Differential α-amylase/α-glucosidase inhibitory activities of plant-derived phenolic compounds: a virtual screening perspective for the treatment of obesity and diabetes

Exploring the anti-inflammatory, sedative, antidiabetic, and antioxidant potential in in-vitro and in-vivo models and phenolic profiling of Atractylis aristata Batt

ETHNOPHARMACOLOGICAL RELEVANCE

Atractylis aristata batt., as an endemic plant from the Asteraceae family, holds a significant position in the Ahaggar region of southern Algeria's traditional medicine. The aerial parts of Atractylis aristata was used to cure inflammation, fever, and stomach disorders.

AIM OF THE STUDY

The objective of the present investigation was to ascertain the overall bioactive components and phytochemical components and examine the antioxidant, antidiabetic, anti-inflammatory, acute toxicity, and sedative properties of the crude extract obtained from the aerial portions of Atractylis aristata (AaME).

MATERIALS AND METHODS

The AaME's antioxidant activity was assessed by the use of pyrogallol autoxidation, (1,1 diphenyl-2-picrylhydrazyl) (DPPH), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and reducing power (RP) techniques. 1 mg/mL of AaME was used to evaluate the antidiabetic activity by applying the enzyme α-amylase inhibitory power test. At the same time, the bovine serum albumin (BSA) denaturation method was employed to quantify the in vitro anti-inflammatory activity at different concentrations (1.5625, 0.78125, 0.390625, 0.1953125 and 0.09765625 mg/mL). In contrast, following the Organization for Economic Co-operation and Development (OECD) guideline No. 423, which covers acute oral toxicity testing protocols, the limit dosage test was employed to assess in vivo acute toxicity. At the dose of 0.08 mg/mL, the carrageenan-induced paw edema approach was used to assess the anti-inflammatory efficacy in vivo, and the sedative activity was carried out at the dose of 0.08 mg/mL using the measurement of the locomotor method. Different bioactive compounds were identified within AaME using LC-MS/MS and HPLC-UV analysis.

RESULTS

The acute toxicity study showed no fatalities or noticeable neurobehavioral consequences at the limit test; this led to their classification in Globally Harmonized System (GHS) category Five, as the OECD guideline No 423 recommended. At a concentration of 0.08 mg/mL (2000 mg/kg), AaME showed apparent inhibition of paw edema and a significant (p = 0.01227) reduction in locomotor activity compared to the control animals. Our findings showed that AaME exhibited considerable antioxidant (IC50 = 0.040 ± 0.003 mg/mL (DPPH), IC50 = 0.005 ± 5.77 × 10-5 mg/mL (ABTS), AEAC = 91.15 ± 3.921 mg (RP) and IR% = 23.81 ± 4.276 (Inhibition rate of pyrogallol) and rebuts antidiabetic activities (I% = 57.6241% ± 2.81772). Our findings revealed that the maximum percentage of BSA inhibition (70.84 ± 0.10%) was obtained at 1.562.5 mg/mL. Thus, the AaME phytochemical profile performed using phytochemical screening, HPLC-UV, and LC-MS/MS analysis demonstrated that A. aristata can be a valuable source of chemicals with biological activity for pharmaceutical manufacturers.

CONCLUSION

The phytochemical profiling, determined through HPLC-UV and LC-MS/MS applications, reveals this plant's therapeutic value. The aerial parts of Atractylis aristata contain bioactive molecules such as gallic acid, ascorbic acid, and quercetin, contributing to its significant antioxidant capabilities. Furthermore, identifying alizarin, the active compound responsible for its anti-inflammatory properties, could provide evidence supporting the anti-inflammatory capabilities of this subspecies.

Exploring the composition and properties of Centella asiatica metabolites and investigating their impact on BSA glycation, LDL oxidation and α-amylase inhibition

Centella asiatica (L.) Urb. is a small herbaceous plant belonging to the Apiaceae family that is rich in triterpenes, such as asiaticoside and madecassoside. Centella asiatica finds broad application in promoting wound healing, addressing skin disorders, and boosting both memory and cognitive function. Given its extensive therapeutic potential, this study aimed not only to investigate the Centella asiatica ethanolic extract but also to analyze the biological properties of its organic fractions, such as antioxidant antiglycation capacity, which are little explored. We also identified the main bioactive compounds through spectrometry analysis. The ethanolic extract (EE) was obtained through a static maceration for seven days, while organic fractions (HF: hexane fraction; DF: dichloromethane fraction; EAF: ethyl acetate fraction; BF: n-butanol fraction and HMF: hydromethanolic fraction) were obtained via liquid-liquid fractionation. The concentration of phenolic compounds, flavonoids, and tannins in each sample was quantified. Additionally, the antiglycation (BSA/FRU, BSA/MGO, and ARG/MGO models) and antioxidant (FRAP, ORAC, and DPPH) properties, as well as the ability to inhibit LDL oxidation and hepatic tissue peroxidation were evaluated. The inhibition of enzyme activity was also analyzed (α-amylase, α-glycosidase, acetylcholinesterase, and butyrylcholinesterase). We also evaluated the antimicrobial and cytotoxicity against RAW 264.7 macrophages. The main compounds present in the most bioactive fractions were elucidated through ESI FT-ICR MS and HPLC-ESI-MS/MS analysis. In the assessment of antioxidant capacity (FRAP, ORAC, and DPPH), the EAF and BF fractions exhibited notable results, and as they are the phenolic compounds richest fractions, they also inhibited LDL oxidation, protected the hepatic tissue from peroxidation and inhibited α-amylase activity. Regarding glycation models, the EE, EAF, BF, and HMF fractions demonstrated substantial activity in the BSA/FRU model. However, BF was the only fraction that presented non-cytotoxic activity in RAW 264.7 macrophages at all tested concentrations. In conclusion, this study provides valuable insights into the antioxidant, antiglycation, and enzymatic inhibition capacities of the ethanolic extract and organic fractions of Centella asiatica. The findings suggest that further in vivo studies, particularly focusing on the butanol fraction (BF), may be promising routes for future research and potential therapeutic applications.

Epigallocatechin gallate attenuated high glucose-induced pancreatic beta cell dysfunction by modulating DRP1-mediated mitochondrial apoptosis pathways

Long-term exposure to hyperglycemic conditions leads to β-cell dysfunction, particularly mitochondrial dysfunction, and inflammatory and oxidative stress responses, which are considered the primary causes of β-cell death and the hallmarks of diabetes. Plant-active ingredients may play a key role in glycemic control. Epigallocatechin gallate (EGCG) is a characteristic catechin derived from tea that possesses anti-diabetic properties. Nonetheless, its underlying mechanisms remain elusive. Herein, the protective role of EGCG on high glucose (33 mM)-induced pancreatic beta cell dysfunction and its possible molecular mechanisms were investigated. Briefly, MIN6 cells were treated with glucose and EGCG (10 µM, 20 µM, and 40 µM) for 48 h. Our results revealed that EGCG dose-dependently restored mitochondrial membrane potential and concomitantly alleviated cell apoptosis. Mechanistically, the expression level of apoptotic protein BAX and Dynamic related protein 1 (DRP1) was significantly downregulated following EGCG treatment, whereas that of the anti-apoptotic protein BCL-2 was significantly upregulated. Taken together, EGCG alleviated high glucose-induced pancreatic beta cell dysfunction by targeting the DRP1-related mitochondrial apoptosis pathway and thus can serve as a nutritional intervention for the preservation of beta cell dysfunction in patients with type 2 diabetes mellitus.

In Vivo Glycemic Response of Fruit-Based Mango (Mangifera indica) and Pineapple (Ananas comosus) Bars in In Vitro and In Silico Enzyme Inhibitory Effects Studies

The habitual consumption of snacks has the potential to enrich or harm the diet. They can contribute to excessive caloric intake and hyperglycemia. Thus, there is an increasing interest in snacks with health-promoting properties. This study aimed to demonstrate the beneficial effect of two fruit-based bars on glucose levels through in vitro, in vivo, and in silico assays. Mango (Mangifera indica L.) and pineapple (Ananas comosus L.) bars (MB and PB) were prepared, and chemical composition, postprandial glycemic response, glycemic index (GI), and glycemic load (GL) were evaluated. The inhibitory effect of fruit bar extracts on α-amylase and α-glucosidase activity and their respective molecular docking was assessed. MB and PB showed the lowest postprandial glycemic response vs. the control bar (p < 0.005), a lower GI (CB: 64.20, PB: 53.20, MB: 40.40), and a GL of 10.9 (CB), 7.9 (PB), and 6.1 (MB), (p < 0.05). MB and PB showed the highest inhibition % of α-amylase (61.44 and 59.37%, respectively) and α-glucosidase (64.97 and 64.57%). Naringenin (-1692.5985 and -2757.674 kcal/mol) and ferulic acid (-1692.8904 and -2760.3513 kcal/mol) exhibited more favorable interaction energies against α-amylase and α-glucosidase activity. The presence of polyphenols from the fruit influenced enzymatic inhibition. Likewise, the dietary fiber in the bars evaluated allowed us to observe a positive effect that favors glycemic control, making them a healthy alternative for snacking.

