More still needs to be learned regards the relative contamination of heavy metals and pesticide residues, particularly those found in widely consumed Nigerian food crops like cereals, vegetables, and tubers. In this current study, the heavy metals and pesticide residues detectable in widely consumed Nigerian food crops were respectively quantified using atomic absorption spectroscopy (AAS) and gas chromatography (GC). Specifically, the widely consumed Nigerian food crops included cereals (rice, millet, and maize), legume (soybean), tubers (yam and cassava), as well as leaf (fluted pumpkin, Amaranthus leaf, waterleaf, and scent leaf) and fruit vegetables (okro, cucumber, carrot, and watermelon). Results showed that the detected heavy metals included arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), and nickel (Ni), whereas the pesticide residues included Aldrin, Carbofuran, g-chlordane, Chlorpyrifos, DichloroBiphenyl, Dichlorodiphenyldichloroethane (DDD), Dichlorodiphenyltrichloroethane (DDT), Dichlorvos, Endosulfan, Heptachlor, Hexachlorobenzene (HCB), Isopropylamine, Lindane, t-nonachlor, and Profenofos. Across the studied food crops, the concentrations of heavy metals and pesticides were varied, with different trends as they largely fell below the established maximum permissible limits, and with some exceptions. Our findings suggest there could be a somewhat gradual decline in the concentration of the heavy metals and pesticide residues of these studied food crops when compared to previously published reports specific to Nigeria. To help substantiate this observation and supplement existing information, further investigations are required into the concentration of these heavy metals and pesticide residues specific to these studied food crops at other parts of the country.

Lipases are enzymes of industrial importance responsible for the hydrolysis of ester bonds of triglycerides. A lipolytic fungus was isolated and subsequently identified based on the ITS sequence analysis as putative Aspergillus flavus with accession number LC424503. The gene coding for extracellular triacylglycerol lipase was isolated from Aspergillus flavus species, sequenced, and characterised using bioinformatics tools. An open reading frame of 420 amino acid sequence was obtained and designated as Aspergillus flavus lipase (AFL) sequence. Alignment of the amino acid sequence with other lipases revealed the presence GHSLG sequence which is the lipase consensus sequence Gly-X1-Ser-X2-Gly indicating that it a classical lipase. A catalytic active site lid domain composed of TYITDTIIDLS amino acids sequence was also revealed. This lid protects the active site, control the catalytic activity and substrate selectivity in lipases. The 3-Dimensional structural model shared 34.08% sequence identity with a lipase from Yarrowia lipolytica covering 272 amino acid residues of the template model. A search of the lipase engineering database using AFL sequence revealed that it belongs to the class GX-lipase, superfamily abH23 and homologous family abH23.02, molecular weight and isoelectric point values of 46.95 KDa and 5.7, respectively. N-glycosylation sites were predicted at residues 164, 236 and 333, with potentials of 0.7250, 0.7037 and 0.7048, respectively. O-glycosylation sites were predicted at residues 355, 358, 360 and 366. A signal sequence of 37 amino acids was revealed at the N-terminal of the polypeptide. This is a short peptide sequence that marks a protein for transport across the cell membrane and indicates that AFL is an extracellular lipase. The findings on the structural and molecular properties of Aspergillus flavus lipase in this work will be crucial in future studies aiming at engineering the enzyme for biotechnology applications. Communicated by Ramaswamy H. Sarma

