Research Progress on Hypoglycemic Mechanisms of Resistant Starch: A Review

Strategic exploration of whole grain cereals in modulating the glycaemic response

In the current context, diabetes presents itself as a widespread and complex global health issue. This study explores the significant influence of food microstructure and food matrix components interaction (protein, lipid, polyphenols, etc.) on the starch digestibility and the glycaemic response of post-prandial glycemia, focusing on the potential effectiveness of incorporating bioactive components from whole grain cereals into dietary strategies for the management and potential prevention of diabetes. This study aims to integrate the regulation of postprandial glycaemic homeostasis, including the complexities of starch digestion, the significant potential of bioactive whole grain components and the impact of food processing, to develop a comprehensive framework that combines these elements into a strategic approach to diabetes nutrition. The convergence of these nutritional strategies is analyzed in the context of various prevalent dietary patterns, with the objective of creating an accessible approach to mitigate and prevent diabetes. The objective remains to coalesce these nutritional paradigms into a coherent strategy that not only addresses the current public health crisis but also threads a preventative approach to mitigate future prevalence and impact.

Preparation of Resistant Starch Types III + V with Moderate Amylopullulanase and Its Effects on Bread Properties

The potential of PulY103A (a moderate amylopullulanase originating from Bacillus megaterium) for resistant starch production under moderate conditions (40 °C; a pH of 6.5) was investigated. PulY103A was much more suitable for pea resistant starch production with a high growth rate of 3.63. The pea resistant starch (PSpa) produced with PulY103A had lower levels of swelling power and solubility and a better level of thermostability than native pea starch (PSn) and autoclaved PS (PSa). The starch crystallinity pattern was B + V, which indicated that the PSpa belonged to RS types III + V. In addition, PSpa was used for breadmaking. The results showed that the bread quality was not significantly influenced compared to the control group when the content of PSpa was under 10% (p > 0.05). The bread supplemented with 10% PSpa had a significantly increased TDF content compared to that of the control (p < 0.05). Moreover, the in vitro mineral bioavailability of the bread sample was influenced gently compared to other dietary fibers, and the bread sample changed from a high-glycemic-index (GI) food to a medium-GI food corresponding to white bread at the same concentration of PSpa. These results indicated that PSpa is a good candidate for the production of dietary foods.

Hypoglycemic Activity of Rice Resistant-Starch Metabolites: A Mechanistic Network Pharmacology and In Vitro Approach

Rice (Oryza sativa L.) is one of the primary sources of energy and nutrients needed by the body, and rice resistant starch (RRS) has been found to have hypoglycemic effects. However, its biological activity and specific mechanisms still need to be further elucidated. In the present study, 52 RRS differential metabolites were obtained from mouse liver, rat serum, canine feces, and human urine, and 246 potential targets were identified through a literature review and database analysis. A total of 151 common targets were identified by intersecting them with the targets of type 2 diabetes mellitus (T2DM). After network pharmacology analysis, 11 core metabolites were identified, including linolenic acid, chenodeoxycholic acid, ursodeoxycholic acid, deoxycholic acid, lithocholic acid, lithocholylglycine, glycoursodeoxycholic acid, phenylalanine, norepinephrine, cholic acid, and L-glutamic acid, and 16 core targets were identified, including MAPK3, MAPK1, EGFR, ESR1, PRKCA, FYN, LCK, DLG4, ITGB1, IL6, PTPN11, RARA, NR3C1, PTPN6, PPARA, and ITGAV. The core pathways included the neuroactive ligand-receptor interaction, cancer, and arachidonic acid metabolism pathways. The molecular docking results showed that bile acids such as glycoursodeoxycholic acid, chenodeoxycholic acid, ursodeoxycholic acid, lithocholic acid, deoxycholic acid, and cholic acid exhibited strong docking effects with EGFR, ITGAV, ITGB1, MAPK3, NR3C1, α-glucosidase, and α-amylase. In vitro hypoglycemic experiments further suggested that bile acids showed significant inhibitory effects on α-glucosidase and α-amylase, with CDCA and UDCA having the most prominent inhibitory effect. In summary, this study reveals a possible hypoglycemic pathway of RRS metabolites and provides new research perspectives to further explore the therapeutic mechanism of bile acids in T2DM.

