Taofik O. Sunmonu

The effect of Aloe ferox Mill. in the treatment of loperamide-induced constipation in Wistar rats.

BackgroundConstipation is the most common gastrointestinal complaint all over the world and it is a risk factor of colorectal cancer. In this study, the efficacy of aqueous leaf extract of Aloeferox Mill. was studied against loperamide-induced constipation in Wistar rats.MethodsConstipation was induced by oral administration of loperamide (3 mg/kg body weight) while the control rats received normal saline. The constipated rats were treated with 50, 100 and 200 mg/kg body weight/day of the extract for 7 days during which the feeding characteristics, body weight, fecal properties and gastrointestinal transit ratio were monitored.ResultsThe extract improved intestinal motility, increased fecal volume and normalized body weight in the constipated rats, which are indications of laxative property of the herb with the 200 mg/kg body weight of the extract showing the best efficacy.ConclusionThe effect of the extract compares favourably well with senokot, a standard laxative drug. These findings have therefore, lent scientific credence to the folkloric use of the herb as a laxative agent by the people of the Eastern Cape of South Africa.

In vivo Studies on Antidiabetic Plants Used in South African Herbal Medicine

Diabetes is one of the most common metabolic disorders worldwide. It is a major health problem with its frequency increasing every day in most countries. The disease is generally believed to be incurable; and the few orthodox drugs available to manage the disease are not readily affordable to the poor. Based on the historical success of natural products as antidiabetic agents and the ever increasing need for new antidiabetics, a number of South African medicinal plants have been evaluated for their antidiabetic properties. In this article, we review the major studies conducted based on ethnobotanical surveys carried out between 2005 and 2008 in South Africa on plants that are traditionally used for the treatment of diabetes. Overall, the results of the studies conducted confirmed the potential of South African medicinal plants in antidiabetic drug discovery and identified a number of promising taxa for further in vivo investigation as plant-based antidiabetic agents.

Protective effect of Artemisia afra Jacq. on isoproterenol-induced myocardial injury in Wistar rats.

Artemisiaafra Jacq. ex Willd. is a widely used medicinal plant in South Africa for the treatment of various diseases. In this study, the effect of the herb on isoproterenol (ISO)-induced myocardial injury in rats was investigated. Pretreatment with the aqueous leaf extract of the plant at 100 and 200 mg/kg body weight for 30 days prevented the elevation of serum marker enzymes namely lactate dehydrogenase (LDH), aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP) in myocardial injured rats. ISO-induced animals exhibited decreased levels of glutathione reductase (GR), glutathione peroxides (GPx), superoxide dismutase (SOD) and glutathione (GSH) in the heart, which were restored to near normal levels following treatment with the herb. The extract also attenuated lipid peroxidation (LPO) in the heart and improved the imbalance in lipid profile caused by ISO. The effect was more prominent at 200 mg/kg body weight. These findings revealed the cardioprotective effect of A. afra against isoproterenol-induced myocardial injury.

Artemisia afra Jacq. Ameliorates Oxidative Stress in the Pancreas of Streptozotocin-Induced Diabetic Wistar Rats

Diabetes is characterized by hyperglycemia resulting from defects in pancreatic insulin secretion and/or impaired target cell responsiveness to insulin, and Artemisia afra Jacq. is widely used in South Africa to treat the disease, but the mechanism of action is yet to be elucidated. This study explored the effect of oral administration of aqueous leaf extract of A. afra on the pancreas of streptozotocin-induced diabetic rats. We found that the extract significantly reduced blood glucose levels, accompanied by an increase in the serum insulin concentration. Moreover, the antioxidant enzymic activities of glutathione peroxidase, glutathione reductase, and superoxide dismutase also improved significantly after treatment with the extract. Increased pancreatic lipid peroxidation in the diabetic rats was also normalized by the extract. This study indicates that A. afra possesses hypoglycemic and antioxidant activities. Our findings suggest that the herb might exert its anti-diabetic activity by regenerating pancreatic beta cells, thereby stimulating the release of insulin.

Toxicological evaluation of aqueous extract of Aloe ferox Mill. in loperamide-induced constipated rats.

