The Chinese researchers spotlighted legume sources such as lupin, black beans and soybeans, reporting their illustrated in vivo and in vitro anti-diabetic mechanisms.
The review states their potential efficacy results, in part, from the structure of the native peptide aglycin, whereby the knotted shape enables its resistance to enzymatic breakdown within the digestive tract.
Yet, the report also regards the associated challenges with these sources, including poor chemical and physical stability and poor bioavailability, which must be considered.
“Based on their inherent amino acid composition and sequence, bioactive peptides exhibit different activities in regulating glucose and lipid metabolism, which exert beneficial effects on the control of diabetic progress,” they conclude.
Plants against disease
T2D is a vastly present metabolic disease across the globe, characterised by consistently high blood glucose levels resulting from insulin resistance or its insufficient production. Such hyperglycaemia has been associated with a myriad of further health complications, including damage to multiple organs such as the kidneys and heart.
Research into the potential treatments for those suffering from T2D has been a continuous area of interest, recently shifting to natural plant-derived options to incur an array of health benefits in addition to effectively controlling blood sugar. Such compounds may also increase weight loss, improve β-cell function, and delay disease progression to enable for effective long-term treatment and prevention.
Specifically, treatment options using oral peptides has been an area of interest in recent years, with legume-derived types presenting a strong protein source, as well as additional beneficial phytochemicals.
The evidence specifying the potential hypoglycaemic action of such legume bioactive peptides has been increasing. Thus, the researchers in the current study pooled the evidence from the literature, to conclude on their efficacy in managing T2D for their potential use in anti-diabetic drug development.
The review highlights studies demonstrating the potentials of peptides derived from Andean lupin legumes, black beans, and soybeans, which were observed to significantly lower postprandial glucose levels in rat models. A further study was discussed with regards to proposing that soy peptides improved glucose metabolism via “up regulating the expression of GLUT1 and GLUT4 in cultured hepatic cells.”
The scientists explain the mechanism of action behind the findings: “Crucially, some oligopeptides with short sequences of 2–20 amino acids can be absorbed by the intestine into the blood circulation and exert systemic or local physiological anti-diabetic activities, such as decreasing blood glucose levels, improving glucose and insulin sensitivity in target tissues, and inhibiting key enzymes like α-amylase, α-glucosidase, and DPP-4 related to T2D.
“The hypoglycaemic mechanism of legume diabetic peptides mainly includes reducing glucose absorption, promoting pancreatic β-cells proliferation, enhancing insulin secretion and sensitivity through signalling pathways associated with diabetes, and inhibiting carbohydrate-digesting enzymes (α-amylase and α-glucosidase) and DPP-4 in target organs,” they add.
Whilst the report suggests “tremendous potential” in the use of legume-derived peptides for T2D therapies, associated disadvantages with their use is noted, resulting from their stability and bioavailability.
“Despite their tremendous potential value in anti-T2D therapies, legume-derived peptides have intrinsic disadvantages, including poor chemical and physical stability, poor bioavailability, short effective half-life, and inefficiency of oral delivery, which must be considered for their application as nutraceuticals or medicines,” they specify.
Yet, the researchers describe how the oral delivery of such peptides can be improved by rational design, increasing biological activity or selectivity.
“Undoubtedly, legume-derived peptides research can benefit from pharmaceutical approaches for the discovery, design, and development of nutraceutical or oral medicinal peptides for T2D,” they conclude, stressing the need for future studies to be conducted.
“Legume-Derived Bioactive Peptides in Type 2 Diabetes: Opportunities and Challenges”
by Kanghong Hu, Huizhong Huang, Hanluo Li, Yanhong Wei and Chenguang Yao