Green leafy vegetable is one of the major cuisines in Southern Nigeria and they are not only consumed for their palatability, but also for their nutritional and medicinal properties as reported in folklore. Notable among them are afang (Gnetum africanum), editan (Lasianthera africana) and utazi (Gongronema latifolium). In this study, we investigated the effect of aqueous extracts from afang, editan and utazi leaves on cholinesterases [acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)] and monoamine oxidase (MAO) activities. Fe^2 + chelating abilities were also determined as an assessment of their neuroprotective potentials in vitro. We also assayed for their total phenol contents while the constituent phenolics were characterized using high performance liquid chromatography coupled with diode array detector (HPLC-DAD). The results revealed that the extracts inhibited AChE, BChE and MAO activities and also chelated Fe^2 + in concentration dependent manner. The HPLC-DAD characterization showed that gallic, caffeic and ellagic acids and rutin were the dominant phenolic compounds in the extracts; nevertheless, utazi had the highest distribution of identified phenolics while afang had the least. The ability of the aqueous extracts of the vegetables to inhibit key enzymes (AChE, BChE and MAO) relevant to neurodegeneration, as well chelate metal ion could help suggest their possible neuroprotective properties. These vegetables could be use as dietary intervention in the management of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases.

Introduction: Africa faces immense food and health insecurity challenges, a problem partly attributed to food loss and waste during postharvest handling and distribution. In the context of research to meet the sustainable development goals, this project specifically addressed the postharvest loss of the ripe indigenous eggplant (Solanum anguivi lam) fruit called “Igba Yinrin” by Yoruba in South-West Nigeria, which is usually discarded in farms. The study was carried out on ripe and unripe fruits to better understand their value by comparing their effects in diabetes treatment. Methods: The study sought to assess the effects of a diet including ripe or unripe mature eggplant fruits in the sucrose-induced diabetic-like fruit fly. Bioactive compounds were identified and quantified with HPLC–UV, while the antioxidant vitamin (A, C, E), carotenoid, and mineral (Na, K, Ca, Mg, Fe, P, and Zn) content was analyzed in the fruits. Extracts were used to investigate their in vitro anti-inflammatory properties on cyclooxygenases (COX 1 and 2), 5-lipoxygenase (5-LOX), and anti-diabetes enzymes [α-amylase and α-glucosidase], while extract-supplemented diets (0.25–1% concentration) were fed to the fruit flies for 14 days. Results: Interestingly, the results showed that the ripe fruits had a significantly (p < 0.05) higher total phenol and flavonoid content, as well as a higher content of vitamins, carotenoids, and minerals, than the unripe fruits. The in vivo activities of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), and glutathione transferase (GST)] and the total thiol level increased, while the blood glucose, reactive oxygen species (ROS), and malondialdehyde (MDA) levels decreased in Drosophila melanogaster (fruit fly). An in silico docking analysis showed strong binding affinity of the above-mentioned enzymes under investigation with the ligands hesperidin, naringin, and myricetin, which are bioactive compounds contained in the examined extracts. Conclusions: There was no significant difference in the biological effects of the ripe and unripe fruit extracts on inflammatory and anti-diabetes enzyme activities, which means that the ripe fruit, usually discarded, could serve as a sustainable alternative source of food nutrients.

This study sought to investigate the inhibitory effect of methanolic extract of different species of African eggplant (Solanum melongena L.) and (Solanum macrocarpon) on starch hydrolysing enzymes relevant to type-2 diabetes (α-amylase and α-glucosidase). The phenolic content and antioxidant properties of the eggplant varieties were also assessed. The results revealed that both extracts exhibited mild α-amylase and stronger α-glucosidase inhibitory activities in a dose dependent manner. Furthermore, S. macrocarpon exhibited stronger radicals (1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging ability, nitric-oxide (NO·) scavenging ability and ferric reducing antioxidant property (FRAP) than S. melongena, while S. melongena had stronger hydroxyl (OH·) radical ability. The inhibition of starch hydrolysing enzymes and antioxidant activities suggested the potential use of eggplants in the dietary management or control of postprandial hyperglycemia associated with type-2 diabetes. Key words: Antioxidant activity, diabetes, α-amylase, α-glucosidase, Solanum macrocarpon,Solanum melongena.