Aloe ferox Mill. is a widely used medicinal plant in South Africa for the treatment of many ailments including constipation. The present study evaluated the toxicological effect of aqueous leaf extract of the herb at 50, 100 and 200 mg/kg body weight for 7 days on the haematological parameters as well as liver and kidney function indices in loperamide—induced constipated rats. The extract did not cause any significant (p > 0.05) effect on the kidney and liver—body weight ratio as well as the kidney function indices including serum levels of creatinine, uric acid, urea, calcium and potassium ions at all the dosages investigated. Whereas the serum levels of total protein, albumin, bilirubin and gamma glutamyl trasferase (GGT) were not affected, the elevated activities of alkaline phosphatase (ALP), alanine transaminase (ALT) and aspartate transaminase (AST) in the untreated constipated animals were normalized following treatment with extract. The data obtained with respect to the haematological analysis indicated that the extracts had no significant (p > 0.05) effect on the haematological parameters with the exception of lymphocyte count which was increased in the untreated constipated rats. This was however attenuated after administering the herb. The available evidence in this study suggests that A. ferox may be safe as an oral remedy for constipation. Generally, the effect of the extract compared favourably well with senokot, a recommended drug for the treatment of constipation.

Evaluation of Antidiabetic Activity and Associated Toxicity of Artemisia afra Aqueous Extract in Wistar Rats

Artemisia afra Jacq. ex Willd. is a widely used medicinal plant in South Africa for the treatment of diabetes. This study aimed to evaluate the hypoglycemic activity and possible toxicity effect of aqueous leaf extract of the herb administered at different dosages for 15 days in streptozotocin-induced diabetic rats. Administration of the extract at 50, 100, and 200 mg/kg body weight significantly (P < 0.05) increased body weight, decreased blood glucose levels, increased glucose tolerance, and improved imbalance in lipid metabolism in diabetic rats. These are indications of antidiabetic property of A. afra with 200 mg/kg body weight of the extract showing the best hypoglycemic action by comparing favourably well with glibenclamide, a standard hypoglycemic drug. The extract at all dosages tested also restored liver function indices and haematological parameters to normal control levels in the diabetic rats, whereas the kidney function indices were only normalized in the diabetic animals administered with 50 mg/kg body weight of the extract. This investigation clearly showed that in addition to its hypoglycemic activity, A. afra may also protect the liver and blood against impairment due to diabetes. However, some kidney functions may be compromised at high dosages of the extract.

Toxicological evaluation of aqueous leaf and berry extracts of Phytolacca dioica L. in male Wistar rats.

Despite the widespread use of Phytolacca dioica L. in folklore medicine of South Africa, there is dearth of information on its safety/toxicity. The aim of this study was to evaluate the toxicological effect of aqueous leaf and berry extracts of the plant at different dosages for 14 days on the liver and kidney function indices in male Wistar rats. Phytochemical screening indicated that the extracts are rich in phytonutrients including alkaloid, tannin, saponins, phenolics, lectins and flavonoids; while triterpenoids and phlobatanins were absent. The extracts significantly reduced the body and absolute organ weights of the animals at all the dosages investigated. Whereas, significant increase was observed in the serum levels of alkaline phosphatase (ALP), gamma glutamyl transferase (GGT), alanine transaminase (ALT), aspartate transaminase (AST), bilirubin, calcium, creatinine, urea and uric acid; the serum concentration of total protein, albumin and globulin were reduced in the serum following treatment with the extracts. Generally, the effect of the herb appeared to be dosage dependent. This investigation clearly showed that P. dioica can impair normal hepatic and renal functions. This is an indication that the extracts may not be completely safe in male rats when continuously administered for 14 days.

