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Antioxidant versus anti-diabetic properties of leaves from Vernonia amygdalina Del. growing in Malaysia

Atangwho IJ, Egbung GE, Ahmad M, Yam MF, Asmawi MZ

Food Chem, 2013 Dec 15;141(4):3428-34.
PMID: 23993503 DOI: 10.1016/j.foodchem.2013.06.047

The antioxidant and anti-diabetic properties of the sequential extracts of Vernonia amygdalina based on the chemical composition of the most effective anti-diabetic extract were studied. Using DPPH and ABTS radical scavenging as well as FRAP assays, the extracts showed a consistent dose-dependent trend of potent antioxidant activity in the following solvents: water extract>methanol extract>chloroform extract>and petroleum ether extracts. In the oral glucose tolerance test, the chloroform extract exerted the highest response (33.3%), similar to metformin (27.2%), after 2h compared to the control (50.8%, P<0.05). After a 14-day administration in diabetic rats, the chloroform extract recorded the highest blood (23.5%) and serum (21.4%) glucose-lowering effects (P<0.05). GC-MS analysis of the chloroform extract revealed high levels of linoleic acid (4.72%), α-linolenic acid (10.8%) and phytols (12.0%), as well as other compounds.
Hyptis verticillata attenuates dyslipidaemia, oxidative stress and hepato-renal damage in streptozotocin-induced diabetic rats

Ogar I, Egbung GE, Nna VU, Atangwho IJ, Itam EH

Life Sci, 2019 Feb 15;219:283-293.
PMID: 30668955 DOI: 10.1016/j.lfs.2019.01.027

AIMS: Chronic hyperglycaemia in diabetes mellitus (DM) increases the production of free radicals which results in oxidative stress and related disorders such as cardiovascular diseases, compromised hepatic and renal functions. Hyptis verticillata reportedly demonstrated glucose lowering activity in previous studies. The present study therefore evaluated the effect of H. verticillata on hyperglycaemia-induced dyslipidaemia, hepatorenal distortions, oxidative stress, as well as calculated indices of cardiovascular function.
METHODS: Wistar rats employed for this study consisted of normoglycaemic and diabetic rats in nine experimental groups. The normoglycaemic and diabetic rats were either treated with metformin (500 mg/kg b.w.), quercetin (10 mg/kg b.w.), or ethanol extract of H. verticillata leaf (250 mg/kg b.w. and 500 mg/kg b.w.) administered orally for 28 days.
KEY FINDINGS: Results revealed that H. verticillata significantly lowered blood glucose level, attenuated dyslipidaemia, decreased atherogenic coefficient, atherogenic and coronary risk indices, and increased cardioprotective index in diabetic rats. Also, H. verticillata significantly decreased serum urea, creatinine, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and unconjugated bilirubin levels, relative to untreated diabetic rats. Further, H. verticillata increased serum superoxide dismutase, catalase and glutathione peroxidase activities and glutathione level, and decreased malondialdehyde level in diabetic rats in a manner similar to metformin and quercetin. Histopathological investigation of the liver and kidney revealed restored hepatocytes and amelioration of congested interstitial blood vessel of the Bowman's space of the kidneys upon intervention with H. verticillata.
SIGNIFICANCE: H. verticillata in addition to its anti-hyperglycaemic activity ameliorates oxidative stress, dyslipidaemia, atherogenicity and hepatorenal lesions in DM.
Anti-hyperglycemic potential of Hyptis verticillata jacq in streptozotocin-induced diabetic rats

Ogar I, Egbung GE, Nna VU, Iwara IA, Itam E

Biomed Pharmacother, 2018 Nov;107:1268-1276.
PMID: 30257341 DOI: 10.1016/j.biopha.2018.08.115

Uncontrolled hyperglycaemia and oxidative stress have been implicated in the pathophysiology of diabetes mellitus. Hyptis verticillata is reportedly explored traditionally for its therapeutic benefits. Resulting from the paucity of information on the anti-hyperglycaemic potential of this plant, the present study assessed the anti-hyperglycaemic activity of H. verticillata leaf extract. Fifty-four albino Wistar rats were divided into two main groups consisting of diabetic and non-diabetic rats. The diabetic and non-diabetic rats were either treated with oral doses of metformin (500 mg/kg b.w.), quercetin (10 mg/kg b.w.), ethanol extract of H. verticillata leaf (low dose: 250 mg/kg b.w.) or H. verticillata (high dose: 500 mg/kg b.w.) for 28 days. Results showed significantly decreased body weight, increased fasting blood glucose (FBG) and glycated haemoglobin (HbA1c) levels, decreased pancreatic islet area and β-cell number in the diabetic untreated group, relative to normal control. H. verticillata - treated diabetic rats showed decreased FBG and HbA1c, increased body weight, pancreatic islet area and β-cell number, comparable to the effects of metformin. GCMS analysis of H. verticillata showed the presence of ten bioactive volatile compounds, with squalene which possess strong antioxidant, hypoglycaemic and hypotriglyceridemic effects, as the most abundant. We therefore conclude that H. verticillata has anti-hyperglycaemic properties.
Fulltext African walnuts attenuate ectopic fat accumulation and associated peroxidation and oxidative stress in monosodium glutamate-obese Wistar rats

Uti DE, Atangwho IJ, Eyong EU, Umoru GU, Egbung GE, Nna VU, et al.