Exploring the formation mechanism of resistant starch (RS3) prepared from high amylose maize starch by hydrothermal-alkali combined with ultrasonic treatment

In this study, type III resistant starch (RS3) was prepared from high amylose maize starch (HAMS) using hydrothermal (RS-H), hydrothermal combined ultrasonication (RS-HU), hydrothermal-alkali (RS-HA), and hydrothermal-alkali combined ultrasonication (RS-HAU). The role of the preparation methods and the mechanism of RS3 formation were analyzed by studying the multiscale structure and digestibility of the starch. The SEM, NMR, and GPC results showed that hydrothermal-alkali combined with ultrasonication could destroy the granule structure and α-1,6 glycosidic bond of HAMS and reduce the molecular weight of HAMS from 195.306 kDa to 157.115 kDa. The other methods had a weaker degree of effect on the structure of HAMS, especially hydrothermal and hydrothermal combined ultrasonication. The multiscale structural results showed that the relative crystallinity, short-range orderliness, and thermal stability of RS-HAU were significantly higher compared with native HAMS. In terms of digestion, RS-HAU had the highest RS content of 69.40 %. In summary, HAMS can generate many short-chain amylose due to structural damage, which rearrange to form digestion-resistant crystals. With correlation analysis, we revealed the relationship between the multiscale structure and the RS content, which can be used to guide the preparation of RS3.

The structural properties and resistant digestibility of maize starch-glyceride monostearate complexes

This study investigated the effects of pullulanase debranching on the structural properties and digestibility of maize starch (MS)-glyceryl monostearate (GMS) complexes. According to our results, the apparent amylose content of MS increased from 36.34 % to 95.55 % and complex index reached 93.09 % after 16 h of pullulanase debranching. The crystallinity of prepared MS-GMS complexes increased to 33.24 % with a blend of B-type and V-type crystals. The surface of prepared MS-GMS complexes granules emerged more small lamellar crystals tightly adhering to the surface of granules. The Fourier transforms infrared spectroscopy analysis showed that debranching pretreatment MS-GMS complexes exhibited higher levels of short-range orders structure. These results indicated that maize starch was favorable to form more ordered starch-lipid complexes structure after debranching pretreatment, which resulted in the restriction of starch hydrolysis. In vitro digestion data implied that resistant starch (RS) content increased with the extension of the debranching time, and the highest RS content (69.58 %) appeared with 16 h pullulanase debranching. This work suggests that debranching pretreatment could be an efficient way to produce ordered starch-lipid complexes with controllable structure and anti-digestibility.

Postprandial glucose-lowering effects by sago (Metroxylon sagu Rottb.) resistant starch in spontaneously type 2 diabetes, Goto-Kakizaki rat

Introduction: The beneficial effects of resistant starch (RS) consumption on health in terms of reducing postprandial hyperglycaemia are evident. However, the potential of local Sarawak sago RS in regulating glucose has not been extensively studied. Objectives: This study aims to identify glucose-lowering effects of Sarawak sago RS, namely native (RS2) and chemically modified (RS4). Methodology: An oral glucose tolerance test (OGTT) was performed before and after 1 month treatment with sago RS2 and RS4 in spontaneously type 2 diabetes (T2D), Goto-Kakizaki (GK) rat. The mechanisms involved were further explored by screening the in vitro inhibitory activities of α-glucosidase and dipeptidyl peptidase (DPP)-IV. Histopathology examination for pancreas, kidney and liver tissues was done in response to sago RS intake using haematoxylin and eosin (H&E) staining. Results and discussion: The incremental area under the curve (iAUC) for blood glucose in RS-treated groups was decreased and significant in RS2-treated group (p < 0.05). Improved iAUC for insulin and higher glucagon-like peptide (GLP-1) levels were observed in all RS-treated groups (p < 0.05). Both sago RS may have potential roles in regulating glucose via α- glucosidase and DPP-IV inhibitory activities by reducing intestinal glucose absorption. For histopathology, although insignificant, sago RS2 and RS4 attenuated lesion scores of pancreatic tissue whereas the liver and kidney tissues significantly showed lesser lesion scores compared to the control diabetic group suggesting the potential of RS in reducing cell degeneration. Conclusion: Findings of this study indicates that RS2 showed greater glucose-lowering effect when compared to RS4, thus the therapeutic potential in the T2D management should be further explored.