Inhibition mechanism of ferulic acid against α-amylase and α-glucosidase

Prebiotic properties of extruded maize starch-caffeic acid complexes: A study from the small intestine to colon in vitro

Recent studies show that starch-polyphenols complexes exert positive effects on gut health, but the probiotic effects of maize starch-caffeic complexes remain underexplored. Therefore, this study aimed to investigate the probiotic effect of maize starch-caffeic complexes from the small intestine to the colon. First, maize starch was extruded with caffeic acid and subjected to in vitro digestion, and the undigested parts were fermented in vitro, and the structural characteristics, short chain fatty acids (SCFAs) and microbiota communities were investigated. Results showed that caffeic acid reduced the long/short-range order of maize starch after extrusion, significantly increasing resistant starch to 30.35 ± 2.36 %. In vitro fermentation indicated that microbiota utilized the amorphous area of the residues first, promoting SCFAs production and the growth of Bifidobacterium and Lactococcus genus. Overall, the probiotic properties of extruded maize starch-caffeic acid complexes suggest they could serve as a functional food for health benefits.

New insights into rice starch-gallic acid-whey protein isolate interactions: Effects of multiscale structural evolution and enzyme activity on starch digestibility

In starch-based food where proteins and polyphenols coexist, the impact of protein on the inhibition of starch digestion by polyphenols is unclear. Therefore, the aim of this study was to investigate the impact of whey protein isolate (WPI) on the inhibition of rice starch digestion by gallic acid (GA) from the aspects of multiscale structure and enzyme activity. Rice starch-gallic acid-whey protein isolate complex (RS-GA-WPI) was formed predominantly by hydrogen bonding and hydrophobic interactions. Compared to rice starch-gallic acid complex (RS-GA), RS-GA-WPI exhibited higher short-range ordering and thermal stability, and lower relative crystallinity. Fluorescence spectra and molecular docking showed that the interactions between GA and WPI weakened the hydrogen bond between GA and enzyme active site, so that WPI significantly reduced the enzyme inhibitory activity of GA. The above factors led to the result that the presence of WPI weakened the inhibitory effect of GA on starch digestibility. RS-GA-WPI showed higher starch digestibility and lower resistant starch content compared to RS-GA. This study provided a new understanding of starch digestion mechanism in starch-polyphenol-protein coexistence system.

Inhibitory effects and mechanisms of sorghum 3-deoxyanthocyanidins as a dual-target inhibitor against α-amylase and α-glucosidase

Sorghum 3-deoxyanthocyanidins (3-DAS) can potentially reduce postprandial hyperglycemia to treat type 2 diabetes, but its mechanisms remain unknown. Herein, the inhibitory effects of different 3-DAS and their structural analogs on α-amylase and α-glucosidase were investigated. Results showed that luteolinidin (LN) had more potent inhibitory effects. The related inhibitory mechanism was clarified by inhibition kinetics and multi-spectroscopy. Results indicated that LN could inhibit the activities of the two enzymes in a non-competitive and reversible mixed mode, along with altering the hydrophobic environment around the amino acid residues of enzymes. Besides, LN could statically quench the endogenous fluorescence of enzymes and reduce the content of the α-helix structure of the enzymes. Molecular docking analysis suggested that hydrogen bonding and Van der Waals forces were the primary interactions responsible for LN binding to the enzyme. These findings provide essential data support for high-value utilization of sorghum resources in food nutrition and healthcare.

Exploring synergistic inhibitory mechanisms of flavonoid mixtures on α-glucosidase by experimental analysis and molecular dynamics simulation

The study was the first to evaluate the synergistic interaction of luteolin + quercetin, luteolin + 3-O-methylquercetin, and quercetin + 3-O-methylquercetin mixtures on α-glucosidase and the binding mechanisms were explored using both experimental and theoretical approaches. The results showed that three flavonoid mixtures exhibited a mixed type of inhibition and demonstrated the most potent synergistic effects on α-glucosidase inhibition at 6:4 ratio, with interaction index (γ) of 0.85, 0.78 and 0.73, respectively. The three mixtures had a great influence on α-glucosidase secondary structures. Molecular simulation further demonstrated that three flavonoid mixtures formed hydrophobic interactions and hydrogen bonds with amino acid residues at different sites of α-glucosidase. Collectively, luteolin + quercetin, luteolin + 3-O-methylquercetin and quercetin + 3-O-methylquercetin were found to inhibit α-glucosidase in a synergistic manner and can be potentially used for the development of hypoglycemic food products.

Establishing a link between the chemical composition and biological activities of Gladiolus italicus Mill. from the Turkish flora utilizing in vitro, in silico and network pharmacological methodologies

OBJECTIVES

Five solvent extracts (n-hexane, ethyl acetate, ethanol, ethanol/water (70%), and water) of Gladiolus italicus Mill. from Turkey were evaluated for chemical and biological properties.

METHODS

Antioxidant activities, inhibitory properties against key enzymes involved in the etiology of chronic diseases were tested, as well as cytotoxic effects on different cell lines. Chemical characterization was also carried out to determine the most abundant compounds of each extract.

RESULTS

The highest total phenolic content (TPC) was observed in the water extract while highest TFC in ethanol/water extract. The most abundant compounds in the extracts were hyperoside (69041.06 mg kg-1), isoquercitrin (46239.49 mg kg-1), delphindin-3,5-diglucoside (42043.81 mg kg-1), myricetin (21486.61 mg kg-1), and kaempferol-3-glucoside (21199.76 mg kg-1). Molecular dynamic (MD) simulations confirmed the structural stability and dynamic conformational integrity of these complexes over a period of 100 ns. In network pharmacology, A total of 657 unique target genes were screened: 52 associated with programmed cell death-1 (PD-1), 85 with vascular endothelial growth factor receptor-2 (VEGFR2), and 130 with fibroblast growth factor receptor-2 (FGFR2), identifying crucial gene interactions for these proteins. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted, revealing significant interactions and pathways such as the advanced glycation end products (AGE) and their receptors (RAGE) signaling pathway in diabetic complications and T- helper 17 (Th17) cell differentiation, among others. This elucidation of complex networks involving key genes like AKT Serine/Threonine Kinase 1 (AKT1), MYC proto-oncogene (MYC), tumor protein 53 (TP53), Interleukin 6 (IL6), and tumor necrosis factor (TNF) provides a promising foundation for the development of targeted therapies in the treatment of non-communicable diseases.

CONCLUSION

These results show that G. italicus could be a natural source of potent antioxidants and enzyme inhibitors which need to be further explored for the development of biopharmaceuticals.

Effects of hydrodynamic cavitation combined with snail enzyme treatment on the structure and functional properties of water-soluble dietary fiber in rice husks

In this study, we adopted the synergistic modification technology of hydrodynamic cavitation and snail enzyme, to improve the yield and activity of soluble dietary fibers (SDFs) of rice husk. The physicochemical properties, structural changes, and inhibition of α-glucosidase and α-amylase of SDFs were examined in vitro. This synergistic treatment significantly increased the yield of SDFs to 18.64 % ± 0.16 %, significantly reduced the particle size to 122.33 ± 0.26 nm, and significantly increased the specific surface area to 1.718 ± 0.002 m2/g. The absolute value of the zeta potential significantly increased to -36.39 ± 0.12 mV, indicating an excellent solution stability and gel-forming ability. At the same time, the water-holding, oil-holding, and swelling capacities were significantly enhanced, reaching 8.52 ± 0.09 g/g, 4.85 ± 0.29 g/g, and 7.29 ± 0.25 mL/g, respectively. Structural analysis showed that the synergistic treatment destroyed the fiber structure, produced a large number of small molecule fragments, and significantly changed the monosaccharide components and functional group distribution. Functional evaluation showed that the inhibitory effect of CE-SDF on α-glucosidase and α-amylase was significantly enhanced, and enzymatic reaction kinetic analysis revealed that both enzymes were competitive inhibitors, with IC50 values of 2.893 and 1.727 mg/mL, respectively. In summary, the synergistic modification of hydrodynamic cavitation and snail enzyme greatly optimized the structural and functional properties of rice husk SDFs, providing a theoretical basis for its application in the field of hypoglycemic drugs and functional foods.

Avicularin is a minor aldose reductase inhibitor in defatted seeds of Oenothera biennis L.: Screening, inhibitory kinetics, and interaction mechanism

Inhibition of aldose reductase (AR) activity is promising for mitigating diabetic complications. Defatted evening primrose seeds (DO), a byproduct of evening primrose oil production, exhibits significant AR inhibitory effects. This study optimized extraction conditions of DO using response surface methodology to maximize the recovery of AR inhibitors (ARIs). A combination of high-speed countercurrent chromatography, affinity-based ultrafiltration, and high-performance liquid chromatography was used to screen ARIs from DO extract. Five compounds were identified as ARIs, with avicularin, a minor ARI, demonstrating the strongest inhibitory activity (IC50 = 4.17 μg mL-1). The inhibitory kinetics and interaction mechanisms of avicularin against AR were investigated, revealing that avicularin acts as a non-competitive inhibitor of AR (Ki = 4.42 μM). Avicularin quenched the intrinsic fluorescence of AR through static quenching, forming non-covalent complexes primarily via hydrogen bonds and van der Waals forces, while also altering the conformational structure and microenvironment of AR, impairing AR activity.