In Silico Investigation against Inhibitors of Alpha-Amylase Using Structure-based Screening, Molecular Docking, and Molecular Simulations Studies

Type-II diabetes mellitus is a chronic disorder that results from fluctuations in the glucose level leading to hyperglycemia with severe adverse effects increasing worldwide. Alpha-Amylase is the key enzyme involved in the mechanism of glucose formation therefore Alpha-Amylase inhibitors have become a therapeutic target in the development of new leads as they have the potential to suppress glucose levels. Existing drugs targeting Alpha-Amylase highlight major drawbacks in terms of poor absorption rate that causes several gastrointestinal issues. So, this research is aimed to develop novel inhibitors interacting with Alpha-Amylase's active site using structural-based screening, binding pattern analysis, and molecular dynamic simulation. Hence, to search for a potential lead, we analyzed a total of 133 valiolamine derivatives and 535 desoxynojirimycin derivatives that exhibited drug-like properties screened through Lipinski filters. Virtual screening followed by binding interaction analysis we identified ten compounds that exhibited better binding energy scores compared to the standard drugs voglibose and miglitol, used in our study. The docking analysis, ADMET and metabolic site prediction estimated the best top two compounds with good drug profiles. Further, top compounds VG9 and VG15 were promoted to simulation study using the Biovia Discovery study to access the stability at a time interval of 100 ns. MD simulation results revealed that our compound VG9 possesses better conformational stability in the complex to the active site residues of Alpha-Amylase target protein than standard drug voglibose. Thus, our investigation revealed that compound VG9 also exhibits the best pharmacokinetic as well as binding affinity results and could act as a potential lead compound targeting Alpha-Amylase for Type II diabetes.

Structure-function relationships in (poly)phenol-enzyme binding: Direct inhibition of human salivary and pancreatic α-amylases

(Poly)phenols inhibit α-amylase by directly binding to the enzyme and/or by forming starch-polyphenol complexes. Conventional methods using starch as the substrate measure inhibition from both mechanisms, whereas the use of shorter oligosaccharides as substrates exclusively measures the direct interaction of (poly)phenols with the enzyme. In this study, using a chromatography-based method and a short oligosaccharide as the substrate, we investigated the detailed structural prerequisites for the direct inhibition of human salivary and pancreatic α-amylases by over 50 (poly)phenols from the (poly)phenol groups: flavonols, flavones, flavanones, flavan-3-ols, polymethoxyflavones, isoflavones, anthocyanidins and phenolic acids. Despite being structurally very similar (97% sequence homology), human salivary and pancreatic α-amylases were inhibited to different extents by the tested (poly)phenols. The most potent human salivary α-amylase inhibitors were luteolin and pelargonidin, while the methoxylated anthocyanidins, peonidin and petunidin, significantly blocked pancreatic enzyme activity. B-ring methoxylation of anthocyanidins increased inhibition against both human α-amylases while hydroxyl groups at C3 and B3' acted antagonistically in human salivary inhibition. C4 carbonyl reduction, or the positive charge on the flavonoid structure, was the key structural feature for human pancreatic inhibition. B-ring glycosylation did not affect salivary enzyme inhibition, but increased pancreatic enzyme inhibition when compared to its corresponding aglycone. Overall, our findings indicate that the efficacy of interaction with human α-amylase is mainly influenced by the type and placement of functional groups rather than the number of hydroxyl groups and molecular weight.

Mothana R, M. Noman O, Eto B, Chigr F, Chigr M. Synthesis and In Silico Analysis of New Polyheterocyclic Molecules Derived from [1,4]-Benzoxazin-3-one and Their Inhibitory Effect against Pancreatic α-Amylase and Intestinal α-Glucosidase

This study focuses on synthesizing a new series of isoxazolinyl-1,2,3-triazolyl-[1,4]-benzoxazin-3-one derivatives 5a-5o. The synthesis method involves a double 1,3-dipolar cycloaddition reaction following a "click chemistry" approach, starting from the respective [1,4]-benzoxazin-3-ones. Additionally, the study aims to evaluate the antidiabetic potential of these newly synthesized compounds through in silico methods. This synthesis approach allows for the combination of three heterocyclic components: [1,4]-benzoxazin-3-one, 1,2,3-triazole, and isoxazoline, known for their diverse biological activities. The synthesis procedure involved a two-step process. Firstly, a 1,3-dipolar cycloaddition reaction was performed involving the propargylic moiety linked to the [1,4]-benzoxazin-3-one and the allylic azide. Secondly, a second cycloaddition reaction was conducted using the product from the first step, containing the allylic part and an oxime. The synthesized compounds were thoroughly characterized using spectroscopic methods, including 1H NMR, 13C NMR, DEPT-135, and IR. This molecular docking method revealed a promising antidiabetic potential of the synthesized compounds, particularly against two key diabetes-related enzymes: pancreatic α-amylase, with the two synthetic molecules 5a and 5o showing the highest affinity values of 9.2 and 9.1 kcal/mol, respectively, and intestinal α-glucosidase, with the two synthetic molecules 5n and 5e showing the highest affinity values of -9.9 and -9.6 kcal/mol, respectively. Indeed, the synthesized compounds have shown significant potential as antidiabetic agents, as indicated by molecular docking studies against the enzymes α-amylase and α-glucosidase. Additionally, ADME analyses have revealed that all the synthetic compounds examined in our study demonstrate high intestinal absorption, meet Lipinski's criteria, and fall within the required range for oral bioavailability, indicating their potential suitability for oral drug development.

The Effects of Raspberry Consumption on Glycemic Control and Inflammation Markers in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Despite observing the health benefits of raspberry consumption in some recent studies, there is still no consensus regarding this effectiveness on inflammatory markers and glycemic control. This study aimed to investigate this effectiveness by performing a meta-analysis. The PubMed, Web of Science, and Scopus databases were comprehensively searched until December 2023 to find relevant randomized controlled trials. Eligible studies were screened, and relevant information was extracted. The overall effect size of raspberry consumption on each of the outcomes was estimated by following the random-effects model in the form of a 95% confidence interval (CI) and a weighted mean difference (WMD). Raspberry consumption led to a significant increase in insulin concentrations (WMD: 1.89 μU/mL; 95%CI: 1.45, 2.34; P < 0.001) and a significant decrease in tumor necrosis factor-α (TNF-α) concentrations (WMD: -3.07 pg/mL; 95%CI: -5.17, -0.97; P = 0.004), compared with the control groups. Raspberry consumption did not have a significant effect on fasting blood glucose, insulin, hemoglobin A1C, glucose tolerance tests, homeostatic model assessment for insulin resistance, C-reactive protein, and interleukin-6 concentrations. This review revealed that raspberry consumption led to a significant increase and decrease in insulin and TNF-α concentrations, respectively. However, to draw a more accurate conclusion, it is necessary to conduct studies with a larger sample size in the future. The current study's protocol has been registered in the PROSPERO system as CRD42023477559.

Phenolic enriched fraction of Clerodendrum glandulosum Lindl. leaf extract ameliorates hyperglycemia and oxidative stress in streptozotocin-nicotinamide induced diabetic rats

BACKGROUND

Clerodendrum glandulosum Lindl. is an important ethnomedicinal shrub of Northeast India, used by traditional healers to control various ailments like diabetes, hypertension, arthritis, etc. OBJECTIVES: The present study was conducted to explore the anti-hyperglycemic and antioxidative effects of the polyphenol-rich fraction (PRF) of C. glandulosum leaf extract and identification of its major bioactive compounds. Further, an in-silico molecular docking study was also performed to understand the molecular interactions of the identified major compounds with some target proteins associated with diabetic complications.

MATERIALS AND METHODS

PRF was purified from the hydromethanolic (80% MeOH) extract of leaves and subjected to assessment of in-vitro antioxidant and anti-diabetic properties. It was also subjected to evaluate the ameliorative effect during streptozotocin-nicotinamide-induced hyperglycemia in Wistar albino rats. An in-silico molecular docking study was also performed to complement the in-vitro/in-vivo studies.

