Interaction of antidiabetic α-glucosidase inhibitors and gut bacteria α-glucosidase

The phytochemistry and pharmacology of three Rheum species: A comprehensive review with future perspectives

BACKGROUND

Rheum palmatum, R. tanguticum, and R. officinale, integral species of the genus Rheum, are widely used across global temperate and subtropical regions. These species are incorporated in functional foods, medicines, and cosmetics, recognized for their substantial bioactive components.

PURPOSE

This review aims to synthesize developments from 2014 to 2023 concerning the botanical characteristics, ethnopharmacology, nutritional values, chemical compositions, pharmacological activities, mechanisms of action, and toxicity of these species.

METHODS

Data on the three Rheum species were gathered from a comprehensive review of peer-reviewed articles, patents, and clinical trials accessed through PubMed, Google Scholar, Web of Science, and CNKI.

RESULTS

The aerial parts are nutritionally rich, providing essential amino acids, fatty acids, and minerals, suitable for use as health foods or supplements. Studies have identified 143 chemical compounds, including anthraquinones, anthrones, flavonoids, and chromones, which contribute to their broad pharmacological properties such as laxative, anti-diarrheal, neuroprotective, hepatoprotective, cardiovascular, antidiabetic, antitumor, anti-inflammatory, antiviral, and antibacterial effects. Notably, the materials science approach has enhanced understanding of their medicinal capabilities through the evaluation of bioactive compounds in different therapeutic contexts.

CONCLUSION

As medicinal and economically significant herb species, Rheum species provide both edible aerial parts and medicinal underground components that offer substantial health benefits. These characteristics present new opportunities for developing nutritional ingredients and therapeutic products, bolstering the food and pharmaceutical industries.

Human fecal alpha-glucosidase activity and its relationship with gut microbiota profiles and early stages of intestinal mucosa damage

OBJECTIVES

We investigated potential relationships among initial lesions of the intestinal mucosa, fecal enzymatic activities and microbiota profiles.

METHODS

Fecal samples from 54 volunteers were collected after recruitment among individuals participating in a colorectal cancer (CRC) screening program in our region (Northern Spain) or attending for consultation due to clinical symptoms; intestinal mucosa samples were resected during colonoscopy. Enzymatic activities were determined in fecal supernatants by a semi-quantitative method. The fecal microbiota composition was determined by 16S rRNA gene-based sequencing. The results were compared between samples from clinical diagnosis groups (controls and polyps), according with the type of polyp (hyperplastic polyps or conventional adenomas) and considering the grade of dysplasia for conventional adenomas (low and high grade dysplasia).

RESULTS

High levels of α-glucosidase activity were more frequent among samples from individuals diagnosed with intestinal polyps, reaching statistical significance for conventional adenomas and for low grade dysplasia adenomas when compared to controls. Regarding the microbiota profiles, higher abundance of Christensenellaceae_R-7 group and Oscillospiraceae_UCG-002 were found in fecal samples displaying low α-glucosidase activity as compared with those with higher activity as well as in controls with respect to conventional adenomas. A relationship was evidenced among intestinal mucosal lesions, gut glucosidase activities and intestinal microbiota profiles.

CONCLUSIONS

Our findings suggest a relationship among altered fecal α-glucosidase levels, the presence of intestinal mucosal lesions, which can be precursors of CRC, and shifts in defined microbial groups of the fecal microbiota.

Establishment and application of a screening method for α-glucosidase inhibitors based on dual sensing and affinity chromatography

α-Glucosidase plays a direct role in the metabolic pathways of starch and glycogen, any dysfunction in its activity could result in metabolic disease. Concurrently, this enzyme serves as a target for diverse drugs and inhibitors, contributing to the regulation of glucose metabolism in the human body. Here, an integrated analytical method was established to screen inhibitors of α-glucosidase. This step-by-step screening model was accomplished through the biosensing and affinity chromatography techniques. The newly proposed sensing program had a good linear relationship within the enzyme activity range of 0.25 U mL-1 to 1.25 U mL-1, which can quickly identify active ingredients in complex samples. Then the potential active ingredients can be captured, separated, and identified by an affinity chromatography model. The combination of the two parts was achieved by an immobilized enzyme technology and a microdevice for reaction, and the combination not only ensured efficiency and accuracy for inhibitor screening but also eliminated the occurrence of false positive results in the past. The emodin, with a notable inhibitory effect on α-glucosidase, was successfully screened from five traditional Chinese medicines using this method. The molecular docking results also demonstrated that emodin was well embedded into the active pocket of α-glucosidase. In summary, the strategy provided an efficient method for developing new enzyme inhibitors from natural products.

