Green synthesis of Ag, Zn and Cu nanoparticles from aqueous extract of Spondias mombin leaves and evaluation of their antibacterial activity

Background: Nanotechnology offers an advantage as a green route for synthesis of metal nanoparticles (NPs) with plant extracts as capping agent. Spondias mombin is a fruit-bearing tree and its leaf extracts have been reported to possess anxiolytic, hypoglycaemic, antiepileptic, antipsychotic, sedative, antioxidant, and antimicrobial properties. The objective of the study is to determine the antibacterial potential of a simple non-toxic product of green synthesis of metallic (Ag, Zn and Cu) nanoparticles using the leaf of Spondias mombin aqueous extracts (SMAE) as a reducing and capping agents of the metal ions.Methodology: Nanoparticles were characterized by UV visible spectrophotometeric analysis, Fourier Transform Infra-Red (FT-IR) spectrophotometer and scanning electron microscope (SEM). Antimicrobial activities of synthesized NPs against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were determined by agar well diffusion technique.Results: The synthesized NPs varied in colour from dark brown to green and appears dominantly spherical, occasionally rod or triangular shaped with size ranging from 65-90 nm. UV spectroscopy absorption spectra of Ag, Zn and Cu NPs had absorbance peak at 267, 262 and 765 nm respectively. FT-IR spectrometry of Zn NP, Cu NP, and SMAE gave wave number ranging from 895.71-3320.67, 747.02-3225.45 and 658.25-3674.49 respectively. FT-IR analysis showed that SMAE acted as reducing and stabilizing agent while the NPs exhibited lower energy absorption band when compared to the plant extract. The NPs demonstrated higher antimicrobial activities against S. aureus than Ps. aeruginosa and E. coli. The antimicrobial activity was higher with copper NP than Ag and Zn NPs, and also higher than SMAE.Conclusion: The result from this study presents an indication for an alternative means for development of novel antimicrobial agents for clinical and biotechnological applications.Keywords: synthesis, nanoparticles, FT-IR, UV-visible spectrophotometry, antibacterial activitiesFrench Title: Synthèse verte de nanoparticules d'Ag, de Zn et de Cu à partir d'extrait aqueux de feuilles de Spondias mombin et évaluation de leur activité antibactérienneContexte: La nanotechnologie offre un avantage en tant que voie verte pour la synthèse de nanoparticules métalliques (NP) avec des extraits de plantes comme agent de coiffage. Spondias mombin est un arbre fruitier et ses extraits de feuilles possèdent des propriétés anxiolytiques,  hypoglycémiques, antiépileptiques, antipsychotiques, sédatives,  antioxydantes et antimicrobiennes. L’objectif de l’étude est de déterminer le potentiel antibactérien d’un simple produit non toxique de synthèse verte de nanoparticules métalliques (Ag, Zn et Cu) à l’aide de la feuille d’extraits aqueux de Spondias mombin (SMAE) en tant qu’agent réducteur et coiffant de la ions métalliques.Méthodologie: Les nanoparticules ont été caractérisées par analyse  spectrophotométrique UV visible, spectrophotomètre à transformée de Fourier infrarouge (FT-IR) et microscope électronique à balayage (MEB). Lesactivités antimicrobiennes de NP synthétisées contre Escherichia coli, Staphylococcus aureus et Pseudomonas aeruginosa ont été déterminées par une technique de diffusion sur puits d’agar.Résultats: Les NP synthétisés ont une couleur allant du brun foncé au vert et apparaissent principalement sphériques, parfois en bâtonnets ou en triangles, avec des tailles allant de 65 à 90 nm. Les spectres  d'absorption par spectroscopie UV des NP Ag, Zn et Cu présentaient des pics  d'absorbance à 267, 262 et 765 nm respectivement. La spectrométrie FT-IR de Zn NP, Cu NP et SMAE a donné un nombre d'onde allant de 895,71 à 3320,67, 747,02 à 3225,45 et 658,25 à 3674,49 respectivement. L'analyse FT-IR a montré que le SMAE agissait en tant qu'agent réducteur et  stabilisant, alors que les NP présentaient une bande d'absorption d'énergie inférieure à celle de l'extrait de plante. Les NP ont démontré des activités antimicrobiennes plus élevées contre S. aureus que Ps. aeruginosa et E. coli. L'activité antimicrobienne était plus élevée avec les NP en cuivre que dans les NP Ag et Zn, et également supérieure à celle du SMAE.Conclusion: le résultat de cette étude présente une indication d'un autre moyen de développement de nouveaux agents antimicrobiens pour des applications cliniques et biotechnologiques.Mots-clés: synthèse, nanoparticules, FT-IR, spectrophotométrie UV-visible, activités antibactériennes