RESULTS

Chemical analysis of PRF showed the presence of phenolics like caffeic acid, verbascoside, isoverbascoside, and apigenin, of which verbascoside (598.14 ± 1.24 mg/g) was found to be the principal compound. In-vitro studies showed potent antioxidant (IC50 of DPPH:32.45 ± 2.16 μg/mL; ABTS:39.08 ± 0.53 μg/mL) properties and excellent aldose reductase inhibition potential (IC50 2.18 ± 0.10 μg/mL). Treatment with PRF showed reduced blood glucose levels and increased plasma insulin levels. The results also indicate an improvement of endogenous antioxidants and suppression of inflammatory cytokines (IL-6 and TNF-α) comparable to the standard. Molecular docking studies predicted promising interactions between the identified molecules and the crucial amino acid residues of the enzymes involved in the development of hyperglycemia.

CONCLUSION

This study revealed the antihyperglycemic and antioxidant potential of partially purified fraction PRF of C. glandulosum leaves.

Deciphering the binding behavior and interaction mechanism of apigenin and α-glucosidase based on multi-spectroscopic and molecular simulation studies

This study investigated the molecular mechanism underlying the binding interaction between apigenin (API) and α-glucosidase (α-glu) by a combination of experimental techniques and computational simulation strategies. The spontaneously formation of stable API-α-glu complex was mainly driven by hydrogen bonds and hydrophobic forces, leading to a static fluorescence quenching of α-glu. The binding of API induced secondary structure and conformation changes of α-glu, decreasing the surface hydrophobicity of protein. Computational simulation results demonstrated that API could bind into the active cavity of α-glu via its interaction with active residues at the binding site. The important roles of key residues responsible for the binding stability and affinity between API and α-glu were further revealed by MM/PBSA results. In addition, it can be found that the entrance of active site tended to close after API binding as a result of its interaction with gate keeping residues. Furthermore, the structural basis for the binding interaction behavior of API was revealed and visualized by weak interaction analysis. The findings of our study revealed atomic-level mechanism of the interaction between API, which might shed light on the development of better inhibitors.

Metabolomics Characterization of Phenolic Compounds in Colored Quinoa and Their Relationship with In Vitro Antioxidant and Hypoglycemic Activities

Chenopodium quinoa Willd. is rich in phenolic compounds and exhibits diverse biological activities. Few studies have focused on the effect of colored quinoa's phenolic profile on potential biological activity. This study used a UPLC-MS/MS-based metabolomic approach to examine the quinoa phenolics and their association with in vitro antioxidant and hypoglycemic properties. In total, 430 polyphenols, mainly phenolic acids, flavonoids, and flavonols, were identified. Additionally, 121, 116, and 148 differential polyphenols were found between the white and black, white and red, and black and red comparison groups, respectively; 67 polyphenols were screened as shared key differential metabolites. Phenylalanine, tyrosine, and the biosynthesis of plant secondary metabolites were the main differently regulated pathways. Black quinoa had better total phenolic contents (643.68 mg/100 g DW) and antioxidant capacity, while white quinoa had better total flavonoid contents (90.95 mg/100 g DW) and in vitro α-amylase (IC50 value of 3.97 mg/mL) and α-glucosidase (IC50 value of 1.08 mg/mL) inhibition activities. Thirty-six polyphenols, including epicatechin and linarin, etc., were highly correlated with in vitro antioxidant activity, while six polyphenols, including tiliroside and chrysoeriol, etc., were highly correlated with in vitro hypoglycemic activity. This study may provide important information for colored quinoa resources to develop their healthy food applications.

In vitro inhibitory effect of five natural sweeteners on α-glucosidase and α-amylase

A promising and efficacious approach to manage diabetes is inhibiting α-glucosidase and α-amylase activity. Therefore, the inhibitory activities of five natural sweeteners (mogrosides (Mog), stevioside (Ste), glycyrrhizinic acid (GA), crude trilobatin (CT), and crude rubusoside (CR)) against α-glucosidase and α-amylase and their interactions were evaluated in vitro using enzyme kinetics, fluorescence spectroscopy, Fourier infrared spectroscopy, and molecular docking. The inhibitor sequence was CT > GA > Ste, as GA competitively inhibited α-glycosidase activity while CT and Ste exhibited mixed inhibitory effects. Compared to a positive control acarbose, the inhibitory activity of CT was higher. For α-amylase, the mixed inhibitors CT, CR, and Mog and the competitive inhibitor Ste effectively inhibited the enzyme, with the following order: CT > CR > Ste > Mog; nevertheless, the inhibitors were slightly inferior to acarbose. Three-dimensional fluorescence spectra depicted that GA, CT, and CR bound to the hydrophobic cavity of α-glucosidase or α-amylase and changed the polarity of the hydrophobic amino acid-based microenvironment and structure of the polypeptide chain backbone. Infrared spectroscopy revealed that GA, CT, and CR could disrupt the secondary structure of α-glucosidase or α-amylase, which decreased enzyme activity. GA, trilobatin and rubusoside bound to amino acid residues through hydrogen bonds and hydrophobic interactions, changing the conformation of enzyme molecules to decrease the enzymatic activity. Thus, CT, CR and GA exhibit promising inhibitory effects against α-glucosidase and α-amylase.

Physicochemical properties, in vitro digestibility, and pH-dependent release behavior of starch-steviol glycoside composite hydrogels

Steviol glycosides possess Bola-form amphiphilic structure, which can solubilize hydrophobic phytochemicals and exert physical modification to the hydrophilic matrix. However, the effect of steviol glycosides on the starch hydrogel is still unclear. Herein, the physicochemical properties, in vitro digestibility, and release behavior of starch hydrogel in the presence of steviol glycosides were investigated. The results showed that the addition of steviol glycosides promoted the gelatinization and gelation of starch, and endowed the starch hydrogel with softer texture, larger volume, and higher water holding capacity. The hydrophobic curcumin was well integrated into hydrogel by steviol glycosides, providing the gel with improved colour brilliance. The introduction of steviol glycosides hardly affected the digestibility of starch gel, but it promoted the release rate of curcumin. Notably, this release behavior was pH dependent, which tended to target the alkaline intestine. This work provided some theoretical supports for the development of sugar-free starchy foods.

Assessing the Chemical Composition, Antioxidant and enzyme Inhibitory Effects of Pentapleura subulifera and Cyclotrichium glabrescens Extracts

The Lamiaceae family, encompassing diverse plant species, holds significant value in food, medicine, and cosmetics. Within this family, Pentapleura subulifera and Cyclotrichium glabrescens, relatively unexplored species, were investigated for their chemical composition, antioxidant capacity, and enzyme-inhibiting effects. The chemical composition of hexane, methanolic, and aqueous extracts from P. subulifera and C. glabrescens were analyzed using LC-ESI-MS/MS and the non-polar hexane fraction was investigated via GC-MS. The antioxidant potential of the extracts was determined through radical scavenging, reducing power and metal chelating assays. Additionally, inhibitory activity against six enzymes - acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, amylase, and glucosidase - was examined. The aqueous extract of P. subulifera and the methanolic extract of C. glabrescens exhibited elevated phenolic content at 129.47 mg gallic acid equivalent (GAE)/g and 55.97 mg GAE/g, respectively. Chemical profiling of the constituents of the two plant species resulted in the identification of a total of twenty compounds. The majority of which belonged to flavonoids and quinic acid derivatives, primarily concentrated in the methanol and aqueous extracts. Among all antioxidant assays, the aqueous extracts of P. subulifera demonstrated superior antioxidant activity, with the highest recorded activity of 404.93 mg trolox equivalent (TE)/g in the cupric reducing antioxidant capacity (CUPRAC) test. Meanwhile, the hexane extract of C. glabrescens exhibited the highest AChE inhibitory activity at 2.71 mg galanthamine equivalent (GALAE)/g, followed by the methanol extract of P. subulifera at 2.41 mg GALAE/g. These findings unequivocally establish the notable antioxidant and enzyme inhibitory activity of P. subulifera and C. glabrescens extracts, underscoring their potential as a source of valuable natural antioxidants.

Inhibitory mechanism of chrysin and diosmetin to α-glucosidase: insights from kinetics, multispectroscopy and molecular docking investigations

Inhibition of α-glucosidase activity is a promising method to prevent postprandial hyperglycemia. The inhibitory effect and interaction of chrysin and diosmetin on α-glucosidase were studied in this study. The results of inhibition kinetics showed that chrysin and diosmetin reversibly inhibited α-glucosidase activity with IC50 value of 26.445 ± 1.406 μmol L-1 and 18.380 ± 1.264 μmol L-1, respectively. Further research revealed that chrysin exhibited a mixed-type inhibitory pattern against α-glucosidase, while diosmetin was noncompetitive inhibitory with Ki value of (2.6 ± 0.04) ×10-4 mol L-1. Fluorescence spectroscopy showed that both chrysin and diosmetin could quench the intrinsic fluorescence of α-glucosidase, the maximum emission wavelength of tyrosine (Tyr) and tryptophan (Trp) were not moved by chrysin, but red shifted by diosmetin. UV-Vis, fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD) measurements showed that the secondary structure and microenvironment of α-glucosidase were changed by chrysin and diosmetin. Further analysis of molecular docking showed that chrysin and diosmetin could bind with α-glucosidase and might cause the decrease of α-glucosidase activity. The results of molecular dynamics (MD) simulation showed that the stability of chrysin (or diosmetin)-α-glucosidase complex system was changed during binding process. In conclusion, chrysin and diosmetin are good α-glucosidase inhibitors.Communicated by Ramaswamy H. Sarma.

