Ighodaro Igbe

Hypoglycemic activity of aqueous seed extract of Hunteria umbellata in normal and streptozotocin-induced diabetic rats.

The present study evaluated the aqueous seed extract of Hunteria umbellata K. Schum (Apocynaceae) for hypoglycemic activity in rats. Diabetes was induced by a single dose of streptozotocin (50 mg/kg i.p.). Daily doses of 400, 800, and 1000 mg/kg of extract were orally administered to fasted normal and diabetic rats. Blood glucose levels were monitored after 0, 2, 4, 8, 12 h and on day 14 post treatment. Liver glycogen levels were also estimated on day 14. In normal rats, only 400 mg/kg of the extract produced a significant reduction in blood glucose at the 4 h (P < 0.05) which was 22.15 ± 4.88%. In diabetic rats, the extract, 400, 800 mg/kg, caused significant reduction (P < 0.01), 51.87% ± 5.79% and 43.47% ± 8.06% respectively, with maximum effect at 8 h. This reduction in blood glucose was greater than that of glibenclamide (31.03% ± 8.86%). Diabetic rats administered with 400 mg/kg extract produced a significant reduction (P < 0.01) on day 14 (43.60% ± 8.10%). Liver glycogen levels were significantly increased (P < 0.05) in diabetic rats administered with doses of 400 and 800 mg/kg extracts and these were comparable to glibenclamide. Acute toxicity data showed no mortality in mice up to 17.5 g/kg. We conclude that the extract possesses marked hypoglycemic effects in diabetic rats possibly through increased glycogenesis, thus justifying its use in herbal medicine for the treatment of diabetes.

The Effect of Leaf Aqueous Extract of Brachystegia eurycoma Harms (Fabaceae) in Acute and Chronic Inflammatory Animal Models

Aims: To investigate the effect of the leaf extract of Brachystegia eurycoma Harms (Leguminosae) in acute and chronic Inflammatory animal models. Study Design : Extraction and anti-inflammatory evaluation. Place and Duration of Study : Department of Pharmacology and Toxicology, Faculty of Pharmacy, University of Benin. Methodology: The anti-inflammatory effect of the aqueous leaf extract of B. eurycoma Harm (Leguminosae) was evaluated using the carrageenan- and dextran-induced rat paw edema, xylene-induced ear edema and formalin-induced arthritis inflammation test. Results: In the carrageenan-induced paw edema, B. eurycoma at 100 mg/kg significantly (P<0.001) inhibited paw edema within four hours (1‐4 h) The extract also produced significant inhibitory effects (P<0.05) at 200 mg/kg (1h and 4 h) and 400 mg/kg (2 h). B. eurycoma (100 mg/kg) produced a significant (P<0.01) inhibition of paw edema induced by dextran from 0 h and 4 th h and at the 5 th h (P<0.05) The extract (100 mg/kg) produced a significant inhibition (41.84 %, p<0.05) in the xylene induced ear edema model but in chronic inflammation (formalin induced arthritis) did not show any significant antiinflammatory activity after seven (7) days. Oral acute toxicity assays did not show any

Effects of Leaf Extracts of Piliostigma thonningii Schum on Aortic Ring Contractility and Bleeding Time in Rats

The leaves of Piliostigma thonningii Schum have been used in herbal medicine to treat inflammations, bacterial infections, and worm infestations and to arrest bleeding. In an investigation of the possible scientific basis for the use of P. thonningii as a hemostatic agent, the contractility of isolated rat aortic rings and wound bleeding times were measured after exposure of the tissues to aqueous and ethanol extracts of P. thonningii leaves. The extracts produced responses on the isolated aortic rings. The maximum contractile response produced by 32 mg mL−1 of the aqueous extract was 30.8% ± 1.6% of the contractile response produced by 1 μM phenylephrine. The ethanol extract was much less potent with 64 mg mL−1 producing only 12.3% ± 0.9% of the contractile response produced with the phenylephrine. In addition, the aqueous extract, but not the ethanol extract, significantly reduced bleeding time as compared with saline solution (p < .05) but was significantly less than the reduction produced with 0.1% epinephrine solution. The constriction of blood vessels may be the basis for P. thonningiis use as a hemostatic agent in traditional herbal medicine.

Role of GLUT4 on angiotensin 2-induced systemic and renal hemodynamics

Cross-talk between insulin and the renin angiotensin system signaling system shows that angiotensin 2 (A2) negatively modulates insulin signaling by stimulating multiple serine phosphorylation events in the early stages of the insulin-signaling cascade; however, the biological actions of A2 on insulin sensitivity remain controversial. Preservation of glucose transporter 4 (GLUT4) expression during hypertension has been shown to prevent the increased vascular reactivity associated with hypertension. This study tested the hypothesis that GLUT4 contributes to the renal actions of A2. In the euvolemic anesthetized rat, acute infusion of the GLUT4 antagonist, indinavir (1 mg/kg/minute), enhanced an A2-induced increase in mean arterial blood pressure (MABP) (P < 0.01), but attenuated an A2-induced increase in medullary blood flow (MBF) and glomerular filtration rate (P < 0.01). Insulin, a GLUT4 activator (20 mU/kg/minute and 40 mU/kg/minute), decreased basal MABP and urine volume (P < 0.05), but it increased MBF, and these effects were reversed and blunted by indinavir. Subchronic indinavir treatment (80 mg/kg/day orally for 15 days) did not affect A2-induced changes in MABP, cortical blood flow, and MBF, but significantly decreased basal MBF (P < 0.01) and global kidney perfusion (P < 0.05). We concluded that acute but not subchronic inhibition of GLUT4 alters A2-induced changes in systemic and renal hemodynamics by attenuating A2-induced increase in MBF and glomerular filtration rate.

