Dorcas Bolanle James

Oxidative Stress and Carcinogenesis: Potential of Phytochemicals in Breast Cancer Therapy

ABSTRACT Breast cancer remains a burden in both developed and developing countries, with higher mortality in developing countries. Attempts to eradicate cancer have not been successful despite the progress made in the development of more novel chemotherapeutic drugs. Reactive-oxygen-species-mediated oxidative stress is known to play a role in breast cancer pathogenesis via genetic and epigenetic modifications, resulting in uncontrolled cell proliferation. Phytochemicals could provide leads for the development of alternative therapeutic agents due to their antioxidant activity, as well as their ability to induce apoptosis in cancer cells. However, most of the studies carried out using in vitro models do not continue with further studies in estrogen-receptor-positive in vivo breast cancer models, or fail to examine the possible biochemical mechanisms of phytochemical-based amelioration. This review examines oxidative-stress-mediated carcinogenesis and the potential of phytochemicals as anticancer agents.

Evaluation of extraction protocols for anti-diabetic phytochemical substances from medicinal plants

AIM To examine the efficacy of three extraction techniques: Soxhlet-extraction (SE), cold-maceration (CM) and microwave-assisted-extraction (MAE) using 80% methanol as solvent. METHODS The study was performed on each of 50 g of Vernonia amygdalina (VA) and Occimum gratissimum (OG) leaves respectively. The percentage yield, duration of extraction, volume of solvent used, qualitative and quantitative phytoconstituents present was compared. The biological activities (hypoglycemic effect) were investigated using albino wistar rat model of diabetes mellitus (n = 36) with a combined dose (1:1) of the two plants leaf extracts (250 mg/kg b.w.) from the three methods. The extracts were administered orally, once daily for 21 d. RESULTS In this report, the percentage VA extract yield from MAE was highest (20.9% ± 1.05%) within 39 min using 250 mL of solvent, when compared to the CM (14.35% ± 0.28%) within 4320 min using 900 mL of solvent and SE (15.75% ± 0.71%) within 265 min using 500 mL of solvent. The percentage differences in OG extract yield between: MAE vs SE was 41.05%; MAE vs CM was 46.81% and SE vs CM was 9.77%. The qualitative chemical analysis of the two plants showed no difference in the various phytoconstituents tested, but differs quantitatively in the amount of the individual phytoconstituents, as MAE had significantly high yield (P > 0.05) on phenolics, saponins and tannins. SE technique gave significantly high yield (P > 0.05) on alkaloid, while CM gave significant high yield on flavonoids. The extracts from CM exhibited a significantly (P > 0.05) better hypoglycemic activity within the first 14-d of treatment (43.3% ± 3.62%) when compared to MAE (36.5% ± 0.08%) and SE methods (33.3% ± 1.60%). However, the percentage hypoglycemic activity, 21 d post-treatment with 250 mg/kg b.w. extract from MAE was 72.6% ± 1.03% and it was more comparable to 10 mg/kg b.w. glibenclamide treated group (75.0% ± 0.73%), unlike the SE (69.5% ± 0.71%) and CM (69.1% ± 1.03%). CONCLUSION CM technique produces extract with better hypoglycemic activity, whereas; MAE is a better option for high yield of phytoconstituents using less solvent within a short time.

Appropriate Insulin Level in Selecting Fortified Diet-Fed, Streptozotocin-Treated Rat Model of Type 2 Diabetes for Anti-Diabetic Studies

Background Pathophysiological investigation of disease in a suitable animal model is a classical approach towards development of a credible therapeutic strategy. This study examined appropriate insulin level in selecting animal model for type 2 diabetes (T2D) studies. Method Albino Wistar rats (150-200g) were divided into two groups fed with commercially available normal-diet-feed (NDF) and water or fortified diet feed (FDF) (10g NDF per gram of margarine) with 20% fructose solution as drinking water. After 6 weeks of dietary regimen both groups were divided into 5 sub-groups and injected intraperitoneally with a graded dose of streptozotocin (STZ) (0, 25, 35, 45 & 55mg/kg bw.). Result The result showed that the FDF-fed rats increased significantly in body weight, basal serum insulin, total cholesterol, triglycerides and blood glucose levels as compared to NDF-fed rats. Ten days post STZ induction, the groups treated with STZ (45 & 55 mg/kg) developed frank hyperglycaemia with < 46.8% serum insulin, a severe deficiency typical of diabetes type 1. The NDF25 and NDF35 groups with 75.7% and 64.4% serum insulin respectively presented relative normoglycemia, whereas the FDF35 (85.8% serum insulin) were notably hyperglycaemia (>300 mg/dL) throughout the 6weeks post diabetes confirmation. These FDF35 rats were sensitive to glibenclamide, metformin and pioglitazone in lowering hyperglycaemia, hypertriglyceridemia and hypercholesterolemia Conclusion The hyperglycaemia stability of the FDF35 rats (85.5% insulin) together with their sensitivity to 3 different hypoglycaemic drugs strongly suggests their suitability as a non-genetic model of T2D. Hence the study shows that circulating serum insulin ≥ 85.8% with overt hyperglycaemia may be utilized as the benchmark in selecting rat models for T2D studies.