Enhancement of anti-diabetic activity of pomelo peel by the fermentation of Aspergillus oryzae CGMCC23295: In vitro and in silico docking studies

In this work, pomelo peel was fermented by Aspergillus oryzae CGMCC23295 to enhance its anti-diabetic properties. Results showed the total phenolic and flavonoids contents, ferric reducing antioxidant power (FRAP), scavenging capacities against 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals, as well as inhibitory abilities against α-amylase and α-glucosidase of pomelo peel were increased and fermentation for 8 days was the best. Additionally, the fermented sample could also enhance the glucose consumption and glycogen of HepG2 cell. Based on UPLC-MS/MS analysis, binding energy calculation, concentration determination and IC50 measurement, purpurin, apigenin, genistein, and paxilline could be concluded to be the main compounds to enhance the inhibition activities of fermented sample against α-amylase and α-glucosidase. Furthermore, computational studies were performed to reveal the the binding site and molecular interactions between paxilline and α-amylase, as well as purpurin and α-glucosidase. These findings provide a base for the utilization and valorization of pomelo peels as functional food additives by fermentation.

Assessment of Anticholinergic and Antidiabetic Properties of Some Natural and Synthetic Molecules: An In vitro and In silico Approach

INTRODUCTION

This study aimed to determine the in vitro and in silico effects of some natural and synthetic molecules on acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and α-glucosidase enzymes.

BACKGROUND

Alzheimer's disease (AD) and Type II diabetes mellitus (T2DM) are considered the most important diseases of today's world. However, the side effects of therapeutic agents used in both diseases limit their use. Therefore, developing drugs with high therapeutic efficacy and better pharmacological profile is important.

OBJECTIVES

This study sets out to determine the related enzyme inhibitors used in treating AD and T2DM, considered amongst the most important diseases of today's world.

METHODS

In the current study, the in vitro and in silico effects of dienestrol, hesperetin, Lthyroxine, 3,3',5-Triiodo-L-thyronine (T3) and dobutamine molecules on AChE, BChE and α - glycosidase enzyme activities were investigated.

RESULTS

All the molecules showed an inhibitory effect on the enzymes. The IC50 and Ki values of the L-Thyroxine molecule, which showed the strongest inhibition effect for the AChE enzyme, were determined as 1.71 μM and 0.83 ± 0.195 μM, respectively. In addition, dienestrol, T3, and dobutamine molecules showed a more substantial inhibition effect than tacrine. The dobutamine molecule showed the most substantial inhibition effect for the BChE enzyme, and IC50 and Ki values were determined as 1.83 μM and 0.845 ± 0.143 μM, respectively. The IC50 and Ki values for the hesperetin molecule, which showed the strongest inhibition for the α -glycosidase enzyme, were determined as 13.57 μM and 12.33 ± 2.57 μM, respectively.

CONCLUSION

According to the results obtained, the molecules used in the study may be considered potential inhibitor candidates for AChE, BChE and α-glycosidase.

Synthesis and antitumor activity of bagasse xylan derivatives modified by graft-esterification and cross-linking

A crucial aspect in achieving sustainable development of biomass materials is the modification of renewable polysaccharides to create various high-value functional materials. In this paper, bagasse xylan (BX) was used as a raw material to introduce benzyl methacrylate (BMA) through graft copolymerization reaction to generate the intermediate product BX-g-BMA. Subsequently, the target product (CA-BX-g-BMA) was synthesized by catalytic esterification of BX-g-BMA with citric acid (CA) in AmimCl ionic liquid. Meanwhile, the characterization and bioactivity studies of CA-BX-g-BMA were carried out. The graft copolymerization and esterification reactions induced significant changes in the morphological structure of BX and obviously improved its thermal stability and crystallinity. The application of density functional theory (DFT), molecular electrostatic potential (MEP) and molecular docking has revealed that CA-BX-g-BMA possesses multiple active sites, strong biological activity and a strong binding affinity to 6RCF tumor protein with a binding energy of -32.26 kJ/mol. The in vitro antitumor activity of this novel derivative was tested by MTT assay, and the results showed that CA-BX-g-BMA was non-toxic to normal cells and inhibited MDA-MB-231 (breast cancer cells) by up to 32.16 % ± 4.89 %, which is approximately 11 times higher than that of BX. The exploration of these properties is essential to promote future multidisciplinary applications of BX derivatives.

Natural Inhibitors of Mammalian α-Amylases as Promising Drugs for the Treatment of Metabolic Diseases

α-Amylase is a generally acknowledged molecular target of a distinct class of antidiabetic drugs named α-glucosidase inhibitors. This class of medications is scarce and rather underutilized, and treatment with current commercial drugs is accompanied by unpleasant adverse effects. However, mammalian α-amylase inhibitors are abundant in nature and form an extensive pool of high-affinity ligands that are available for drug discovery. Individual compounds and natural extracts and preparations are promising therapeutic agents for conditions associated with impaired starch metabolism, e.g., diabetes mellitus, obesity, and other metabolic disorders. This review focuses on the structural diversity and action mechanisms of active natural products with inhibitory activity toward mammalian α-amylases, and emphasizes proteinaceous inhibitors as more effective compounds with significant potential for clinical use.

Antioxidant and Hypoglycemic Potential of Essential Oils in Diabetes Mellitus and Its Complications

Since the earliest times, essential oils (EOs) have been utilized for medicinal and traditional purposes. However, in recent decades, an increasing interest has developed due to the need to rediscover herbal remedies and adjuvant therapies for the management of various diseases, particularly chronic ones. The present narrative review examines the potential for EOs to exert hypoglycemic and antioxidant effects in diabetes mellitus, analyzing the main publications having evaluated plant species with potentially beneficial effects through their phytocompounds in diabetes mellitus and its complications. Numerous species have shown promising characteristics that can be used in diabetes management. The hypoglycemic effects of these EOs are attributed to their capacity to stimulate glucose uptake, suppress glucose production, and increase insulin sensitivity. Moreover, EOs can alleviate the oxidative stress by manifesting their antioxidant effects via a variety of mechanisms, including the scavenging of free radicals, the regulation of antioxidant enzymes, and the decreasing of lipid peroxidation, due to their diverse chemical composition. These findings demonstrate the possible benefits of EOs as adjuvant therapeutic agents in the management of diabetes and its complications. The use of EOs in the treatment of diabetes shows good potential for the development of natural and effective strategies to enhance the health outcomes of people with this chronic condition, but additional experimental endorsements are required.

Phenolic profile and α-glucosidase inhibitory potential of wampee (Clausena lansium (Lour.) Skeels) peel and pulp: In vitro digestion/in silico evaluations

To investigate the changes in phenolics, flavonoids, and their bio-activities of wampee (Clausena lansium (Lour.) Skeels) during digestion, the peel and pulp were subjected to simulated in vitro digestion, encompassing oral, gastric, small intestine, and large intestine digestion stages. The peel exhibited a total release of 91.93 mg GAE/g DW of phenolics and 61.86 mg RE/g DW of flavonoids, whereas the pulp displayed a release of 27.83 mg GAE/g DW of phenolics and 8.94 mg RE/g DW of flavonoids. Notably, the phenolics and flavonoids were mostly released during the oral digestion stage for peel, while they were mostly released during the small intestine digestion stage for pulp. The results of the targeted flavonoids analysis indicated that rutin and l-epicatechin were the two most widely released compounds in each digestion step. Moreover, myricetin has been identified as the best inhibitor against α-glucosidase, probably because it formed the most H-bonds, 8, with 6 catalytic residues, which was the highest number. Furthermore, the soluble substances released from the peel exhibited significantly higher antioxidant activities and inhibitory activity against α-glucosidase (p < 0.05) compared to those from the pulp. Positive correlations were observed between the total phenolic content or total flavonoid content and the antioxidant activities (r > 0.73 (peel), > 0.61 (pulp)), as well as α-glucosidase inhibitory activity (r <  - 0.48 (peel), < -0.64 (pulp)) of peel and pulp. In conclusion, these findings provide valuable insights into the digestive characteristics and health benefits of both wampee peel and pulp.

