An overview of anti-diabetic plants used in Gabon: Pharmacology and Toxicology

© 2017 Elsevier B.V. All rights reserved.Ethnopharmacological relevance: The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed. Materials and methods: Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including ‘Diabetes’ ‘Gabon’ ‘Toxicity’ ‘Constituents’ ‘hyperglycaemia’ were used. Results: A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver. Conclusion: An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon.Peer reviewedFinal Accepted Versio

ANTIHYPERGLYCEMIC AND ANTI-OXIDANT POTENTIAL OF ETHANOL EXTRACT OF VITEX THYRSIFLORA LEAVES ON DIABETIC RATS

Objective: Vitex thyrsiflora Baker (Verbenaceae) is a glabrous under shrub that is widely distributed in Cameroon. Diabetes is characterized by chronic hyperglycemia, a source of increased oxidative stress and tissue oxidative damage. The objective of current study was to estimate the antihyperglycemic and anti-oxidant potential of ethanol extract of Vitex thyrsiflora leaves on diabetic rats Methods: The antihyperglycemic effect of an ethanol extract of Vitex thyrsiflora leaves was investigated in normal male rats and streptozotocin induced diabetic male rats and its antioxidant potential was evaluated. After preparation of the extract, it was subjected to a phytochemistry screening, and tested on male rats made hyperglycemic in the Oral Glucose Tolerance Test (OGTT) and in streptozotocin diabetic rats. Glibenclamide (10 mg/Kg) was served as a positive control in both experiments. The evaluation of the antioxidant potential was done through the determination of the total polyphenols and total flavonoid contents, and by using the ferric reducing antioxidant power assay and the free radical scavenging activity on DPPH method. Results: The results show that the extract contains alkaloids, flavonoids, steroids, saponins and phenolic compounds. The test on hyperglycemic rats in OGTT showed that, the extract was effective (at a dose of 200 mg/Kg) to significantly decreased glucose-induced hyperglycemia (**p ˂ 0.01). The extract was ineffective on streptozotocin induced diabetic rats. The study of the antioxidant potential showed that, polyphenols and flavonoids increase with the concentration of the extracts. IC50 value was found to be 65.97, based on the log (inhibitor) vs. normalized response-Variable slope. Conclusion: FRAP appears to be significantly highly correlated with total polyphenols content and total flavonoids content. This shows that the ethanol extract of V. thyrsiflora leaves could be served to prevent acute hyperglycema, but not a chronic hyperglycemic state.   Peer Review History: Received 28 May 2018;   Revised 24 June; Accepted 4 July, Available online 15 July 2018 UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file:        Reviewer's Comments: Average Peer review marks at initial stage: 6.5/10 Average Peer review marks at publication stage: 7.5/10 Reviewer(s) detail: Dr. Sabah Hussien El-Ghaiesh, Tanta University, Egypt, [email protected] Prof. Dr. Ali Gamal Ahmed Al-kaf, Sana'a university, Yemen, [email protected] Similar Articles: COMPARATIVE CHARACTERIZATION OF ANTIOXIDANT PROFILE OF VITAMIN-E AND RED DATES IN PLACEBO AND TESTED GROUPS OF HYPERLIPIDEMIC PATIENT

MYOCARDIAL POTENCY OF AQUEOUS EXTRACT OF HARUNGANA MADAGASCARIENSIS STEM BARK AGAINST ISOPROTERENOL-INDUCED MYOCARDIAL DAMAGE IN RATS