New Perspectives on the Risks of Hydroxylated Polychlorinated Biphenyl (OH-PCB) Exposure: Intestinal Flora α-Glucosidase Inhibition

Polychlorinated biphenyls (PCBs) are a group of colorless and odorless environmental pollutants with a wide range of toxic effects. Some PCBs, especially less chlorinated ones, will rapidly undergo phase I metabolism after entering the body, and hydroxylated polychlorinated biphenyls (OH-PCBs) are the main metabolites of PCBs. Intestinal flora α-glucosidase is a common carbohydrate-active enzyme which is ubiquitous in human intestinal flora. It can convert complex dietary polysaccharides into monosaccharides, assisting the body in degrading complex carbohydrates and providing energy for the survival and growth of bacterial flora. The present study aims to investigate the inhibition of the activity of intestinal flora α-glucosidase by OH-PCBs. 4-Nitrophenyl-α-D-glucopyranoside (PNPG) was used as a probe substrate for α-glucosidase, and in vitro incubation experiments were conducted to study the inhibition of 26 representative OH-PCBs on α-glucosidase. Preliminary screening of in vitro incubation was performed with 100 μM of OH-PCBs. The results showed that 26 OH-PCBs generally exhibited strong inhibition of α-glucosidase. The concentration-dependent inhibition and half inhibition concentrations (IC50s) of OH-PCBs on α-glucosidase were determined. 4'-OH-PCB 86 and 4'-OH-PCB 106 were chosen as representative OH-PCBs, and the inhibition kinetic parameters (Kis) of inhibitors for α-glucosidase were determined. The inhibition kinetic parameters (Kis) of 4'-OH-PCB 86 and 4'-OH-PCB 106 for α-glucosidase are 1.007 μM and 0.538 μM, respectively. The silico docking method was used to further analyze the interaction mechanism between OH-PCBs and α-glucosidase. All these results will help us to understand the risks of OH-PCB exposure from a new perspective.

Evaluation of Acarbose Bioequivalence in Healthy Chinese Populations Using Novel Pharmacodynamic End Points

Acarbose is a widely used α-glucosidase inhibitor for the management of postprandial hyperglycemia in patients with type 2 diabetes mellitus. Recent pilot studies on acarbose bioequivalence (BE) have successfully identified additional pharmacodynamic (PD) parameters as valid end points. Nevertheless, there was a scarcity of published pivotal studies using novel PD parameters. The purpose of the study is to investigate the acarbose BE using the new PD parameters. The study was conducted with an open, randomized, 2-period crossover design. A total of 64 healthy Chinese volunteers received either the reference (R) or test (T) acarbose at a dose of 2×50 mg orally, followed by a 1-week washout period. After sucrose treatment (baseline) and sucrose/acarbose co-administration, serum glucose, and insulin concentrations were assessed. The rectifying approach yielded geometric mean ratios of 102.9% for maximum serum glucose concentration with deduction of glucose concentration at 0 hour and 105.3% for the area under the serum glucose concentration-time curve profile 0-2 hours after coadministration of sucrose and acarbose with deduction of baseline (AUC0-2 h,r ). The 90% confidence intervals of maximum serum glucose concentration with deduction of glucose concentration at 0 hour and the area under the serum glucose concentration-time curve profile 0-2 hours after coadministration of sucrose and acarbose with deduction of baseline all fell within the acceptance limits. The incidence of adverse events after the T or R drug was comparable, and healthy subjects were well tolerated. The findings of our investigation clearly show that the PD parameters of the rectifying method exhibit enhanced suitability and sensitivity when assessing acarbose BE in healthy participants. The T and R drugs were bioequivalent using the novel PD parameters, and both drugs demonstrated good safety and tolerability.