Inhibitory Mechanism of Quercimeritrin as a Novel α-Glucosidase Selective Inhibitor

In this study, 12 flavonoid glycosides were selected based on virtual screening and the literature, and Quercimeritrin was selected as the best selective inhibitor of α-glucosidase through in vitro enzyme activity inhibition experiments. Its IC50 value for α-glucosidase was 79.88 µM, and its IC50 value for α-amylase >250 µM. As such, it could be used as a new selective inhibitor of α-glucosidase. The selective inhibition mechanism of Quercimeritrin on the two starch-digesting enzymes was further explored, and it was confirmed that Quercimeritrin had a strong binding affinity for α-glucosidase and occupied the binding pocket of α-glucosidase through non-covalent binding. Subsequently, animal experiments demonstrated that Quercimeritrin can effectively control postprandial blood glucose in vivo, with the same inhibitory effect as acarbose but without side effects. Our results, therefore, provide insights into how flavone aglycones can be used to effectively control the rate of digestion to improve postprandial blood glucose levels.

Antioxidant and Anti-Diabetic Properties of Olive (Olea europaea) Leaf Extracts: In Vitro and In Vivo Evaluation

(1) Objective: The main objective of the current study was to evaluate in vitro and in vivo an antioxidant property of three genotypes of olive leaf extract (OLE) (picual, tofahi and shemlali), and furthermore to assess potential activity in the treatment and/or prevention of diabetes mellitus type II and related implications. (2) Methodology: Antioxidant activity was determined by using three different methods (DDPH assay, reducing power and nitric acid scavenging activity). In vitro α-glucosidase inhibitory activity and hemolytic protective activity were assessed for the OLE. Five groups of male rats were used in in vivo experiment for evaluating the antidiabetic potential of OLE. (3) Results: The genotypes of the extracts of the three olive leaves exhibited meaningful phenolic and flavonoids content with superiority for picual extract (114.79 ± 4.19 µg GAE/g and 58.69 ± 1.03 µg CE/g, respectively). All three genotypes of olive leaves demonstrated significant antioxidant activity when using DPPH, reducing power and nitric oxide scavenging activity with IC₅₀ ranging from 55.82 ± 0.13 to 19.03 ± 0.13 μg/mL. OLE showed a significant α-glucosidase inhibition activity and dose-dependent protection from hemolysis. In vivo experimentation revealed that the administration of OLE alone and the combination of OLE+ metformin clearly restored the blood glucose and glycated hemoglobin, lipid parameters and liver enzymes to the normal level. The histological examination revealed that the OLE and its combination with metformin successfully repaired the liver, kidneys and pancreatic tissues to bring them close to the normal status and maintain their functionality. (4) Conclusion: Finally, it can be concluded that the OLE and its combination with metformin is a promising treatment for diabetes mellitus type 2 due to their antioxidant activity, which emphasizes the potential use of OLE alone or as an adjuvant agent in the treatment protocol of diabetes mellitus type II.

Molecular Modeling and Synthesis of Indoline-2,3-dione-Based Benzene Sulfonamide Derivatives and Their Inhibitory Activity against α-Glucosidase and α-Amylase Enzymes

Diabetes is also known as a critical and noisy disease. Hyperglycemia, that is, increased blood glucose level is a common effect of uncontrolled diabetes, and over a period of time can cause serious effects on health such as blood vessel damage and nervous system damage. However, many attempts have been made to find suitable and beneficial solutions to overcome diabetes. Considering this fact, we synthesized a novel series of indoline-2,3-dione-based benzene sulfonamide derivatives and evaluated them against α-glucosidase and α-amylase enzymes. Out of the synthesized sixteen compounds (1-16), only three compounds showed better results; the IC₅₀ value was in the range of 12.70 ± 0.20 to 0.90 ± 0.10 μM for α-glucosidase against acarbose 11.50 ± 0.30 μM and 14.90 ± 0.20 to 1.10 ± 0.10 μM for α-amylase against acarbose 12.20 ± 0.30 μM. Among the series, only three compounds showed better inhibitory potential such as analogues 11 (0.90 ± 0.10 μM for α-glucosidase and 1.10 ± 0.10 μM for α-amylase), 1 (1.10 ± 0.10 μM for α-glucosidase and 1.30 ± 0.10 μM for α-amylase), and 6 (1.20 ± 0.10 μM for α-glucosidase and 1.60 ± 0.10 μM for α-amylase). Molecular modeling was performed to determine the binding affinity of active interacting residues against these enzymes, and it was found that benzenesulfonohydrazide derivatives can be indexed as suitable inhibitors for diabetes mellitus.

Polyphenols in twenty cultivars of blue honeysuckle (Lonicera caerulea L.): Profiling, antioxidant capacity, and α-amylase inhibitory activity

The polyphenols extracted from 20 blue honeysuckle cultivars were comprehensively characterized and quantified by HPLC-DAD and HPLC-ESI-QTOF-MS² analyses and evaluated for antioxidant capacity (ABTS, DPPH, FRAP) and α-amylase inhibitory activity. The 17 anthocyanins and 59 non-anthocyanin phenolics were characterized. Among them, cyanidin-3-glucoside, quercetin-3-galactoside, myricetin-3-galactoside, and 3-caffeoylquinic acid were the major polyphenols. These polyphenols not only contributed to the antioxidant capacity, but were also good α-amylase inhibitors. 'Lanjingling' showed the strongest antioxidant capacity evaluated by FRAP, while 'CBS-2' and '14-13-1' showed the strongest antioxidant capacity evaluated by ABTS and DPPH. All the twenty cultivars showed α-amylase inhibitory activity, and the IC₅₀ values ranged from 0.12 ± 0.01 to 0.69 ± 0.02 mg/mL. 'Lanjingling' showed the most potent α-amylase inhibitory activity. Additionally, principal component analysis indicated that Lonicera. caerulea subsp. emkuyedao bred in Japan differed markedly in phenolics and bioactivity compared to the other four subspecies bred in China and Russia.

Effects of hydroxylation at C3' on the B ring and diglycosylation at C3 on the C ring on flavonols inhibition of α-glucosidase activity

The structure-activity relationship and inhibitory mechanism of flavonols on α-glucosidase were studied by inhibition kinetics, multispectral study, and molecular docking. The flavonols of rutin, quercetin and kaempferol effectively inhibit the activity of α-glucosidase, among which quercetin and rutin showed the strongest and weakest inhibitory abilities, respectively. The inhibitory ability of flavonols was enhanced by hydroxylation at C3' of B ring, while it was weakened by diglycosylation at C3 of C ring. Remarkably, the quenching affinity and inhibitory ability of flavonols were inconsistent, which was different from the conclusions reported by some previous studies. This may be ascribed to the hydroxyl groups of C3' of B ring and C3 of C ring. Furthermore, three flavonols were spontaneously bound to α-glucosidase through hydrophobic interactions and hydrogen bonding, which caused the structure and hydrophobic microenvironment of α-glucosidase to change, resulting in significant inhibition of α-glucosidase by flavonols.

Unearthing of the Antidiabetic Potential of Aqueous Extract of Solanum betaceum Cav. Leaves

Solanum betaceum Cav., commonly known as tamarillo or Brazilian tomato, belongs to the Solanaceae family. Its fruit is used in traditional medicine and food crops due to its health benefits. Despite the numerous studies involving the fruit, there is no scientific knowledge about the tamarillo tree leaves. In this work, the phenolic profile of aqueous extract obtained from S. betaceum leaves was unveiled for the first time. Five hydroxycinnamic phenolic acids were identified and quantified, including 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, chlorogenic acid, caffeic acid and rosmarinic acid. While the extract displayed no effect on α-amylase, the extract inhibited the activity of α-glucosidase (IC₅₀ = 1617 mg/mL), and it was particularly effective for human aldose reductase (IC₅₀ = 0.236 mg/mL): a key enzyme in glucose metabolism. Moreover, the extract exhibited interesting antioxidant properties, such as a potent capacity to intercept the in vitro-generated reactive species O₂^•- (IC₅₀ = 0.119 mg/mL) and ^•NO (IC₅₀ = 0.299 mg/mL), as well as to inhibit the first stages of lipid peroxidation (IC₅₀ = 0.080 mg/mL). This study highlights the biological potential of S. betaceum leaves. The scarcity of research on this natural resource underscores the need for additional studies in order to fully explore its antidiabetic properties and to promote the value of a species currently at risk of extinction.

