Inhibitory effect of polyphenolic-rich extract from Cola nitida (Kolanut) seed on key enzyme linked to type 2 diabetes and Fe(2+) induced lipid peroxidation in rat pancreas in vitro

Potential molecular mechanisms underlying the ameliorative effect of Cola nitida (Vent.) Schott & Endl. on insulin resistance in rat skeletal muscles

ETHNOPHARMACOLOGICAL RELEVANCE

Cola nitida (Vent.) Schott & Endl. are among the common medicinal plants employed in traditional medicine for treating diabetes and its complications.

AIM OF THE STUDY

The present study investigated the effect of Cola nitida infusion on the expression of key genes involved in insulin signaling vis-à-vis Insulin receptor substrate 1 (IRS-1), tumor protein P53 gene, glucose transporter type 4 (GLUT4), phosphoinositide 3-kinases (PI3K) and B-cell lymphoma-2 (BCL2) in skeletal muscles of type 2 diabetic (T2D) rats.

METHODS

Type 2 diabetic rats were administered C. nitida infusion at low and high doses (150 and 300 mg/kg bodyweight, respectively), while a high dose of the infusion was also administered to a normal toxicological group. Metformin served as the standard antidiabetic drug. The rats were sacrificed at the end of the experimental period. Their psoas muscles were harvested and assayed for the expressions of IRS1, p53, GLUT4, PI3K and BCL2. The studied genes were further subjected to enrichment analysis using the ShinyGO 0.76 online software.

RESULTS

Induction of T2D upregulated the expressions of IRS-1, p53, PI3K and BCL2 in psoas muscles, while concomitantly downregulating GLUT4 expression. These expressions were significantly reversed in type 2 diabetic rats treated with C. nitida infusion, and the results were statistically significant compared to metformin. Gene enrichment analysis revealed that the genes were linked to intrinsic pathways and biological processes involved in insulin resistance. The infusion further improved muscle glucose uptake, ex vivo. Molecular docking and molecular dynamics stimulation of C. nitida infusion phytoconstituents, caffeine and theobromine with IRS-1, p53, GLUT4, PI3K and BCL2 revealed a strong binding affinity as evident by the RMSD and RMSF values.

CONCLUSION

These results indicate the potentials of C. nitida infusion to improve glucose homeostasis in skeletal muscles of type 2 diabetic rats.

Optimisation of microwave-assisted extraction and functional elucidation of bioactive compounds from Cola nitida pod

INTRODUCTION

The quality characteristics and stability of phenolic by-products from Cola nitida wastes are critical factors for drug formulation and food nutraceutical applications.

OBJECTIVES

In this study, the effect of electromagnetic-based microwave-reflux extraction on the total phenolic content, antioxidant capacity, morphological characteristics, physisorption and chromatographic phenolic profiles were successfully investigated. These physicochemical analyses are often employed in the standardisation of dried herbal and food nutraceutical products.

MATERIAL AND METHODS

In this study, the electromagnetic-based extraction process was optimised using the Box-Behnken design. The oleoresin bio-products were subsequently characterised to determine the total phenolic content, morphological and microstructural degradation. These analyses were conducted to elucidate the effect of the microwave heating on the C. nitida pod powder.

RESULTS

From the predicted response, the optimal percentage yield was achieved at 26.20% under 5.39 min of irradiation time, 440 W microwave power and oven temperature of 55°C. Moreover, the rapid estimation of the phenolic content and antioxidant capacity were recorded at 124.84 ± 0.064 mg gallic acid equivalent (GAE)/g dry weight (d.w.) and 6.93 ± 0.34 μg/mL, respectively. The physicochemical characterisation results from the Fourier-transform infrared spectroscopy, field emission scanning electron microscopy and physisorption analyses showed remarkable changes in the micro-surface area (13.66%) characteristics.

CONCLUSION

The recorded optimal conditions established a basis for future scale-up of microwave extraction parameters with a potential for maximum yield. The physiochemical characterisation revealed the functional characteristics of C. nitida and their tolerance to microwave heating.

Multifunctional titanium dioxide nanoparticles biofabricated via phytosynthetic route using extracts of Cola nitida: antimicrobial, dye degradation, antioxidant and anticoagulant activities

First study of phytosynthesis of TiO₂ NPs using the leaf (KL), pod (KP), seed (KS) and seed shell (KSS) extracts of kola nut tree (Cola nitida) is herein reported. The TiO₂ NPs were characterized and evaluated for their antimicrobial, dye degradation, antioxidant and anticoagulant activities. The nearly spherical-shaped particles had λmax of 272.5–275.0 nm with size range of 25.00–191.41 nm. FTIR analysis displayed prominent peaks at 3446.79, 1639.49 and 1382.96 cm⁻¹, indicating the involvement of phenolic compounds and proteins in the phytosynthesis of TiO₂ NPs. Both SAED and XRD showed bioformation of crystalline anatase TiO₂ NPs which inhibited multidrug-drug resistant bacteria and toxigenic fungi. The catalytic activities of the particles were profound, with degradation of malachite green by 83.48–86.28 % without exposure to UV-irradiation, scavenging of DPPH and H₂O₂by 51.19–60.08 %, and 78.45–99.23 % respectively. The particles as well prevented the coagulation of human blood. In addition to the antimicrobial and dye-degrading activities, we report for the first time the H₂O₂ scavenging and anticoagulant activities of TiO₂ NPs, showing that the particles can be useful for catalytic and biomedical applications.