This study sought to characterize the phyto-oil extracted from an unexploited seed of African star apple (Udara) using soxhlet extraction method, normal hexane was used as the solvent at 67 °C for 4 h. The percentage oil yield was 23.8%. The extracted oil was liquid at room temperature, pleasant sweet smell with honey-like colour. The oil physicochemical properties such as acid value, peroxide value and saponification value were 17.41 ± 0.43 mg/KOH/g, 57.74 ± 2.77 meq/kg−1 and 236.341 ± 6.80 mg/KOH/g, respectively. Also, free fatty acid of 8.75% and iodine value of 29 ± 0.16 mg/100g were obtained. The identified fatty acids present included n-hexadecanoic acid (7.55%), 13-hexyloxacyctri-dec-10-en-2-one (1.19%), oleic acids (30.21%), octadecanoic acid (5.28%), hexadecanoic acid (2.37%), undecylenic acid (40.33%), 9-octadecanal (7.09%), and 9, 17-octadecadienal (5.98%). The properties of oil extracted revealed that the seed is a good source of oil which could be employed for industrial purposes. Cette étude visait à caractériser l’huile extraite d’une graine non exploitée d’un arbre appelé African star apple (Udara), par la méthode d’extraction au Soxhlet ; de l’hexane normal a été utilisé comme solvant à 67 °C pendant 4 h. Le pourcentage de rendement en huile était de 23,8 %. L’huile extraite était liquide à température ambiante, de couleur miel et dégageait une agréable odeur. Les propriétés physicochimiques de l’huile telles que l’indice d’acide, l’indice de peroxyde et l’indice de saponification étaient respectivement de 17,41 ± 0,43 mg/KOH/g, de 57,74 ± 2,77 meq/kg−1 et de 236,341 ± 6,80 mg/KOH/g. Des acides gras libres à hauteur de 8,75 % et un indice d’iode de 29 ± 0,16 mg/100g ont également été mesurés. Les acides gras identifiés présents comprenaient l’acide n-hexadécanoïque (7,55 %), le 13-hexyloxacyctri-déc-10-ène-2-one (1,19 %), les acides oléiques (30,21 %), l’acide octadécanoïque (5,28 %), l’acide hexadécanoïque (2,37 %), acide undécylénique (40,33 %), le 9-octadécanal (7,09 %) et le 9,17-octadécadiénal (5,98 %). Les propriétés de l’huile extraite ont révélé que la graine est une bonne source d’huile pouvant être utilisée à des fins industrielles.

Background: Medicinal plant contains multiple bioactive compounds with therapeutic potentials. Due to their availability, affordability, and minimal known side effects, they are widely practiced. Identification, quantification, and establishment of their interaction with physiological enzymes help in the standardization of plant-based medicinal extracts. In this study, gas chromatography/flame ionization detector (GC–FID) and high-performance liquid chromatography (HPLC) analysis were used to determine the bioactive components in the ethanol extract of Newbouldia laevis stem bark. The antioxidant activity of the extract was determined. Enzyme inhibitory potency of the flavonoids’ components was investigated against acetylcholinesterase, butyrylcholinesterase, phospholipase A2, α-glucosidase, and α-amylase. Results: Analysis of ethanol extract of N. laevis stem-bark revealed alkaloids (0.37%), tannins (1.82 mg/TEq/g), flavonoids (5.85 mg/QEq), steroids (0.11 mg/10 g) and glycosides (0.08 mg/10 g). The HPLC fingerprint of flavonoids showed high concentrations (mg/100 g) of catechin (47.11), apigenin (15.68), luteolin (18.90), kaempferol (41.54), and quercetin (37.64), respectively. In vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging ability of the extract was exhibited at 150 and 200 mg/mL, respectively. At 300 mg, most in vitro antioxidant potentials (lipid peroxidation, metal chelating ability, hydroxyl, nitric oxide, sulfide oxide radicals scavenging abilities) were obtained. The extract showed varying inhibitory abilities (> 50%) on acetylcholinesterase, butyrylcholinesterase, phospholipase A2, α-glucosidase and α-amylase at 300 mg/mL, IC₅₀ of 129.46, 237.10, 169.50, 251.04 and 243.06 mg/mL, respectively, with inhibition constants (Ki) of 3.92, 1.63, 1.11, 2.95 and 2.11. Results showed an affinity for the targeted enzymes with free energies higher than the standard drugs. Conclusion: The results revealed that the N. laevis stem bark possesses antioxidant activity and enzyme inhibitory activity on the physiological enzyme that has been implicated in diabetes. In vitro and in silico inhibition of these physiological enzymes by extract suggests that the stem bark can be effective in ameliorating the complications associated with diabetes mellitus.