Composition of Powdered Freeze-Dried Orange Juice Co-Product as Related to Glucose Absorption In Vitro

The reuse of food by-products is crucial for the well-being of the planet. Considering the high content of nutrients and other bioactive compounds in many of them, investigating their suitability for use as human food ingredients is an interesting challenge. In this study, in addition to the proximate composition, phenol content and antioxidant activity (AOA = 3.2 mmol Trolox equivalent (TE)/100 g, db) of orange juice powder by-product (CoP), different in vitro properties related to carbohydrate metabolism have been characterised. Specifically, the glycaemic index (GI), the glycaemic load (GL), the glucose dialysis retardation index (GDRI = 13.6%), the glucose adsorption capacity (GAC = 22.5 mM) and the inhibition capacity of α-amylase (α-A = 46.9%) and α-glucosidase (α-G = 93.3%) of powdered orange juice waste have been determined and related to fibre and phenolics composition. Taking advantage of the high fibre content of the by-product (36.67%), its GL was calculated for a CoP dose that allows labelling the food to which it is added as a source of fibre. The low GI value (24.4%) and the low GL (0.918 g available carbohydrates per serving) allowed us to conclude that the product studied could be an interesting opportunity for the food industry to offer it as a healthy food ingredient to be included in the diet, especially for those suffering from type 2 diabetes mellitus. Of the total phenolic compounds (TP = 509 mg equivalent of gallic acid (GAE)/100 g, db), 68% were found in free fraction (FP), and their contribution to the total AOA was 40.6%, while this was 54.9% for the 32% of phenols bound to plant tissues (BP).

Structural characteristics and antioxidant and hypoglycemic activities of a heteropolysaccharide from Anemarrhena asphodeloides Bunge

In this study, an acid polysaccharide (AABP-1B) was extracted from the rhizome of Anemarrhena asphodeloides Bunge and purified using 60 % alcohol precipitation and DEAE-52 cellulose. The molecular weight of AABP-1B was 105 kDa, and it consisted of mannose (Man), rhamnose (Rha), galacturonic acid (GalA), glucose (Glc), galactose (Gal), and arabinose (Ara) in a ratio of 6.3:1.3:1.1:0.2:0.4:0.7. Methylation and NMR analyses revealed that the backbone of AABP-1 consists of 4)-β-D-Manp-(1 and 4)-2-O-acetyl-β-D-Manp-(1. In addition, the biological activity assays showed that AABP-1B not only displays potential antioxidant activity but also exhibits the α-glucosidase and α-amylase inhibitory effect. Moreover, AABP-1B enhanced glucose consumption and glycogen synthesis in insulin-resistant (IR) HepG2 cells. These results suggest that AABP-1B has potential hypoglycemic activity.

An Innovative Mei-Gin Formula Exerts Anti-Adipogenic and Anti-Obesity Effects in 3T3-L1 Adipocyte and High-Fat Diet-Induced Obese Rats

BACKGROUND

To investigate the potential anti-obesity properties of an innovative functional formula (called the Mei-Gin formula: MGF) consisting of bainiku-ekisu, Prunus mume (70% ethanol extract), black garlic (water extract), and Mesona procumbens Hemsl. (40% ethanol extract) for reducing lipid accumulation in 3T3-L1 adipocytes in vitro and obese rats in vivo.

MATERIAL AND METHODS

The prevention and regression of high-fat diet (HFD)-induced obesity by the intervention of Japan Mei-Gin, MGF-3 and -7, and positive health supplement powder were investigated in male Wistar rats. The anti-obesity effects of MGF-3 and -7 in rats with HFD-induced obesity were examined by analyzing the role of visceral and subcutaneous adipose tissue in the development of obesity.

RESULTS

The results indicated that MGF-1-7 significantly suppressed lipid accumulation and cell differentiation through the down-regulation of GPDH activity, as a key regulator in the synthesis of triglycerides. Additionally, MGF-3 and MGF-7 exhibited a greater inhibitory effect on adipogenesis in 3T3-L1 adipocytes. The high-fat diet increased body weight, liver weight, and total body fat (visceral and subcutaneous fat) in obese rats, while these alterations were effectively improved by the administration of MGF-3 and -7, especially MGF-7.

CONCLUSION

This study highlights the role of the Mei-Gin formula, particularly MGF-7, in anti-obesity action, which has the potential to be used as a therapeutic agent for the prevention or treatment of obesity.

Polyphenol Profile and In Vitro Antioxidant and Enzyme Inhibitory Activities of Different Solvent Extracts of Highland Barley Bran

Five different solvent extracts of highland barley bran were analyzed and compared for their polyphenol profile, antioxidant activity, and α-glucosidase and α-amylase inhibitory activities. The highland barley bran acetone extract had the highest total phenolic content, total flavonoid content, and antioxidant capacity. It was followed by the methanol and ethanol extracts, while n-butanol and ethyl acetate extracts exhibited lower measured values. Diosmetin, luteolin, protocatechuic acid, vanillic acid, ferulic acid, phlorogucinol, diosmin, isoquercitrin, catechin, and isovitexin were among the most abundant phenolic compounds identified in different solvent extracts, and their concentrations varied according to the solvent used. The highest α-glucosidase and α-amylase inhibitory activity were observed in the ethyl acetate extract of highland barley bran, followed by the acetone and methanol extracts. In contrast, n-butanol and ethanol extracts exhibited lower measured values. The different solvent extracts were effective inhibitors for α-glucosidase and α-amylase with activity reaching to 34.45-94.32% and 22.08-35.92% of that of positive control acarbose, respectively. There were obvious correlations between the phenolic content and composition of different solvent extracts and their in vitro antioxidant activity, α-glucosidase inhibition activity and α-amylase inhibition activity. Black barley bran is an excellent natural raw material for developing polyphenol-rich functional foods and shows good antioxidant and hypoglycemic potential to benefit human health.

Konjac Glucomannan: An Emerging Specialty Medical Food to Aid in the Treatment of Type 2 Diabetes Mellitus

There are many factors causing T2DM; thus, it is difficult to prevent and cure it with conventional treatment. In order to realize the continuous intervention of T2DM, the treatment strategy of combining diet therapy and traditional medication came into being. As a natural product with the concept of being healthy, konjac flour and its derivatives are popular with the public. Its main component, Konjac glucomannan (KGM), can not only be applied as a food additive, which greatly improves the taste and flavor of food and extends the shelf life of food but also occupies an important role in T2DM. KGM can extend gastric emptying time, increase satiety, and promote liver glycogen synthesis, and also has the potential to improve intestinal flora and the metabolic system through a variety of molecular pathways in order to positively regulate oxidative stress and immune inflammation, and protect the liver and kidneys. In order to establish the theoretical justification for the adjunctive treatment of T2DM, we have outlined the physicochemical features of KGM in this article, emphasizing the advantages of KGM as a meal for special medical purposes of T2DM.

Phenolic compounds from Tradescantia pallida ameliorate diabetes by inhibiting enzymatic and non-enzymatic pathways

Diabetes is a chronic metabolic disorder marked by postprandial hyperglycemia due to several etiologies including abnormal carbohydrate digestion and glycation of hemoglobin. The prolong use of synthetic drugs results in characteristic side effects which necessitates the discovery of safe and cost-effective substitutes. The aim of the current study is to isolate and evaluate the antidiabetic potential of the phenolic compounds from the leaves of Tradescantia pallida. Syringic acid, p-coumaric acid, morin and catechin (compounds 1-4) were isolated and characterized from Tradescantia pallida leaves using column chromatography and spectroscopic techniques. The in vitro antidiabetic potential of the phenolic compounds were assessed using α-amylase and non-enzymatic glycosylation of hemoglobin protein assays. A mechanistic insight of interactions between phenolic compounds and human α-amylase and hemoglobin protein were scrutinized by employing molecular docking method. Prime Molecular Mechanics/Generalized Born Surface Area (MM-GBSA) calculations were carried out to find the binding energies of the ligand-protein complexes. Morin and catechin were further analyzed to find the dynamic and thermodynamic constraints of the complexes under specific biological conditions using molecular dynamic simulation trajectories. The stability and flexibility of the complexes were justified by fluctuation of α-carbon chain, Root Mean Square Deviation (RMSD), Root Mean Square Fluctuation (RMSF) and type of interactions involved which authenticated the in vitro inhibitory potential of morin and catechin against enzymatic and non-enzymatic pathways. The current study could be fruitful in rational designing of safe antidiabetic drugs of natural origin.Communicated by Ramaswamy H. Sarma.

