Antioxidative properties of Mallotus oppositifolium decoction leaves extract using in vitro models

In an attempt to explain the scientific basis for the medicinal benefits of Mallotus oppositifolium (Euphorbiaceae), the phytochemical constituent and the antioxidative properties of the aqueous decoction leaves extract of the plant versus standard Vitamin C were assessed. The phytochemical analysis (screening and quantitative assay), the 1,1- Diphenyl-2-picrylhydrazyl (DPPH), Nitric oxide, and hydroxyl radicalscavenging, the reducing power, ferrous reducing antioxidant power (FRAP) and the β carotene bleaching of the extract were performed using colorimetric or spectrophotometric methods. Qualitative screening of the extract showed the presence of alkaloids, flavonoids, steroids, phenolic compounds, tannins, phlobatannins, saponins, lipids, carbohydrates, mucilages, and proteins. The phytochemical quantitative assay of the decoction extract revealed that the plant depicted flavonols (38.278 mg.g-1 catechin equivalent), tannins (23.13 mg.g-1 tannic acid equivalent), phenolics (13.73 mg.g-1 tannic acid content), flavonoids (10.62 mg.g-1 quercetin equivalent), proanthocyanidins (2.53 mg.g-1 quercetin equivalent) contents. Alkaloids and saponins content were 200 mg.g-1 and 285 mg.g-1, respectively. The ferric reducing antioxidant power (FRAP) of Mo extract and the IC50 of vitamin C were 228±0.4 mg.mL-1 and 592.0±0.8 mg.mL-1 , respectively. The DPPH radicalscavenging properties of IC50 of vitamin C was 480.0±0.8mg.mL-1 and that of Mo extract was 360.0±0.8 mg.mL-1. The IC50 of Mo’s reduce abilities was 39.2±0.8 mg.mL-1 and that of vitamin C was 320.0±0.8 mg.mL-1.The IC50 of the hydroxyl radical scavenging activity of Mo was 75.2±0,8 mg.mL-1 whereas that of IC50 of vitaminC was not defined. The nitric oxide radical scavenging activity of IC50 of Mo was 121.6±0.8 mg.mL-1 and that of the vitamin C was 130.4±0.8 mg.mL-1, respectively. The β carotene bleanching gives the IC50 of M. oppositifolium was 12,0±0,0 mg.mL-1 and for the vitamin C was 16.0±0,0 mg.mL-1. The decoction leaves of Mallotus oppositifolium (Mo) exhibited powerful antioxidative properties as vitamin C. The plant can be a source of antioxidative materials.Keywords: Traditional medicine, phytochemical analysis, antioxidan

CARACTÉRISTIQUES MORPHOLOGIQUES ET GÉOCHIMIQUES DES MANTEAUX D’ALTÉRATION DÉVELOPPÉS SUR GRANITOÏDES DANS LA RÉGION DE L’ADAMAOUA (CAMEROUN)

Seven samples of rocks, including three parent rock and four weathered rock from Wack (Vina division, Adamawa Region, Cameroon) have been studied. According to chemical analysis and chemical weathering indices calculated, weathering rocks conserve the structure of parent rocks. During weathering and the influence of the steep slope, the chemical elements are completely disorganized. The quantitative determination of the degree of chemical weathering of these rocks based on whole rock chemistry was performed. The slope of the straight regression absolute value is closed to 1. These various chemical weathering indices calculated has shown that they are significantly related

Geotechnical, mechanical and geological characterization of lateritic gravels of Boumpial (Cameroon) used in road construction

The present study deals with a geological, mechanical and geotechnical characterization of lateritic gravels developed on gneiss in the Boumpial region (East Cameroon). The raw materials description was done during the fieldwork. The collected samples were subjected to mechanical and geotechnical tests. The rock sample powder and lateritic gravels mineralogy were determined using optical microscopy and X-rays diffraction on the total fractions and the fine ones. The overall chemical compositions of major elements of lateritic gravels were determined by the use of X-fluorescence and titrimetry. The results obtained show that lateritic gravels of East Cameroon present: fines (18 wt.%), plasticity index (21%), CBR (72%), compressive strength (1.27 Mpa) and tensile strength of 0.08Mpa. The X-ray diffraction and the chemical analysis revealed 34 wt.% kaolinite, 24 wt.% of hematite, 13 wt.% of goethite, 11 wt.% of quartz, 10 wt.% of gibbsite and 1 wt.% of anatase. The silica/sesquioxides ratio (1.04) showed that the lateritic gravels is suitable for the sub-base course in road construction. By mixing 20 wt.% of the 5/20 rock fragment fraction (with LA< 60) and 80 wt.% of lateritic gravels (CBR = 92 %), the studied material can be employed for constructing foundations.Keywords: Lateritic gravels; Geotechnical and mechanical tests; Mineralogical and chemical analyses; Road construction; Cameroo

