Thaddée Boudjeko

Anti-hyperglycaemic globulins from selected Cucurbitaceae seeds used as antidiabetic medicinal plants in Africa

BackgroundThe recent epidemic of diabetes mellitus (DM) in Africa, coupled with rampant poverty, is an indication of the urgent need to develop new efficacious, cheaper and more available drugs to face this growing public health challenge. A number of plants products among which the protein-rich Cucurbitaceae seeds are commonly used in traditional medicine with increasing acclaimed efficacy against DM. The aim of this study was to analyse and evaluate the hypoglycaemic activity of storage proteins of five species of Cucurbitaceae, which include Telfairia occidentalis, Citrullus lanatus, Lagenaria siceraria, Cucumeropsis mannii and Cucurbita moschata.MethodsThe different families of storage proteins were extracted following differential solubility, and their contents were estimated using the Bradford method. The analysis of these proteins was done by electrophoresis in non-denaturing and denaturing conditions. The evaluation of hypoglycaemic properties of various globulins extracted was performed on male Wistar rats by the oral glucose tolerance test.ResultsThe results showed that among the proteins extracted, globulins constitute the most abundant class of storage proteins in all five species selected. Citrullus lanatus and Cucurbita moschata presented the highest levels of globulin (275.34 and 295.11 mg/g dry matter, respectively). The results of electrophoresis showed that all species possess acidic and neutrals albumins and globulins, with molecular weight of protein subunits ranging from 6.36-44.11 kDa for albumins, 6.5-173.86 kDa for globulins and 6.5-49.66 kDa for glutelins. The 6.36 kDa of albumin subunit protein and the 6.5 kDa of globulin subunit protein were present in all the species. The oral glucose tolerance test showed that the globulins of the seeds of all species except Cucumeropsis mannii caused significant drop in blood sugar (88 – 137.80%, compared to the controls, p<0.05).ConclusionsThese findings showed that the selected Cucurbitaceae seeds contained globulins with significant anti-hyperglycaemic activity. It is therefore highly encouraged to pursue investigations towards development of peptide-drugs and/or phytomedicines from these bioactive proteins which could be used as affordable alternative therapy against DM.

Morphological, Physiological, and Taxonomic Characterization of Actinobacterial Isolates Living as Endophytes of Cacao Pods and Cacao Seeds

Vascular plants are commonly colonized by endophytic actinobacteria. However, very little is known about the relationship between these microorganisms and cacao fruits. In order to determine the physiological and taxonomic relationships between the members of this community, actinobacteria were isolated from cacao fruits and seeds. Among the 49 isolates recovered, 11 morphologically distinct isolates were selected for further characterization. Sequencing of the 16S rRNA gene allowed the partition of the selected isolates into three phylogenetic clades. Most of the selected endophytic isolates belonged to the Streptomyces violaceusniger clade. Physiological characterization was carried out and a similarity index was used to cluster the isolates. However, clustering based on physiological properties did not match phylogenetic lineages. Isolates were also characterized for traits commonly associated with plant growth-promoting bacteria, including antibiosis and auxin biosynthesis. All isolates exhibited resistance to geldanamycin, whereas only two isolates were shown to produce this antibiotic. Endophytes were inoculated on radish seedlings and most isolates were found to possess plant growth-promoting abilities. These endophytic actinobacteria inhibited the growth of various plant pathogenic fungi and/or bacteria. The present study showed that S. violaceusniger clade members represent a significant part of the actinobacterial community living as endophytes in cacao fruits and seeds. While several members of this clade are known to be geldanamycin producers and efficient biocontrol agents of plant diseases, we herein established the endophytic lifestyle of some of these microorganisms, demonstrating their potential as plant health agents.

Optimization of Variables for Aqueous Extraction of Gum from Grewia mollis Powder

Grewia gum is a polysaccharide derived from the inner stem bark of the edible plant Grewia mollis. Juss (family Tiliaceae). It is a savanna shrub that grows wildly but is usually cultivated in Nigeria and Northern part of Cameroon. The main goal of the present study was to investigate the effect of aqueous extraction conditions on the extraction yield and physicochemical properties of the Grewia mollis. The studied aqueous extraction variables were water/powder (W/P) ratio (10 : 1–80 : 1 w/p), temperature (25.0–85.0∘C), time (1–3 h), and pH (4.0–10.0). The results indicated that the aqueous extraction variables exhibited the least significant () effect on the yield and the viscosity of the gum. The result shows that the ratio of extraction is the main factor affecting the extraction of gum. The optimized extraction condition for higher viscosity was at the powder/water ratio of 1 : 55.4, pH of 7, time of 1 h, and temperature of 50∘C. However, the optimized extraction condition for higher yield was at the powder/water ratio of 1 : 80, pH of 4, time of 3 h, and temperature of .

Hypolipidemic and antioxidative effects of dika nut ( Irvingia gabonensis ) seeds and nkui ( Trimphetta cordifolia ) stem bark mucilages in triton WR-1339 induced hyperlipidemic rats

Two different mucilages were extracted from dika nut (Irvingia gabonensis) kernels and nkui (Trimphetta cordifolia) stem barks and the hypolipidemic and antioxidant effects were studied on Triton WR-1339 induced hyperlipidemic rats. The GC analysis revealed that, dika nut mucilage is an arabinogalactan type while nkui is a rhamnogalacturonane type. The mucilage of nkui (200 mg/kg) showed the greatest hypolipidemic effect (p<0.05). An oxidative stress marker analysis suggested that the level of malonyl dialdehyde was significantly decreased in serum by the 2 mucilages (p<0.05). There was also a significant decrease in hydroperoxide level for the tested fibers. Moreover, nkui mucilage gave the highest levels in liver homogenate and in the hemolysate and tissues (p<0.05). The results suggest that the hypolidemic effect of mucilages varies with their chemical nature. They would be effective in the prevention of increase of serum lipid levels, in the reduction of lipid peroxidation and in the improvement of antioxidant status.