In Vitro Evaluation of Antidiabetic Potential of Cleistocalyx nervosum var. paniala Fruit Extract

Diabetes mellitus is a complex global public health condition. Medicinal plants are significant resources in the research of alternative new drug active compounds. Cleistocalyx nervosum var. paniala (C. nervosum) is an indigenous berry fruit widely grown in Southeast Asia. The fruit of C. nervosum exhibit various medicinal properties and health benefits. This study aimed to investigate antidiabetic properties of C. nervosum fruit extract by in vitro assays and in vitro models. C. nervosum fruit extracted using three different solvents (hexane, ethanol, and distilled water) were tested for α-amylase and α-glucosidase inhibitory activities, followed by glucose uptake in HepG2 and L6 myoblasts. Lipid accumulation in 3T3-L1 cells treated with C. nervosum fruit extracts was then examined. The results revealed that ethanolic extract of C. nervosum fruit showed better inhibition against α-amylase (IC₅₀ of 0.42 μg/mL) and α-glucosidase (IC₅₀ of 0.23 μg/mL) compared with other extracts. Furthermore, ethanolic extract showed higher glucose uptake potential than the standard antidiabetic drug, metformin, in HepG2 cells. The ethanolic extracts resulted in enhanced glucose utilization in L6 myoblasts compared to untreated control. All extractions showed no significantly increased lipid accumulation in 3T3-L1 cells compared to the untreated control cells. The investigation confirmed that the ethanolic extract exhibited the highest antidiabetic activity among all extracts. These results imply that C. nervosum fruit extract has antidiabetic properties and therefore they may be used as useful therapeutic agents for treating diabetes.

The antioxidant and antidiabetic potentials of polyphenolic-rich extracts of Cyperus rotundus (Linn.)

In this study, the rhizome of Cyperus rotundus L was investigated for its antioxidant and antidiabetic effects using in vitro and in silico experimental models. Its crude extracts (ethyl acetate, ethanol and aqueous) were screened in vitro for their antioxidant activity using ferric-reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH), as well as their inhibitory effect on α-glucosidase enzyme. Subsequently, the extracts were subjected to Gas Chromatography-Mass Spectrometry (GC-MS) analysis to elucidate their possible bioactive compounds. Furthermore, computational molecular docking of selected phenolic compounds was conducted to determine their mode of α-glucosidase inhibitory activity. The aqueous extract displayed the highest level of total phenolic content and significantly higher scavenging activity in both FRAP and DPPH assays compared to ethyl acetate and ethanol extracts. In FRAP and DPPH assays, IC₅₀ values of aqueous extract were 448.626 µg/mL and 418.74 µg/mL, respectively. Aqueous extract further presented higher α-glucosidase inhibitory activity with an IC₅₀ value of 383.75 µg/mL. GC-MS analysis revealed the presence of the following phenolic compounds: 4-methyl-2-(2,4,4-trimethylpentan-2-yl) phenol, Phenol,2-methyl-4-(1,1,3,3-tetramethylbutyl)- and 1-ethoxy-2-isopropylbenzene. Molecular docking study revealed 1-ethoxy-2-isopropylbenzene formed two hydrogen bonds with the interacting residues in the active site of α-glucosidase enzyme. Furthermore, 4-methyl-2-(2,4,4-trimethylpentan-2-yl) phenol had the lowest binding energy inferring the best affinity for α-glucosidase active site. These results suggest the possible antioxidant and antidiabetic potential of Cyperus rotundus.Communicated by Ramaswamy H. Sarma.

The consumption of sea buckthorn (Hippophae rhamnoides L.) effectively alleviates type 2 diabetes symptoms in spontaneous diabetic rats

Sea buckthorn (Hippophae rhamnoides L.) is described by various beneficial effects as it contains several bioactive substances characterized by antioxidant effects. These effects are closely related to the reduction of oxidative stress that is involved in the development of the disease. One such diseases is Diabetes mellitus, the prevalence of which is growing and is associated primarily with diet, lack of exercise and/or genetics. This study intends to examine the effects of sea buckthorn and metformin on body weight, water and feed intake, glycaemia, insulinemia, sorbitol accumulation and cataract development in Zucker diabetic fatty rats, which represent an animal model of type 2 Diabetes mellitus, as well as to characterize the individual content of bioactive substances and the antioxidant activity of sea buckthorn. Particular concentrations were applied (500 and 1000 mg.kg-1 body weight of sea buckthorn, and combinations with 150 mg.kg-1 body weight of metformin) by gastric gavage. The total antioxidant capacity and bioactive compounds were determined by spectrophotometric analysis. The best results of the study showed suppression of hyperglycaemia, water intake, decreased sorbitol levels in the lens of the eyes after sea buckthorn treatment. Determination of bioactive compounds showed significantly higher values in dry berries when compared to fresh berries of sea buckthorn and high total antioxidant capacity. Our results represent an interest in sea buckthorn and its potential use in the treatment of Diabetes mellitus as well as other experimental studies.

Hibiscus sabdariffa L. polyphenolic-rich extract promotes muscle glucose uptake and inhibits intestinal glucose absorption with concomitant amelioration of Fe2+ -induced hepatic oxidative injury

In this current study, the antidiabetic effectiveness of Hibiscus sabdariffa and its protective function against Fe²⁺ -induced oxidative hepatic injury were elucidated using in vitro, in silico, and ex vivo studies. The oxidative damage was induced in hepatic tissue by incubation with 0.1 mMolar ferrous sulfate (FeSO4) and then treated with different concentrations of crude extracts (ethyl acetate, ethanol, and aqueous) of H. sabdariffa flowers for 30 min at 37°C. When compared to ethyl acetate and aqueous extracts, the ethanolic extract displayed the most potent scavenging activity in ferric-reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and nitric oxide (NO) assays, with IC₅₀ values of 2.8 μl/ml, 3.3 μl/ml, and 9.2 μl/ml, respectively. The extracts significantly suppressed α-glucosidase and α-amylase activities (p < .05), with the ethanolic extract demonstrating the highest activity. H. sabdariffa significantly (p < .05) raised reduced glutathione (GSH) levels while simultaneously decreasing malondihaldehyde (MDA) and NO levels and increasing superoxide dismutase (SOD) and catalase activity in Fe²⁺ induced oxidative hepatic injury. The extract of the plant inhibited intestinal glucose absorption and increased muscular glucose uptake. The extract revealed the presence of several phenolic compounds when submitted to gas chromatography-mass Spectroscopy (GC-MS) screening, which was docked with α-glucosidase and α- amylase. The molecular docking displayed the compound 4-(3,5-Di-tert-butyl-4-hydroxyphenyl)butyl acrylate strongly interacted with α-glucosidase and α-amylase and had the lowest free binding energy compared to other compounds and acarbose. These results suggest that H. sabdariffa has promising antioxidant and antidiabetic activity. PRACTICAL APPLICATIONS: In recent years, there has been increased concern about the side effects of synthetic anti-diabetic drugs, as well as their expensive cost, especially in impoverished nations. This has instigated a radical shift towards the use of traditional plants, which are rich in phytochemicals many years ago. Among these plants, H. sabdariffa has been used to treat diabetes in traditional medicine. In this present study, H. sabdariffa extracts demonstrated the ability to inhibit carbohydrate digesting enzymes, facilitate muscle glucose uptake and attenuate oxidative stress in oxidative hepatic injury. Hence, demonstrating H. sabdariffa's potential to protect against oxidative damage and the complications associated with diabetes. Consumption of Hibiscus tea or juice may be a potential source for developing an anti-diabetic drug.

Synthesis of activity evaluation of flavonoid derivatives as ɑ-glucosidase inhibitors

Six flavonoid derivatives were synthesized and tested for anti-α-glucosidase activities. All derivatives were confirmed using NMR and HRMS and exhibited excellent inhibitory effects on α-glucosidase. Derivative four exhibited the highest anti-α-glucosidase activity (IC50: 15.71 ± 0.21 μM). Structure-activity relationship results showed that bromine group would be the most beneficial group to anti-α-glucosidase activity. Inhibitory mechnism and inhibition kinetics results showed derivative four was a reversible and mixed-type inhibitor. Molecular docking revealed that derivative four was tightly bind to the amino acid residues of active pocket of α-glucosidase and formed hydrogen bond, π-π stacking, and Pi-Donor hydrogen with α-glucosidase. Moreover, the physicochemical parameters of all derivatives were assessed using SwissADME software. This results also showed that the hybridization of flavonoid and phenylpropionic acid would be a useful strategy for the development of α-glucosidase inhibitors.