Optimization of Extraction Process, Structural Characterization, and Antioxidant and Hypoglycemic Activity Evaluation of Polysaccharides From the Medicinal and Edible Plant: Cistanche deserticola Ma

INTRODUCTION

Cistanche deserticola Ma (CD), an edible and medicinal plant native to Xinjiang, Inner Mongolia, and Gansu in China, is rich in bioactive polysaccharides known for their health-promoting properties. The polysaccharides of C. deserticola (CDPs) have been shown to possess a range of beneficial activities, including immunomodulatory, anti-aging, antioxidant, and anti-osteoporosis effects.

OBJECTIVE

This study seeks to identify the optimal conditions for extracting CDPs using hot water. Additionally, it aims to evaluate their chemical properties, antioxidant activity, hypoglycemic effects, and cytotoxicity. The findings will provide a theoretical foundation for the potential use of CDPs in functional foods and pharmaceuticals.

METHODOLOGY

The study employed response surface methodology to optimize the hot water extraction conditions for CDPs. The extracted CDPs were characterized using a range of chemical, spectroscopic, and instrumental analyses. Furthermore, their antioxidant activity, hypoglycemic effects, and cytotoxicity were evaluated through relevant assays to assess their potential health benefits.

RESULTS

Under optimal conditions, the yield of CDPs was 45.85% ± 1.91%. CDPs were identified as acidic heteropolysaccharides with a wide molecular weight distribution, ranging from 0.3 to 128.2 kDa. They were composed primarily of glucose (51.21%), arabinose (32.86%), galactose (17.88%), and smaller amounts of galacturonic acid (4.66%), rhamnose (1.85%), mannose (1.32%), glucosamine hydrochloride (1.08%), and xylose (0.56%). Antioxidant assays demonstrated that CDPs exhibited significant free radical scavenging activity, metal ion chelation, and reducing power. Additionally, CDPs inhibited α-glucosidase and α-amylase in vitro through a mixed-type mechanism, as well as static fluorescence quenching. Cytotoxicity assays showed that CDPs were nontoxic to L02 and AML12 cells.

CONCLUSION

This study offers a theoretical foundation for the potential use of CDPs in functional foods and pharmaceuticals and provides valuable insights for the development of new antioxidant and hypoglycemic agents from natural sources.

Effect of different thermal treatments on starch digestion of Tsamba (Highland barley products): Insights from starch structural properties and enzyme activity

This study elucidated the mechanisms involved in the impact of Tsamba (a highland barley product) starch digestibility by different thermal treatments. The results demonstrate that different thermal processing methods (microwave, roasting, sand frying, frying, baking, and steaming) significantly alter the polyphenol content of highland barley, which in turn affects its ability to inhibit α-amylase activity. SEM, CLSM, XRD and FTIR were used to evaluate the effects on starch microstructure and digestibility. The microstructure, short-range order, and crystalline structure of starch would modify after different thermal treatments. Notably, the starch structure with the least disruption and improvement in resistance to enzyme hydrolysis suggests that microwaves may be an effective way to produce foods with higher resistant starch content. This study provides valuable insights into dietary strategies for the management of starch digestibility in people with diabetes.

Ultrasonic collaborative pulse extraction of sugarcane polyphenol with good antiaging and α-glucosidase inhibitory activity

Sugarcane, as one important and heavily planted industrial crop, is meaningful to develop its byproducts. In this paper, the ultrasonic collaborative pulse was beneficial for the yield improvement and good bioactivity protection. The sugarcane polyphenol extract (SPE) yield reached 2.42 ± 0.08 mg/g DW at the optimized conditions: pulse time of 60 s, pulse intensity of 2 kV/cm, ultrasonic time of 90 min, and ultrasonic power of 120 W. The SPE contained the total phenolic content of 6.01 ± 0.12 mg GAE/g extract and total flavonoids content of 7.15 ± 0.24 mg RE/g extract. The SPE was mainly composed of chlorogenic acid, schaftoside, hyperoside, quercitrin, and trans-3-hydroxycinnamic acid with 10.24 %, 14.92 %, 4.22 %, 12.05 %, 25.54 %, respectively. The SPE showed good radical scavenging activity with ORAC value of 134.57 μmol/g. The SPE could reduce the oxidative stress and extend the mean lifespan of nematodes by 7.19 % in vivo through increasing the activity of SOD and CAT to decrease the ROS level and MDA content. In addition, the SPE showed strong α-glucosidase inhibitory activity with IC50 of 0.53 mg/mL in a mixed inhibition type, which suggested that the SPE had good hypoglycemic potential.

Effect of Planting Systems on the Physicochemical Properties and Bioactivities of Strawberry Polysaccharides

Suitable planting systems are critical for the physicochemical and bioactivities of strawberry (Fragaria × ananassa Duch.) polysaccharides (SPs). In this study, SPs were prepared through hot water extraction, and the differences in physicochemical characteristics and bioactivities between SPs derived from elevated matrix soilless planting strawberries (EP-SP) and those from and conventional soil planting strawberries (GP-SP) were investigated. A higher extraction yield was observed for EP-SP (5.88%) than for GP-SP (4.67%), and slightly higher values were measured for the average molecular weight (632.10 kDa vs. 611.88 kDa) and total sugar content (39.38% vs. 34.92%) in EP-SP. In contrast, a higher protein content (2.12% vs. 1.65%) and a more ordered molecular arrangement were exhibited by GP-SP. Monosaccharide composition analysis revealed that EP-SP contained higher levels of rhamnose (12.33%) and glucose (49.29%), whereas GP-SP was richer in galactose (11.06%) and galacturonic acid (19.12%). Thermal analysis indicated only minor differences in decomposition temperatures (approximately 225-226 °C) and thermal stability between the samples. However, GP-SP showed a higher enthalpy change (ΔHg = 18.74 J/g) compared to EP-SP (13.93 J/g). Biological activity assays revealed that GP-SP generally exerted stronger non-enzymatic glycation inhibition at both early and final stages (IC50: 7.47 mg/mL vs. 7.82 mg/mL and 11.18 mg/mL vs. 11.87 mg/mL, respectively), whereas EP-SP was more effective against intermediate α-dicarbonyl compounds (maximum inhibition of 75.32%). Additionally, GP-SP exerted superior α-glucosidase inhibition (IC50 = 2.4583 mg/mL), in line with kinetic and fluorescence quenching analyses showing a higher enzyme-substrate complex binding affinity (Kis = 1.6682 mg/mL; Ka = 5.1352 × 105 M-1). Rheological measurements demonstrated that EP-SP solutions exhibited a pronounced increase in apparent viscosity at higher concentrations (reaching 3477.30 mPa·s at 0.1 s-1 and 70 mg/mL) and a stronger shear-thinning behavior, while GP-SP showed a comparatively lower viscosity and lower network order. These findings suggest that different planting systems significantly affect both the molecular structures and functionalities of SPs, with GP-SP demonstrating enhanced hypoglycemic and anti-glycation properties. It is therefore recommended that suitable planting systems be selected to optimize the functionality of plant-derived polysaccharides for potential applications in the food and pharmaceutical industries.

New C-linked diarylheptanoid dimers as potential α-glucosidase inhibitors evidenced by biological, spectral and theoretical approaches

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by elevated blood glucose levels, generally due to defects of insulin action or secretion. Inhibition of α-glucosidase, an enzyme responsible for carbohydrate degradation, is a promising strategy for managing postprandial hyperglycemia in diabetic patients. In this study, two new C-linked diarylheptanoid dimers, kaemgalanganols A (1) and B (2), were isolated from K. galanga, which showed obvious inhibitory activity on α-glucosidase but weak activity on protein tyrosine phosphatase 1B (PTP1B). Kaemgalanganol B had an IC50 value of 35.1 μM against α-glucosidase, obviously more potent than kaemgalanganol A (IC50 = 78.5 μM) and acarbose (IC50 = 363.0 μM). Enzyme kinetic study indicated that 2 was a reversible mixed-type inhibitor of α-glucosidase via non-competitive and anti-competitive inhibition modes. Fluorescence quenching and UV-visible spectroscopic study revealed that fluorescence quenching mechanism of 2 on α-glucosidase is a combination of dynamic quenching and static quenching, accompanied by non-radiative energy transfer. Compound 2 formed complex with α-glucosidase closer to the Tyr residue, and induced changes in both the microenvironment and peptide backbone. Surface hydrophobicity and CD spectra measurement indicated that 2 affected the function of α-glucosidase by decreasing the surface hydrophobicity of α-glucosidase as well as altering the secondary structure instead of the overall three-dimensional framework, which is consistent with the results of fluorescence experiment. Molecular docking manifested that compound 2 had a strong binding affinity (-7.27 kcal/mol) with α-glucosidase, higher than 1 (-9.82 kcal/mol) and acarbose (-4.48 kcal/mol), consistent with the enzyme inhibitory assay. Besides hydrogen bonds, electrostatic interactions and hydrophobic interactions played important roles in the binding of 2 with α-glucosidase. This study disclosed the inhibitory activity and mechanism of 2 against α-glucosidase, which provides a theoretical basis for the development of new antidiabetic drugs form K. galanga.