Exogenous Co-Reactant-Free Electrochemiluminescent Biosensor for Ratiometric Measurement of α-Glucosidase Based on a ZIF-67-Regulated Hydrogen-Bonded Organic Framework

The development of highly sensitive and selective analytical approaches for monitoring enzymatic activity is critical for disease diagnosis and biomedical research. Herein, we develop an exogenous co-reactant-free electrochemiluminescence (ECL) biosensor for the ratiometric measurement of α-glucosidase (α-Glu) based on a zeolitic imidazolate framework (ZIF-67)-regulated pyrene-based hydrogen-bonded organic framework (HOF-101). Target α-Glu can hydrolyze maltose to α-d-glucose, which can subsequently react with GOx to produce gluconic acid. The resultant gluconic acid can dissolve ZIF-67, leading to the recovery of the HOF-101 cathodic ECL signal and the decrease of the luminol anodic ECL signal. The long-range ordered structure of HOF-101 can speed up charge transfer, resulting in a stable and strong cathodic ECL signal. Moreover, ZIF-67 can not only efficiently quench the ECL signal of HOF-101 due to ECL resonance energy transfer between HOF-101 and ZIF-67 as well as the steric hindrance effect of ZIF-67 but also enhance the anodic ECL emission of luminol in dissolved O2 system because of its ordered and porous crystalline structure and the atomically dispersed Co2+. Notably, HOF-101 possesses a higher ECL efficiency (32.22%) compared with the Ru(bpy)32+ standard. Importantly, this ratiometric ECL biosensor shows high sensitivity (a detection limit of 0.19 U L-1) and a broad linear range (0.2-50 U L-1). This biosensor can efficiently eliminate systematic errors and enhance detection reliability without the involvement of exogenous co-reactants, and it displays good assay performance in human serum samples, holding great promise in biomedical research studies.

In Silico and In Vitro Analyses to Repurpose Quercetin as a Human Pancreatic α-Amylase Inhibitor

Human pancreatic α-amylase (HPA), situated at the apex of the starch digestion hierarchy, is an attractive therapeutic approach to precisely regulate blood glucose levels, thereby efficiently managing diabetes. Polyphenols offer a natural and multifaceted approach to moderate postprandial sugar spikes, with their slight modulation in carbohydrate digestion and potential secondary benefits, such as antioxidant and anti-inflammatory effects. Taking into consideration the unfavorable side effects of currently available commercial medications, we aimed to study a library of polyphenols attributed to their remarkable antidiabetic properties and screened the most potent HPA inhibitor via a comprehensive in silico study encompassing molecular docking, molecular mechanics with generalized Born and surface area solvation (MM/GBSA) calculation, molecular dynamics (MD) simulation, density functional theory (DFT) study, and pharmacokinetic properties followed by an in vitro assay. Significant hydrogen bonding with the catalytic triad residues of HPA, prominent MM/GBSA binding energy of -27.03 kcal/mol, and the stable nature of the protein-ligand complex with regard to 100 ns MD simulation screened quercetin as the best HPA inhibitor. Additionally, quercetin showed strong reactivity in the substrate-binding pocket of HPA and exhibited favorable pharmacokinetic properties with a considerable inhibitory concentration (IC50) of 57.37 ± 0.9 μg/mL against α-amylase. This study holds prospects for HPA inhibition and suggests quercetin as an approach to therapy for diabetes; however, it is imperative to conduct further research.

Pneumatosis intestinalis associated with α-glucosidase inhibitors: a pharmacovigilance study of the FDA adverse event reporting system from 2004 to 2022

BACKGROUND

A-glucosidase inhibitors (AGIs) are suitable for type 2 diabetes mellitus patients with carbohydrate-rich diets while were reported associated with the rare but potentially life-threatening pneumatosis intestinalis (PI).

RESEARCH DESIGN AND METHODS

Data from the US Food and Drug Administration Adverse Event Reporting System (FAERS) were examined for AGIs, acarbose, voglibose, miglitol, or other anti-hyperglycemic drug classes. The reporting odds ratio (ROR), proportional reporting ratio, gamma poisson shrinker, and bayesian confidence propagation neural network were applied to determine the safety signals, which were performed under two other models to control for bias from type 2 diabetes mellitus and other anti-hyperglycemic drugs.

RESULTS

We found a significantly higher reporting of PI in all AGIs group [ROR = 73.85 (61.56-88.58)]. When further subdivided, voglibose and miglitol had a larger ROR than acarbose whether models were adjusted or not. The safety signals of biguanides, sulfonylureas, thiazolidinediones, dipeptidyl peptidase 4 inhibitors inhibitors, glucagon-like peptide-1 receptor agonists, sodium-glucose co-transporter-2 inhibitors, and other drug classes were not detected in three models.

CONCLUSIONS

Our study identified the safety signals of the PI-AGIs pair, primarily based on disproportionality analysis while controlling for confounders such as the disease-associated risk of PI and concomitant drug exposure.

