.3 ± 0.001 µg/ml, SI 2.3-28.1) and anti-leishmanial activity IC50 2.7 ± 0.001 - 20.4 ± 0.003 µg/ml, SI 1.7-15.6). Conclusion: The strong anti-plasmodial activity makes these alkaloids good lead structures for drug development programs.
Reactions of Lead Tetraacetate. I. Formation of Acylamines from Primary Carboxamides
(CSIRO Publishing, 1968) Hassanali, Ahmed; Acot, B.; Beckwit, A. L. J.
Pentanamide, when treated with lead tetraacetate in hot benzene, affords a mixture of N-butylacetamide and N,N?-dibutylurea. Examples of similar transformations of a number of primary carboxamides are described. The reaction, which may also be conducted in acetic acid or benzene-acetic acid mixture, is catalysed by pyridine. Cyclohexanecarboxamide, when oxidized by lead tetraacetate in the presence of propionic or benzoic acid, is converted into the appropriate acylcyclohexylamine. The reaction mechanism involves intermediate formation of alkyl isocyanate, possibly via Curtius rearrangement of acylnitrene.
Reactions of Lead Tetraacetate. II. Formation of Carbamic Acid Esters from Primary Carboxamides
(CSIRO Publishing, 1968) Hassanali, Ahmed; Acott, B.; Beckwith, A. L. J.
Treatment of primary carboxamides with lead tetraacetate in benzene-alcohol mixtures or neat alcohol affords a convenient, flexible, and efficient method for the preparation of N-substituted carbamic acid esters. The reaction is applicable to amides and alcohols of a wide range of structural types including compounds containing oleflnic, ester, aromatic, and other reactive functions. The reaction mechanism appears to involve intermediate formation of isocyanates.
The Structure and Synthesis of Barakol: a Novel Dioxaphenalene Derivative from Cassia siamea
(Royal Society of Chemistry, 1970) Hassanali, Ahmed; Bycroft, B. W.; Johnson, A. W.; King, T. J.
Barakol, from the leaves of Cassia siamea, is shown to be a novel dioxaphenalene derivative. A synthesis from 3,5-dihydroxyphenylacetic acid is described.
Reaction of some arylacetic acids and related compounds with alkaline sodium hypochlorite solution
(Royal Society of Chemistry, 1978) Kaberia, Festus; Brian, Vickery
Synthesis, Spectral and Structural Studies, and an Evaluation of the Hydrogen Bonding of Some Phenylhydrazone
(Royal Society of Chemistry, 1980) Kaberia, Festus; Brian, Vickery
A series of 46 phenylhydrazones, soms novel, containing a variety of structural types has been synthesised. These have been studied by lH n.m.r. and i.r. spectroscopy with respect to potential inter- and intra-mslecular hydrogen bonding. ortho-Nitro or -carbony1 groups form strong hydrogen bonds to the imino-group which are readily observed by lH n.m.r. but not by i.r. spectroscopy. ' Terminal ' carbonyl groups also form strong hydrogen bonds to the imino-group and these can be detected by both i.r. and lH n.m.r. spectroscopy. When both ortho-nitro- or -carbony1 groups and ' terminal ' carbonyl groupsare present the imino hydrogen atom is doubly hydrogen bonded and this is apparent in the lH n.m.r. spectrum. The formation of an intramolecular hydrogen bond in the phenyl- hydrazone prevents the formation of an interm Aecular hydrogen bond between the phenylhydrazone and a polar solvent
Crystal and molecular structures of butan-2-one p-nitrophenylhydrazone (1), propanal 2,4-dinitrophenylhydrazone (2), dimethyl 2-oxo-propanedioate phenylhydrazone (3), and dimethyl 2-oxopropanedioate 2,4-dinitrophenylhydrazone (4): hydrogen bonding and bond order in phenylhydrazones
(Royal Society of Chemistry, 1981) Brian, Vickery; Willey, G. R.; Drew, M. G. B.
Crystals of the title compound (1), C10H13N3O2, are monoclinic, a= 4.119(11), b= 18.992(12), c= 13.992(10)Å, β= 96.0(1)°, space group P21/c, Z= 4. Compound (2), C9H10N4O4, is monoclinic a= 5.333(7), b= 11.488(8), c= 17.713(10)Å, β= 95.0(1)°, space group P21/c, Z= 4. Compound (3), C11H12N2O4, is monoclinic, a= 21.331(14), b= 4.153(10), c= 13.640(12)Å, β= 102.8(1)°, space group P21/a, Z= 4. Compound (4), C11H10N4O8, is monoclinic, a= 11.198(8), b= 14.779(9), c= 8.443(7)Å, β= 92.4(1)°, space group P21/a, Z= 4. All four structures were solved by the statistical method using the SHEL-X-76 system of programs, and refined using full matrix least squares. The numbers of reflexions used in refinement and the final R values are (1) 330, 0.103; (2) 611, 0.059; (3) 863, 0.061; and (4) 1 274, 0.070, respectively. In all cases the (NO2)–Ar–NH–N C–(C O) fragment is essentially planar. The NO2 HN and C O HN separations suggest that there is substantial intramolecular hydrogen bonding. In addition in compound (2) there is evidence for intermolecular as well as intramolecular NO2 H–N bonding in the crystal. In phenylhydrazones whose structures are known, there is an inverse relationship between Ar–NH and N–N bond lengths, and a direct relationship between Ar–N(H) and N C bond lengths.
