Daniel U. Owu

Serum liver enzymes profile of Wistar rats following chronic consumption of fresh or oxidized palm oil diets

The effect of chronic consumption of palm oil diets on serum levels of some liver enzymes in rat was investigated. Two groups of rats were fed on either fresh or thermally oxidized palm oil, mixed at 15% level for 18 weeks and their effects on serum levels of alkaline phosphatase (EC 3.1.3.1), aspartate aminotransferase (EC 2.6.1.1) and alanine aminotransferase (EC 2.6.1.2) enzymes were compared with a control group receiving normal rat feed. The levels of alkaline phosphatase (ALP) in the two groups were significantly higher (P < 0.05-0.01) than control. Mean ALP levels were significantly different in the two test groups (P < 0.05). Similarly, there was significant elevation (P < 0.05-0.01) of aspartate aminotransferase (AST) levels in oxidized oil-fed and fresh oil-fed groups when compared with the control. The mean alanine aminotransferase (ALT) level was significantly higher (P < 0.01) in the oxidized oil-fed group than the control and fresh oil-fed groups. The results indicate that chronic consumption of thermoxidized palm oil, with its accompanying hazardous free radicals, may be more injurious to liver cell integrity than fresh palm oil.

Influence of palm oil ( Elaesis guineensis) on health

In recent times there has been a growing research interest in palm oil, one of the major edible plant oils in the tropical countries, because of the link between dietary fats and coronary heart disease. Obtained from a tropical plant, Elaesis guineensis, it has a polyunsaturated fatty acid/saturated fatty acid ratio close to unity and a high amount of antioxidant vitamin A precursors and vitamin E. Palm oil is consumed in the fresh state and/or at various levels of oxidation. Feeding experiments in various animal species and humans have highlighted the beneficial role of fresh palm oil to health. These benefits include reduction in the risk of arterial thrombosis and atherosclerosis, inhibition of cholesterol biosynthesis and platelet aggregation, and reduction in blood pressure. However, a considerable amount of the commonly used palm oil is in the oxidized state which possesses potential dangers to the physiological and biochemical functions of the body. Oxidation is as a result of processing the oil for various culinary purposes. Studies have revealed that relative to fresh palm oil, oxidized palm oil induces an adverse plasma lipid profile, free fatty acids, phospholipids and cerebrosides. Additionally, oxidized palm oil induces reproductive toxicity and organotoxicity particularly of the kidneys, lungs, liver and heart. Available evidence suggests that at least part of the oxidized oil impact on health reflects generation of toxicants due to oxidation. The reduction of the dietary level of oxidized oil and/or the level of oxidation may reduce the health risk associated with consumption of oxidized fats.

Vitamin C improves basal metabolic rate and lipid profile in alloxan-induced diabetes mellitus in rats.

Diabetes mellitus (DM) is a multi-factorial disease which is characterized by hyperglycaemia, lipoprotein abnormalities and oxidative stress. This study evaluated effect of oral vitamin C administration on basal metabolic rate and lipid profile of alloxan-induced diabetic rats. Vitamin C was administered at 200 mg/kg body wt. by gavage for four weeks to diabetic rats after which the resting metabolic rate and plasma lipid profile was determined. The results showed that vitamin C administration significantly (P<0.01) reduced the resting metabolic rate in diabetic rats; and also lowered plasma triglyceride, total cholesterol and low-density lipoprotein cholesterol. These results suggest that the administration of vitamin C in this model of established diabetes mellitus might be beneficial for the restoration of basal metabolic rate and improvement of lipid profile. This may at least in part reduce the risk of cardiovascular events seen in diabetes mellitus.

Comparative study on the efficacy of Allium sativum (garlic) in reducing some heavy metal accumulation in liver of wistar rats.

SCOPE Heavy metals are known to cause damage through indirect oxidative effects. This study was undertaken to compare the therapeutic efficacy and protective ability of garlic extracts on reducing toxicity induced by mercury, lead and cadmium in the liver. METHODS AND RESULTS Rats were fed with rat chow mixed with raw garlic (7% w/w) while mercury (10ppm), cadmium (200ppm) and lead (100ppm) were given in drinking water. Garlic was administered either at the same time with the metals (group 2), a week after exposure to heavy metals (group 3) or a week before heavy metal exposure (group 4) for 6weeks. The heavy metal accumulations in the liver were determined using AAS. The percentage protection showed a time-dependent effect and was significantly (P<0.01) higher for cadmium compared to mercury and lead-treated groups. Analysis between the groups showed that garlic treatment after exposure had a significantly (P<0.05) higher percentage protection when compared with other modes. CONCLUSION These results suggest that garlic offered more hepatoprotective effect to cadmium followed by mercury and least protection to lead at the selected dose of each metal in this study through the processes of uptake, assimilation and elimination of these metals.