A Basic Study of the Effects of Mulberry Leaf Administration to Healthy C57BL/6 Mice on Gut Microbiota and Metabolites

Mulberry leaves contain α-glucosidase inhibitors, which have hypoglycemic effects and are considered functional foods. However, few reports have covered the effects of mulberry leaf components on normal gut microbiota and gut metabolites. Herein, gut microbiota analysis and NMR-based metabolomics were performed on the feces of mulberry leaf powder (MLP)-treated mice to determine the effects of long-term MLP consumption. Gut microbiota in the mouse were analyzed using 16S-rRNA gene sequencing, and no significant differences were revealed in the diversity and community structure of the gut microbiota in the C57BL/6 mice with or without MLP supplementation. Thirty-nine metabolites were identified via 1H-NMR analysis, and carbohydrates and amino acids were significantly (p < 0.01-0.05) altered upon MLP treatment. In the MLP-treated group, there was a marked increase and decrease in maltose and glucose concentrations, respectively, possibly due to the degradation inhibitory activity of oligosaccharides. After 5 weeks, all amino acid concentrations decreased. Furthermore, despite clear fluctuations in fecal saccharide concentrations, short-chain fatty acid production via intestinal bacterial metabolism was not strongly affected. This study provides the knowledge that MLP administration can alter the gut metabolites without affecting the normal gut microbiota, which is useful for considering MLP as a healthy food source.

Anti-α-Glucosidase, SAR Analysis, and Mechanism Investigation of Indolo[1,2-b]isoquinoline Derivatives

To find potential α-glucosidase inhibitors, indolo[1,2-b]isoquinoline derivatives (1-20) were screened for their α-glucosidase inhibitory effects. All derivatives presented potential α-glucosidase inhibitory effects with IC₅₀ values of 3.44 ± 0.36~41.24 ± 0.26 μM compared to the positive control acarbose (IC₅₀ value: 640.57 ± 5.13 μM). In particular, compound 11 displayed the strongest anti-α-glucosidase activity, being ~186 times stronger than acarbose. Kinetic studies found that compounds 9, 11, 13, 18, and 19 were all reversible mix-type inhibitors. The 3D fluorescence spectra and CD spectra results revealed that the interaction between compounds 9, 11, 13, 18, and 19 and α-glucosidase changed the conformational changes of α-glucosidase. Molecular docking and molecular dynamics simulation results indicated the interaction between compounds and α-glucosidase. In addition, cell cytotoxicity and drug-like properties of compound 11 were also investigated.

Identification and Isolation of α-Glucosidase Inhibitors from Siraitia grosvenorii Roots Using Bio-Affinity Ultrafiltration and Comprehensive Chromatography

The discovery of bioactive compounds from medicinal plants has played a crucial role in drug discovery. In this study, a simple and efficient method utilizing affinity-based ultrafiltration (UF) coupled with high-performance liquid chromatography (HPLC) was developed for the rapid screening and targeted separation of α-glucosidase inhibitors from Siraitia grosvenorii roots. First, an active fraction of S. grosvenorii roots (SGR2) was prepared, and 17 potential α-glucosidase inhibitors were identified based on UF-HPLC analysis. Second, guided by UF-HPLC, a combination of MCI gel CHP-20P column chromatography, high-speed counter-current countercurrent chromatography, and preparative HPLC were conducted to isolate the compounds producing active peaks. Sixteen compounds were successfully isolated from SGR2, including two lignans and fourteen cucurbitane-type triterpenoids. The structures of the novel compounds (4, 6, 7, 8, 9, and 11) were elucidated using spectroscopic methods, including one- and two-dimensional nuclear magnetic resonance spectroscopy and high-resolution electrospray ionization mass spectrometry. Finally, the α-glucosidase inhibitory activities of the isolated compounds were verified via enzyme inhibition assays and molecular docking analysis, all of which were found to exhibit certain inhibitory activity. Compound 14 exhibited the strongest inhibitory activity, with an IC₅₀ value of 430.13 ± 13.33 μM, which was superior to that of acarbose (1332.50 ± 58.53 μM). The relationships between the structures of the compounds and their inhibitory activities were also investigated. Molecular docking showed that the highly active inhibitors interacted with α-glucosidase through hydrogen bonds and hydrophobic interactions. Our results demonstrate the beneficial effects of S. grosvenorii roots and their constituents on α-glucosidase inhibition.