Exploring the capability of yeasts isolated from colombian fermented cocoa beans to form and degrade biogenic amines in a lab-scale model system for cocoa fermentation

Yeast starters for cocoa fermentation are usually tested according to their enzymatic activities in terms of mucilage degradation and flavor improvement, disregarding their influence on the production or elimination of toxic compounds as biogenic amines (BAs), important for human health. In this work, we tested 145 strains belonging to 12 different yeast species and isolated from the Colombian fermented cocoa beans (CB) for their capability of producing BAs in vitro. Sixtyfive strains were able to decarboxylate at least one of the amino acids tested. Pichia kudriavzevii ECA33 (Pk) and Saccharomyces cerevisiae 4 (Sc) were selected to evaluate their potential to modulate BAs, organic acids, and volatile organic compounds (VOCs) accumulation during a simulated cocoa fermentation. The growth of Sc or Pk in the presence of CB caused a significant reduction (p < 0.05) of 2-phenylethylamine (84% and 37%) and cadaverine (58% and 51%), and a significant increase of tryptamine and putrescine with a strong influence of temperature in BA formation and degradation. In addition, our findings pointed out that Pk induced a major production of fatty acidand amino acid-derived VOCs, while Sc induced more VOCs derived from fatty acids metabolism. Our results suggest the importance of considering BA production in the choice of yeast starters for cocoa fermentation

CARACTÉRISTIQUES MORPHOLOGIQUES ET GÉOCHIMIQUES DES MANTEAUX D’ALTÉRATION DÉVELOPPÉS SUR GRANITOÏDES DANS LA RÉGION DE L’ADAMAOUA (CAMEROUN)

Seven samples of rocks, including three parent rock and four weathered rock from Wack (Vina division, Adamawa Region, Cameroon) have been studied. According to chemical analysis and chemical weathering indices calculated, weathering rocks conserve the structure of parent rocks. During weathering and the influence of the steep slope, the chemical elements are completely disorganized. The quantitative determination of the degree of chemical weathering of these rocks based on whole rock chemistry was performed. The slope of the straight regression absolute value is closed to 1. These various chemical weathering indices calculated has shown that they are significantly related

Genetic Structure of the Tiger Mosquito, Aedes albopictus, in Cameroon (Central Africa)

Background: Aedes albopictus (Skuse, 1884) (Diptera: Culicidae), a mosquito native to Asia, has recently invaded all five continents. In Central Africa it was first reported in the early 2000s, and has since been implicated in the emergence of arboviruses such as dengue and chikungunya in this region. Recent genetic studies of invasive species have shown that multiple introductions are a key factor for successful expansion in new areas. As a result, phenotypic characters such as vector competence and insecticide susceptibility may vary within invasive pest species, potentially affecting vector efficiency and pest management. Here we assessed the genetic variability and population genetics of Ae. albopictus isolates in Cameroon (Central Africa), thereby deducing their likely geographic origin. Methods and Results: Mosquitoes were sampled in 2007 in 12 localities in southern Cameroon and analyzed for polymorphism at six microsatellite loci and in two mitochondrial DNA regions (ND5 and COI). All the microsatellite markers were successfully amplified and were polymorphic, showing moderate genetic structureamong geographic populations (F-ST = 0.068, P<0.0001). Analysis of mtDNA sequences revealed four haplotypes each for the COI and ND5 genes, with a dominant haplotype shared by all Cameroonian samples. The weak genetic variation estimated from the mtDNA genes is consistent with the recent arrival of Ae. albopictus in Cameroon. Phylogeographic analysis based on COI polymorphism indicated that Ae. albopictus populations from Cameroon are related to tropical rather than temperate or subtropical outgroups. Conclusion: The moderate genetic diversity observed among Cameroonian Ae. albopictus isolates is in keeping with recent introduction and spread in this country. The genetic structure of natural populations points to multiple introductions from tropical regions