A UPLC-MS/MS coupled with GC-MS method for quantification of twenty-one chemical ingredients from Suxiao Jiuxin pill in multiple tissue of rat and its application to tissue distribution study

Suxiao Jiuxin pill (SJP) was a commonly-used traditional Chinese medicine for treating cardiovascular diseases. It was composed of the rhizome of Ligusticum chuanxiong Hort. and Borneolum Syntheticum. The distribution of SJP in vivo was still ambiguous. A UPLC-MS/MS coupled with GC-MS method was developed to quantify twenty-one chemical ingredients in multiple tissues from rat after administration of SJP. Protein precipitation and liquid-liquid microextraction were both utilized in sample pretreatment. All analytes were detected under acceptable specificity, linearity (correlation coefficient > 0.992), sensitivity (LLOQ < 12.5 ng/mL), precision (RSD < 14.8 %), accuracy (RE < ±14.6 %), extraction recovery (between 52.8 % and 124.1 %), matrix effect (ranged from 60.5 % and 149.7 %) and stability (RE < ±16.0 %). The established method was successfully applied in the tissue distribution study of SJP in rats. As a result, the distribution characteristics of ten analytes were clearly elucidated, including borneol, isoborneol, ligustilide, senkyunolide A, ferulic acid, senkyunolide I, levistolide A, neocnidilide, senkyunolide H and angelicide. The information provided by this research was greatly meaningful for the active chemical ingredient exploration and clinical application of SJP.

Investigation of physicochemical properties and structure of ball milling pretreated modified starch-ferulic acid complexes

In this study, the formation mechanism, physicochemical properties, and intermolecular interactions of ball milling pretreated high amylose corn starch (HACS)-ferulic acid (FA) complexes were elucidated by density functional theory (DFT) calculations, and examined their structural and digestive properties. The results showed that the average molecular weight decreased to 92.155 kDa during ball milling pretreatment. The complexation degree of the ball milling pretreated HACS-FA complexes was increased, the relative crystallinity was increased by 11.74 %, and the short-range ordering was significantly improved. Notably, the content of single helix and double helix showed an increasing trend, indicating that HACS-FA complexes had a more compact V-type structure, which corresponded to a 22.39 % increase in resistant starch. DFT calculations further showed that the intermolecular interactions between HACS and FA were mainly hydrophobic, hydrogen bonding, and van der Waals forces. This study is expected to provide a new method for the efficient preparation of HACS-FA complexes.

Quercetin slow-release system delays starch digestion via inhibiting transporters and enzymes

This study investigates the potential of a quercetin-based emulsion system to moderate starch digestion and manage blood glucose levels, addressing the lack of in vivo research. By enhancing quercetin bioaccessibility and targeting release in the small intestine, the emulsion system demonstrates significant inhibition of starch digestion and glucose spikes through both in vitro and in vivo experiments. The system inhibits α-amylase and α-glucosidase via competitive and mixed inhibition mechanisms, primarily involving hydrogen bonds and van der Waals forces, leading to static fluorescence quenching. Additionally, this system downregulates the protein expression and gene transcription of SGLT1 and GLUT2. These findings offer a novel approach to sustaining glucose equilibrium, providing a valuable foundation for further application of quercetin emulsion in food science.

Effect of sorghum bran addition on antioxidant activities, sensory properties, and in vitro starch digestibility of Chinese southern-style steamed bread

BACKGROUND

Chinese steamed bread (CSB) is one of the most important staple foods in China and is also popular in South-East Asia. Developing functional CSB could improve people's resistance to inflammatory and non inflammatory diseases. This work investigated the effect of sorghum bran addition on antioxidant activities, sensory properties, and in vitro starch digestibility of Chinese southern-style steamed bread (CSSB).

RESULTS

In this study, the enhanced CSSB with 0-200 g kg-1 of fine black and tannin (sumac) sorghum bran addition was developed. A small change in phenol content and antioxidant activity was observed at various stages in the processing procedure before steaming. Moreover, a high retention of antioxidant phenolics CSSB with sorghum bran addition was observed. Sorghum bran addition significantly increased the total phenol content and antioxidant activity of CSSB by 4.5-10 times, on average, relative to control. Sorghum bran addition significantly also increased the content of resistant starch, and significantly decreased in vitro starch digestibility in CSSB; these effects were likely due to the joint inhibitory effect of tannins and ferulic acid on starch digestibility. Interestingly, the sorghum bran breads scored higher or similar to control in sensory color preference and overall appearance, but lower on most textural and mouthfeel attributes.

CONCLUSION

Sorghum bran addition significantly increased the antioxidant activity of CSSB and significantly decreased starch digestibility. Moreover, the color and appearance properties were maintained or improved. However, the sensorial textural attributes were negatively impacted by the sorghum bran substitutions. Strategies to improve the texture of bran-fortified breads would likely enhance their consumer acceptability. © 2024 Society of Chemical Industry.

Pectin enhances the inhibition of α-amylase via the mixture of rutin and quercetin

The human dietary system, which contains a variety of compounds such as polyphenols and polysaccharides, is very complex. Whether polysaccharides affect the inhibitory of polyphenol mixtures on α-amylase needs to be further investigated. The aim of this study was to analyze the effect and mechanism of pectin on the inhibition of α-amylase by a mixture of rutin and quercetin (R-Q). Results revealed that the inhibition and quenching affinity of R-Q for α-amylase was enhanced by pectin. The Stern-Volmer quenching constant of R-Q-α-amylase was increased by pectin from (6.08 ± 0.453) × 103 mL/mg to (9.80 ± 0.285) × 103 mL/mg. Pectin enhanced the ability of R-Q to inhibit α-amylase for two main reasons. On the one hand, it was owing to the binding of pectin to rutin, which increased the opportunity for quercetin to bind to the active center of α-amylase, thus enhancing the inhibitory effect of R-Q on α-amylase. On the other hand, pectin and quercetin simultaneously bound to different sites of α-amylase by noncovalent interactions to form the ternary complex of pectin-α-amylase-quercetin. The conformation of α-amylase and the hydrophobicity of amino acid residues were altered by the ternary complex, thereby enhancing the hydrogen bonding in the reaction system.

A comprehensive review on pharmacokinetic mechanism of herb-herb/drug interactions in Chinese herbal formula

Oral administration of Chinese Herbal Medicine (CHM) faces various challenges in reaching the target organs including absorption and conversion in the gastrointestinal tract, hepatic metabolism via the portal vein, and eventual systemic circulation. During this process, factors such as gut microbes, physical or chemical barriers, metabolic enzymes, and transporters play crucial roles. Particularly, interactions between different herbs in CHM have been observed both in vitro and in vivo. In vitro, interactions typically manifest as detectable physical or chemical changes, such as facilitating solubilization or producing precipitates when decoctions of multiple herbs are administered. In vivo, such interactions cause alterations in the ADME (absorption, distribution, metabolism, and excretion) profile on metabolic enzymes or transporters in the body, leading to competition, antagonism, inhibition, or activation. These interactions ultimately contribute to differences in the therapeutic and pharmacological effects of multi-herb formulas in CHM. Over the past two thousand years, China has cultivated profound expertise and solid theoretical frameworks over the scientific use of herbs. The combination of multiple herbs in one decoction has been frequently employed to synergistically enhance therapeutic efficacy or mitigate toxic and side effects in clinical settings. Additionally combining herbs with increased toxicity or decreased effect is also regarded as a remedy, a practice that should be approached with caution according to Traditional Chinese Medicine (TCM) physicians. Such historical records and practices serve as a foundation for predicting favorable multi-herb combinations and their potential risks. However, systematic data that are available to support the clinical practice and the exploration of novel herbal formulas remain limited. Therefore, this review aims to summarize the pharmacokinetic interactions and mechanisms of herb-herb or herb-drug combinations from existing works, and to offer guidance as well as evidence for optimizing CHM and developing new medicines with CHM characteristics.

Consumption of Plant-Derived Phenolic Acids Modulates Hunger and Satiety Responses Due to Chemical Interactions with Enteroendocrine Mediators

Energy-dense foods are commonly rich in fat and simple sugars and poor in dietary fiber and micronutrients; regularly consuming them decreases the concentration and/or effect of anorexigenic hormones and may increase that of orexigenic ones, thereby decreasing satiety. In contrast, plant-derived phenolic-rich foods exert positive effects on satiety. In silico, in vitro, and in vivo investigations on some of most representative phenolic acids like chlorogenic acid (CGA), gallic acid (GA), ferulic acid (FA), and protocatechuic acid (PCA) have shown that they are able to modulate various hunger and satiety processes; however, there are few studies that show how their chemical structure contributes to achieve such effects. The objective of this review is to summarize how these phenolic acids can favorably modulate hormones and other satiety mediators, with emphasis on the chemical interactions exerted between the core of these compounds and their biological targets. The evidence suggests that they form interactions with certain hormones, their receptors, and/or enzymes involved in regulating hunger and satiety, which are attributed to their chemical structure (such as the position of hydroxyl groups). Further research is needed to continue understanding these molecular mechanisms of action and to utilize the knowledge in the development of health-promoting foods.