Targeting the human gut microbiome with small-molecule inhibitors

The human gut microbiome is a complex microbial community that is strongly linked to both host health and disease. However, the detailed molecular mechanisms underlying the effects of these microorganisms on host biology remain largely uncharacterized. The development of non-lethal, small-molecule inhibitors that target specific gut microbial activities enables a powerful but underutilized approach to studying the gut microbiome and a promising therapeutic strategy. In this Review, we will discuss the challenges of studying this microbial community, the historic use of small-molecule inhibitors in microbial ecology, and recent applications of this strategy. We also discuss the evidence suggesting that host-targeted drugs can affect the growth and metabolism of gut microbes. Finally, we address the issues of developing and implementing microbiome-targeted small-molecule inhibitors and define important future directions for this research.

Antidiabetic Potential of Novel 1,3,5-Trisubstituted-2-Thioxoimidazloidin-4-One Analogues: Insights into α-Glucosidase, α-Amylase, and Antioxidant Activities

As the ninth leading cause of death globally, diabetes mellitus (DM) is considered to be the worst chronic metabolic disease requiring an enormous need for healthcare with over 578 million expected cases by 2023. Several recent findings have demonstrated that mediating the activity of carbohydrate-hydrolyzing enzymes, including α-amylase and α-glucosidase, could be a potential strategy for managing the development of DM. In the presented study, a novel set of 1,3,5-trisubstituted-2-thioxoimidazolidin-4-ones was designed, synthesized, and characterized. The antidiabetic activity of the synthesized compounds was explored by assessing their inhibitory activity toward α-amylase and α-glucosidase enzymes. The results demonstrated that this class of compounds exhibits considerable inhibitory activity toward both α-amylase and α-glucosidase enzymes. Among the synthesized compounds, compound 5a demonstrated the most inhibitory activity with IC₅₀ of 5.08 and µg/mL and 0.21 µg/mL toward α-glucosidase and α-amylase activities, respectively, as compared to the drug Acarbose (IC₅₀ = 5.76 µg/mL and 0.39 µg/mL, respectively). To gain insights into the antidiabetic potential of compound 5a, we assessed the cytotoxic and antioxidant activities. Our findings indicated that compound 5a displays considerable cytotoxicity toward WI-38 cells with an IC₅₀ of 88.54 µg/mL, as compared to the drug Celecoxib (IC₅₀ = 93.05 µg/mL). Further, compound 5a exhibited a high scavenging activity toward 2,2-Diphenyl1-picrylhydrazyl (DPPH) free radicals (IC₅₀ = 51.75 µg/mL) and showed a low potential to produce ROS as indicated by the monitoring of the generated H₂O₂ (132.4 pg/mL), as compared to Trolox (IC₅₀ = 58.09 µg/mL) and Celecoxib (171.6 pg/mL). Finally, we performed extensive molecular modeling studies to affirm the binding affinity of this class of compounds to the binding pocket of α-amylase and α-glucosidase enzymes. Collectively, our findings indicate that this class of compounds, particularly compound 5a, could be utilized as a lead structure for the development of novel compounds with potential antidiabetic and antioxidant activities.

Gut microbiota is correlated with gastrointestinal adverse events of metformin in patients with type 2 diabetes

Aim

Gastrointestinal discomfort is the most common adverse event in metformin treatment for type 2 diabetes. The mechanism of action of metformin is associated with gut microbiota. However, the gut microbial community structure related to metformin-induced gastrointestinal adverse events remains unclear. This study aimed to investigate it.

Methods

50 patients with newly diagnosed diabetes were treated with metformin 1500mg/d for 12 weeks. The patients were divided into two groups according to whether gastrointestinal adverse events occurred (group B) or did not occur (group A) after treatment. The fecal bacterial communities and short-chain fatty acids (SCFAs) were sequenced and compared. 70 diabetes mice were randomly divided into 8 groups and treated with metformin (Met), clindamycin (Clin) and/or SCFA, which were the Met+/Clin+, Met+/Clin-, Met-/Clin+, Met-/Clin-, Met+/SCFA+, Met+/SCFA-, Met-/SCFA+ and Met-/SCFA- group. After 4 weeks of metformin treatment, blood glucose, food intake, fecal SCFAs, gut microbiota and gut hormones were measured.