Global genetic diversity of Aedes aegypti

Mosquitoes, especially Aedes aegypti, are becoming important models for studying invasion biology. We characterized genetic variation at 12 microsatellite loci in 79 populations of Ae. aegypti from 30 countries in six continents, and used them to infer historical and modern patterns of invasion. Our results support the two subspecies Ae. aegypti formosus and Ae. aegypti aegypti as genetically distinct units. Ae. aegypti aegypti populations outside Africa are derived from ancestral African populations and are monophyletic. The two subspecies co-occur in both East Africa (Kenya) and West Africa (Senegal). In rural/forest settings (Rabai District of Kenya), the two subspecies remain genetically distinct, whereas in urban settings, they introgress freely. Populations outside Africa are highly genetically structured likely due to a combination of recent founder effects, discrete discontinuous habitats and low migration rates. Ancestral populations in sub-Saharan Africa are less genetically structured, as are the populations in Asia. Introduction of Ae. aegypti to the New World coinciding with trans-Atlantic shipping in the 16th to 18th centuries was followed by its introduction to Asia in the late 19th century from the New World or from now extinct populations in the Mediterranean Basin. Aedes mascarensis is a genetically distinct sister species to Ae. aegypti s.l. This study provides a reference database of genetic diversity that can be used to determine the likely origin of new introductions that occur regularly for this invasive species. The genetic uniqueness of many populations and regions has important implications for attempts to control Ae. aegypti, especially for the methods using genetic modification of populations.Centro de Estudios Parasitológicos y de Vectore

Global genetic diversity of Aedes aegypti

Mosquitoes, especially Aedes aegypti, are becoming important models for studying invasion biology. We characterized genetic variation at 12 microsatellite loci in 79 populations of Ae. aegypti from 30 countries in six continents, and used them to infer historical and modern patterns of invasion. Our results support the two subspecies Ae. aegypti formosus and Ae. aegypti aegypti as genetically distinct units. Ae. aegypti aegypti populations outside Africa are derived from ancestral African populations and are monophyletic. The two subspecies co-occur in both East Africa (Kenya) and West Africa (Senegal). In rural/forest settings (Rabai District of Kenya), the two subspecies remain genetically distinct, whereas in urban settings, they introgress freely. Populations outside Africa are highly genetically structured likely due to a combination of recent founder effects, discrete discontinuous habitats and low migration rates. Ancestral populations in sub-Saharan Africa are less genetically structured, as are the populations in Asia. Introduction of Ae. aegypti to the New World coinciding with trans-Atlantic shipping in the 16th to 18th centuries was followed by its introduction to Asia in the late 19th century from the New World or from now extinct populations in the Mediterranean Basin. Aedes mascarensis is a genetically distinct sister species to Ae. aegypti s.l. This study provides a reference database of genetic diversity that can be used to determine the likely origin of new introductions that occur regularly for this invasive species. The genetic uniqueness of many populations and regions has important implications for attempts to control Ae. aegypti, especially for the methods using genetic modification of populations.Centro de Estudios Parasitológicos y de Vectore

First report of field evolved resistance to agrochemicals in dengue mosquito, Aedes albopictus (Diptera: Culicidae), from Pakistan

<p>Abstract</p> <p>Background</p> <p>Agrochemicals have been widely used in Pakistan for several years. This exposes mosquito populations, particularly those present around agricultural settings, to an intense selection pressure for insecticide resistance. The aim of the present study was to investigate the toxicity of representative agrochemicals against various populations of <it>Aedes albopictus </it>(Skuse) collected from three different regions from 2008-2010.</p> <p>Results</p> <p>For organophosphates and pyrethroids, the resistance ratios compared with susceptible Lab-PK were in the range of 157-266 fold for chlorpyrifos, 24-52 fold for profenofos, 41-71 fold for triazofos, and 15-26 fold for cypermethrin, 15-53 fold for deltamethrin and 21-58 fold for lambdacyhalothrin. The resistance ratios for carbamates and new insecticides were in the range of 13-22 fold for methomyl, 24-30 fold for thiodicarb, and 41-101 fold for indoxacarb, 14-27 fold for emamectin benzoate and 23-50 fold for spinosad. Pair wise comparisons of the log LC_50sof insecticides revealed correlation among several insecticides, suggesting a possible cross resistance mechanism. Moreover, resistance remained stable across 3 years, suggesting field selection for general fitness had also taken place for various populations of <it>Ae. albopictus</it>.</p> <p>Conclusion</p> <p>Moderate to high level of resistance to agrochemicals in Pakistani field populations of <it>Ae. albopictus </it>is reported here first time. The geographic extent of resistance is unknown but, if widespread, may lead to problems in future vector control.</p