The preparation of synthetic analogues of strigol
(Royal Society of Chemistry, 1981-01-01) Hassanali, Ahmed; Gowada, G.
Distribution of Fungicide-derived Copper in Soils, Litter and Vegetation of Different Aged Stands of Coffee (Coffea arabica L.) in Kenya
(Martinus Nijhoff/Dr. W. Junk Publishers, 1984) Ormand, K. L.; Lepp, N. W.; Dickinson, N. M.
Samples of soils, litter and vegetation, collected from 24, 14 and 4 years old stands of coffee (Coffea arabica L.), which had been routinely treated with copper fungicides, were analysed for copper content. Total soil copper content was found to be a function of (a) stand age and (b) soil depth. Highest levels were encountered in the 0–20 cm zone of the 24 year old stand; soil collected beneath these bushes showed significant contamination to a depth of 80 cm. Soils from the younger stands showed proportionally less copper contamination. Copper levels in litter samples showed increases relative to stand age; litter from the oldest stand was heavily contaminated and leaf litter showed a higher copper content than that of the woody fraction. Tissues from coffee bushes could be divided into 2 groups on the basis of their copper content; those tissues which demonstrated a progressive age-dependent increase (bark, lateral stems and fine roots) and those tissues where copper levels did not reflect the cumulative exposure of the plant to this element (wood, different age classes of foliage).
Phytochemical Screening of Tanzanian Medicinal Plants. I.
(Elsevier, 1984-07) Chhabra, S. C.; Uiso, F. C.; Mshiu, E. N.
To evaluate traditional medicine, which is an important part of the health-care system in Tanzania, three different regions, Coast, Morogoro and Kilimanjaro were surveyed for the herbs used by traditional healers. For each species, the botanical name, vernacular name, collection number and medical uses are given. Phytochemical screening of the 52 plant samples collected representing 49 species, 42 genera and 28 families was carried out. The analyses indicated that 94% plant samples contained steroids/triterpenoids, 50% saponins, 40% carotenoids and 17% alkaloids.
Iron content of some samples of the black murrams and red ochres from different parts of Kenya
(Penerbit UTHM, 1985) Muriithi, Naftali T.
A number of samples of the black or dark ironstone(commonly referred to as murram) and some red ochres collected from different parts of Kenya were analysed, particularly for their iron content. The results show that some of the materials examined are potential iron ores. Heating the black murram or the red ochres to 5000C increases the iron content in the residue by between 10% and 20%. On the other hand boiling the materials with 3M sodium hydroxide increases the proportion of iron in the residue by only 7%. X-ray analysis shows that most of the murrams and the red ochres examined contain the mineral geothite as the main iron-bearing material. (author)
Identification of tsetse attractants from excretory products of a wild host animal, Syncerus caffer
(International Journal of Tropical Insect Science, 1986-01-01) Hassanali, Ahmed; McDowell, P. G.; Owaga, Mary L. A.; Saini, R. K.
Urine from the buffalo, Syncerus caffer, a natural host of the tsetse, has been shown previously to be a potent olfactory attractant for tsetse in the field. The attractant compounds have been found to be extractable into dichloromethane. Fractionation of the extracts by liquid flash chromatography yielded four fractions one of which gave a seven-fold increase in trap catches in the field compared to the control traps. Gas Chromatographie and gas chromatography–mass spectrometric analysis of this fraction revealed the presence of seven simple phenols including phenol itself.RésuméL'urine de buffle, Syncerus caffer un hôte naturel de mouche tsé-tsé, s'est récement montré d'être un attracteur potentiel d'olfaction pour la mouche tsé-tsé sur le terrain. Les composés de cet attracteur ont été trouvés extractable dans le dichlorométhane. Le fractionnement de ces extraits par le liquide chromatographique a donné quatre fractions dont l'une d'elles, placée dans les pièges de capture a permis de récolter sept fois plus de mouches que les pièges-contrôles. L'analyse de cette fraction par gaz chromatographique et par gaz chromatographique associé à la masse spectrométrique a révélé la présence de sept phénols simple comprenant le phénol lui-même.
