Francis B. Lewu

Completely green synthesis of dextrose reduced silver nanoparticles, its antimicrobial and sensing properties

We herein report the green synthesis of highly monodispersed, water soluble, stable and smaller sized dextrose reduced gelatin capped-silver nanoparticles (Ag-NPs) via an eco-friendly, completely green method. The synthesis involves the use of silver nitrate, gelatin, dextrose and water as the silver precursor, stabilizing agent, reducing agent and solvent respectively. By varying the reaction time, the temporal evolution of the growth, optical, antimicrobial and sensing properties of the as-synthesised Ag-NPs were investigated. The nanoparticles were characterized using UV-vis absorption spectroscopy, Fourier transform infra-red spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HR-TEM). The absorption maxima of the as-synthesized materials at different reaction time showed characteristic silver surface plasmon resonance (SPR) peak. The as-synthesised Ag-NPs show better antibacterial efficacy than the antibiotics; ciproflaxin and imipenem against Pseudomonas aeruginosa with minimum inhibition concentration (MIC) of 6 μg/mL, and better efficacy than imipenem against Escherichia coli with MIC of 10 μg/mL. The minimum bactericidal concentration (MBC) of the as-synthesised Ag-NPs is 12.5 μg/mL. The sensitivity of the dextrose reduced gelatin-capped Ag-NPs towards hydrogen peroxide indicated that the sensor has a very good sensitivity and a linear response over wide concentration range of 10(-1)-10(-6)M H2O2.

Chemical Composition and Larvicidal Activity of the Essential Oil of Tarchonanthus camphoratus Against Anopheles arabiensis Mosquito Larvae

Abstract The chemical composition of the essential oil of Tarchonanthus camphoratus was analysed using GC and GC-MS instruments. The major monoterpene was 1,8-cineole (5.4 %), while α-copaene (3.8 %) and γ-cadinene (3.1 %) were major sesquiterpenes. Major oxygenated monoterpenes and sesquiterpenes identified in the oil were 1,6-octadien-3-ol (4.5 %) and (-)-globulol (3.3 %) respectively. Hexadecanoic acid (3.5 %) was the major fatty acid present. The larvicidal assay of the essential oil against larvae of Anopheles arabiensis mosquito revealed that at a concentration of 300 ppm, the oil caused 100 % mortality after 24 hr exposure with an LC50 value of 78.7 %.

Completely green synthesis of silver nanoparticle decorated MWCNT and its antibacterial and catalytic properties

Abstract We herein report a simple large scale green synthesis route for the synthesis of silver nanoparticle (Ag-NP) multi walled carbon nanotubes (MWCNTs) hybrid nanocomposite (Ag-MWCNTs). The as-synthesized hybrid nanocomposite were characterized using UV-Vis absorption spectroscopy, Fourier transform infra-red spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction analysis (XRD) and high resolution transmission electron microscopy (HR-TEM). Raman spectroscopy analysis showed an increase in the D/G ratio of Ag-MWCNTs hybrid nanocomposites when compare with that of functionalized MWCNTs (F-MWCNTs) attributed to the presence of Ag-NPs on the surface of the F-MWCNTs. The as-synthesized Ag-MWCNTs nanocomposites showed strong antibacterial efficacy against Escherichia coli compared to the Ag-NPs and MWCNTs. The catalytic potential of the Ag-MWCNTs hybrid nanocomposite was investigated for the first time by studying the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride at 299 K at various reaction times. The reaction follows first order kinetics with a rate constant of 5.18×10−1 s−1. It is believed that, the large scale synthesis of such hybrid nanocomposites via simple method using non-toxic reagent will not only enhance its antibacterial efficacy, durability and biocompatibility, it will also minimize its biotoxcity and environmental impacts.