Biomed Pharmacother, 2020 Apr;124:109879.
PMID: 31991383 DOI: 10.1016/j.biopha.2020.109879

AIMS: African walnuts were previously shown to modulate hepatic lipid bio-accumulation in obesity. Herein, we investigated the impact of the nuts on fat accumulation in adipose and ectopic regions, and associated oxidatiive stress status in obese rats.
MATERIALS AND METHODS: Whole ethanol extract (WE) of the nuts, and its liquid-liquid fractions-ethyl acetate (ET) and residue (RES) were separately administered to obese rats for 6 weeks. The normal (NC) and obese (OC) controls received normal saline and the standard control (SC), orlistat (5.14 mg/kg b.w.), during the same period. Thereafter, the animals were euthanized and the adipose, brain, kidneys and heart tissues were studied.
RESULTS: The change in body weight to naso-anal length which increased by 63.52 % in OC compared to NC (p < 0.05), decreased by 57.88, 85.80 and 70.20 % in WE, ET and RES-treated groups, respectively, relative to the OC (p < 0.05). Also, adipose tissue weights were lowered upon treatment with the extracts and fractions versus OC (p < 0.05). Total lipids, phospholipids, triacylglycerol and cholesterol concentrations in the studied tissues which were higher in OC (p < 0.05) were lowered (p < 0.05) and compared favorably with SC. Further, malondialdehyde levels in the tissues were lowered upon treatment, compared to the OC (p < 0.05). Glutathione level and activities of glutathione peroxidase, superoxide dismutase and glutathione-S-transferase which were decreased (p < 0.05) in OC, were restored upon treatment with the extracts, relative to the obese control (p < 0.05).
SIGNIFICANCE: African walnuts assuaged lipogenesis, oxidative stress and peroxidation in extra-hepatic tissues of obese rats, hence, may attenuate ectopic fat accumulation and its associated pathogenesis.
African Walnuts (Tetracarpidium conophorum) Modulate Hepatic Lipid Accumulation in Obesity via Reciprocal Actions on HMG-CoA Reductase and Paraoxonase

Uti DE, Atangwho IJ, Eyong EU, Umoru GU, Egbung GE, Rotimi SO, et al.

Endocr Metab Immune Disord Drug Targets, 2020;20(3):365-379.
PMID: 31339080 DOI: 10.2174/1871530319666190724114729

BACKGROUND: Obesity is characterized by increased body fat and involves an imbalance between the synthesis and degradation of lipids.
OBJECTIVE: The study aimed to investigate the effect of African walnuts (Tetracarpidium conophorum) on lipids storage and the regulatory enzymes of hepatic lipid metabolism in obese rats.
METHODS: Nuts were extracted in ethanol (WE) and further separated to obtain the ethyl-acetate fraction (ET) and the residue (RES). These were administered orally to 3 groups of monosodium glutamate- obese rats (n = 6), respectively, for 6 weeks. Other groups in the study were: normal (NC), obese control (OC) and standard control (SC) which received orlistat. Hepatic total lipids, total phospholipids, triacylglycerol (TG), total cholesterol (TCHOL), 3-hydroxyl-3-methylglutaryl-CoA (HMG-CoA) reductase and paraoxonase were studied.
RESULTS: Total lipids, TG and TCHOL which increased in OC compared to NC group, decreased. HMG-CoA reductase activity decreased in the 3 study groups relative to OC. Paraoxonase activity which decreased in OC was up-regulated, while the magnitude of hepatic cholesterol decreased from 94.32 % in OC to 52.19, 65.43 and 47.04 % with WE, ET and RES, respectively. Flavonoids, alkaloids, glycosides, tannins and saponins were detected in the nut. GC-MS analysis revealed 16, 18 and 10 volatile components in WE, ET and RES, respectively. Unsaturated fatty acids (linolenic acids: 33.33, 47.95 and 50.93 %, and α-linolenic acids: 25, 19.66 and 26.63 %) in WE, ET and RES, respectively, are the most abundant, and likely to be responsible for the observed activity.
CONCLUSION: African walnuts can prevent hepatic lipid accumulation through reciprocal actions on HMG-CoA reductase and paraoxonase in obesity.