Anti-diabetic effects of Holarrhena antidysentrica extracts: Results from a Longitudinal Meta-analysis

Abstract

Background Holarrhena antidysenterica (HA), a twining shrub belonging to the Apocynaceae family is found in tropical regions of Africa and over a large part of Asia including India, Philippines and Malayan Peninsula. In Indian traditional system of medicine, HA has been used to treat gastric ailments, for wound healing and also to improve glycaemic control. Glucose lowering activity of HA root, bark, seed, leaf and fruit extract in different parts of India as well as in Chinese traditional medicine is widely reported. Purpose In the meta-analysis reported in this article, we summarize glucose-lowering effects of HA extracts from different plant parts as reported in multiple studies involving animal models of diabetes. Our analysis helps to quantify the glucose-lowering effect of HA in comparison with standard diabetes drugs. The analysis also sheds light on differential efficacy levels of HA extracted from different plant parts. Study design The meta-analysis was carried out following PRISMA guidelines. Literature was searched to identify studies published between years 2011 to 2019 reporting glucose-lowering effects of HA extract on rodent models of diabetes. Methods Longitudinal meta-analysis was carried out on time-course data extracted from selected studies to calculate standardized mean change of glucose value from day 1 to days 7, 14 and 21 post-treatment by HA extract or standard anti-diabetic drug. Subgroup analysis was carried out for studies reporting effects of HA on leaf and seed extracts. Standardized mean difference in levels of cholesterol, triglycerides and serum total protein between treatment and control groups were also assessed. Results We shortlisted nine articles to be used for this meta-analysis. Summarized standardized mean changes of glucose value between day 1 and day 21 post-treatment indicated glucose-lowering effects of HA extracts to be marginally lower but comparable to that of standard anti-diabetic drugs like Glibenclamide or Sitagliptin. However, subgroup analysis revealed seed extracts of HA to be more potent than leaf extracts or even standard drugs. Effects of the extract on levels of cholesterol, triglyceride and serum total protein was also commensurate with its glucose-lowering property. Conclusions Our results, summarized over multiple studies, present a clear quantitative assessment of the anti-diabetic property of HA, in particular the seed extracts compared to standard anti-diabetic drugs. Further differential analysis of the seed extracts will be useful to arrive at a herbal formulation with superior anti-diabetic property and possibly lesser side effects than chemical entities.