Hypoglycemic Activity of the Hydroalcoholic Extract of Porophyllum ruderale in CD1 Mice

Diabetes, considered one of the main causes of death in the Mexican population, is a chronic disease caused by alterations in the synthesis of pancreatic insulin or because it is not used effectively by the body. Insufficient action of insulin causes hyperglycemia, which, if not controlled, causes damage to blood capillaries and nerve endings over time, affecting the functioning of various organs and systems. As mentioned above, controlling glucose levels in the population suffering from chronic diseases becomes an essential part of their treatment. The aim of this study was to evaluate the hypoglycemic effect of a hydroalcoholic extract of the aerial parts of Porophyllum ruderale (HEPr). A glucose tolerance curve was developed by monitoring at different times (0-120 min) glucose levels in blood samples taken from an apical tail slice of CD1 mice. HEPr showed a significant effect from baseline on basal glucose levels (114.33 ± 14.74 mg/dL) compared with the control group (60.33 ± 4.16 mg/dL) and the metformin-treated group (129 ± 13 mg/dL). In addition, the values at the end of the tolerance curve (120 min) showed a significant decrease in the study group (66 ± 10.39 mg/dL) compared with the metformin-treated group (108.67 ± 4.50 mg/dL). This effect can be attributed to the presence of chlorogenic acid, cryptochlorogenic acid, ferulic acid, quercetin, and kaempferol 3-O-glucosides in HEPr. In conclusion, P. ruderale constitutes an important source of compounds for use as an adjuvant treatment for the control of hypoglycemia in different chronic diseases.

Cell-free and cell-based antidiabetic effects and chemical characterization of rice bran from Thai cultivars

Rice bran is a valuable by-product of rice milling, prized for its nutritional value and health benefits. This study investigates the antidiabetic properties of rice bran from fifteen commercially available Thai rice cultivars (six brown, four red and five purple). Bran samples were initially screened on their antioxidant potential and ability to inhibit α-glucosidase, as well as on γ-oryzanol levels, total phenolic and total flavonoid contents. Top-ranked cultivars were thoroughly investigated for their antidiabetic potential, samples from red and purple cultivars exhibiting greater activity. Samples from the red cultivar Hom Mali Dang (HMD) demonstrated higher potential to inhibit the activity of α-amylase and aldose reductase (IC50 values of 413.19 ± 57.04 and 205.42 ± 26.47 µg/mL, respectively), along with potent α-glucosidase inhibition in Caco-2 cells (IC50 = 158 µg/mL). Our study highlights the potential of underexplored Thai rice bran cultivars, particularly HMD, as a promising ingredient for diabetic-friendly food supplements.

The combined effects of bisphenol S and hexavalent chromium on alpha-glucosidase: Intermolecular interaction, structural and functional changes

The co-contamination of heavy metal ions and organic pollutants has posed a threat to human health. Herein, this study investigated the intermolecular interactions of bisphenol S (BPS) and hexavalent chromium (Cr(VI)) under both individual and coexisting conditions, with alpha-glucosidase (AG), a key enzyme in carbohydrate metabolism, and the corresponding effects on the structure and function of AG. Multiple spectroscopic and molecular docking methods were employed to conduct the investigation in vitro and in silico. The results indicated that both BPS and Cr(VI) quenched the fluorescence of AG via a combined static and dynamic quenching processes. At 310 K, the binding constants of AG with BPS in the AG-BPS and (AG-Cr(VI))-BPS systems were 1.84 × 104 and 2.03 × 104 L mol-1, and the binding constants of AG with Cr(VI) in the AG-Cr(VI) and (AG-BPS)-Cr(VI) systems were 6.14 × 103 and 4.35 × 103 L mol-1. Cr(VI) could significantly affect the binding site of BPS in AG, while BPS had a minimal impact on the binding site of Cr(VI) in AG. BPS and Cr(VI) caused varied structural alterations of AG, and the impact of their coexistence on the structure of AG was related to the order in which they were added. Both BPS and Cr(VI) had a concentration-related effect on AG activity. This study provides valuable insights into the molecular mechanisms underlying the combined toxic effects of BPS and Cr(VI) on AG, highlighting the potential health risks associated with their environmental co-exposure.

Understanding the multiscale structure and in vitro digestibility changes of corn starch-ferulic acid complexes induced by high hydrostatic pressure

High hydrostatic pressure (HHP) was used to synthesize corn starch (CS) and ferulic acid (FA) complex (CS-FA). Its effects on the structure of the complex at multiple scales and its digestibility were examined. The results demonstrated that HHP significantly influenced the digestibility of the CS-FA complex, decreasing the content of rapidly digestible starch (RDS) while increasing slowly digestible starch (SDS) and resistant starch (RS). Notably, the combined SDS and RS content in the HHP-treated CS-FA complex with 2.0 % FA addition (38.13 %) was significantly higher (p < 0.05) than those in the CS-FA complex without HHP treatment (29.21 %) and pure CS (21.72 %). The results indicated that HHP treatment reduced the enthalpy change (ΔH), number of short-range order structures, and relative crystallinity (RC) while increasing the average particle size of these CS-FA complexes. This treatment also increased the proportion of amorphous starch regions and the degree of agglomeration between the starch and FA. HHP treatment-induced CS-FA complexes exhibited a denser fractal structure and higher short-range order, affecting the interaction sites between the starch and digestive enzymes. These findings suggest the potential application of HHP treatment and FA in modulating the postprandial glycemic response to starchy food.

Investigation on the anti-α-glucosidase mechanism of aspergillus triazolate A from Oxalis corniculate L

Diabetes mellitus characterized by abnormal glucose concentration is a metabolic disease. α-Glu inhibitors from natural sources are a good choice for searching for high-efficiency and low-toxicity hypoglycemic drugs. In this study, a naturally effective α-Glu inhibitor aspergillus triazolate A (ATA) with a peculiar structure was first found in Oxalis corniculate L., then its activity and mechanism were first elucidated through various methods. These mechanisms included enzyme kinetics, circular dichroism spectra, fluorescence spectra, synchronous fluorescence spectrum, 3D fluorescence spectrum, and molecular docking. Meanwhile, the ability to reduce postprandial blood glucose was further investigated in vivo. Research results revealed that ATA was a mixed type α-Glu inhibitor with an IC50 value of 66.87 ± 1.50 μM, which bound to the enzyme from a single site through hydrogen bonding and hydrophobic forces causing the looser secondary structure of α-Glu. It was also found that the binding site of α-Glu was closer to the Trp residue, and the endogenous fluorescence of α-Glu was quenched in a static quenching form. Moreover, the sucrose loading test in vivo revealed that the ATA of 20 mg/kg could effectively reduce the postprandial blood glucose level. Hence, ATA could be used as lead compound to develop novel α-Glu inhibitors.

Investigation of the Chemical Composition and Biological Activities of Eremurus spectabilis M. Bieb through Antioxidant, Enzyme Inhibition, COX-2and iNOS Assessment

Eremurus spectabilis is widespread and used primarily for medicinal and culinary purposes. This study aimed to evaluate the chemical composition, antiradical and antioxidant activities, enzyme inhibitory activities, and anti-inflammatory properties of various extracts from the aerial parts of E. spectabilis. Various assays were used to investigate the antioxidant and enzyme inhibitory properties. The chemical composition of the tested extracts was analyzed using High-Performance Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry (HPLC-ESI-MS/MS). Additionally, the extracts were tested on isolated mouse colon tissue challenged with E. coli lipopolysaccharide (LPS) to replicate the inflammation and oxidative stress burden characteristic of inflammatory bowel diseases. In the chemical composition, vanillic, ferulic, and 4-hydroxybenzoic acids were the prominent compounds. The greatest antioxidant activity was observed in the methanol and water extracts from the aerial parts. Enzyme inhibition tests showed that the ethyl acetate extract had the highest anti-acetylcholinesterase activity. The gene expression of pro-inflammatory cyclooxygenase-2 (COX-2) and pro-oxidant inducible nitric oxide synthase (iNOS) biomarkers were assayed. Among the extracts, the methanol extract was the most effective in blunting LPS-induced gene expression of COX-2. E. spectabilis may serve as a valuable source of phytochemicals for combating oxidative stress and inflammation-driven diseases, with a particular emphasis on colon inflammatory condition.

