Mamoudou H. Dicko

Sorghum grain as human food in Africa: relevance of content of starch and amylase activities

Sorghum is a staple food grain in many semi-arid and tropic areas of the world, notably in Sub-Saharan Africa because of its good adaptation to hard environments and its good yield of production. Among important biochemical components for sorghum processing are levels of starch (amylose and amylopectin) and starch depolymerizing enzymes. Current research focus on identifying varieties meeting specific agricultural and food requirements from the great biodiversity of sorghums to insure food security. Results show that some sorghums are rich sources of micronutrients (minerals and vitamins) and macronutrients (carbohydrates, proteins and fat). Sorghum has a resistant starch, which makes it interesting for obese and diabetic people. In addition, sorghum may be an alternative food for people who are allergic to gluten. Malts of some sorghum varieties display

Composition and Antimicrobial Activities of Lippia multiflora Moldenke, Mentha x piperita L. and Ocimum basilicum L. Essential Oils and Their Major Monoterpene Alcohols Alone and in Combination

Essential oils from leaves of Lippia multiflora, Mentha x piperita and Ocimum basilicum from Burkina Faso were analysed by GC–FID and GC–MS. Major components were p-cymene, thymol, β-caryophyllene, carvacrol and carvone for L. multiflora, menthol and iso-menthone for M. x piperita and, linalool and eugenol for O. basilicum. The essential oils and their major monoterpene alcohols were tested against nine bacterial strains using the disc diffusion and broth microdilution methods. The essential oils with high phenolic contents were the most effective antimicrobials. The checkerboard method was used to quantify the efficacy of paired combinations of essential oils and their major components. The best synergetic effects among essential oils and major components were obtained with combinations involving O. basilicum essential oil and eugenol, respectively. As phenolic components are characterized by a strong spicy aroma, this study suggests that the selection of certain combinations of EOs could help to reduce the amount of essential oils and consequently reduce any adverse sensory impact in food.

Chemical composition and antimicrobial activity of Cymbopogon citratus and Cymbopogon giganteus essential oils alone and in combination.

As part of ongoing research on the chemical composition and the antimicrobial properties of Burkinabe plants essential oils alone and in combination, essential oils (EOs) from leaves of Cymbopogon citratus and Cymbopogon giganteus from Burkina Faso were analyzed by GC-FID and GC-MS. Five constituents, which accounted for 96.3% of the oil, were identified in the EO of C. citratus. Geranial (48.1%), neral (34.6%) and myrcene (11.0%) were the major constituents. For C. giganteus a total of eight compounds were identified which represented 86.0% of the oils extracted. The dominant compounds were limonene (42%) and a set of monoterpene alcohols: trans-p-mentha-1(7),8-dien-2-ol (14.2%), cis-p-mentha-1(7),8-dien-2-ol (12%), trans-p-mentha-2,8-dien-1-ol (5.6%) and cis-p-mentha-2,8-dien-1-ol (5.2%). The EOs were tested against nine bacteria by using disc diffusion and microdilution methods. C. giganteus EO showed antimicrobial effects against all microorganisms tested whereas C. citratus EO failed to inhibit Pseudomonas aeruginosa. The antimicrobial activity of combinations of the two EOs was quantified by the checkerboard method. Combinations of the two EOs exerted synergistic, additive and indifferent antimicrobial effects. Results of the present investigation provide evidence that the combinations of plant EOs could be assessed for synergistic activity in order to reduce their minimum effective dose.

An X-linked haplotype of Neandertal origin is present among all non-African populations

Recent work on the Neandertal genome has raised the possibility of admixture between Neandertals and the expanding population of Homo sapiens who left Africa between 80 and 50 Kya (thousand years ago) to colonize the rest of the world. Here, we provide evidence of a notable presence (9% overall) of a Neandertal-derived X chromosome segment among all contemporary human populations outside Africa. Our analysis of 6,092 X-chromosomes from all inhabited continents supports earlier contentions that a mosaic of lineages of different time depths and different geographic provenance could have contributed to the genetic constitution of modern humans. It indicates a very early admixture between expanding African migrants and Neandertals prior to or very early on the route of the out-of-Africa expansion that led to the successful colonization of the planet.