Medicinal Plants Used in the Management of Diabetes Mellitus 2015

Diabetes mellitus is one of the common endocrine disorders prevalent in almost all of the countries. This chronic pathology is characterized by hyperglycemia caused by defective insulin action, insulin secretion, or the combination of both. Prolonged persistence of elevated blood glucose level consequently caused a series of complications such as nephropathy, retinopathy, and cardiomyopathy. Currently available synthetic drugs for treating this disease are found to be associated with many adverse effects. The use of plants in medicine is an age-long practice in various parts of the globe for both preventive and curative purposes. Several warnings have been issued over lack of quality control, scientific evidence for the efficacy, and potential adverse effects of herbal remedies including hepatotoxicity, nephrotoxicity, cardiotoxicity, and reproductive toxicity among others. Despite all of these, reliance on herbs as medicine for the management of diabetes mellitus is still much practiced by a large proportion of the world population because they are readily available and affordable with perceived reduced toxicity. Therefore, with the upsurge of interests in medicinal plants, there is a need for thorough scientific investigations of these plants for both efficacy and potential toxicity. In this issue, we present some recent advances in the use of medicinal plants for treating diabetes mellitus. B. Pang et al. (“Innovative Thoughts of Treating Diabetes from the Perspective of Traditional Chinese Medicine”)presented a review article on the contribution of traditional Chinese medicine to the development of alternative and complementary medicine for the treatment and prevention of diabetes mellitus. In another paper (“Effect of Rhizoma Coptidis (Huang Lian) on Treating Diabetes Mellitus”), B. Pang et al. discussed the efficacy and safety of Rhizoma Coptidis in the treatment of diabetes mellitus. In another study (“Evaluation of the Effects of Cornus mas L. Fruit Extract on Glycemic Control and Insulin Level in Type 2 Diabetic Adult Patients: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial”), R. Soltani et al. reported the results of a clinical trial on the effect of Cornus mas L. fruit extract on hyperglycemia in type 2 diabetic patients. In addition, W. Liu et al. (“The Effects of Chinese Medicine on Activation of Wnt/β-Catenin Signal Pathway under High Glucose Condition”) present a valuable review on some compounds implicated in the regulation of Wnt/β-catenin signal pathway as a mechanism of action involved in the antihyperglycemic activity from Chinese medicine. Furthermore, A. O. T. Ashafa and M. I. Kazeem (“Toxicopathological Evaluation of Hydroethanol Extract of Dianthus basuticus in Wistar Rats”) reported on the effects of Dianthus basuticus (a Basotho plant with acclaimed antidiabetic activity) on some biochemical parameters and histology of Wistar rats. Finally, X.-J. Li et al. (“TCM Formula Xiaoyaosan Decoction Improves Depressive-Like Behaviors in Rats with Type 2 Diabetes”) evaluated the effect of traditional medicine formula, Xiaoyaosan, on the cognitive function of diabetic rats. After the first volume of this special issue that was published in 2014, we hope that this issue will present additional valuable information for scientists and clinicians.

Morphological characters and ascorbic acid content of an elite genotype of Corchorus olitorius : the influence of moisture stress

Moisture stress can be deleterious to physicochemical properties of crop species to a varying degree. The influence of moisture stress on the ascorbic acid content in the leaf and morphological characters of an elite genotype of Corchorus olitorius were tested in a glasshouse experiment. The experiment was arranged in a completely randomized design replicated four times. The results of the study showed that a distinct moisture-stress threshold, described as heavy moisture stress, existed for the genotype and ascorbic acid accumulation in the leaves decreased by up to 88.7% because of moisture stress. A comparison of the control with heavy moisture stress showed a decline of 57.1% and 68.4% for plant height and number of leaves, respectively. A degree of resilience of C. olitorius to moisture stress was observed with increasing plant age, but with a significant trade-off in the nutritional quality of the genotype at harvest.

Vigna subterranea ammonium transporter gene (VsAMT1): Some bioinformatics insights

Graphical abstract

Insecticidal activities and chemical composition of the essential oil from Tarchonanthus camphoratus (L.), leaves against Sitophilus zeamais Motschulsky, and Sitophilus oryzae (L.)

1 Department of Chemistry, University of Zululand, Private Bag X1001, KwaDlangewa, 3886, South Africa. 2 Department of Bio-Chemistry and Microbiology, University of Zululand, Private Bag X1001, KwaDlangewa, 3886, South Africa. 3 Department of Agriculture, Cape Peninsula University of Technology, Private Bag X8, Wellington, 7654, South Africa. 4 Department of Chemistry and Chemical Technology, Walter Sisulu University, Private Bag X1, Mthatha, 5099, South Africa.

Efficacy and Safety of Medicinal Plants Used in the Management of Diabetes Mellitus