Results

Metformin increased the abundance of Phascolarctobacterium, Intestinimonas and Clostridium III. Functional prediction analysis showed that the propanoate metabolism pathway was significantly up-regulated. The concentrations of acetic acid and propanoic acid in feces were significantly increased. The abundance of Clostridium sensu stricto, Streptococcus and Akkermansia induced by metformin in group B was higher than that in group A. The propanoate metabolism pathway and propanoic acid in feces were significantly up-regulated in group B. In the animal experiments, the food intake decreased and glucose control increased in metformin groups compared with those in the control groups. The total GLP-1 level in the Met+/Clin- group was significantly higher than that in the Met-/Clin- group, while there was no statistical difference between the Met-/Clin- and Met+/Clin+ group. The total GLP-1 level in the Met-/SCFA+ group was significantly higher than that in the Met-/SCFA-group, while the levels of total GLP-1 and active GLP-1 in the Met+/SCFA- group and the Met+/SCFA+ group were significantly higher than those in the Met-/SCFA-group.

Conclusions

Our data suggest that metformin promotes the secretion of intestinal hormones such as GLP-1 by increasing the abundance of SCFA-producing bacteria, which not only plays an anti-diabetic role, but also may causes gastrointestinal adverse events.

Gut Microbiota and Antidiabetic Drugs: Perspectives of Personalized Treatment in Type 2 Diabetes Mellitus

Alterations in the composition and function of the gut microbiota have been reported in patients with type 2 diabetes mellitus (T2DM). Emerging studies show that prescribed antidiabetic drugs distort the gut microbiota signature associated with T2DM. Even more importantly, accumulated evidence provides support for the notion that gut microbiota, in turn, mediates the efficacy and safety of antidiabetic drugs. In this review, we highlight the current state-of-the-art knowledge on the crosstalk and interactions between gut microbiota and antidiabetic drugs, including metformin, α-glucosidase inhibitors, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, sodium-glucose cotransporter 2 inhibitors, traditional Chinese medicines and other antidiabetic drugs, as well as address corresponding microbial-based therapeutics, aiming to provide novel preventative strategies and personalized therapeutic targets in T2DM.

Bio-affinity ultra-filtration combined with HPLC-ESI-qTOF-MS/MS for screening potential α-glucosidase inhibitors from Cerasus humilis (Bge.) Sok. leaf-tea and in silico analysis

Cerasus humilis(Bge.) Sok. leaf-tea (CLT) has a potential anti-α-glucosidase effect. However, its anti-α-glucosidase functional compositions remain unclear. Results showed that 70% methanol extract of CLT (IC₅₀ = 36.57 μg/mL) with the highest total phenolic/flavonoid contents exhibited significantly higher α-glucosidase inhibitory activity (α-GIA) than acarbose (IC₅₀ = 189.57 μg/mL). Additionally, phenolic constituents of the CLT extract were analyzed for the first time in this work. Ten major potential α-glucosidase inhibitors (α-GIs) with high bio-affinity degree in the CLT extract were recognized using a bio-affinity ultra-filtration and HPLC-ESI-qTOF-MS/MS method. In vitro α-GIA assay confirmed that myricetin (IC₅₀ = 36.17 μg/mL), avicularin (IC₅₀ = 69.84 μg/mL), quercitrin, isoquercitrin, prunin and guajavarin were responsible for the α-GIA of the CLT extract. More importantly, the interaction mechanism between α-GIs and α-glucosidase was investigated via in silico analysis. This study provides a high-throughput screening platform for identification of the potential α-GIs from natural products.

Hypoglycemic effects of Rhodiola crenulata (HK. f. et. Thoms) H. Ohba in vitro and in vivo and its ingredient identification by UPLC-triple-TOF/MS

Rhodiola crenulata (HK. f. et. Thoms) H. Ohba (RC), mainly distributed in the highly cold region of China, has long been used as a medicine/healthy food for eliminating fatigue and increasing blood circulation. This study aimed to evaluate the inhibitory effects of the RCRS extract on α-amylase and α-glucosidase (sucrase and maltase) in vitro and in vivo, and tentatively analyze and identify its chemical ingredients using UPLC-Triple-TOF/MS. The Rhodiola crenulata RCRS extract had strong inhibitory activities against α-amylase, sucrase and maltase with an IC₅₀ of 0.031 mg mL^-1, 0.142 mg mL^-1 and 0.214 mg mL^-1, respectively. Furthermore, the RCRS extract could significantly decrease the postprandial blood glucose (PBG) level of normal mice in a starch tolerance test, and reduce the PBG levels of diabetic mice in a starch/maltose/sucrose tolerance test. UHPLC-Triple-TOF-MS/MS analysis indicated that hydroxybenzoic acids, hydroxycinnamic acids, alcohol glycosides, flavonols and their derivatives were the main active ingredients in the RCRS extract. The results demonstrate that the RCRS extract of Rhodiola crenulata could be employed as a healthy food or medicine for controlling postprandial blood glucose levels.