Possible mechanisms of action of the aqueous extract of Artocarpus altilis (breadfruit) leaves in producing hypotension in normotensive Sprague-Dawley rats.

Context and objectives: Artocarpus altilis (Parkinson) Fosberg (Moraceae) (breadfruit) leaves are used as an antihypertensive remedy. We investigated the possible mechanisms of action of its aqueous extract and its effect on cytochromes P450 (CYP) enzyme activities. Materials and methods: Intravenous administration of an aqueous leaf extract (20.88–146.18 mg/kg) of A. altilis on mean arterial pressure and heart rate were recorded via cannulation of the carotid artery on anaesthetized normotensive Sprague–Dawley rats. Recordings of the contractile activity of the aortic rings to the extract (0.71–4.26 mg/mL) were studied using standard organ bath techniques. Inhibitions of human CYP3A4 and CYP2D6 enzyme activities were evaluated by means of a fluorometric assay in 96 well plates using heterologously expressed microsomes. Results: A. altilis caused significant (p < 0.05) hypotensive and bradycardiac responses unaffected by atropine (2 mg/kg) and mepyramine (5 mg/kg), but attenuated by propranolol (1 mg/kg) and N(G)-nitro-l-arginine methyl ester (5 mg/kg). The extract (0.71–4.26 mg/mL) significantly (p < 0.05) relaxed phenylephrine (10−9–10−4 M) and 80 mM KCl-induced contractions in endothelium intact and denuded aortic rings; and caused a significant (p < 0.05) rightward shift of the Ca2+ dose-response curves in Ca2+-free Kreb’s solution. Moderate inhibitions of cytochrome P450s (CYP3A4 and CYP2D6) enzyme activities with IC50 values of 0.695 ± 0.187 and 0.512 ± 0.131 mg/mL, respectively, were produced. Conclusion: A. altilis exhibits negative chronotropic and hypotensive effects through α-adrenoceptor and Ca2+ channel antagonism. Drug adversity effects are unlikely if the aqueous leaf extract is consumed with other medications reliant on CYP3A4 and CYP2D6 metabolism. This study thus provides scientific evidence for the use of the breadfruit in the treatment of hypertension.

Comparative study on the efficacy of Garcinia kola in reducing some heavy metal accumulation in liver of Wistar rats.

Garcinia kola is regarded as an antidote and anti-hepatotoxic agent. We examined its protection ability against mercury (Hg), lead (Pb) and cadmium (Cd) accumulation in the liver. The ground seed was mixed with rat feed (5%, w/w) and fed to rats while Hg (10 ppm), Cd (200 ppm) and Pb (100 ppm) was given in drinking water. Garcinia kola was administered either at the same time with the metals (group 2), a week after exposure to heavy metals (group 3) or given a week before heavy metal exposure (group 4) for six weeks. The heavy metal accumulations in the liver were determined using AAS. Garcinia kola could not reverse the weight reduction in the heavy metal exposed groups although it offers more protection and aid greater elimination of heavy metals from the liver. There was a significant (P<0.01) increase in protection by Garcinia kola to Cd (72.4%) and Pb (56.2%) accumulation when compared to Hg (40%) at week 2 which was significantly (P<0.01) decreased at week 4 when compared to week 2. At week 6, the percentage protection to both Hg (64.2%) and Cd (62.2%) were comparable to each other while protection to Pb (49.9%) accumulation was significantly (P<0.01) reduced. The percentage protection was time-dependent in some groups but treatment during and after the exposure provided a greater protection. Garcinia kola has the highest hepatoprotective effect to Cd followed by Hg and least protection against Pb toxicity in rats and its administration is beneficial in reducing heavy metal accumulation in the liver.

Comparative analysis on the effect of Lycopersicon esculentum (tomato) in reducing cadmium, mercury and lead accumulation in liver

SCOPE L. esculentum (tomato) contain compounds with anti-oxidant and anti-inflammatory properties, able to synthesize metal chelating proteins. We examined the ability of fruit extract to protect against mercury (Hg), lead (Pb) and cadmium (Cd) accumulation in the liver. METHODS AND RESULTS Rats were fed on tomato mixed with rat chow (10% w/w), while Hg (10 ppm), Cd (200 ppm) and Pb (100 ppm) was given in drinking water. Tomato was administered together with the metals (group 2), a week after exposure (group 3) or a week before metal exposure (group 4) for a period of six weeks. The metal accumulations in the liver were determined using AAS. There was a significant (P<0.05) increase in protection by tomato to Cd and Hg accumulation but not to Pb (P<0.05) in weeks 2 and 4 for groups 2 and 3. The protective ability was significantly (P<0.05) increased for Pb in group 4, but was less comparable to Cd and Hg. CONCLUSION Tomato reduces uptake while enhancing the elimination of these metals in a time dependent manner. The highest hepatoprotective effect was to Cd followed by Hg and least to Pb. Its administration is beneficial in reducing heavy metal accumulation in the liver.