Pesticide residues and heavy metal content of cassava, yam, cocoyam, potato, water yam and carrot were evaluated by gas chromatography–mass spectrometry and atomic absorption spectroscopy. The detected pesticide residues in the samples were 2,4-dichlorophenoxyacetic acid, glyphosate, hexachlorobenzene (HCB), dichlorobiphenyl, aldrin, endosulfan, profenofos, g-chlordane, carbofuran, biphenyl, heptachlor, lindane and t-Nonachlor. The concentration of HCB ranged between 0.0799 ± 0.06 mg/kg and 0.1596 ± 0.00 mg/kg, which was greater than the permitted maximum limit of 0.5 mg/kg established by the US Environmental Protection Agency. The concentration of aldrin and profenofos detected was lower than the predetermined maximum allowed limits. Endosulfan concentrations in cocoyam (0.2500 mg/kg) and potato (0.3265 mg/kg) were higher than the limits allowed by the Canadian Department of Industrial Research. The heavy metals detected in these samples include cobalt, nickel, lead, manganese, chromium, arsenic and mercury in at least one of the samples evaluated. There was not much difference between the concentration of cobalt in yam (0.036 mg/kg) and the maximum allowed concentration (0.043 mg/kg). Lead was detected in potatoes and carrots but was below detectable concentration in cassava, yam, cocoyam and water yam. Similarly, cocoyam was found to have a significant mercury content (0.658 mg/kg), but mercury content was below detectable concentrations in cassava, yam and water yam.

Food insecurity and undernourishment constitute a major challenge in Africa and the world at large. To meet key nutritional targets and tackle the menace of undernourishment, we need to exploit available but underutilised food crops. A common underutilised food crop with the potential to improve daily nutrition is tiger nut. This potential is evidenced in the number of essential amino acids detected, which constitute 74.425% of the entire amino acids detected, in addition to important minerals and vitamins. The nutritional composition of the yellow variety of tiger nut (Cyperus esculentus) was determined using the standard methods of high-performance liquid chromatography and UV-spectroscopy. Ten amino acids were identified and quantified, including six essential amino acids, of which valine had the highest concentration (67.59 μg/100 g), followed by leucine (3.019 μg/100 g), phenylalanine (1.767 μg/100 g), lysine (0.946 μg/100 g), histidine (1.048 μg/100 g) and tryptophan (0.055 μg/100 g). The other amino acids were proline (24.124 μg/100 g), cysteine (1.269 μg/100 g), glycine (0.024 μg/100 g), and glutamine (0.022 μg/100 g). Monosaccharides detected were ribose (41.76%), glucose (21.52%), sedoheptulose (17.94%), fructose (4.566%), rhamnose (1.78%) and mannose (1.58%), whilst disaccharides detected were sucrose (87.66%) and maltose (11.39%). Mineral concentrations were K 144.80 ± 1.10 mg/100 g, Ca 94.39 ± 0.02 mg/100 g, Na 83.92 ± 0.04 mg/100 g, Fe 19.36 ± 0.54 mg/100 g, Mg 17.63±0.13 mg/100 g, Cu 13.28±0.05 mg/100 g and Zn 5.18±0.01 mg/100 g Vitamins A, B2, C and E were detected and quantified as 53.93±1.03, 7.61±1.20, 31.70±1.25 and 128.75±0.74 μg/100 g, respectively. The chemical and nutritional properties of the yellow variety of tiger nut suggest that it is rich in essential amino acids, minerals, and some vitamins. Hence, it should be recommended to persons with nutritional deficiencies as it is cheap and available all year round. Significance: The nutritional composition of the yellow tiger nut will assist in meeting the recommended daily intake of essential amino acids, monosaccharides, disaccharides, minerals, and vitamins, thus contributing towards solving the challenge of food insecurity and malnutrition, particularly in the African sub-region. The rich concentration of these nutrients could be harnessed in the biofortification of food materials known to be deficient in one nutrient or another. These important attributes of tiger nut, if harnessed, will add value to this underutilised crop and enhance the economic livelihood of the local farmers.