Hypoglycemic Potential Of Fractions From The Methanol Stem Extract Of Olax Subscorpioidea Oliv (olaceaces)

Background: Diabetes mellitus is a metabolic condition which is characterized by high blood glucose. It is becoming the third common killer of mankind after cancer and cardiovascular disease, because of its high prevalence, morbidity and mortality.Objective: In this study, the hypoglycaemic potential of fractions from the methanol extract of the stem of Olax subscorpioideaOliv was investigated. Olax subscorpioidea is a shrub or tree which belongs to the family of Olacaceae. It is used in traditional medicine for the management of inflammatory disorders, infectious diseases, diabetes and mental illness.Method: The hypoglycaemic potential was investigated using the α-amylase inhibitory method. Alpha amylase inhibition experiment was carried out at concentration of extracts ranging from 20- 1000μg/mL.Results: Acarbose had its highest inhibitory activity of 57.8% at 1000 μg/mLwhile ethylacetate fraction had the highest activity of 52.5% at the same concentration. Solvent fractions from the methanol extract of Olax subscorpioidea stem inhibited the αamylase enzyme with IC values of 454.3 μg/mLfor 50 acarbose, 719.7 μg/mLfor ethylacetate fraction and >1000 μg/mLeach for n-hexane, chloroform, butanol and aqueous fractions.Conclusion: The ethylacetate fraction exhibited a more potent α-amylase inhibitory activity than all the other fractions; hence further studies should be focused at investigating the bioactive constituents present in the ethyl acetate fraction of the plant in pursuit of potential anti-diabetic agents. Keywords: Olax subscorpioidea,hypoglycaemia, alpha-amylase, acarbos

Comparative studies on the yield of some herbaceous legumes and effects of storage on the quality of their pellets

Dry matter yield of herbaceous legumes and effects of storage length of their pellets on the chemical composition were investigated. A two phased field and laboratory experiment were conducted. In the first experiment, the yield of the forage legumes using a 5 x 2 factorial experiment consisting of five herbaceous legumes (Lablab purpureus, Mucuna pruriens, Centrosema molle, Centrosema pascorum and Calopogonium mucunoides) and two harvesting ages (6 and 12 weeks after sowing) laid out in a split-plot design was determined. The second experiment was the selection of herbaceous legumes with higher yields from Experiment 1 using a 3 x 4 factorial experiment consisting of the three herbaceous legumes (L. purpureus, C. mucunoides and M. pruriens) used to make pellets and four storage lengths (0 i.e. fresh, 30, 60 and 90 days). Treatments in both experiments were replicated three times. Results showed that legumes harvested 12 weeks after sowing (WAS) had significantly (P < 0.05) higher dry matter yield (2.73 t ha-1) than legumes at 6 WAS, while Lablab purpureus produced the highest (P < 0.05) dry matter yield (2.94 t ha-1) of the legumes evaluated.. The physical characteristics of the herbaceous legumes pellets such as colour, odour and moldiness at different storage length showed that they were between fair and good pellets. The L. purpureus and M. pruriens had higher (P < 0.05) CP content than C. mucunoides. Differences in the CP content of pellets with the storage lengths employed was not significant (P > 0.05). Higher oxalate, phytate and saponin contents were found in C. mucunoides pellets than in other legumes pellets while the tannin content was in the order of M. pruriens (43.63 mg kg-1) > L. purpureus (26.00 mg kg-1) > C. mucunoides (20.31 mg kg-1). In conclusion, increasing age at harvest increased the yield of the legumes, while increasing storage duration decreased the CP content but increased the NDF, ADF and saponin content of the pellets