Impact of Phenolic Compounds and Related Enzymes in Sorghum Varieties for Resistance and Susceptibility to Biotic and Abiotic Stresses

Contents of phenolic compounds and related enzymes before and after sorghum grain germination were compared between varieties either resistant or susceptible to biotic (sooty stripe, sorghum midge, leaf anthracnose, striga, and grain molds) and abiotic (lodging, drought resistance, and photoperiod sensitivity) stresses. Independent of grain germination, sorghum varieties resistant to biotic and abiotic stresses had on average higher contents of proanthocyanidins (PAs), 3-deoxyanthocyanidins (3-DAs), and flavan-4-ols than susceptible varieties. Results show that content of 3-DAs is a good marker for sorghum resistance to both biotic and abiotic stresses because it correlates with resistance to all stresses except for photoperiod sensitivity. The second good marker for stress resistance is content of PAs. Total phenolic compounds and the activities of related enzymes are not good markers for stress resistance in sorghum grains.

Purification and characterization of β-amylase from Curculigo pilosa

Curculigo pilosa is traditionally used in the manufacture of sorghum beer in West Africa. β-Amylase was purified 100-fold with 38% yield from a crude extract, giving final specific activities of 4850 U/mg and 5650 U/mg using soluble starch and p-nitrophenyl maltopentaoside, respectively, as substrates. The molecular mass of the monomeric enzyme was 64 kDa and its pI 4.2. Both activity and thermostability are higher than reported for other plant β-amylases. The catalytic efficiency was lower for amylose than for starches and amylopectin. In contrast to other plant amylases, the β-amylase from C. pilosa is able to degrade raw starches from wheat, corn, potato and rice. In this respect, it resembles β-amylases from microbial origin. This property, and its high activity and stability, explain its traditional use in the manufacture of infant food and sorghum beer in Burkina Faso and could make it applicable for other biotechnological purposes.

Antibacterial activity against β- lactamase producing Methicillin and Ampicillin-resistants Staphylococcus aureus: fractional Inhibitory Concentration Index (FICI) determination

BackgroundThe present study reports the antibacterial capacity of alkaloid compounds in combination with Methicillin and Ampicillin-resistants bacteria isolated from clinical samples. The resistance of different bacteria strains to the current antibacterial agents, their toxicity and the cost of the treatment have led to the development of natural products against the bacteria resistant infections when applied in combination with conventional antimicrobial drugs.MethodThe antibacterial assays in this study were performed by using inhibition zone diameters, MIC, MBC methods, the time-kill assay and the Fractional Inhibitory Concentration Index (FICI) determination. On the whole, fifteen Gram-positive bacterial strains (MRSA/ARSA) were used. Negative control was prepared using discs impregnated with 10 % DMSO in water and commercially available Methicillin and Ampicillin from Alkom Laboratories LTD were used as positive reference standards for all bacterial strains.ResultsWe noticed that the highest activities were founded with the combination of alkaloid compounds and conventional antibiotics against all bacteria strains. Then, results showed that after 7 h exposition there was no viable microorganism in the initial inoculums.ConclusionThe results of this study showed that alkaloid compounds in combination with conventional antibiotics (Methicillin, Ampicillin) exhibited antimicrobial effects against microorganisms tested. These results validate the ethno-botanical use of Cienfuegosia digitata Cav. (Malvaceae) in Burkina Faso. Moreover, this study demonstrates the potential of this herbaceous as a source of antibacterial agent that could be effectively used for future health care purposes.