Targeting Hypoglycemic Natural Products from the Cloud Forest Plants Using Chemotaxonomic Computer-Assisted Selection

The cloud forest (CF), a hugely biodiverse ecosystem, is a hotspot of unexplored plants with potential for discovering pharmacologically active compounds. Without sufficient ethnopharmacological information, developing strategies for rationally selecting plants for experimental studies is crucial. With this goal, a CF metabolites library was created, and a ligand-based virtual screening was conducted to identify molecules with potential hypoglycemic activity. From the most promising botanical families, plants were collected, methanolic extracts were prepared, and hypoglycemic activity was evaluated through in vitro enzyme inhibition assays on α-amylase, α-glucosidase, and dipeptidyl peptidase IV (DPP-IV). Metabolomic analyses were performed to identify the dominant metabolites in the species with the best inhibitory activity profile, and their affinity for the molecular targets was evaluated using ensemble molecular docking. This strategy led to the identification of twelve plants (in four botanical families) with hypoglycemic activity. Sida rhombifolia (Malvaceae) stood out for its DPP-IV selective inhibition versus S. glabra. A comparison of chemical profiles led to the annotation of twenty-seven metabolites over-accumulated in S. rhombifolia compared to S. glabra, among which acanthoside D and cis-tiliroside were noteworthy for their potential selective inhibition due to their specific intermolecular interactions with relevant amino acids of DPP-IV. The workflow used in this study presents a novel targeting strategy for identifying novel bioactive natural sources, which can complement the conventional selection criteria used in Natural Product Chemistry.

Influence of Harvesting Stage on Phytochemical Composition, Antioxidant, and Antidiabetic Activity of Immature Ceratonia siliqua L. Pulp from Béni Mellal-Khénifra Region, Morocco: In Silico, In Vitro, and In Vivo Approaches

Ceratonia siliqua L. is a medicinal plant that has long been used in traditional Moroccan medicine to treat many diseases. This study aimed to assess the impact of the stages of the immature phase of carob pulp (M1, M2, M3, M4, and M5) on phytochemical composition, antioxidant activity, and antidiabetic activity of Ceratonia siliqua L. The identification of the phenolic profile by HPLC-UV/MS-MS and the study of the antidiabetic effect by in silico, in vitro, and in vivo studies were carried out for extracts with high contents of phenolic compounds from immature wild carob pulp from the communes of Timoulit (TM), Bin Elouidane (AW), and Ouaouizerth (TG) in the province of Azilal in the Béni Mellal-Khénifra region. The results revealed a gradual increase in total sugar content over the pulp's ripening period, reaching a value of 2134 ± 56.23 mg GE/100 g fresh weight (FW) for TG. The three locations showed peak values for total polyphenol content (TPC), total flavonoid content (TFC), and total condensed tannin (TCT) at the M2 stage. AW had the highest concentrations of TPC (3819 ± 226.4 mg GAE/100 g FM), TFC (1034 ± 57.08 mg QE/100 g FM), and TCT (1472 ± 28.46 mg CE/100 g FM). The DPPH assay (7892 ± 296.1 mg TE/100 g FM) and the FRAP assay (278.2 ± 7.85 mg TE/100 g FM) both demonstrated that the TG zone is a highly potent antioxidant zone. In contrast, the AW site exhibited a markedly elevated value of 725.4 ± 103.6 mg TE/100 g FM in the ABTS assay. HPLC-UV-MS/MS analysis showed that the methanolic extracts of immature carob pulp (MEICP) from the three areas contained several different chemical compounds. The most prevalent were 3-O-p-coumaroyl-5-O-caffeoylquinic acid, quercetin 3-methyl ether, gallic acid, and galloylquinic acid. Immature carob pulp extract (ICPE) from AW showed the strongest in vitro inhibition of pancreatic α-amylase (IC50 = 0.405 µg/mL) and TG extracts were most potent against intestinal α-glucosidase (IC50 = 0.063 µg/mL). In vivo, AW, TG, and TM extracts significantly reduced postprandial glycemia in rats, with AW having the greatest effect. These results highlight the antidiabetic potential of ICPE. The 3-O-p-Coumaroyl-5-O-caffeoylquinic acid showed better affinity for α-amylase compared to acarbose and interacted significantly with several amino acid residues of the enzyme. Similarly, this molecule and 3,4-Dicaffeoylquinic acid demonstrated a strong affinity for α-glucosidase, suggesting their potential as natural inhibitors of enzymes involved in carbohydrate metabolism. Most of the compounds are not substrates of P-glycoprotein and exhibited high intestinal absorption. Furthermore, the majority of these compounds did not act as inhibitors or substrates of CYP450 enzymes, reinforcing their suitability for development as oral medications. These results underscore the potential of immature carob pulp as a promising antidiabetic agent.

Novel carbazole-oxadiazole derivatives as anti-α-glucosidase and anti-α-amylase agents: Design, synthesis, molecular docking, and biological evaluation

To find novel inhibitors of α-glucosidase and α-amylase, a series of new carbazole-oxadiazole derivatives (6a-6n) were prepared, and screened for their anti-α-glucosidase and anti-α-amylase effects. Most of the tested derivatives showed different degrees of α-glucosidase and α-amylase inhibitory activity (IC50: 21.39 ± 0.69-92.05 ± 1.54 μM, 45.53 ± 1.50-126.14 ± 6.33 μM, respectively) compared to the standard acarbose (IC50: 427.00 ± 9.56 μM, 24.68 ± 1.10 μM, respectively). Thereinto, 6c (IC50 = 21.39 ± 0.69 μM) displayed the most effective anti-α-glucosidase activity and 6e presented the best anti-α-amylase activity with an IC50 value of 45.53 ± 1.50 μM. Lineweaver-Burk plot analysis suggested that 6c and 6e behaved as mixed α-glucosidase inhibitor and mixed α-amylase inhibitor, respectively. The results of circular dichroism, atomic force microscope, and molecular docking simulation exposed interaction mechanisms between two preferred compounds (6c and 6e) and their corresponding enzymes. Combined with the possible properties of reducing the elevation in postprandial blood glucose, oral activity, positive bioavailability, and low cytotoxicity of 6c and 6e, it could be concluded that the target derivatives may be able to act as lead molecules for the development of new hypoglycemic agents.

Effect of Genistein on Starch Digestion In Vitro and Its Mechanism of Action

The digestive properties of starch are crucial in determining postprandial glycaemic excursions. Genistein, an active phytoestrogen, has the potential to influence starch digestion rates. We investigated the way genistein affected the digestive properties of starch in vitro. We performed enzyme kinetics, fluorescence spectroscopy, molecular docking, and molecular dynamics (MD) simulations for analysing the inhibitory properties of genistein on starch digestive enzymes as well as clarifying relevant mechanism of action. Our findings demonstrated that, following the addition of 10% genistein, the contents of slowly digestible and resistant starches increased by 30.34% and 7.18%, respectively. Genistein inhibited α-amylase and α-glucosidase, with half maximal inhibitory concentrations of 0.69 ± 0.06 and 0.11 ± 0.04 mg/mL, respectively. Genistein exhibits a reversible and non-competitive inhibiting effect on α-amylase, while its inhibition on α-glucosidase is a reversible mixed manner type. Fluorescence spectroscopy indicated that the presence of genistein caused declining fluorescence intensity of the two digestive enzymes. Molecular docking and MD simulations showed that genistein binds spontaneously to α-amylase via hydrogen bonds, hydrophobic interactions, and π-stacking, whereas it binds with α-glucosidase via hydrogen bonds and hydrophobic interactions. These findings suggest the potential for developing genistein as a pharmacologic agent for regulating glycaemic excursions.

Deciphering the Potential Therapeutic Effects of Hydnocarpus wightianus Seed Extracts using in vitro and in silico approaches

Phytocompounds possess the potential to treat a broad spectrum of disorders due to their remarkable bioactivity. Naturally occurring compounds possess lower toxicity profiles, which making them attractive targets for drug development. Hydnocarpus wightianus seeds were extracted using ethanol, acetone, and hexane solvents. The extracts were evaluated for phytochemicals screening and other therapeutic characteristics, such as free radicals scavenging, anti α-amylase, anti α-glucosidase, and anti-bacterial activities. The ethanolic extract exhibited noteworthy antibacterial characteristics and demonstrated considerable antioxidant, and anti-diabetic effects. The IC50 value of the ethanolic extract for Dpph, α-amylase, and α-glucosidase were found to be 77.299 ± 3.381 μg/mL, 165.56 2.56 μg/mL, and 136.58 ± 5.82 μg/mL, respectively. The ethanolic extract was effective against Methicillin resistant Staphylococcus aureus (26 mm zone of inhibition at 100 μL concentration). Molecular docking investigations revealed the phytoconstituent's inhibitory mechanisms against diabetic, free radicals, and bacterial activity. Docking score for phytocompounds against targeted protein varies from -7.2 to -5.1 kcal/mol. The bioactive compounds present in the ethanolic extract were identified by Gas chromatography/Mass spectrometry analysis, followed by molecular docking and molecular dynamic simulation studies to further explore the phytoconstituent's inhibitory mechanism of α-glucosidase, ∝-amylase, radical scavenging, and bacterial activity. The electronic structure and possible pharmacological actions of the phytocompound were revealed through the use of Density Functional Theory (DFT) analysis. Computational and in vitro studies revealed that these identified compounds have anti-diabetic, anti-oxidant, and anti-bacterial activities against antibiotic-resistant strain of Staphylococcus aureus.

