Bitter Melon Extract Yields Multiple Effects on Intestinal Epithelial Cells and Likely Contributes to Anti-diabetic Functions

Abstract

The intestines have been recognized as important tissues for metabolic regulation, including glycemic control, but their vital role in promoting the anti-diabetic effects of bitter melon, the fruit of Momordica charantia L, has seldom been characterized, nor acknowledged. Evidence suggests that bitter melon constituents can have substantial interactions with the intestinal epithelial cells before circulating to other tissues. We therefore characterized the effects of bitter melon extract (BME) on intestinal epithelial cells. BME was found to contain substantial amounts of carbohydrates, proteins, and triterpenoids. TNF-α induced insulin resistance in an enterocyte cell line of IEC-18 cells, and BME promoted glucose utilization of the insulin-resistant cells. Further analysis suggested that the increased glucose consumption was a result of the combined effects of insulin sensitizing and insulin substitution functions of BME. The functions of insulin substitution were likely generated due to the activation of AMP-activated protein kinase. Meanwhile, BME acted as a glucagon-like peptide 1 (GLP-1) secretagogue on enteroendocrine cells, which may be mediated by the activation of bitter-taste receptors. Therefore, BME possesses insulin sensitizing, insulin substitution, and GLP-1 secretagogue functions upon intestinal cells. These effects of BME on intestinal cells likely play a significant part in the anti-diabetic action of bitter melon.

Evaluation of acute and sub-chronic toxicity of bitter melon seed extract in Wistar rats

“…The whole plant of bitter melon (e.g., fruit pulp, leaves, and seeds) possesses several pharmacological effects, such as anti-diabetic, anti-hyperlipidemic, contraceptive, laxative, and anti-bacterial effects [2] . In particular, bitter melon is considered a complementary and alternative medicine (i.e., dietary supplement) for glycemic control [3] , [4] , [5] , [6] , [7] . According to the report by the International Diabetes Federation (IDF), the global diabetes prevalence in adults in 2021 is around 10% (537 million), and the number of patients is projected to increase to 643 million by 2030 [8] .…”

Transcriptome analysis of five different tissues of bitter gourd (Momordica charantia L.) fruit identifies full-length genes involved in seed oil biosynthesis

“…7). Antidiabetic properties of bitter gourd fruits have been demonstrated in several in vitro, in vivo, and clinical studies 8,35,36 . Most of the compounds responsible for its bitter taste and antidiabetic properties are triterpenoids and steroids 37 .…”

Cytotoxic and Anti-Inflammatory Triterpenoids in the Vines and Leaves of Momordica charantia

“…Cells were seeded in 96-well plates and treated in triplicate with the desired compound at the indicated concentration (see Section 2.2) or an equal volume of the solvent (control; DMSO for the triterpenoids; phosphate-buffered saline (PBS; pH 7.4) for LPS) in serum-free medium for 24 h. A Quick Cell Proliferation Colorimetric Assay Kit (Bio-Vision, Milpitas, CA, USA) was then employed to analyze the relative cell numbers, as described previously [34]. The survival rate relative to the control was determined, and the mean ± standard deviation was calculated.…”

“…The resulting suspension was centrifuged at 12,000× g for 10 min at 4 • C. The supernatant was collected and analyzed for the protein concentration by using Bradford reagent. Equal amounts of protein were sampled from different treatments and subjected to electrophoresis and Western blotting, as described previously [34,35]. Immunoreactive bands were detected using the UVP BioSpectrum imaging system (Upland, CA, USA).…”