Structural Characterization and Biological Activity of Polysaccharides from Stems of Houttuynia cordata

In this study, water-soluble natural polysaccharides were extracted from the stems of Houttuynia cordata Thunb (HCPS). The optimization of the hot water extraction process using response surface methodology (RSM), and the extraction factors, were analyzed by multiple stepwise regression analysis and Pearson analysis. Then, the structural characterization and biological activity of the HCPS were investigated. The results indicated that the maximum extraction yield (2.43%) of the HCPS was obtained at the optimal condition (extraction temperature for 90 °C, extraction time for 5 h, solid-liquid ratio for 1:30 g/mL). The extraction temperature was determined to be the primary factor influencing the extraction yield. The HCPS molecules had an average molecular weight of 8.854 × 103 kDa and were primarily of mannose (Man), rhamnose (Rha), glucuronic acid (GlcA), galacturonic acid (GalA), glucose (Glc), and xylose (Xyl). In addition, the backbone of the HCPS might consist of →6)-α-d-Glcp-(1→ and →6)-β-d-GalpA-(1→. The HCPS had no triple-helix structure. The scanning electron microscopy (SEM) results showed that the HCPS presented a smooth and uniform appearance, and some sheet and chain structures existed. Moreover, the HCPS exhibited significant anti-oxidant activity and inhibited the activity of α-amylase and α-glucosidase. These findings showed that HCPS might be developed into a potential material for hypoglycemia, and provides a reference for the development of Houttuynia cordata polysaccharide applications in food.

May phytophenolics alleviate aflatoxins-induced health challenges? A holistic insight on current landscape and future prospects

The future GCC-connected environmental risk factors expedited the progression of nCDs. Indeed, the emergence of AFs is becoming a global food security concern. AFs are lethal carcinogenic mycotoxins, causing damage to the liver, kidney, and gastrointestinal organs. Long-term exposure to AFs leads to liver cancer. Almost a variety of food commodities, crops, spices, herbaceous materials, nuts, and processed foods can be contaminated with AFs. In this regard, the primary sections of this review aim to cover influencing factors in the occurrence of AFs, the role of AFs in progression of nCDs, links between GCC/nCDs and exposure to AFs, frequency of AFs-based academic investigations, and world distribution of AFs. Next, the current trends in the application of PPs to alleviate AFs toxicity are discussed. Nearly, more than 20,000 published records indexed in scientific databases have been screened to find recent trends on AFs and application of PPs in AFs therapy. Accordingly, shifts in world climate, improper infrastructures for production/storage of food commodities, inconsistency of global polices on AFs permissible concentration in food/feed, and lack of the public awareness are accounting for a considerable proportion of AFs damages. AFs exhibited their toxic effects by triggering the progression of inflammation and oxidative/nitrosative stress, in turn, leading to the onset of nCDs. PPs could decrease AFs-associated oxidative stress, genotoxic, mutagenic, and carcinogenic effects by improving cellular antioxidant balance, regulation of signaling pathways, alleviating inflammatory responses, and modification of gene expression profile in a dose/time-reliant fashion. The administration of PPs alone displayed lower biological properties compared to co-treatment of these metabolites with AFs. This issue might highlight the therapeutic application of PPs than their preventative content. Flavonoids such as quercetin and oxidized tea phenolics, curcumin and resveratrol were the most studied anti-AFs PPs. Our literature review clearly disclosed that considering PPs in antioxidant therapies to alleviate complications of AFs requires improvement in their bioavailability, pharmacokinetics, tissue clearance, and off-target mode of action. Due to the emergencies in the elimination of AFs in food/feedstuffs, further large-scale clinical assessment of PPs to decrease the consequences of AFs is highly required.

Molecular Mechanistic Pathways Targeted by Natural Compounds in the Prevention and Treatment of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is one of the most common complications of diabetes, and its prevalence is still growing rapidly. However, the efficient therapies for this kidney disease are still limited. The pathogenesis of DKD involves glucotoxicity, lipotoxicity, inflammation, oxidative stress, and renal fibrosis. Glucotoxicity and lipotoxicity can cause oxidative stress, which can lead to inflammation and aggravate renal fibrosis. In this review, we have focused on in vitro and in vivo experiments to investigate the mechanistic pathways by which natural compounds exert their effects against the progression of DKD. The accumulated and collected data revealed that some natural compounds could regulate inflammation, oxidative stress, renal fibrosis, and activate autophagy, thereby protecting the kidney. The main pathways targeted by these reviewed compounds include the Nrf2 signaling pathway, NF-κB signaling pathway, TGF-β signaling pathway, NLRP3 inflammasome, autophagy, glycolipid metabolism and ER stress. This review presented an updated overview of the potential benefits of these natural compounds for the prevention and treatment of DKD progression, aimed to provide new potential therapeutic lead compounds and references for the innovative drug development and clinical treatment of DKD.

Xanthine oxidase inhibitory study of eight structurally diverse phenolic compounds

This project was designed to explore the xanthine oxidase (XO) inhibitory mechanism of eight structurally diverse phenolic compounds [quercetin: C1, quercetin-3-rhamnoside: C2, 4, 5-O-dicaffeoylquinic acid: C3, 3, 5-O-dicaffeoylquinic acid: C4, 3, 4-O-di-caffeoylquinic acid: C5, 4-O-caffeoylquinic acid (C6), 3-O-caffeoylquinic acid: C7, and caffeic acid: C8]. For this purpose, in-vitro and different computational methods were applied to determine the xanthine oxidase (XO) inhibitory potential of eight structurally diverse phenolic compounds. The results revealed that phenolic compounds (C1–C8) possess strong to weak XO inhibitory activity. These results were further confirmed by atomic force microscopy (AFM) and ¹H NMR analysis. Furthermore, computational study results revealed that phenolic compounds (C1–C8) bind with the surrounding amino acids of XO at the molybdenum (MO) site. These in-vitro and in-silico results divulge that phenolic compounds have a strong potential to lower uric acid levels via interacting with the XO enzyme and can be used to combat hyperuricemia.

Exploring the Palynological, Chemical, and Bioactive Properties of Non-Studied Bee Pollen and Honey from Morocco

Bee products are known for their beneficial properties widely used in complementary medicine. This study aims to unveil the physicochemical, nutritional value, and phenolic profile of bee pollen and honey collected from Boulemane–Morocco, and to evaluate their antioxidant and antihyperglycemic activity. The results indicate that Citrus aurantium pollen grains were the majority pollen in both samples. Bee pollen was richer in proteins than honey while the inverse was observed for carbohydrate content. Potassium and calcium were the predominant minerals in the studied samples. Seven similar phenolic compounds were found in honey and bee pollen. Three phenolic compounds were identified only in honey (catechin, caffeic acid, vanillic acid) and six phenolic compounds were identified only in bee pollen (hesperidin, cinnamic acid, apigenin, rutin, chlorogenic acid, kaempferol). Naringin is the predominant phenolic in honey while hesperidin is predominant in bee pollen. The results of bioactivities revealed that bee pollen exhibited stronger antioxidant activity and effective α-amylase and α-glycosidase inhibitory action. These bee products show interesting nutritional and bioactive capabilities due to their chemical constituents. These features may allow these bee products to be used in food formulation, as functional and bioactive ingredients, as well as the potential for the nutraceutical sector.

Zinc(II) - Syringic acid complexation synergistically exerts antioxidant action and modulates glucose uptake and utilization in L-6 myotubes and rat muscle tissue

Zinc and syringic acid have metabolic and antioxidant medicinal potentials. A novel zinc(II)-syringic acid complex with improved anti-hyperglycaemic and antioxidant potential was developed. Zinc(II) was complexed with syringic acid in a 1:2 molar ratio and characterized using FT-IR, ¹H NMR and LC-MS. Different experimental models were used to compare the anti-hyperglycaemic and antioxidant properties between the complex and precursors. A Zn(II)-bisyringate.2H₂O complex was formed. The in vitro radical scavenging and Fe³⁺ reducing antioxidant, antiglycation, and α-glucosidase inhibitory activities of the complex were 1.8-5.2 folds stronger than those of the syringic acid precursor and comparable to those of the positive controls. The complex possessed an increased ability to inhibit lipid peroxidation (by 1.6-1.7 folds) and glutathione depletion (2.8-3 folds) relative to syringic acid in Chang liver cells and liver tissues isolated from rats. The complex exhibited a higher glucose uptake effect (EC₅₀ = 20.4 and 386 µM) than its precursors (EC₅₀ = 71.1 and 6460 µM) in L6-myotubes and psoas muscle tissues isolated from rats, respectively, which may be linked to the observed increased cellular zinc uptake potentiated by complexation. Tissue glucose uptake activity was accompanied by increased hexokinase activity, suggesting increased glucose utilization. Moreover, treatment increased tissue phospho-Akt/pan-Akt ratio. The complex had strong molecular docking scores than syringic acid with target proteins linked to diabetes. The presence of two syringic acid moieties and Zn(II) in the complex influenced its potency. The complex was not hepatotoxic and myotoxic in vitro. Zinc-syringic acid complexation may be a novel promising therapeutic approach for diabetes and oxidative complications.