Objectives: The present study was undertaken to evaluate the effects of Harungana madagascariensis on electrocardiographical, biochemical and histopathological changes in isoproterenol (ISO)-induced myocardial infarction in rats. Methods: Male Wistar albino rats were randomly divided and treated with the aqueous extract of Harungana madagascariensis stem bark (AEHM, 200 and 400 mg/kg per os), or normal saline or vitamin E for 7 days with concomitant administration of ISO (85 mg/kg, subcutaneously) on 8th and 9th days, at 24 h interval. Results: The ISO injections to the rats caused cardiac dysfunction evidenced by a marked (P<0.01) elevation in ST-segment, a reduction in R wave amplitude (P<0.01), decrease in endogenous antioxidant reduced glutathione (GSH), increase in malondialdehyde (MDA), a lipid peroxidation marker, increase of cardiac marker enzymes lactate dehydrogenase (LDH), aspartate amino transferase (AST) and alanine amino transferase (ALT). All these changes in cardiac function as well as GSH, MDA and the enzymes (LDH, AST and ALT) were ameliorated when the rats were pretreated with AEHM. Additionally, the protective effects were strengthened by improved histopathological changes, which specify the protection of cardiomyocytes from the deleterious effects of ISO. Conclusion: This study demonstrates the cardioprotective effect of Harungana madagascariensis on isoproterenol-induced myocardial infarction in rats. The mechanism might be associated with the enhancement of antioxidant defense, reduction of lipid peroxydation and it is confirmed by amending electrocardiographic pattern, improvement of cardiac markers and less histopathological damages following ISO-induced myocardial infarction. It could provide experimental evidence to support the use of Harungana madagascariensis used in traditional medicine to treat cardiovascular disorders. Peer Review History: Received  9 February 2018;   Revised 22 February; Accepted 28 February, Available online 15 March 2018 UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file:        Reviewer's Comments: Average Peer review marks at initial stage: 5.5/10 Average Peer review marks at publication stage: 8.0/10 Reviewer(s) detail: Dr. Mohamed Said Fathy Al-Refaey, University of Sadat City, Menofia, Egypt, [email protected] Dr. Mohamed Salama, Modern University for Technology & Information, Egypt, [email protected] Similar Articles: ANTIHYPERGLYCEMIC AND ANTI-OXIDANT POTENTIAL OF ETHANOL EXTRACT OF VITEX THYRSIFLORA LEAVES ON DIABETIC RATS STUDY ON FRESH LEAF AQUEOUS EXTR STUDY ON FRESH LEAF AQUEOUS EXTRACT OF FLACOURTIA INDICA FOR HEPATOPROTECTIVE, ANTI-ANEMIC AND HYPOGLYCEMIC ABILITIES IN CCL4 INDUCED HEPATOTOXICITY IN ALBINO WISTAR RAT

Acute and Subchronic Oral Toxicity of Aqueous Extract of Ageratum Conyzoides Linn

The whole plant, the leaves and more rarely the root of Ageratum conyzoides (Asteraceae) has medicinal value in traditional medicine wherever it grows and is non-toxic to humans. However it is needed to evaluate the acute and subchronic toxicity potential of Ageratum conyzoides (A. conyzoides) total extract in rats. For the acute study, a crude aqueous extract of A. conyzoides was administered to Wistar rats in single doses of 3- 13 g/kg given by gavage. General behavior, adverse effects and mortality were determined for up to 14 days. For the subchronic toxicology test, the doses of 200, 400, 600 and 800 mg/kg were used in both sexes. The phytochemical study of the aqueous extract revealed the presence of pyrrolizidines alkaloids, tannins, saponins, flavonoids and polyphenols. In subchronic toxicity test, the acute oral toxicity (LD50) of the aqueous extract was estimated to be more than 13 g/kg bw. Furthermore, the aqueous extract showed dose-dependent sedative and analgesic effects. The subchronic toxicity test, showed no effect on the body weight, food consumption and water intake. However, histological studies revealed that the extract caused dose-dependent lesions, resulting in hepatorenal changes correlated with a high level of transaminases activity and hyperleukocytosis at 800 mg/kg dose level. The hemoglobin and hematocrit concentrations were also high in all groups treated with the extract.La plante entière, les feuilles et plus rarement les racines de Ageratum conyzoides (Astéracées) ont une valeur en médecine traditionnelle partout où elle croît et est peu toxique pour les êtres humains. Cependant il est nécessaire d’évaluer le potentiel de toxicité aigüe et subchronique de l’extrait aqueux total de Ageratum conyzoides (A. conyzoides) chez les rats. Pour l’étude de toxicité aigüe, l’extrait aqueux de Ageratum conyzoides a été administré aux rats Wistar en doses uniques de 3 à 13 g/kg par gavage. Le comportement général, les effets indésirables et la mortalité des animaux a été enregistrée pendant 14 jours. Pour le test de toxicité subchronique des doses de 200, 400, 600 et 800 mg/kg ont été utilisées pour les deux sexes. Les études phytochimiques de l’extrait aqueux ont révélées la présence des alcaloïdes pyrrolizidiniques, des tanins, des saponines, flavonoïdes et des polyphénols. La dose létale médiane (DL50) de l’extrait aqueux a été estime supérieur à 13g/kg. Par la suite, l’extrait aqueux a montré des effets sédatifs et analgésiques dose-dépendante. Le test de toxicité subchronique n’a pas montré d’effets ni sur le poids corporel, ni sur la consommation alimentaire ou la prise d’eau. Cependant, les études histologiques ont révélées que l’extrait causait des lésions doses dépendantes, caractérisée par des anomalies hépatorénales corrélées avec le niveau élevé de l’activité des transaminases et l’hyperleucocytose à la dose de 800 mg/kg. Les concentrations d’hémoglobine et d’hématocrite étaient aussi élevées dans tous les groupes traités à l’extrait.Mots clés: Ageratum conyzoides, extrait aqueux, alcaloïdes pyrrolizidiniques, test de toxicité aigüe, test de toxicité subchroniqu

