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studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals.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

Hypoglycaemic and anti-hyperglycaemic activity of Tabernanthe iboga aqueous extract in fructose-fed Streptozotocin type 2 diabetic rats

Publisher Copyright: © 2020, Institute of Korean Medicine, Kyung Hee University. This is a post-peer-review, pre-copyedit version of Bading-Taïka, B., Souza, A., Bourobou Bourobou, HP. et al. Hypoglycaemic and anti-hyperglycaemic activity of Tabernanthe iboga aqueous extract in fructose-fed streptozotocin type 2 diabetic rats. ADV TRADIT MED (ADTM) (2020). https://doi.org/10.1007/s13596-020-00484-0Root bark preparations of the Gabonese plant Tabernanthe iboga (T. iboga) has long been used in traditional medicine in Central and West African regions for the management of type 2 diabetes (T2D). This study is the first investigation of in vivo hypoglycaemic activity in healthy rats and anti-hyperglycaemic activity of T. iboga in a 10% fructose-fed (40 mg/kg i.p.) streptozotocin (STZ) injected type 2 diabetic rat model. T. iboga at 50 to 200 mg/kg induced hypoglycaemia activity over 3 h fasted glucose tolerance in healthy Wistar rats and anti-hyperglycaemic effects on non-fasted and fasted blood glucose in fructose-fed STZ T2D rats with no toxicity. Fructose-fed STZ T2D rats developed characteristic type 2 diabetic complications over 6 weeks exhibiting significantly elevated fasting and non-fasting blood glucose, polydipsia, reduced body weight gain and glucose and insulin tolerance compared with STZ alone and normal control rats. T. iboga (50 mg/kg and 200 mg/kg bw) administered p.o. once daily for 4 weeks significantly improved diabetic symptoms of polydipsia, reduced body weight, hyperglycaemia, glucose and insulin tolerance (as AUC) compared with fructose-fed STZ T2D rats. T. iboga aqueous extract (50 mg/kg and 200 mg/kg) also significantly reversed altered actions of marker enzymes of liver including alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate transaminase (AST), creatinine, HbA1c and elevated triglycerides in fructose-fed STZ type 2 diabetic rats. Our outcomes show that daily oral provision of T. iboga improves type 2 diabetes complications, superior to glibenclamide, in rat fructose-fed STZ model and offers the potential for safe clinical management of T2D in Gabon.Peer reviewe