Effects of Oral Glucose-Lowering Agents on Gut Microbiota and Microbial Metabolites

The current research and existing facts indicate that type 2 diabetes mellitus (T2DM) is characterized by gut microbiota dysbiosis and disturbed microbial metabolites. Oral glucose-lowering drugs are reported with pleiotropic beneficial effects, including not only a decrease in glucose level but also weight loss, antihypertension, anti-inflammation, and cardiovascular protection, but the underlying mechanisms are still not clear. Evidence can be found showing that oral glucose-lowering drugs might modify the gut microbiome and thereby alter gastrointestinal metabolites to improve host health. Although the connections among gut microbial communities, microbial metabolites, and T2DM are complex, figuring out how antidiabetic agents shape the gut microbiome is vital for optimizing the treatment, meaningful for the instruction for probiotic therapy and gut microbiota transplantation in T2DM. In this review, we focused on the literatures in gut microbiota and its metabolite profile alterations beneficial from oral antidiabetic drugs, trying to provide implications for future study in the developing field of these drugs, such as combination therapies, pre- and probiotics intervention in T2DM, and subjects with pregestational diabetes and gestational diabetes mellitus.

A review of alpha-glucosidase inhibitors from plants as potential candidates for the treatment of type-2 diabetes

Diabetes mellitus is a multifactorial global health disorder that is rising at an alarming rate. Cardiovascular diseases, kidney damage and neuropathy are the main cause of high mortality rates among individuals with diabetes. One effective therapeutic approach for controlling hyperglycemia associated with type-2 diabetes is to target alpha-amylase and alpha-glucosidase, enzymes that catalyzes starch hydrolysis in the intestine. At present, approved inhibitors for these enzymes are restricted to acarbose, miglitol and voglibose. Although these inhibitors retard glucose absorption, undesirable gastrointestinal side effects impede their application. Therefore, research efforts continue to seek novel inhibitors with improved efficacy and minimal side effects. Natural products of plant origin have been a valuable source of therapeutic agents with lesser toxicity and side effects. The anti-diabetic potential through alpha-glucosidase inhibition of plant-derived molecules are summarized in this review. Eight molecules (Taxumariene F, Akebonoic acid, Morusin, Rhaponticin, Procyanidin A2, Alaternin, Mulberrofuran K and Psoralidin) were selected as promising drug candidates and their pharmacokinetic properties and toxicity were discussed where available.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11101-021-09773-1.

Anti-diabetics and antimicrobials: Harmony of mutual interplay

Diabetes is one of the four major non-communicable diseases, and appointed by the world health organization as the seventh leading cause of death worldwide. The scientists have turned over every rock in the corners of medical sciences in order to come up with better understanding and hence more effective treatments of diabetes. The continuous research on the subject has elucidated the role of immune disorders and inflammation as definitive factors in the trajectory of diabetes, assuring that blood glucose adjustments would result in a relief in the systemic stress leading to minimizing inflammation. On a parallel basis, microbial infections usually take advantage of immunity disorders and propagate creating a pro-inflammatory environment, all of which can be reversed by antimicrobial treatment. Standing at the crossroads between diabetes, immunity and infection, we aim in this review at projecting the interplay between immunity and diabetes, shedding the light on the overlapping playgrounds for the activity of some antimicrobial and anti-diabetic agents. Furthermore, we focused on the anti-diabetic drugs that can confer antimicrobial or anti-virulence activities.

Diabetes medications as potential calorie restriction mimetics-a focus on the alpha-glucosidase inhibitor acarbose

