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

Assessment of the rainfall exceedance in Nigeria

This study assessed rainfall extremes for agricultural overview in Nigeria using trend analysis and probability of exceedance expressed as normal for an average at 50% exceedance, wet for greater than average 20% exceedance and dry for lower than average 80% exceedance. The annual rainfall trend indicated variability in the six geopolitical regions with North-East having the lowest range and South-South area with highest. The average monthly rainfall exceedance showed that all part of the Nigeria experienced rainfall more than 100 mm at all levels of probability. The rainfall exceedance time series indicated extremes as well as critical values of 20% and 80% exceedance conditions at many stations during the study period. The critical values of exceedances in dry occurrences are in short-time scales in Northern region while, wet exceedances occurrences for long time scales in South-East, South-West, North-Central and North-West. The study revealed periods of extreme rainfall of significant magnitude susceptible to crop failure in the different regions if reliable cropping management plans is not put in place

Analysis of selected metallic impurities in soft drinks marketed in Lagos, Nigeria

ArticleTwenty brands of soft drinks commonly consumed in Lagos, Nigeria were analyzed for lead, cadmium, nickel, silver, chromium and zinc using standard biochemical procedures. The aim was to determine whether the concentrations of toxic metals in commonly consumed soft drinks are below or above the upper limit for each of the metals as set by World Health Organization (WHO). Results showed that cadmium was present in four of the samples at a concentration ranging from 0.023 to 0.158 mg/L, lead was present in three of the samples at a concentration ranging from 0.5045 to 3.0275 mg/L, nickel was present in six of the samples at a concentration ranging from 0.016 to 0.063 mg/L while silver was absent in all of the samples. Some of the samples analyzed can be said to be safe for human consumption because the values of the metals were below the allowable limits as set by WHO while others could not be said to be safe as the levels of metals were above the allowable limits set by WHO. Therefore, it is suggested that health authorities and soft drink producing companies should pay more attention to the sources of these metals in soft drink

Phytochemical Screening and Antioxidant Activities of Some Selected Medicinal Plants Used for Malaria Therapy in Southwestern Nigeria

Purpose: Oxidative stress has been shown to play an important role in the development of anaemia in malaria. Indeed, increase in total antioxidant status has been shown to be important in recovery from malaria. The antioxidant activities of four medicinal plants traditionally used in the treatment of malaria in southwestern Nigeria were determined. Methods: The ethanolic extracts of the leaves of Carica papaya Linn. [Caricaceae] , stem bark of Magnifera indica Linn. [Anacardiaceae], leaves of Psidium guajava Linn. [Myrtaceae] and the leaves of Vernonia amygdalina Del. [Compositae], were used in the present study. The plant parts commonly used in the locality in malaria therapy were employed in this study. The plants were screened for the presence of phytochemicals and, their effect on 2,2-Diphenyl-1-picryl-hydrazyl radical (DPPH) was used to determine their free radical scavenging activity. Results: Phytochemical screening of the plants showed the presence of flavonoids, terpenoids, saponins, tannins and reducing sugars. M. indica did not contain cardiac glycosides and alkaloids while, P. guajava also showed the absence of alkaloids and anthraquinones. Anthraquinones was similarly absent from V. amygdalina. Concentrations of the plant extracts required for 50% inhibition of DPPH radical scavenging effect (IC50) were recorded as 0.04 mg/ml, 0.313 mg/ml, 0.58 mg/ml, 2.30 mg/ml and 0.054 mg/ml for P. guajava, M. Indica, C. papaya, V. amygdalina and Vitamin C, respectively. Conclusion: All the plants showed potent inhibition of DPPH radical scavenging activity, P. guajava being the most potent. The free radical scavenging (antioxidant) activities of these plants probably contribute to the effectiveness of the above plants in malaria therapy