Hypoglycaemic And Antihyperglycaemic Activity Of Ageratum Conyzoides L. In Rats.

The hypoglycaemic and antihyperglycaemic properties of the aqueous extracts of the leaves of Ageratum Conyzoides L. were evaluated in normoglycemic and in streptozotocin-induced diabetic rats, in order to validate its use in folk medicine. Tested animals were given the aqueous extracts of the plant at the doses of 100, 200 and 300mg/kg. These doses were tested also on glucose loaded normal male rats (Oral Glucose Tolerance Test). Of all the doses, the aqueous extracts at 200 and 300mg/kg showed statistically significant hypoglycaemic and antihyperglycaemic activities. For the oral glucose tolerance test, 100mg/kg dose only attenuated significantly the rise of blood glucose in normal fasted rats. Consequently, these results confirmed the hypoglycaemic properties of the leaves of Ageratum conyzoides

Hypoglycaemic And Antihyperglycaemic Activity Of Ageratum Conyzoides L. In Rats.

The hypoglycaemic and antihyperglycaemic properties of the aqueous extracts of the leaves of Ageratum Conyzoides L. were evaluated in normoglycemic and in streptozotocin-induced diabetic rats, in order to validate its use in folk medicine. Tested animals were given the aqueous extracts of the plant at the doses of 100, 200 and 300mg/kg. These doses were tested also on glucose loaded normal male rats (Oral Glucose Tolerance Test). Of all the doses, the aqueous extracts at 200 and 300mg/kg showed statistically significant hypoglycaemic and antihyperglycaemic activities. For the oral glucose tolerance test, 100mg/kg dose only attenuated significantly the rise of blood glucose in normal fasted rats. Consequently, these results confirmed the hypoglycaemic properties of the leaves of Ageratum conyzoides

Anti-hyperglycemic and Antioxidant Potential of Water-Ethanol Extract of Musanga cecropioides Stem Bark

The study investigated the effect of Musanga cecropioides (MC) water-ethanol stem bark extract on blood glucose level in both hyperglycemic loaded glucose rats and streptozotocin (STZ)-induced diabetic rats, and evaluated its antioxidant capacity. The Wistar rats were induced diabetes after fasting. Oral Glucose Tolerance Test (OGTT) was conducted on normoglycemic rats, and anti-hyperglycemic test on diabetic rats; five groups with five rats each were constituted. Group 1: negative control was treated with vehicle; Group 2, Group 3, and Group 4 were treated with increasing water-ethanol extract (200, 300 and 400 mg/kg b.w); Group 5 was the positive control, treated with glibenclamide. The antioxidant capacity of the extract was also evaluated by measuring the Ferric Reducing Antioxidant Power, Total Phenolic Content, Total Flavonoid Content, and radical scavenging activity of water-ethanol stem bark extract. In OGTT the water-ethanol extract of MC, at the dose of 300 mg/kg, significantly lowered the Area under Curve (AUC) induced by glucose. In STZ diabetic rats, the extract significantly lowered the AUC of blood glucose, at all doses. Glibenclamide was more efficient in both OGTT and anti-hyperglycemic test. The MC extract presented relevant antioxidant activity with IC50 = 6.23 mg/mL. Both the Total Phenolic Content and the Total Flavonoid Content increased in a dose-dependent manner. The correlation of DPPH % free radical scavenged and Total Flavonoid Content was positive and statistically significant. MC water-ethanol extract possesses a good antioxidant potential, and could be helpful to lower hyperglycemic state associated with diabetes.</jats:p