Medicinal Plants Used in the Management of Diabetes Mellitus 2015

Diabetes mellitus is one of the common endocrine disorders prevalent in almost all of the countries. This chronic pathology is characterized by hyperglycemia caused by defective insulin action, insulin secretion, or the combination of both. Prolonged persistence of elevated blood glucose level consequently caused a series of complications such as nephropathy, retinopathy, and cardiomyopathy. Currently available synthetic drugs for treating this disease are found to be associated with many adverse effects. The use of plants in medicine is an age-long practice in various parts of the globe for both preventive and curative purposes. Several warnings have been issued over lack of quality control, scientific evidence for the efficacy, and potential adverse effects of herbal remedies including hepatotoxicity, nephrotoxicity, cardiotoxicity, and reproductive toxicity among others. Despite all of these, reliance on herbs as medicine for the management of diabetes mellitus is still much practiced by a large proportion of the world population because they are readily available and affordable with perceived reduced toxicity. Therefore, with the upsurge of interests in medicinal plants, there is a need for thorough scientific investigations of these plants for both efficacy and potential toxicity. In this issue, we present some recent advances in the use of medicinal plants for treating diabetes mellitus. B. Pang et al. (“Innovative Thoughts of Treating Diabetes from the Perspective of Traditional Chinese Medicine”)presented a review article on the contribution of traditional Chinese medicine to the development of alternative and complementary medicine for the treatment and prevention of diabetes mellitus. In another paper (“Effect of Rhizoma Coptidis (Huang Lian) on Treating Diabetes Mellitus”), B. Pang et al. discussed the efficacy and safety of Rhizoma Coptidis in the treatment of diabetes mellitus. In another study (“Evaluation of the Effects of Cornus mas L. Fruit Extract on Glycemic Control and Insulin Level in Type 2 Diabetic Adult Patients: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial”), R. Soltani et al. reported the results of a clinical trial on the effect of Cornus mas L. fruit extract on hyperglycemia in type 2 diabetic patients. In addition, W. Liu et al. (“The Effects of Chinese Medicine on Activation of Wnt/β-Catenin Signal Pathway under High Glucose Condition”) present a valuable review on some compounds implicated in the regulation of Wnt/β-catenin signal pathway as a mechanism of action involved in the antihyperglycemic activity from Chinese medicine. Furthermore, A. O. T. Ashafa and M. I. Kazeem (“Toxicopathological Evaluation of Hydroethanol Extract of Dianthus basuticus in Wistar Rats”) reported on the effects of Dianthus basuticus (a Basotho plant with acclaimed antidiabetic activity) on some biochemical parameters and histology of Wistar rats. Finally, X.-J. Li et al. (“TCM Formula Xiaoyaosan Decoction Improves Depressive-Like Behaviors in Rats with Type 2 Diabetes”) evaluated the effect of traditional medicine formula, Xiaoyaosan, on the cognitive function of diabetic rats. After the first volume of this special issue that was published in 2014, we hope that this issue will present additional valuable information for scientists and clinicians.

Efficacy and Safety of Medicinal Plants Used in the Management of Diabetes Mellitus