Polyphenol oxidase mediates (-)-epigallocatechin gallate to inhibit endogenous cathepsin activity in Apostichopus japonicus

Apostichopus japonicus (A. japonicus) has rich nutritional value and is an important economic crop. Due to its rich endogenous enzyme system, fresh A. japonicus is prone to autolysis during market circulation and storage, resulting in economic losses. In order to alleviate this phenomenon, we investigated the effect of polyphenol oxidase (PPO) mediated (-)-epigallocatechin gallate (EGCG) on the activity and structure of endogenous cathepsin series protein (CEP) from A. japonicus. Research on cathepsin activity showed that PPO mediated EGCG could significantly reduce enzyme activity, resulting in a decrease in enzymatic reaction rate. SDS-PAGE and scanning electron microscopy results showed that PPO mediates EGCG could induce CEP aggregation to form protein aggregates. Various spectral results indicated that EGCG caused changes in the structure of CEP. Meanwhile, the conjugates formed by PPO mediated EGCG had lower thermal stability. In conclusion, PPO mediated EGCG was an effective method to inhibit the endogenous enzyme activity.

Inhibition mechanism of different structural polyphenols against α-amylase studied by solid-state NMR and molecular docking

Polyphenol has the considerable effects for inhibition of digestive enzymes, however, inhibition mechanism of molecular size-dependent polyphenols on enzyme activity is still lacking. Herein, inhibition effect and binding interactions of three different structural polyphenols (catechol, quercetin and hesperidin) on α-amylase were studied. Inhibition assays proved that polyphenols significantly inhibited α-amylase and their effects were increased with their molecular sizes. Hesperidin showed the highest inhibition ability of α-amylase, which was determined as IC50 = 0.43 mg/mL. Fluorescence and FT-IR spectroscopy proved that inter-molecular interactions between polyphenols and α-amylase occurred through non-covalent bonds. Besides, the secondary structure of α-amylase was obviously changed after binding with polyphenols. Inter-molecular interactions were investigated using solid-state NMR and molecular docking. Findings proved that hydrogen bonds and π-π stacking interactions were the mainly inter-molecular interactions. We hope this contribution could provide a theoretical basis for developing some digestive enzyme inhibitors from natural polyphenols.

Efficient biotransformation of naringenin to naringenin α-glucoside, a novel α-glucosidase inhibitor, by amylosucrase from Deinococcus wulumuquiensis

Amylosucrase (ASase) efficiently biosynthesizes α-glucoside using flavonoids as acceptor molecules and sucrose as a donor molecule. Here, ASase from Deinococcus wulumuqiensis (DwAS) biosynthesized more naringenin α-glucoside (NαG) with sucrose and naringenin as donor and acceptor molecules, respectively, than other ASases from Deinococcus sp. The biotransformation rate of DwAS to NαG was 21.3% compared to 7.1-16.2% for other ASases. Docking simulations showed that the active site of DwAS was more accessible to naringenin than those of others. The 217th valine in DwAS corresponded to the 221st isoleucine in Deinococcus geothermalis AS (DgAS), and the isoleucine possibly prevented naringenin from accessing the active site. The DwAS-V217I mutant had a significantly lower biosynthetic rate of NαG than DwAS. The kcat/Km value of DwAS with naringenin as the donor was significantly higher than that of DgAS and DwAS-V217I. In addition, NαG inhibited human intestinal α-glucosidase more efficiently than naringenin.

Optimization of Enzymolysis Modification Conditions of Dietary Fiber from Bayberry Pomace and Its Structural Characteristics and Physicochemical and Functional Properties

Bayberry pomace, a nutrient-rich material abundant in dietary fiber (DF), has historically been underutilized due to a lack of thorough research. This study aimed to investigate the physicochemical and functional properties of the DF. Ultrasonic enzymatic treatment was performed to extract the total DF, which was then optimized to produce modified soluble dietary fiber (MSDF) and insoluble dietary fiber (MIDF). The optimized conditions yielded 15.14% of MSDF with a water-holding capacity (WHC) of 54.13 g/g. The DFs were evaluated for their structural, physicochemical, and functional properties. The MSDF showed a higher (p < 0.05) WHC, oil-holding capacity (OHC), swelling capacity (SC), cation exchange capacity (CEC), and glucose adsorption capacity (GAC) (about 14.15, 0.88, 1.23, 1.22, and 0.34 times) compared to the DF. Additionally, the MSDF showed strong, superior radical scavenging and blood sugar-lowering capabilities, with a more porous surface morphology. A Fourier-transform infrared (FT-IR) spectroscopy analysis indicated that enzymatic modification degraded the cellulose and hemicellulose, reducing the DF crystallinity. Overall, the results demonstrated that cellulase hydrolysis could effectively improve the physicochemical and functional properties of DF, thereby paving the way for its development into functional food products.

Inhibition mechanism of theaflavins on matrix metalloproteinase-2: inhibition kinetics, multispectral analysis, molecular docking and molecular dynamics simulation

Dental caries is a chronic and destructive disease and matrix metalloproteinase-2 (MMP-2) plays a major role in caries. The inhibitory mechanisms of theaflavins [theaflavin (TF1), theaflavin-3-gallate (TF2A), theaflavin-3'-gallate (TF2B), and theaflavin-3,3'-digallate (TF3)] on MMP-2 were investigated using techniques such as enzyme inhibition kinetics, multi-spectral methods, molecular docking, and molecular dynamics simulations. The results showed that TF1, TF2A, TF2B, and TF3 all competitively and reversibly inhibited MMP-2 activity. Fluorescence spectra and molecular docking indicated that four theaflavins spontaneously bind to MMP-2 through noncovalent interactions, driven by hydrogen bonds and hydrophobic interactions, constituting a static quenching mechanism and resulting in an altered tryptophan residue environment around MMP-2. Molecular dynamic simulations demonstrated that four theaflavins can form stable, compact complexes with MMP-2. In addition, the order of theaflavins' ability to inhibit MMP-2 was found to be TF1 > TF2B > TF2A > TF3. Interestingly, the order of binding capacity between MMP-2 and TF1, TF2A, TF2B, and TF3 was consistent with the order of inhibitory capacity, and was opposite to the order of steric hindrance of theaflavins. This may be due to the narrow space of the active pocket of MMP-2, and the smaller the steric hindrance of theaflavins, the easier it is to enter the active pocket and bind to MMP-2. This study provided novel insights into theaflavins as functional components in the exploration of natural MMP-2 inhibitors.

Comparative Study of Binding Behaviors of Cyanidin, Cyanidin-3-Galactoside, Peonidin with Tyrosinase

Cyanidin, peonidin and cyanidin-3-galactoside are the common anthocyanins with a variety of biological activities. Tyrosinase is a speed-limiting enzyme associated with melanin production. The inhibition of tyrosinase activity can prevent melanin disease while contributing to whitening. The interaction behaviors of the three anthocyanins against tyrosinase have been discussed in this paper. Cyanidin has strongest inhibitory effect on tyrosinase, and then peonidin, cyanidin-3-galactoside. Furthermore, the inhibition of tyrosinase by the three anthocyanins is mixed modes. The three anthocyanins can induce the static fluorescence quenching of tyrosinase. Cyanidin exhibits strongest binding affinity on tyrosinase, and then peonidin, cyanidin-3-galactoside based on Ka values obtain by fluorescence analysis. The binding of all anthocyanin to tyrosinase induce its conformation changes. According to molecular docking and fluorescence studies, they bind to tyrosinase by hydrogen bond and van der Waals force. In addition, the optimal modes of the three anthocyanins with tyrosinase are predicated by molecular docking. This work emphasizes that cyanidin, peonidin and cyanidin-3-galactoside may be potential drugs for the treatment of diseases caused by melanin.

Effect of structural characteristics on the physicochemical properties and functional activities of dietary fiber: A review of structure-activity relationship

Dietary fibers come from a wide range of sources and have a variety of preparation methods (including extraction and modification). The different structural characteristics of dietary fibers caused by source, extraction and modification methods directly affect their physicochemical properties and functional activities. The relationship between structure and physicochemical properties and functional activities is an indispensable basic theory for realizing the directional transformation of dietary fibers' structure and accurately regulating their specific properties and activities. In this paper, since a brief overview about the structural characteristics of dietary fiber, the effect of structural characteristics on a variety of physicochemical properties (hydration, electrical, thermal, rheological, emulsifying property, and oil holding capacity, cation exchange capacity) and functional activities (hypoglycemic, hypolipidemic, antioxidant, prebiotic and harmful substances-adsorption activity) of dietary fiber explored by researchers in last five years are emphatically reviewed. Moreover, the future perspectives of structure-activity relationship are discussed. This review aims to provide theoretical foundation for the targeted regulation of properties and activities of dietary fiber, so as to improve the quality of their applied products and physiological efficiency, and then to realize high value utilization of dietary fiber resources.