Possible mechanisms of action of the hypotensive effect of Annona muricata (soursop) in normotensive Sprague–Dawley rats

Context: Annona muricata Linn (Annonaceae) (soursop) is a food plant reported to have antihypertensive properties. Objective: We investigated the blood pressure reducing effect of its aqueous leaf extract and the possible mechanisms that may be responsible. Methods: Intravenous administration of an aqueous leaf extract (9.17–48.5 mg/kg) of A. muricata on the mean arterial pressure and heart rate were recorded invasively on anaesthetized, normotensive Sprague–Dawley rats. Contractile responses of rat aortic rings to the extract (0.5–4.0 mg/mL) were studied using standard organ bath techniques. Results: A. muricata (9.17–48.5 mg/kg) caused significant (p < 0.05) dose-dependent reduction in blood pressure without affecting the heart rates. The hypotensive effects were unaffected by atropine (2 mg/kg), mepyramine (5 mg/kg), propranolol (1 mg/kg) and L-NAME (5 mg/kg). A. muricata leaf aqueous extract significantly (p < 0.05) relaxed phenylephrine (10−9–10−4 M) and 80 mM KCl induced contractions in endothelium intact and denuded aortic rings; and caused a significant (p < 0.05) rightward shift of the Ca2+ dose response curves in Ca2+-free Kreb’s solution containing 0.1 mM EGTA. Conclusions: The hypotensive effects of A. muricata are not mediated through muscarinic, histaminergic, adrenergic and nitric oxide pathways, but through peripheral mechanisms involving antagonism of Ca2+.

Intestinal Fluid and Glucose Transport in Wistar Rats following Chronic Consumption of Fresh or Oxidised Palm Oil Diet

Chronic ingestion of thermoxidized palm oil causes functional derangement of various tissues. This study was therefore carried out to determine the effect of chronic ingestion of thermoxidized and fresh palm oil diets on intestinal fluid and glucose absorption in rats using the everted sac technique. Thirty Wistar rats were divided into three groups of 10 rats per group. The first group was the control and was fed on normal rat chow while the second (FPO) and third groups (TPO) were fed diet containing either fresh or thermoxidized palm oil (15% wt/wt) for 14 weeks. Villus height and crypt depth were measured. The gut fluid uptake and gut glucose uptake were significantly (P < .001) lower in the TPO group than those in the FPO and control groups, respectively. The villus height in the TPO was significantly (P < .01) lower than that in FPO and control. The villus depth in TPO was significantly (P < .05) higher than that in FPO and control groups, respectively. These results suggest that ingestion of thermoxidized palm oil and not fresh palm oil may lead to distortion in villus morphology with a concomitant malabsorption of fluid and glucose in rats due to its harmful free radicals.

In vivo distribution of lead in male and female rats after intraperitoneal and oral administration

The resultant effects of lead exposure are seen in almost all the systems of the body and results in toxicity to many organs. Since toxicity depends on its degree of uptake, distribution and metabolism, the authors investigated the differential uptake, accumulation and distribution of lead in organs of males and female Wistar rats following various routes of administration. Group 1 served as control male and control female; group 2 males and females received 5 mg/kg body weight of lead intraperitoneally for 8 days while group 3 males and female rats were administered drinking water containing 100 ppm of lead acetate for 18 days. Tissues were collected for analysis of the lead content using atomic absorption spectroscopy. The relative retention of lead by the tissues was greater in rats exposed to lead by the i.p. route varying in the order of accumulation / uptake in males as lungs > spleen > stomach > kidney > blood > heart and in females as spleen > stomach > heart > kidney > blood > lungs (i.p. route) and (oral route) as for males kidney > lungs > stomach > blood > heart > spleen, and females as kidney > lungs > stomach > blood > heart > spleen. Male Wistar rats showed more accumulation with oral exposure in lungs, spleen and blood with values for kidney and stomach being significantly (p < 0.05) higher when compared with females. Female Wistar rats showed more accumulation with i.p. exposure for spleen and stomach tissues while values for the heart was significantly (p < 0.05) higher than the males. Our findings suggest that lead retention and the organ distribution varied depending upon the sex and route of lead administration.