Studies on limonoid insect antifeedants
(International Journal of Tropical Insect Science, 1986-01-07) Hassanali, Ahmed; Bentley, M. D.; Yatagai, M.; Njoroge, P. E. W.; Ole Sitayo, E. N.
Limonin, deoxylimonin, citrolin, obacunone, harrisonin and acetoxyharrisonin were assayed as potential antifeedanfe against the African crop pests, Spodoptera exempta, Eldana saccharina and Manica testulalis. Even at the highest applied concentration, limonin, deoxylimonin, citrolin and acetoxyharrison were not active against S. exempta. At high concentrations, obacunone and harrisonin were mildly active in S. exempta assays. Harrisonin and obacunone displayed potent activity against E. saccharina and M. testulalis.RésuméLa limonine, la deoxylimonine, le citroline, l'obacunone, l'harrisonine et l'acetoxyharrisonine étaient tous essayés comme anti-nourrissants potentiels contre les pestes des plantes Africains sur la liste suivante: Spodoptera exempta, Eldana saccharina et Maruca testulalis. Mème avec le plus grand niveau de concentration appliqué, la limonine, la deoxylimonine, le citrolinine et l'acetoxyharrisone n'étaient pas actives contre S. exempta. Avec beaucoup de concentrations de liquide, l'obacunone et l'harrisonine ont montré très peu de reponse dans l'analyse de S. exempta. L'harrisonine et l'obacunone ont montré l'activité potentielle contre E. saccharina et M. testulalis.
Laboratory Observations on the Molluscicidal Properties of Swartzia Madagascariensis (Leguminosae).
(Elsevier, 1986-02) Chhabra, S. C.; Sarda, R. K.; Minjas, J. N.
A new pterocarpan from the roots of Tephrosia hildebrandtii
(Elsevier, 1987) Hassanali, Ahmed; Lwande, W.; Bentley, M. D.; Macfoy, C.; Lugemwa, F. N.; Nyandat, E.
A new 6a-hydroxylated pterocarpan has been isolated from the roots ofTephrosia hildebrandtii and its structure established on the basis of its spectral data.
Insect antifeedants from Tephrosia elata Deflers
(International Journal of Tropical Insect Science, 1987-01-01) Hassanali, Ahmed; Bentley, M. D.; Lwande, W.; Njoroge, P. E. W.; Ole Sitayo, E. N.; Yatagai, M.
Two antifeedants, isopongaflavone and tephrosin have been isolated from Tephrosia elata. Tephrosin displayed high activity against Spodoptera exempta, while isopongaflavone was shown to be very active against Maruca testulalis and Eldana saccharina. Rotenone was found to be active as an antifeedant against S. exempta, E. saccharina and M. testulalis. Insects in the orders Coleoptera, Hymenoptera, Lepidoptera and Diptera, all associated with T. elata seed pods, were identified.RésuméDeux antifondants, l'isopongaflavone et le tephrosin sont ete isoles de Tephrosia elata. Le tephrosin a montre la tres grande activité contre Spodoptera exampta, tandis que l'isopongaflavone a montre d'etre tres active contre Maruca testulalis et Eldana saccharina. On a trouve que la rotenone etait active comme un antifondant contre S. exempta, E. saccharina et M. testulalis. On a identifie que les insectes dans les groupes de Coleoptera, Hymenoptera, Lepidoptera et Diptera sont êtes tous associes avec les cosses des graines de T. elata.
The Role of 4-Cresol and 3-n-Propylphenol in the Attraction of Tsetse Flies to Buffalo Urine
(International Journal of Tropical Insect Science, 1988-01-01) Hassanali, Ahmed; McDowell, P. G.; Owaga, Mary L. A.
Seven phenolic compounds (phenol, 3- and 4-cresols, 3- and 4-ethylphenols, and 3- and 4-n-propylphenols) previously shown to be components of a fraction of an extract of buffalo urine which was active as a tsetse attractant, were evaluated in field experiments, individually at different concentrations, and in blends. The results indicate that 4-cresol and 3-n-propylphenol are the most important components for the of the attractancy phenolic mixture.RésuméSept composés phenoliques (phenol, 3- et 4-cresols, 3- et 4-ethylphenols ainsique 3- et 4-n-propylphenols) demotrés être les composantes d'une fraction de l'urine de buffle qui est un attractant des mouches tsé-tsé, ont èté testé individuellement à diflferentes concentrations et en groupes sur le terrain. Les resultats obtenus indiquent que 4-cresol et 3-n-propylphenol sont les plus importantes composantes de ce melange phenolique pour l'attraction.

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