Tropical Solanum species contains a high level of phenolic acids and flavonoids, which were found to inhibit some key enzymes associated with the incidence of type 2 diabetes in in vitro and in vivo models based on earlier studies. This study was further designed to compare the nutritional properties, glycemic index, and hypolipidemic and the antioxidant effects of three species of tropical eggplant fruit (Solanum kumba, Solanum aethiopicum, and Solanum gilo) diet on streptozotocin (STZ)‐induced nephrotoxicity in male Wistar rats. The animal model was subjected to high‐fat diet prior to interperitional administration of streptozotocin (35 mg/kg wt); thereafter, the rats were given supplemented eggplant fruit diet, which lasted for 14 days. Determination of lipid content [triglycerides (TG), low‐density lipoproteins (LDLs), high‐density lipoproteins (HDLs), and total cholesterol (TC)], was assessed, while the liver biomarker enzymes alanine aminotransferase (ALT) alkaline phosphatase (ALP) and aspartate aminotransferase (AST), also endogenous enzymes such as superoxide dismutase (SOD) and catalase (CAT), were determined. Histopathological assessment of inflammation was carried out on kidney while the blood urea nitrogen (BUN), uric acid, and creatinine level on the kidney function were determined. The results showed that the groups with supplemented eggplant diet had significant (p < 0.05) reduction in lipid profile, decreased leakages of the liver, and kidney function enzymes while there was restoration of depleted endogenous antioxidant enzymes. The inflammatory cells and fat deposit from the histopathological view were reduced. However, S. kumba had the best nutritional output.

Solanum aethiopicum is commonly cultivated in Nigeria for its nutritional and medicinal properties. Although, information on the possible effect of location on the biological activities of S. aethiopicum has not been reported, however, present research work investigated the phenolic contents and distribution, antioxidative properties, and enzyme inhibitory activities of S. aethiopicum collected from two locations in Nigeria. HPLC phenolic profile, polyphenol contents, free radical scavenging activities, and inhibitory effect of eggplant extracts on carbohydrate metabolizing enzymes were carried out. Significant variations were observed in the phenolic profile, polyphenol contents, antioxidant activities, and enzymes inhibitory properties of the extracts from different locations. In most of the analyses carried out, extract of eggplant fruit collected from Uyo (UEF) showed higher activities than the one obtained from Ibadan (IEF). Thus, findings from this study revealed that geographical location may influence the phenolic contents, antioxidant, and enzymes inhibitory properties of eggplant fruits. Practical applications The geographical location of a particular place determines the nature and biological activities of plants cultivated in the area. Hence, we presented the effect of location on the phenolic profile, antioxidant, and enzyme inhibitory properties of eggplant fruit (S. aethiopicum) cultivated in two different locations in Nigeria. However, data generated in this study showed the effect of location on phenolic composition and biological activities of eggplant fruit cultivated in Nigeria.

Most alkaloids are produced by plants as a defense mechanism against herbivores. Since alkaloids are known to possess pharmacological effects, this study sought to investigate the in vitro modulatory effect of alkaloid obtained from two commonly consumed vegetables in southern Nigeria, Lasianthera africana (editan) and Gongronema latifolium (utazi), on some enzyme activities relevant to neurodegeneration. Effects of the alkaloids on cholinesterases (acetylcholinesterase [AChE] and butyrylcholinesterase [BChE]) and monoamine oxidase (MAO) activities were determined in vitro. In addition, Fe²⁺ chelating ability as well as radical-scavenging abilities were determined. Alkaloid profile was also determined using gas chromatography coupled with flame ionization detector (GC-FID). The results revealed that the alkaloids inhibited AChE, BChE, and MAO activities in a concentration-dependent manner, such that the alkaloid from G. latifolium showed higher enzyme inhibition (AChE [IC₅₀ = 87.39 µg/ml], BChE [IC₅₀ = 118.65 µg/ml], and MAO [IC₅₀ = 61.37 µg/ml]) than L. africana (AChE = 115.60 µg/ml; BChE = 169.48 µg/ml; MAO = 73.72 µg/ml). In addition, GC-FID analysis revealed abundance of choline in both extracts. Gongronema latifolium and Lasianthera africana alkaloid extracts inhibit enzymes (acetylcholinesterase, butyrylcholinesterase, and monoamine oxidase) implicated in neurodegenerative diseases. Hence, these vegetables could offer dietary supplement in the management of neurodegenerative diseases.