Vitamin D supplementation improves insulin resistance in type 2 diabetes subjects in Lagos, Nigeria

Type 2 diabetes is a disease caused by both insulin resistance and an insulin secretory defect. Reports suggest that vitamin D3 supplementation improves insulin resistance and pancreatic beta-cell function, but there is paucity of data on vitamin D and glycaemia in type 2 diabetes in Nigeria. We have therefore performed a single blind prospective randomised placebo-controlled trial, involving type 2 diabetes participants in Lagos, Nigeria. The participants consisted of 42 type 2 diabetes patients with vitamin D deficiency. These participants were randomised into two equal groups of treatment and a placebo arm. Vitamin D3(3000 IU daily) was given to the participants in the treatment arm. Insulin resistance (HOMA-IR) and pancreatic beta-cell (HOMA-B) function were determined at baseline and after 12 weeks of vitamin D3 supplementation, or placebo treatment. There was a reduction from baseline in the mean insulin resistance level in both the treatment and placebo groups. How-ever, this reduction was only statistically significant in the treatment group (p <0.01). The proportion of subjects with improvement in insulin resistance status (homeostatic model assessment insulin resistance score (HOMA-IR)<2.0) was significantly higher in the treatment arm (p<0.05). There was a reduction in the mean insulin secretory capacity in the treatment group while it increased in the placebo group, though this difference was not statistically significant. We conclude that vitamin D3 supplementation results in a reduction in insulin resistance, but has no effect on pancreatic beta-cell function in type 2 diabetes

Phytochemical Screening and Free Radical Scavenging Activities of the Fruits and Leaves of Allanblackia floribunda Oliv (Guttiferae)

Purpose: To compare the phytochemical constituents in the leaves and fruits of Allanblackia floribunda and determine their free radical scavenging activity. Methods: The fruit and leaves of AF collected from the uncultivated farmlands of Okeigbo; Ondo State; Nigeria; were dried; milled and extracted with methanol. Phytochemical screening was carried out according to standard procedures. Free radical scavenging activity was determined by measuring the decrease in the visible absorbance of 2;2-diphenyl-1 -picrylhydrazyl (DPPH) on addition of the plant extract. The mean inhibitory concentration (IC50); which is the concentration of extract needed to decrease the initial absorbance of DPPH by 50was determined graphically. Total phenolic; flavonoids and proanthocyanidin contents were determined by spectro-photometric methods. Results: Alkaloids; anthraquinones; tannins; saponins; steroids; terpenoids; flavonoids and cardiac glycosides were found to be present in both the fruits and leaves. Only AF fruit contained phlobatannins. IC50 values of 0.01; 0.02 and 0.1 mg/ml were recorded for Vitamin E; AF leaves and AF fruits respectively. Total phenolic; total flavonoid and proanthocyanidin contents were 65; 0.07 and 2.38 mg/g of powdered plant material for AF fruits; and 12; 51.35; 19.5 mg/g of powdered plant material for AF leaves as gallic acid; rutin and catechin equivalents respectively. Conclusion: AF leaves are five times more potent as a free radical scavenger compared to the fruits though the fruit was found to contain a higher phenolic content

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 determi- ned. 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 50inhibition 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