Histomorphological and morphometric studies of the pancreatic islet cells of diabetic rats treated with aqueous extracts of Momordica charantia (karela) fruits

Herbal Medicines Targeting the Improved β-Cell Functions and β-Cell Regeneration for the Management of Diabetes Mellitus

There is an increasing trend of investigating natural bioactive compounds targeting pancreatic β-cells for the prevention/treatment of diabetes mellitus (DM). With the exploration of multiple mechanisms by which β-cells involve in the pathogenesis of DM, herbal medicines are gaining attention due to their multitasking ability as evidenced by traditional medicine practices. This review attempts to summarize herbal medicines with the potential for improvement of β-cell functions and regeneration as scientifically proven by in vivo/in vitro investigations. Furthermore, attempts have been made to identify the mechanisms of improving the function and regeneration of β-cells by herbal medicines. Relevant data published from January 2009 to March 2020 were collected by searching electronic databases “PubMed,” “ScienceDirect,” and “Google Scholar” and studied for this review. Single herbal extracts, polyherbal mixtures, and isolated compounds derived from approximately 110 medicinal plants belonging to 51 different plant families had been investigated in recent years and found to be targeting β-cells. Many herbal medicines showed improvement of β-cell function as observed through homeostatic model assessment-β-cell function (HOMA-β). Pancreatic β-cell regeneration as observed in histopathological and immunohistochemical studies in terms of increase of size and number of functional β-cells was also prominent. Increasing β-cell mass via expression of genes/proteins related to antiapoptotic actions and β-cell neogenesis/proliferation, increasing glucose-stimulated insulin secretion via activating glucose transporter-2 (GLUT-2) receptors, and/or increasing intracellular Ca²⁺ levels were observed upon treatment of some herbal medicines. Some herbal medicines acted on various insulin signaling pathways. Furthermore, many herbal medicines showed protective effects on β-cells via reduction of oxidative stress and inflammation. However, there are many unexplored avenues. Thus, further investigations are warranted in elucidating mechanisms of improving β-cell function and mass by herbal medicines, their structure-activity relationship (SAR), and toxicities of these herbal medicines.

The safety and efficacy of Momordica charantia L. in animal models of type 2 diabetes mellitus: A systematic review and meta-analysis

Type 2 diabetes mellitus is a chronic hyperglycemic condition due to progressively impaired glucose regulation. Momordica charantia L. could potentially improve hyperglycemia because its fruit extracts can alleviate insulin resistance, beta-cell dysfunction, and increase serum insulin level. We evaluated the effect of M. charantia L. in comparison with a vehicle on glycemic control in animal models of type 2 diabetes mellitus. MEDLINE, Web of Science, Scopus, and CINAHL databases were searched without language restriction through April 2019. About 66 studies involving 1861 animals that examined the effect of M. charantia L. on type 2 diabetes mellitus were included. Fruits and seed extracts reduced fasting plasma glucose (FPG) and glycosylated hemoglobin A1c in comparison to vehicle control: (42 studies, 815 animals; SMD, -6.86 [95% CI; -7.95, -5.77], 3 studies, 59 animals; SMD; -7.76 [95% CI; -12.50, -3.01]) respectively. Also, the extracts have hepato-renal protective effects at varying doses and duration of administration. Despite the observed significant glycemic control effect, poor methodological quality calls for future researches to focus on standardizing extract based on chemical markers and adopt measures to improve the quality of preclinical studies such as sample size calculation, randomization, and blinding.

Molecular and biochemical monitoring of the possible herb-drug interaction between Momordica charantia extract and glibenclamide in diabetic rats

Momordica charantia is used in folk medicine to manage diabetes mellitus. In this study, we investigated the possible herb-drug interaction between M. charantia fruit extract (MCFE) and glibenclamide (GLB) in streptozotocin-diabetic rats. Rats were divided into 7 groups. The 1st group received 3% Tween 80. The 2nd–5th groups were diabetic rats received vehicle, GLB (5 mg/kg), MCFE (250 and 500 mg/kg), respectively. The 6th–7th groups administered GLB plus MCFE (250 and 500 mg/kg), respectively. After 8 weeks, fasting blood glucose (FBG), insulin and glycosylated hemoglobin (HbA1c) levels were assessed. Histopathological and immunohistochemical examinations of the pancreases were done. Quantitative RT-PCR was used to analyze hepatic mRNA expression of insulin receptor (INR), glucose transporter 2 (Slc2a2) and peroxisome proliferator-activated receptor α (PPAR-α) genes. All medicaments greatly reduced FBG in diabetic rats when compared with diabetic control group. GLB plus MCFE combination was better than GLB alone in improving levels of insulin and HbA1c. All medicaments restored insulin content of pancreatic β-cells and reduced glucagon and somatostatin of alpha and delta endocrine cells. Moreover, GLB plus MCFE-500 was the most efficient in restoring INR, Slc2a2 and PPAR-α mRNA expression to their normal levels. In conclusion, MCFE in combination with GLB gives greater glycemic improvement than GLB monotherapy.