This special issue edited by a team of five renowned scholars led by an Associate Professor of Biochemistry, M. T. Yakubu, Ph.D. (Lead Guest Editor), and other Guest Editors that included Professor T. O. Sunmonu, Dr. F. B. Lewu, Dr. A. O. T. Ashafa, Dr. Femi J. Olorunniji, and Professor Mohammed Eddouks features 15 original research papers covering various aspects of diabetes mellitus. R. M. P. Gutierrez et al. in the paper entitled “Ameliorative effect of hexane extract of Phalaris canariensis on high fat diet-induced obese and streptozotocin-induced diabetic mice” reported the antiobesity effect of a hexane extract of Phalaris canariensis seed in high-fat diet and streptozotocin-induced diabetic mice. M. T. Sultan et al. in the paper entitled “Nigella sativa fixed and essential oil supplementation modulates hyperglycemia and allied complications in streptozotocin-induced diabetes mellitus” described the modulatory effects of Nigella sativa fixed and essential oil supplementation on hyperglycemia and allied complications in streptozotocin-induced diabetes mellitus. In a related study, M. I. Kazeem et al. in the paper entitled “Protective effect of free and bound polyphenol extracts from ginger (Zingiber officinale Roscoe) on the hepatic antioxidant and some carbohydrate metabolizing enzymes of streptozotocin-induced diabetic rats” evaluated the protective effect of free and bound polyphenol extracts from ginger (Zingiber officinale Roscoe) on the hepatic antioxidant and some carbohydrate metabolizing enzymes of streptozotocin-induced diabetic rats. P.-G. Cheng et al. in the paper entitled “Polysaccharides-rich extract of Ganoderma lucidum (M.A. Curtis:Fr.) P. Karst accelerates wound healing in streptozotocin-induced diabetic rats” evaluated the wound healing activity of the hot aqueous extract of Ganoderma lucidum in streptozotocin-induced diabetic rats. The work reported by da A. A. Rocha et al. in the paper entitled “Lectin from Crataeva tapia bark improves tissue damages and plasma hyperglycemia in alloxan-induced diabetic mice” revealed that lectin extracted from Crataeva tapia bark resulted in improvement of tissue damage and plasma hyperglycemia in alloxan-induced diabetic mice. J. Gu et al. in the paper entitled “A drug-target network-based approach to evaluate the efficacy of medicinal plants for type II diabetes mellitus” used drug-target network-based approach to evaluate the efficacy of medicinal plants for type II diabetes mellitus. The study reported by M. M. Zainudin et al. in the paper entitled “Does oral ingestion of Piper sarmentosum cause toxicity in experimental animals?” investigated the potential toxicity of oral administration of an antidiabetic plant, Piper sarmentosum, in experimental animals. P. V. Rao et al. in the paper entitled “Rhinacanthus nasutus improves the levels of liver carbohydrate, protein, glycogen, and liver markers in streptozotocin-induced diabetic rats” showed that treatment of streptozotocin-induced diabetic rats with Rhinacanthus nasutus resulted in improvement in the levels of liver carbohydrate, protein, glycogen, and other hepatic markers. Y. Xiao et al. in the paper entitled “The effect of Chinese herbal medicine on albuminuria levels in patients with diabetic nephropathy: a systematic review and meta-analysis” presented a systematic review and meta-analysis of the effect of Chinese herbal medicine on albuminuria levels in patients with diabetic nephropathy. J. Wu et al. in the paper entitled “Renal protective role of Xiexin decoction with multiple active ingredients involves inhibition of inflammation through downregulation of the nuclear factor-kB pathway in diabetic rats” presented evidence to suggest that the inhibition of inflammation through downregulation of the nuclear factor-kβ pathway in diabetic rats is the mechanism by which Xiexin decoction with multiple active ingredients exhibits its renal protective role. The paper by L. Zhou et al. in the paper entitled “Hu-Lu-Ba-Wan attenuates diabetic nephropathy in type 2 diabetic rats through PKC-α/NADPH oxidase signaling pathway” reported the attenuation of diabetic nephropathy in type 2 diabetic rats through PKC-α/NADPH oxidase signaling pathway by Hu-Lu-Ba-Wan. The evaluation of antidiabetic activity and associated toxicity of Artemisia afra aqueous extract in Wistar rats was reported by T. O. Sunmonu and A. J. Afolayan in the paper entitled “Evaluation of antidiabetic activity and associated toxicity of Artemisia afra aqueous extract in Wistar rats.” N. A. Ishak et al. in the paper entitled “Antidiabetic and hypolipidemic activities of Curculigo latifolia fruit: root extract in high fat fed diet and low dose STZ induced diabetic rats” evaluated the antidiabetic and hypolipidemic activities of Curculigo latifolia fruit: root extract in high-fat fed diet and low dose STZ-induced diabetic rats. The evaluation of the hypoglycemic properties of Anacardium humile aqueous extract was reported by M. A. Urzeda et al. in the paper entitled “Evaluation of the hypoglycemic properties of Anacardium humile aqueous extract.” Finally, the decrease of plasma glucose by Hibiscus taiwanensis in type-1-like diabetic rats was the focus of the study reported by L.-Y. Wang et al. in the paper entitled “Decrease of plasma glucose by Hibiscus taiwanensis in type-1-like diabetic rats.” The variety of papers on diabetes featured in this special issue highlights the keen awareness of the biomedical community of the potential for exploiting medicinal plants in tackling this debilitating condition. Of particular interest is the large number of contributions from scientists working in developing countries. This level of interest should be encouraged. The gradual improvement in the level of prosperity in developing economies is being accompanied by a significant increase in reported cases of obesity, diabetes, and other metabolic disorders. It is appropriate that scientists and policy makers in these lands devote more resources to exploring newer ways of dealing with these conditions. It is hoped that the encouraging findings reported in this special issue will stimulate further interest in expanding and coordinating efforts on medicinal plants that have clinical potential in the management of diabetes.

The Chemical Composition, Larvicidal and Antibacterial Activities of the Essential Oil of Tarchonanthus trilobus var galpinii.

Abstract The chemical composition of the essential oil of Tarchonanthus trilobus var galpinii was analysed by GC-MS and the major component in the oil was β-caryophyllene (30.40 %). The oil was mainly dominated by sesquiterpene hydrocarbons (84.51 %). The larvicidal assay of the essential oil against larvae of Anopheles arabiensis mosquito revealed that at a concentration of 300 ppm, the oil caused 100 % mortality after 24 hr exposure with an LC50 value of 110.32 ppm. The in vitro antibacterial activity of the essential oil was studied against 9 bacteria strains using disc diffusion and broth micro dilution method. The oil showed a broader spectrum of antibacterial activity than the reference drug, chloramphenical. Pseudomonas aeruginosa, was resistant to both the essential oil and to chloramphenical.