Metabolomics and network pharmacology reveal the mechanism of Castanopsis honey against Streptococcus pyogenes

Streptococcus pyogenes (GAS) is one of the most virulent and infectious bacteria, severely threatening health and lives of people worldwide. Honey has been proven to have effective capability against GAS, but the underlying metabolites and mechanisms are still unclear. In this study, the Castanopsis honey (CH) showed significant antibacterial ability compared to other seven kinds of honey and artificial honey. Furthermore, the antibacterial metabolites and their targets in CH were screened by combined method of metabolomics, network pharmacology, and molecular docking. The results suggested that the activities of two antioxidant enzymes, glutathione peroxidase and tyrosyl tRNA synthetase identified as the primary targets, were significantly inhibited by CH, which significantly increased the level of oxidative stress in GAS. The results revealed a possibly novel mechanism regulating the oxidative stress and inhibits the growth in bacteria, providing strong experimental evidence to support the further development of CH as a novel antibacterial agent.

Inhibition of α-glucosidase activity and intestinal glucose transport to assess the in vivo anti-hyperglycemic potential of dodecyl-acylated phlorizin and polydatin derivatives

A diet containing natural active compounds that can inhibit the hydrolytic activity of α-glucosidase on carbohydrates and intestinal glucose absorption is an effective means of controlling postprandial hyperglycemia. Phlorizin and polydatin as phenolic glycosides have a high affinity for the catalytic site of α-glucosidase, but exhibited unsatisfactory competitive inhibitory capacity, with an IC50 of 0.97 and >2 mM, respectively. However, dodecyl-acylated derivatives of phlorizin and polydatin exerted α-glucosidase inhibitory capacity, with an IC50 of 55.10 and 70.95 μM, respectively, which were greatly enhanced and much stronger than that of acarbose with an IC50 of 2.46 mM. The SPR assay suggested the high affinity of dodecyl phlorizin and dodecyl polydatin to α-glucosidase with equilibrium dissociation constant (KD) values of 12.0 and 7.9 μM, respectively. Both dodecyl phlorizin and dodecyl polydatin reduced the catalytic ability of α-glucosidase by reversible noncompetitive and uncompetitive mixed inhibition, which bind noncovalently to the allosteric site 2 through hydrogen bonds and hydrophobic interactions, thereby inducing the secondary structure unfolding and intrinsic fluorescence quenching of α-glucosidase. Confocal microscopy detection visually showed significant inhibitory effects on FITC-labeled glucose uptake in intestinal Caco-2 cells by phlorizin, polydatin, dodecyl phlorizin and dodecyl polydatin. In addition, based on the differentiated Caco-2 cell monolayer model, dodecyl phlorizin and dodecyl polydatin suppressed intestinal glucose transport more effectively than phlorizin and polydatin, suggesting that they were promising in vivo hypoglycemic active compounds.

Evaluation of antioxidant, antidiabetic and antiobesity potential of phenylpropanoids (PPs): Structure-activity relationship and insight into action mechanisms against dual digestive enzymes by comprehensive technologies

Phenylpropanoids (PPs), a group of natural compounds characterized by one or more C6-C3 units, have exhibited considerable potential in addressing metabolic disease. However, the comprehensive investigation on the relationship of compound structures and involved activity, along with the action mechanisms on the drug target is absent. This study aimed to evaluate the antioxidant and inhibitory activities of 16 PPs against two digestive enzymes, including α-glucosidase and pancreatic lipase, explore the structure-activity relationships and elucidate the mechanisms underlying enzyme inhibition. The findings revealed the similarities in the rules governing antioxidant and enzyme inhibitory activities of PPs. Specifically, the introduction of hydroxyl groups generally exerted positive effects on the activities, while the further methoxylation and glycosylation were observed to be unfavorable. Among the studied PPs, esculetin exhibited the most potent antioxidant activity and dual enzymes inhibition potential, displaying IC50 values of 0.017 and 0.0428 mM for DPPH and ABTS radicals scavenging, as well as 1.36 and 6.67 mM for α-glucosidase and lipase inhibition, respectively. Quantification analysis indicated esculetin bound on both α-glucosidase and lipase successfully by a mixed-type mode. Further analyses by UV-Vis, FT-IR, fluorescence spectra, surface hydrophobicity, SEM, and molecular docking elucidated that esculetin could bind on the catalytic or non-catalytic sites of enzymes to form complex, impacting the normal spatial conformation for hydrolyzing the substrate, thus exhibiting the weakened activity. These results may shed light on the utilization value of natural PPs for the management of hyperglycemia and hyperlipemia, and afford the theoretical basis for designing drugs with stronger inhibition against the dual digestive enzymes based on esculetin.

Effect of ferulic acid incorporation on structural, rheological, and digestive properties of hot-extrusion 3D-printed rice starch

The influence of ferulic acid (FA) on rice starch was investigated by incorporating it at various concentrations (0, 2.5, 5, 7.5, and 10 %, w/w, on dry starch basis) and subjecting the resulting composites to hot-extrusion 3D printing (HE-3DP) process. This study examined the effects of FA addition and HE-3DP on the structural, rheological, and physicochemical properties as well as the printability and digestibility of rice starch. The results indicated that adding 0-5 % FA had no significant effect; however, as the amount of FA increased, the printed product edges became less defined, the product's overall stability decreased, and it collapsed. The addition of FA reduced the elasticity and viscosity, making it easier to extrude the composite gel from the nozzle. Moreover, the crystallinity and short-range ordered structure of the HE-3D printed rice starch gel decreased with the addition of FA, resulting in a decrease in the yield stress and an increase in fluidity. Furthermore, the addition of FA reduced the digestibility of the HE-3D-printed rice starch. The findings of this study may be useful for the development of healthier modified starch products by adding bioactive substances and employing the 3D printing technology.

Rapid screening of the novel bioactive peptides with notable α-glucosidase inhibitory activity by UF-LC-MS/MS combined with three-AI-tool from black beans

This work aimed to propose a rapid method to screen the bioactive peptides with anti-α-glucosidase activity instead of traditional multiple laborious purification and identification procedures. 242 peptides binding to α-glycosidase were quickly screened and identified by bio-affinity ultrafiltration combined with LC-MS/MS from the double enzymatic hydrolysate of black beans. Top three peptides with notable anti-α-glucosidase activity, NNNPFKF, RADLPGVK and FLKEAFGV were further rapidly screened and ranked by the three artificial intelligence tools (three-AI-tool) BIOPEP database, PeptideRanker and molecular docking from the 242 peptides. Their IC50 values were in order as 4.20 ± 0.11 mg/mL, 2.83 ± 0.03 mg/mL, 1.32 ± 0.09 mg/mL, which was opposite to AI ranking, for the hydrophobicity index of the peptides was not included in the screening criteria. According to the kinetics, FT-IR, CD and ITC analyses, the binding of the three peptides to α-glucosidase is a spontaneous and irreversible endothermic reaction that results from hydrogen bonds and hydrophobic interactions, which mainly changes the α-helix structure of α-glucosidase. The peptide-activity can be evaluated vividly by AFM in vitro. In vivo, the screened FLKEAFGV and RADLPGVK can lower blood sugar levels as effectively as acarbose, they are expected to be an alternative to synthetic drugs for the treatment of Type 2 diabetes.

Acetylation of the polysaccharide from Houttuynia cordata rhizome and their α-glucosidase inhibition mechanism

In this study, the polysaccharide (RHCP) extracted from Houttuynia cordata rhizome was acetylated through the acetic anhydride method. The physicochemical properties of RHCP and its acetylated derivatives (Ac-RHCP) were determined by infrared spectra, scanning electron microscopy, and Congo red test. Meanwhile, the α-glucosidase inhibition mechanism of RHCP and Ac-RHCP was analyzed by inhibition kinetics, and circular dichroism and fluorescence spectroscopy. Ac-RHCP resulted in a more porous surface structure and 1.83-fold higher solubility compared with RHCP. At a concentration of 6 mg/mL, the α-glucosidase inhibition rate of Ac-RHCP was 75.40%, while that of RHCP was 44.68%. RHCP and Ac-RHCP inhibited α-glucosidase in a mixed-type manner, reduced the endogenous fluorescence of α-glucosidase, affected the microenvironment of amino acid residues, and changed the conformation of α-glucosidase. The study indicates that Ac-RHCP exhibits a certain level of α-glucosidase inhibition, demonstrating its potential as a functional food for glycemic control.