The antidiabetic properties of the hot water extract of kola nut (Cola nitida (Vent.) Schott & Endl.) in type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cola nitida is amongst the evergreen plants native to West Africa used in the treatment of various ailments including diabetes.

AIM OF THE STUDY

This study aims to investigate the antidiabetic effects of the hot water extract of C. nitida seeds in type 2 diabetic rats.

METHODS

Type 2 diabetic rats were orally administered with low (150 mg/kg bw) and high (300 mg/kg bw) doses of the hot water extract for 6 wk and thereafter, blood glucose, insulin level, lipid profile, pancreatic β-cell function, perfusion and morphology, redox imbalance, glycolytic and cholinergic enzymes, as well as of caspase-3 and Nrf2 expressions were measured.

RESULTS

Treatment with the extract led to significant depletion of blood glucose, serum triglycerides, LDL-cholesterol, fructosamine, ALT, and uric acids, while elevating serum insulin and HDL-cholesterol levels. The infusion also significantly (p < 0.05) elevated GSH level, SOD, catalase, α-amylase, and ATPase activities, with concomitant depletion of myeloperoxidase enzyme activity, and NO and MDA levels in the serum and pancreas. Significantly (p < 0.05) improved pancreatic β-cell function and morphology were observed in rats treated with C. nitida, with restored pancreatic capillary networks. C. nitida inhibited the activities of glycogen phosphorylase, fructose 1,6 biphosphatase, glucose 6 phosphatase, and acetylcholinesterase while downregulated the Nrf2 expression. NMR analysis of the extract revealed the presence of caffeine and theobromine. The molecular docking studies indicated that identified compounds displayed strong molecular interactions with caspase-3 and Nrf2.

CONCLUSION

These results insinuate the antidiabetic activities of C. nitida hot water extract and may be attributed to the NMR-identified compounds.

Hyperglycemia-induced oxidative brain injury: Therapeutic effects of Cola nitida infusion against redox imbalance, cerebellar neuronal insults, and upregulated Nrf2 expression in type 2 diabetic rats

The therapeutic effect of the hot water infusion of Cola nitida against hyperglycemia-induced neurotoxicity, cerebellar neurodegeneration and elemental deregulations was investigated in fructose-streptozotocin induced rat model of type 2 diabetes (T2D). A diabetic group was administered drinking water, two other diabetic groups were treated with C. nitida at 150 and 300 mg/kg bodyweight respectively, while another group was administered metformin (200 mg/kg bodyweight). Two other groups consisting of normal rats, were administered drinking water and C. nitida (300 mg/kg bodyweight). After 6 weeks of treatment, their brains were collected. Treatment with C. nitida led to suppression of oxidative stress, significantly elevating reduced glutathione (GSH) levels, superoxide dismutase and catalase activities, concomitant with depletion of malondialdehyde (MDA) levels. Acetylcholinesterase and ATPase activities were significantly inhibited in C. nitida-treated diabetic rats. Histological and microscopic analysis also revealed a restorative effect of C. nitida on T2D-altered distribution of elements, neurons and axonal nodes. Treatment with C. nitida also led to significant inhibition of Nrf2 expression in the cerebellar cortex. These results suggest the therapeutic effects of C. nitida in maintenance of the neuronal integrity and antioxidant status of the brain in T2D. These neuroprotective activities can be attributed to the identified alkaloid, caffeine in the infusion.

Effects of acetone extract of Cola nitida on brain sodium-potassium adenosine triphosphatase activity and spatial memory in healthy and streptozotocin-induced diabetic female Wistar rats

Background This study was carried out to investigate the effects of acetone extract of Cola nitida on brain Na+/K+-ATPase activity and spatial memory of healthy and streptozotocin (STZ)-induced diabetic female Wistar rats. Methods Forty-two female Wistar rats were used for this study and were randomly distributed into six groups (n=7). Rats in group 1 were used as control and were administered normal saline; group 2 rats were healthy rats administered 50 mg/kg of kola nut extract per day; group 3 rats were healthy rats administered 100 mg/kg of kola nut extract per day; group 4 rats were a diabetic group also administered normal saline; group 5 rats were diabetic rats administered 50 mg/kg of kola nut extract per day; and group 6 rats were diabetic rats administered 100 mg/kg of kola nut extract per day. Diabetes was induced with 50 mg/kg of STZ. After 3 weeks of administration, the spatial memories of the rats were tested using the Y-maze, followed by assay of Na+/K+-ATPase activity. Results The result shows a significant increase in Na+/K+-ATPase activity of diabetic treated groups (5 and 6) when compared with the diabetic group (4) and a significant increase in Na+/K+-ATPase activity of healthy treated groups (2 and 3) when compared with control. Also, there was a significant increase in spatial memory of the diabetic treated groups when compared with diabetic group. Conclusions This study revealed that kola nut extract has restorative effect on brain Na+/K+-ATPase activities and spatial memory of STZ-induced diabetic female Wistar rats.