Anti-inflammatory and Analgesic Effects of the Methanol Stem Bark Extract of Brachystegia eurycoma Harms (Fabaceae)

Aims: The aim of the study was to investigate the analgesic and anti-inflammatory activities of the methanol stem bark extract of Brachystegia eurycoma Harms. Place and Duration of Study: Department of Pharmacology and Toxicology, Faculty of Pharmacy, University of Benin. Methodology: Analgesic activity was examined using the hot plate and acetic acidinduced writhing test while acute anti-inflammatory effect was studied using carrageenan and dextran-induced paw edema. Results: Oral administration of the extract produced significant (P<0.01) antiedematogenic effect with a dose of 100 mg/kg within the 2 nd

Effect of caffeine on alcohol consumption and alcohol-induced conditioned place preference in rodents

Abstract Background The aim of the study was to determine the effect of caffeine on alcohol consumption with or without deprivation and alcohol-induced conditioned place preference. Methods In the present study, we examined the effects of caffeine (2.5, 5 and 10 mg/kg) on alcohol consumption in Wistar rats with or without periods of deprivation in an unlimited-access, two-bottle, free choice drinking procedure after a stable baseline alcohol consumption was established. Conditioned place preference (CPP) was established by intraperitoneal injections of alcohol (2 g/kg) in a 12-day conditioning schedule in mice. The effect of caffeine (3 mg/kg) on CPP expression was determined by a final post-conditioning test following 12 conditioning sessions with alcohol. The effect of caffeine (3 mg/kg) on the reinstatement of alcohol-induced CPP was determined in a final post-conditioning test following 12 conditioning sessions with alcohol and the extinction of alcohol-induced CPP. Results Alcohol deprivation for 3 days did not result in alcohol deprivation effect (ADE). While caffeine (10 mg/kg) caused a significant (p<0.05) reduction in alcohol consumption compared with the baseline following a period of alcohol deprivation, it did not cause a change in alcohol consumption compared with the baseline in the study without alcohol deprivation phase. Caffeine significantly (p<0.05) reduced the expression of alcohol-induced CPP compared to saline and blocked the reinstatement of alcohol-induced CPP following the injection of a priming dose (0.4 g/kg) of alcohol. Conclusions Given that caffeine is an adenosine receptor antagonist, our findings suggest a role for adenosine receptors in the alcohol reward and alcohol-seeking behaviour.

Antinociceptive and antioxidant activities of Hunteria umbellata stem bark: possible role of the serotonergic, opioidergic and dopaminergic pathways

Abstract Background Hunteria umbellata (HU) (K. Schum) is used in ethnomedicine for the management of pain, diabetes mellitus and dysmenorrhoea. This study evaluated the analgesic and antioxidant activities of aqueous extract of HU stem bark and the possible mechanism(s) of action. Methods The antinociceptive effect of HU was evaluated using acetic acid mouse writhing, tail flick, hot plate and formalin-induced paw licking models. To establish the possible mechanism(s) of action of HU, separate group of animals were pretreated with naloxone (1 mg/kg, i.p.), atropine (1 mg/kg, i.p.), haloperidol (0.1 mg/kg, i.p.), ondansetron (1 mg/kg, i.p.) and phenoxybenzamine (0.1 mg/kg, i.p.), 15 min before HU. The in vivo and in vitro antioxidant potential was evaluated using established methods. Results The extract at 150 and 300 mg/kg, significantly (p<0.05) reduced the number of writhes and paw licking times and increased pain threshold in writhing assay, paw licking and hotplate tests respectively. Pretreatment of animals with ondansetron, naloxone and haloperidol, significantly (p<0.05 and p<0.01) attenuated the analgesic activity of HU. The extract demonstrated significant (p<0.05) radical scavenging activity (IC50 0.39 µg/mL), with high phenol content and reducing property. The total phenol content was 124.19 per gram of gallic acid. In vivo antioxidant assay showed significant (p<0.05) increase in catalase and superoxide levels. Conclusions Results obtained in this study suggest the involvement of serotonergic, opioidergic and dopaminergic pathways in the analgesic effect of HU stem bark, in addition to its potent antioxidant potential.

Harnessing the medicinal properties of Cussonia barteri Seem. (Araliaceae) in drug development. A review

Summary Cussonia barteri Seem (Araliaceae) is a deciduous tree growing in savannah of Africa. Ethnomedicinally, it is used in Africa as an analgesic, anti-malarial, anti-inflammatory, anti-anaemic, anti-diarhoea, anti-poison, ani-pyschotic and anti-epileptic agent. This review provides a brief summary on the phytochemical screenings, ethnomedicinal and pharmacological applications of various parts of C. barteri. Leaves, stem bark and seed of C. barteri have been shown to be rich in saponins, flavonoids, phenols, sugars and alkaloids. Some of these constituents have been isolated and elucidated from C. barteri. Several compounds isolated from plant include triterpenes, saponins, polyenyne and quinic esters. Phytochemical constituents are also partly responsible for biological activities of C. barteri. Extracts and components isolated from the plant have demonstrated neuropharmacological, anti-larvicidal, anti-microbial, anti-inflammatory and antioxidant activities. Overall, the insights provided by this review reinforce the potential of C. barteri for drug development and create the need for further scientific probe of constituents of the plant with the aim of developing novel drug candidates.