Anti-Diabetic Potential of Ocimum gratissimum Leaf Fractions in Fortified Diet-Fed Streptozotocin Treated Rat Model of Type-2 Diabetes

Background: Ocimum gratissimum (OG) is used in the traditional management of diabetes in Nigeria. This study investigated the anti-diabetic potential of OG leaf fractions (OGLF) in a rat model of Type-2 diabetes (T2D). Methods: Methanol crude extract of OG leaf was fractionated with solvents of increasing order of polarity (n-hexane, chloroform, ethyl-acetate, n-butanol and water). The anti-diabetic potential of the fractions was evaluated in vivo. T2D was induced in Albino Wistar rats and treated with OGLF. Results: The T2D rats showed significant elevation in serum levels of fasting blood glucose (FBG), liver and kidney function biomarkers. At 4-week of intervention with OGLF, the untreated diabetic control group maintained severe hyperglycaemia in the presence of 61.7% serum insulin, 17.3% pancreatic β-cell function (HOMA-β) and 51.5% Insulin sensitivity. The glucose tolerance ability was enhanced in the n-butanol-fraction (OGb) treated group. With 74.8% available serum insulin and 38.6% improvement in insulin sensitivity, the OGb treated group had a 63.5% reduction in FBG and it was found to be most effective as it ameliorates a majority of the changes caused in the studied parameters in diabetic rats. Conclusions: The data from this study suggest that OGb fraction is a potential candidate for the development of an effective drug for the management of T2D.

Preventive and Therapeutic Effects of Garcinia kola Biflavonoid Fractions on some Haematological Parameters of P407 Induced Hyperlipidemic Albino Rats

The preventive and therapeutic effects of Garcinia kola biflavonoid fractions on some haematological parameters in Poloxamer 407 (P407) induced hyperlipidemic rats was studied for a period of 21 days. Sixty mixed sex Wistar rats weighing 150-200 g were divided into two major groups; Preventive group comprising the following sub-groups: normal control, P407 induced hyperlipidemic control and groups treated orally with atorvastatin as standard drug, root bark, stem bark and seed biflavonoid fractions of Garcinia kola respectively for 19 days and made hyperlipidemic with a single intraperitoneal injection on day 19. Therapeutic group comprising similar subgroups were induced by an intraperitoneal injection of P407 every 48 hours and treated with atorvastatin, root bark, stem bark and seed biflavonoid fractions for 21 days. In both groups, atorvastatin, P407 and the Garcinia kola biflavonoid fractions were administered at 10 mg/kg, 500 mg/kg and 200 mg/kg body weight respectively. Blood samples were collected from the rats in all the groups at the end of the experiment for determination of some haematological parameters levels; Packed Cell Volume (PCV), Platelet, neutrophils, lymphocytes, Haemoglobin (Hb), Mean Corpuscular Haemoglobin (MCH), Mean Corpuscular Haemoglobin Concentration (MCHC), Mean Corpuscular Volume (MCV), Red Blood Cell (RBC) Count and White Blood Cell (WBC) Count were determined using the Sysmex Haematological Autoanalyzer. In both groups, atorvastatin and all biflavonoid fractions significantly (p 0.05) change on the level of neutrophils compared to hyperlipidemic control. The seed biflavonoid fraction significantly (p 0.05) change in the levels of the other determined haematological parameters in both groups. These results suggest that Garcinia kola (root bark, stem bark and seed) biflavonoid fractions could be potential drugs for the prevention and treatment of platelet-activity thrombosis as well as erythropoietic, protective and stimulating effect.