Antioxidant Potential of Crude Powder, Methanol and Aqueous Extracts of Fonio Millet (Digitaria exilis) Grains

This study evaluated the antioxidant potential along with total phenolic content, total flavonoid content of the crude powder, methanol and aqueous extracts of Digitaria exilis grains. The antioxidant activities of the crude powder and extracts were determined by measuring the reducing ability and hydrogen peroxide scavenging activity. The results showed that methanol extracts exhibited the highest total phenolic content (57.96 ± 6.84 mg gallic acid equivalence/g dried weight) and total flavonoid content (38.75 ± 9.76 mg quercetin equivalence/g dried weight) compared to the crude powder and aqueous extracts. A concentration- dependent increase in the reducing ability and hydrogen peroxide scavenging activity was observed in all the samples. The results were comparable to ascorbic acid, the standard antioxidant used. These results indicate that Digitaria exilis grains have antioxidant activity and may account for the use of the grains in traditional systems of medicine.

Biopesticidal Effect of Partitioned Extracts of Zanthoxylum zanthoxyloides (Lam.) Zepernick & Timler on Callosobruchus maculatus (Fab.)

Botanicals have become the focus for discovery of novel bioinsecticides for protection of crops most especially because of their biodegradability, non-toxicity, target organism specificity and environmental friendliness. Partitioned extracts of Zanthoxylum zanthoxyloides were investigated for biopesticidal effect on Callosobruchus maculatus with aim of identifying the most active components and increase ease of handling when compared to bulk crude plant material used by farmers. Crude powder of rootbark of Z. zanthoxyloides was made as well as partitioned extracts using Kupchan partition extraction methods with methanol, acetone, ethyl acetate and n-hexane as solvents. Analysis of the rootbark of the plant showed 19.87% ash content, 24% crude protein, 24.85% crude fibre, 3.13% oil extract, 15.42mg/100g alkaloids, 45.90mg/100g tannins, 1039.14mg/100g saponins, 26.47mg/100g flavonoids, 150.0mg/100g iron, 244.70mg/100g calcium, 36.65mg/100g magnesium, 449.00mg/100g potassium and 128.30mg/100g of phosphorus. The crude powder and extracts were bioassayed on C. maculatus in stored cowpea. Insecticidal activities of the partitioned extracts increased with increasing concentration; toxicity test revealed that n-hexane at 1%, 2% and 3%, acetone extract at 3%, and crude powder at 1.5g all have same effect on the insect as the positive control, achieving 100% mortality at 24 hours post treatment, number of adult emergence of 63.57 was recorded with 1% methanol extract against 28 in 3% of the extract. There was a significant difference in weight loss by the cowpea in the different fractional treatments while positive and negative controls also differed significantly (P>0.05) with all the partitioned treatments. Partition extracts from Z. zanthoxyloides were more bioactive than the crude powder, and n-hexane fractions contain the most active compounds against C. maculatus. n-hexane extract contain most active biomolecules to be explored for bioinsecticide formulation with high potency for development of new biopesticide, eliminate toxic components and increase ease of handling when compared to bulk crude plant material used by farmers.

Evaluación de la capacidad antimicrobiana de las hojas de Laurusnobilis y Thymusvulgaris.// Evaluation of the antimicrobial capacity of the leaves of Laurus nobilis and Thymus vulgaris

El objetivo de esta investigación fue evaluar el efecto antimicrobiano de las hojas deshidratadas de Laurusnobilis(laurel) yThymusvulgaris(tomillo), como conservantes naturales, para ser implementado en lareduccióndela carga microbiana de alimentos de alto consumo, como losquesos frescos artesanales, entre otros alimentos.Las hojas frescas de laurel y tomillo fueron recolectadas al azar, debidamente procesadas, desinfectadas, secadas por arrastre de vapor a 45°C por 14 horas y fraccionadas en un mortero para la obtención de un extracto crudo en polvo. La determinación de la concentración mínima inhibitoria (CMI) se llevó a cabo a partir de la preparación de varias concentraciones del extracto crudo, en polvo, de las plantas en estudio, a través de la técnica de difusión en agar. Éstas se probaron frente a la cepa Staphyloccocusaureus mediante la colocación de discos de papel filtro impregnado de las soluciones antimicrobianas en una caja petri con agar y con inóculo bacteriano estriado en la superficie.Se pudo concluir que a concentraciones 175 y 200 mg/ml de laurel y 125, 175 y 200 mg/ml de tomillo, había presencia de un halo inhibitorio, lo cual constituye una fuente prometedora de extractos antimicrobianos, para el control de Staphyloccocusaureus, contaminante frecuente de los alimentos.ABSTRACTThe objective of this research was to evaluate the antimicrobial effect of dehydrated leaves of Laurus nobilis (laurel) and Thymus vulgaris (thyme), as natural preservatives, to be implemented in reducing the microbial load of high consumption foods, such as the case of artisanal fresh cheese, among other foods. The fresh leaves of laurel and thyme were collected at random, duly processed, disinfected, steam-dried at 45 ° C for 14 hours and crushed in a mortar to obtain a crude powder extract. The determination of the minimum inhibitory concentration (MIC) was carried out from the preparation of several concentrations of the crude powder extract, through the diffusion technique in agar. These were tested against Staphylococcus aureus strain by the placement of filter paper disks impregnated with the antimicrobial solutions in a Petri dish with agar and bacterial inoculum on the surface. It was concluded that at concentrations of 175 and 200 mg /ml of laurel and 125, 175 and 200 mg /ml of thyme there was an inhibitory zone, which is a promising source of antimicrobial extracts for the control of S. aureus, a frequent food contaminant.