This special issue edited by a team of five renowned scholars led by an Associate Professor of Biochemistry, M. T. Yakubu, Ph.D. (Lead Guest Editor), and other Guest Editors that included Professor T. O. Sunmonu, Dr. F. B. Lewu, Dr. A. O. T. Ashafa, Dr. Femi J. Olorunniji, and Professor Mohammed Eddouks features 15 original research papers covering various aspects of diabetes mellitus. R. M. P. Gutierrez et al. in the paper entitled “Ameliorative effect of hexane extract of Phalaris canariensis on high fat diet-induced obese and streptozotocin-induced diabetic mice” reported the antiobesity effect of a hexane extract of Phalaris canariensis seed in high-fat diet and streptozotocin-induced diabetic mice. M. T. Sultan et al. in the paper entitled “Nigella sativa fixed and essential oil supplementation modulates hyperglycemia and allied complications in streptozotocin-induced diabetes mellitus” described the modulatory effects of Nigella sativa fixed and essential oil supplementation on hyperglycemia and allied complications in streptozotocin-induced diabetes mellitus. In a related study, M. I. Kazeem et al. in the paper entitled “Protective effect of free and bound polyphenol extracts from ginger (Zingiber officinale Roscoe) on the hepatic antioxidant and some carbohydrate metabolizing enzymes of streptozotocin-induced diabetic rats” evaluated the protective effect of free and bound polyphenol extracts from ginger (Zingiber officinale Roscoe) on the hepatic antioxidant and some carbohydrate metabolizing enzymes of streptozotocin-induced diabetic rats. P.-G. Cheng et al. in the paper entitled “Polysaccharides-rich extract of Ganoderma lucidum (M.A. Curtis:Fr.) P. Karst accelerates wound healing in streptozotocin-induced diabetic rats” evaluated the wound healing activity of the hot aqueous extract of Ganoderma lucidum in streptozotocin-induced diabetic rats. The work reported by da A. A. Rocha et al. in the paper entitled “Lectin from Crataeva tapia bark improves tissue damages and plasma hyperglycemia in alloxan-induced diabetic mice” revealed that lectin extracted from Crataeva tapia bark resulted in improvement of tissue damage and plasma hyperglycemia in alloxan-induced diabetic mice. J. Gu et al. in the paper entitled “A drug-target network-based approach to evaluate the efficacy of medicinal plants for type II diabetes mellitus” used drug-target network-based approach to evaluate the efficacy of medicinal plants for type II diabetes mellitus. The study reported by M. M. Zainudin et al. in the paper entitled “Does oral ingestion of Piper sarmentosum cause toxicity in experimental animals?” investigated the potential toxicity of oral administration of an antidiabetic plant, Piper sarmentosum, in experimental animals. P. V. Rao et al. in the paper entitled “Rhinacanthus nasutus improves the levels of liver carbohydrate, protein, glycogen, and liver markers in streptozotocin-induced diabetic rats” showed that treatment of streptozotocin-induced diabetic rats with Rhinacanthus nasutus resulted in improvement in the levels of liver carbohydrate, protein, glycogen, and other hepatic markers. Y. Xiao et al. in the paper entitled “The effect of Chinese herbal medicine on albuminuria levels in patients with diabetic nephropathy: a systematic review and meta-analysis” presented a systematic review and meta-analysis of the effect of Chinese herbal medicine on albuminuria levels in patients with diabetic nephropathy. J. Wu et al. in the paper entitled “Renal protective role of Xiexin decoction with multiple active ingredients involves inhibition of inflammation through downregulation of the nuclear factor-kB pathway in diabetic rats” presented evidence to suggest that the inhibition of inflammation through downregulation of the nuclear factor-kβ pathway in diabetic rats is the mechanism by which Xiexin decoction with multiple active ingredients exhibits its renal protective role. The paper by L. Zhou et al. in the paper entitled “Hu-Lu-Ba-Wan attenuates diabetic nephropathy in type 2 diabetic rats through PKC-α/NADPH oxidase signaling pathway” reported the attenuation of diabetic nephropathy in type 2 diabetic rats through PKC-α/NADPH oxidase signaling pathway by Hu-Lu-Ba-Wan. The evaluation of antidiabetic activity and associated toxicity of Artemisia afra aqueous extract in Wistar rats was reported by T. O. Sunmonu and A. J. Afolayan in the paper entitled “Evaluation of antidiabetic activity and associated toxicity of Artemisia afra aqueous extract in Wistar rats.” N. A. Ishak et al. in the paper entitled “Antidiabetic and hypolipidemic activities of Curculigo latifolia fruit: root extract in high fat fed diet and low dose STZ induced diabetic rats” evaluated the antidiabetic and hypolipidemic activities of Curculigo latifolia fruit: root extract in high-fat fed diet and low dose STZ-induced diabetic rats. The evaluation of the hypoglycemic properties of Anacardium humile aqueous extract was reported by M. A. Urzeda et al. in the paper entitled “Evaluation of the hypoglycemic properties of Anacardium humile aqueous extract.” Finally, the decrease of plasma glucose by Hibiscus taiwanensis in type-1-like diabetic rats was the focus of the study reported by L.-Y. Wang et al. in the paper entitled “Decrease of plasma glucose by Hibiscus taiwanensis in type-1-like diabetic rats.” The variety of papers on diabetes featured in this special issue highlights the keen awareness of the biomedical community of the potential for exploiting medicinal plants in tackling this debilitating condition. Of particular interest is the large number of contributions from scientists working in developing countries. This level of interest should be encouraged. The gradual improvement in the level of prosperity in developing economies is being accompanied by a significant increase in reported cases of obesity, diabetes, and other metabolic disorders. It is appropriate that scientists and policy makers in these lands devote more resources to exploring newer ways of dealing with these conditions. It is hoped that the encouraging findings reported in this special issue will stimulate further interest in expanding and coordinating efforts on medicinal plants that have clinical potential in the management of diabetes.