Biochemical characterization of the major sorghum grain peroxidase

The major cationic peroxidase in sorghum grain (SPC4) , which is ubiquitously present in all sorghum varieties was purified to apparent homogeneity, and found to be a highly basic protein (pI∼ 11). MS analysis showed that SPC4 consists of two glycoforms with molecular masses of 34227 and 35629 Da and it contains a type‐b heme. Chemical deglycosylation allowed to estimate sugar contents of 3.0% and 6.7% (w/w) in glycoform I and II, respectively, and a mass of the apoprotein of 33 246 Da. High performance anion exchange chromatography allowed to determine the carbohydrate constituents of the polysaccharide chains. The N‐terminal sequence of SPC4 is not blocked by pyroglutamate. MS analysis showed that six peptides, including the N‐terminal sequence of SPC4 matched with the predicted tryptic peptides of gene indice TC102191 of sorghum chromosome 1, indicating that TC102191 codes for the N‐terminal part of the sequence of SPC4, including a signal peptide of 31 amino acids. The N‐terminal fragment of SPC4 (213 amino acids) has a high sequence identity with barley BP1 (85%), rice Prx23 (90%), wheat WSP1 (82%) and maize peroxidase (58%), indicative for a common ancestor. SPC4 is activated by calcium ions. Ca2+ binding increased the protein conformational stability by raising the melting temperature (Tm) from 67 to 82 °C. SPC4 catalyzed the oxidation of a wide range of aromatic substrates, being catalytically more efficient with hydroxycinnamates than with tyrosine derivatives. In spite of the conserved active sites, SPC4 differs from BP1 in being active with aromatic compounds above pH 5.

Toxicity assessment and analgesic activity investigation of aqueous acetone extracts of Sida acuta Burn f . and Sida cordifolia L. (Malvaceae), medicinal plants of Burkina Faso

BackgroundSida acuta Burn f. and Sida cordifolia L. (Malvaceae) are traditionally used in Burkina Faso to treat several ailments, mainly pains, including abdominal infections and associated diseases. Despite the extensive use of these plants in traditional health care, literature provides little information regarding their toxicity and the pharmacology. This work was therefore designed to investigate the toxicological effects of aqueous acetone extracts of Sida acuta Burn f. and Sida cordifolia L. Furthermore, their analgesic capacity was assessed, in order to assess the efficiency of the traditional use of these two medicinal plants from Burkina Faso.MethodFor acute toxicity test, mice were injected different doses of each extract by intraperitoneal route and the LD50 values were determined. For the subchronic toxicity evaluation, Wistar albinos rats were treated by gavage during 28 days at different doses of aqueous acetone extracts and then haematological and biochemical parameters were determined. The analgesic effect was evaluated in mice by the acetic-acid writhing test and by the formalin test.ResultsFor the acute toxicity test, the LD50 values of 3.2 g/kg and 3.4 g/kg respectively for S. acuta Burn f. and S. cordifolia L. were obtained. Concerning the haematological and biochemical parameters, data varied widely (increase or decrease) according to dose of extracts and weight of rats and did not show clinical correlations. The extracts have produced significant analgesic effects by the acetic acid writhing test and by the hot plate method (p <0.05) and a dose-dependent inhibition was observed.ConclusionThe overall results of this study may justify the traditional uses of S. acuta and S. cordifolia .

Biodepollution of wastewater containing phenolic compounds from leather industry by plant peroxidases

This study deals with the use of peroxidases (POXs) from Allium sativum, Ipomoea batatas, Raphanus sativus and Sorghum bicolor to catalyze the degradation of free phenolic compounds as well as phenolic compounds contained in wastewater from leather industry. Secretory plant POXs were able to catalyze the oxidation of gallic acid, ferulic acid, 4-hydroxybenzoic acid, pyrogallol and 1,4-tyrosol prepared in ethanol 2% (v:v). Efficiency of peroxidase catalysis depends strongly on the chemical nature of phenolic substrates and on the botanical source of the enzymes. It appeared that POX from Raphanus sativus had the highest efficiency. Results show that POXs can also remove phenolic compounds present in industrial wastewater such as leather industry. Removal of phenolic compounds in wastewater from leather industry by POX was significantly enhanced by polyethylene glycol.