Momordica balsamina Fruit Extracts Enhances Selected Aspects of the Insulin Synthesis/Secretion Pathway

Abstract

Previous studies have suggested that crude plant extracts of the anti-diabetic medicinal plant, Momordica balsamina (MB) may exert their anti-diabetic effect through either enhancement of insulin sensitivity or inhibition of intestinal glucose absorption. However, the effects of these MB extracts on insulin synthesis and secretion are not well documented in the literature. Therefore, a main purpose of the current research was to examine in vitro effects of MB crude fruit extracts on selected aspects of the insulin synthesis and secretion pathway. The study results indicated that ethanol, ethyl acetate and hexane MB crude extracts had the significantly enhanced the uptake of glucose by RIN-m5F β-cells in a manner depending on concentration. Furthermore, these same MB fruit extracts significantly increased the quantities of synthesized and secreted insulin by RIN-m5F β-cells. In addition, significant upregulation of the pre-proinsulin gene levels by the same MB fruit extracts was detected by the conventional end-point Polymerase Chain Reaction (RT-PCR), whereas a significant upregulation of gene expression levels of the two pancreatic glucose sensors (glucokinase enzyme and Glucose Transporter 2 (GLUT2)) as well as the two insulin gene transcription factors Musculoaponeurotic Fibrosarcoma homolog A (MafA) and Pancreatic Duodenal Homeobox-1 (PDX-1) were detected by means of quantitative reverse transcriptase PCR. In conclusion, the outcomes of this research propose that MB fruit extracts may, in addition to their effects on sensitivity of insulin and inhibition of intestinal glucose absorption, exert their anti-diabetic effects through stimulation of both the insulin synthesis and secretion.