Screening of α-Glucosidase Inhibitors in Cichorium glandulosum Boiss. et Huet Extracts and Study of Interaction Mechanisms

Cichorium glandulosum Boiss. et Huet (CGB) extract has an α-glucosidase inhibitory effect (IC50 = 59.34 ± 0.07 μg/mL, positive control drug acarbose IC50 = 126.1 ± 0.02 μg/mL), but the precise enzyme inhibitors implicated in this process are not known. The screening of α-glucosidase inhibitors in CGB extracts was conducted by bioaffinity ultrafiltration, and six potential inhibitors (quercetin, lactucin, 3-O-methylquercetin, hyperoside, lactucopicrin, and isochlorogenic acid B) were screened as the precise inhibitors. The binding rate calculations and evaluation of enzyme inhibitory effects showed that lactucin and lactucopicrin exhibited the greatest inhibitory activities. Next, the inhibiting effects of the active components of CGB, lactucin and lactucopicrin, on α-glucosidase and their mechanisms were investigated through α-glucosidase activity assay, enzyme kinetics, multispectral analysis, and molecular docking simulation. The findings demonstrated that lactucin (IC50 = 52.76 ± 0.21 μM) and lactucopicrin (IC50 = 17.71 ± 0.64 μM) exhibited more inhibitory effects on α-glucosidase in comparison to acarbose (positive drug, IC50 = 195.2 ± 0.30 μM). Enzyme kinetic research revealed that lactucin inhibits α-glucosidase through a noncompetitive inhibition mechanism, while lactucopicrin inhibits it through a competitive inhibition mechanism. The fluorescence results suggested that lactucin and lactucopicrin effectively reduce the fluorescence of α-glucosidase by creating lactucin-α-glucosidase and lactucopicrin-α-glucosidase complexes through static quenching. Furthermore, the circular dichroism (CD) and Fourier transform infrared spectroscopy (FT-IR) analyses revealed that the interaction between lactucin or lactucopicrin and α-glucosidase resulted in a modification of the α-glucosidase's conformation. The findings from molecular docking and molecular dynamics simulations offer further confirmation that lactucopicrin has a robust binding affinity for certain residues located within the active cavity of α-glucosidase. Furthermore, it has a greater affinity for α-glucosidase compared to lactucin. The results validate the suppressive impact of lactucin and lactucopicrin on α-glucosidase and elucidate their underlying processes. Additionally, they serve as a foundation for the structural alteration of sesquiterpene derived from CGB, with the intention of using it for the management of diabetic mellitus.

Variations in the effects of extrusion treatments and ferulic acid addition on starch digestibility with different botanical backgrounds

In the current study, the effects of extrusion using a haake rheometer with a twin-roll mixer, with and without FA addition, on the structures and in vitro digestibility of starches from different sources were investigated. After extruding for 15 min at 90 °C with a moisture content of 40 %, no matter FA was added or not, lager Ap molecules were preferentially debranched, while Am with longer CL were depolymerized simultaneously, resulting to reduced averaged molecular size of Ap and shortened Am chains. Of all starches, regardless of their botanical backgrounds, although synergic effects were found between extrusion and FA addition on reducing their relative crystallinity and the ordered structures, distinctly different effects on the in vitro digestibility of these starches have also been observed especially regarding the digestion of starch branches with DP > 10 Particularly, the Am chains with DP 10-1000 was remaining undigested when FA was added. This study provides important information concerning how to adjust starch digestibility into a healthy range through altering the starch structures using extrusion technique with the addition of phytochemicals or not.

Interactions between phosvitin and aldehydes affect the release of flavor from Russian sturgeon caviar

The release mechanism of flavor during caviar storage was studied by the interaction between phosvitin and four aldehydes. Gas chromatography-mass spectrometry showed that the binding rate of phosvitin with 3-methylbutanal, nonanal, (E,Z)-2,6-nonadienal, and (E)-2-octenal decreased with an increase in the aldehyde concentrations. Among them, (E,Z)-2,6-Nonadienal (0.5 mM) had the highest binding rate (84.47%). The main quenching mechanism of (E,Z)-2,6-nonadienal with phosvitin was static quenching and the binding force comprised spontaneous hydrophobic interactions. An increase in the aldehyde concentrations reduced the α-helix content of phosvitin and led to aggregation of the microstructure of phosvitin. The results of molecular docking showed that tyr residue contributed the most to the binding of phosvitin to aldehydes. This study has elucidated the mechanism of the effect of caviar protein on changes in the caviar flavor during storage and provides effective strategies for regulation of caviar flavor during storage.

Water solubility differentiates the impact of tea polyphenols and rutin on the postprandial glycemic response to cooked maize starch

Postprandial hyperglycemia is an independent risk factor for cardiovascular diseases, and the impact of tea polyphenols (TP) and rutin, representative phenolic compounds with different water solubilities, on the postprandial glycemic response to cooked normal corn starch (CCS) was investigated. Comparatively, TP (DPPH50 = 0.12 mmol L-1) are more potent than rutin (DPPH50 = 0.50 mmol L-1) in scavenging the free radicals of DPPH, but both TP and rutin inhibited the activity of porcine pancreatic α-amylase (PPA), the major enzyme in starch digestion, with an IC50 of 4.09 mmol L-1 and 2.71 mmol L-1, respectively. However, an in vivo study showed that a significant reduction in postprandial blood glucose was only observed in the presence of rutin, and TP had no effect on the glycemic response to CCS. To find out the underlying mechanism, fluorescence spectroscopy and molecular docking were carried out and they showed that, compared to TP, rutin bound to the active site of PPA with higher affinity and a lower free energy (ΔG) driven by hydrogen bonds and π-stacking, and rutin also greatly increased the viscosity of starch. Collectively, water-soluble TP have a higher antioxidant property and a lower potency to inhibit PPA compared to water-insoluble rutin, and the weaker interaction between TP and PPA, and starch as well might synergistically contribute to TP's ineffectiveness in lowering the postprandial glycemic response, and water solubility linking the molecular structures and functions of phenolic compounds might be the fundamental basis for the observed difference in their biological functions, and water solubility can also be used to enrich specific phenolic compounds for desired functions.

The inhibition mechanism of bound polyphenols extracted from mung bean coat dietary fiber on porcine pancreatic α-amylase: kinetic, spectroscopic, differential scanning calorimetric and molecular docking

The inhibitory mechanisms of purified bound polyphenols extracted from mung bean coat dietary fiber (pMBDF-BP) on porcine pancreatic α-amylase (PPA) were investigated through inhibition kinetics, fluorescence spectroscopy, circular dichroism, differential scanning calorimetry and molecular docking. It was shown that pMBDF-BP exerted significant reversible inhibition on PPA in a mixed-type inhibition manner (IC50 = 18.57 ± 0.30 μg/mL), and the combination of the three major components exhibited a synergistic inhibitory effect on PPA. Further, pMBDF-BP bound to the active site or form a polyphenol-enzyme complex at the inactive site through hydrogen bonding and hydrophobic forces, via enhancing the hydrophobicity of the microenvironment surrounding tryptophan and tyrosine residues and promoting the secondary structure of PPA towards a more stable conformation, eventually reducing the enzyme activity. This study provided theoretical evidences for the utilization of bound polyphenols extracted from mung bean coat dietary fiber as a functional component in natural inhibitors of α-amylase.

Inhibition of α-amylase digestion by a Lonicera caerulea berry polyphenol starch complex revealed via multi-spectroscopic and molecular dynamics analyses

Polyphenol-starch complexes exhibit synergistic and beneficial effects on both polyphenols and resistant starches. This study evaluates the inhibitory effects and mechanisms of α-amylase on a Lonicera caerulea berry polyphenol-wheat starch (LPWS) complex following high hydrostatic pressure treatments of 400 MPa for 30 min and 600 MPa for 30 min. The IC50 values for α-amylase inhibition by the complex were 3.61 ± 0.10 mg/mL and 3.42 ± 0.08 mg/mL at a 10 % (w/w) polyphenol content. This interaction was further supported by Fourier-transform infrared spectroscopy and circular dichroism, which confirmed that the alpha helix component of the secondary structure of α-amylase was reduced due to the complex. Multifluorescence spectroscopy revealed that the complex induces changes in the microenvironment of fluorophores surrounding the α-amylase active site. Molecular dynamics simulations and molecular docking revealed that the active site of amylose within the complex becomes enveloped in polyphenol clusters. This wrapping effect reduced the hydrogen bonds between amylose and α-amylase, decreasing from 16 groups to just one group. In summary, the LPWS complex represents a low-digestible carbohydrate food source, thus laying the groundwork for the research and development of functional foods aimed at postprandial hypoglycemic effects.

Effect of hawthorn polyphenol extracts on the physicochemical properties and digestibility of corn starch

To investigate the effect of hawthorn polyphenols on the physicochemical properties and digestibility of corn starch, different proportions (1%, 2%, 3%, and 4% [w/w]) of hawthorn polyphenol extracts (HPEs) were mixed with corn starch, and their physicochemical properties and digestive properties were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Rapid Visco Analysis, differential scanning calorimetry, and in vitro/in vivo analysis. Results indicated that small V-type crystal starch tended to be formed in the samples, and the addition of HPEs reduced the viscosity, prolonged the gelatinization temperature of corn starch, and increased the proportion of slowly digestible starch and resistant starch of the corn starch, which accounted for 36.32% ± 1.05% and 33.32% ± 4.07%, respectively. Compared with the raw corn starch, the postprandial blood glucose of mice that were administered the hawthorn polyphenols decreased significantly: the blood glucose peak (30 min) decreased from 14.30 ± 1.52 to 11.77 ± 1.21 mmol/L. Our study might provide some basic theoretical support for the application of hawthorn polyphenols in healthy starchy food processing.