The field of aging research has grown rapidly over the last half-century, with advancement of scientific technologies to interrogate mechanisms underlying the benefit of life-extending interventions like calorie restriction (CR). Coincident with this increase in knowledge has been the rise of obesity and type 2 diabetes (T2D), both associated with increased morbidity and mortality. Given the difficulty in practicing long-term CR, a search for compounds (CR mimetics) which could recapitulate the health and longevity benefits without requiring food intake reductions was proposed. Alpha-glucosidase inhibitors (AGIs) are compounds that function predominantly within the gastrointestinal tract to inhibit α-glucosidase and α-amylase enzymatic digestion of complex carbohydrates, delaying and decreasing monosaccharide uptake from the gut in the treatment of T2D. Acarbose, an AGI, has been shown in pre-clinical models to increase lifespan (greater longevity benefits in males), with decreased body weight gain independent of calorie intake reduction. The CR mimetic benefits of acarbose are further supported by clinical findings beyond T2D including the risk for other age-related diseases (e.g., cancer, cardiovascular). Open questions remain regarding the exclusivity of acarbose relative to other AGIs, potential off-target effects, and combination with other therapies for healthy aging and longevity extension. Given the promising results in pre-clinical models (even in the absence of T2D), a unique mechanism of action and multiple age-related reduced disease risks that have been reported with acarbose, support for clinical trials with acarbose focusing on aging-related outcomes and incorporating biological sex, age at treatment initiation, and T2D-dependence within the design is warranted.

Diabetes medications as potential calorie restriction mimetics-a focus on the alpha-glucosidase inhibitor acarbose

The field of aging research has grown rapidly over the last half-century, with advancement of scientific technologies to interrogate mechanisms underlying the benefit of life-extending interventions like calorie restriction (CR). Coincident with this increase in knowledge has been the rise of obesity and type 2 diabetes (T2D), both associated with increased morbidity and mortality. Given the difficulty in practicing long-term CR, a search for compounds (CR mimetics) which could recapitulate the health and longevity benefits without requiring food intake reductions was proposed. Alpha-glucosidase inhibitors (AGIs) are compounds that function predominantly within the gastrointestinal tract to inhibit α-glucosidase and α-amylase enzymatic digestion of complex carbohydrates, delaying and decreasing monosaccharide uptake from the gut in the treatment of T2D. Acarbose, an AGI, has been shown in pre-clinical models to increase lifespan (greater longevity benefits in males), with decreased body weight gain independent of calorie intake reduction. The CR mimetic benefits of acarbose are further supported by clinical findings beyond T2D including the risk for other age-related diseases (e.g., cancer, cardiovascular). Open questions remain regarding the exclusivity of acarbose relative to other AGIs, potential off-target effects, and combination with other therapies for healthy aging and longevity extension. Given the promising results in pre-clinical models (even in the absence of T2D), a unique mechanism of action and multiple age-related reduced disease risks that have been reported with acarbose, support for clinical trials with acarbose focusing on aging-related outcomes and incorporating biological sex, age at treatment initiation, and T2D-dependence within the design is warranted.

1-Deoxynojirimycin and its Derivatives: A Mini Review of the Literature

1-Deoxynojirimycin (1-DNJ) is a naturally occurring sugar analogue with unique bioactivities. It is found in mulberry leaves and silkworms, as well as in the metabolites of certain microorganisms, including Streptomyces and Bacillus. 1-DNJ is a potent α-glucosidase inhibitor and it possesses anti-hyperglycemic, anti-obese, anti-viral and anti-tumor properties. Some derivatives of 1-DNJ, like miglitol, miglustat and migalastat, were applied clinically to treat diseases such as diabetes and lysosomal storage disorders. The present review focused on the extraction, determination, pharmacokinetics and bioactivity of 1-DNJ, as well as the clinical application of 1-DNJ derivatives.

Water Extract of Potentilla discolor Bunge Improves Hepatic Glucose Homeostasis by Regulating Gluconeogenesis and Glycogen Synthesis in High-Fat Diet and Streptozotocin-Induced Type 2 Diabetic Mice

Potentilla discolor Bunge, as a traditional Chinese medicine, exhibits many phytochemical activities. The aim of the present study was to investigate the effects of Potentilla discolor Bunge water extract (PDBW) and its underlying mechanisms on gluconeogenesis and glycogen synthesis in high-fat diet/streptozotocin (HFD/STZ)-induced type 2 diabetic mice. LC-MS/MS analyses of PDBW identified 6 major compounds including apigenin-7-O-β-D-glucoside, epicatechin, quercetin 3-O-β-D-glucuronide, kaempferol-3-O-β-D-glucopyranoside, scutellarin, and quercitrin. In the study, a mouse model of type 2 diabetes was induced by 4-week HFD combined with STZ (40 mg/kg body weight) for 5 days. After oral administration of PDBW at 400 mg/kg body weight daily for 8 weeks, the mice with type 2 diabetes showed significant decrease in the levels of fasting blood glucose and glycated hemoglobin A1c (HbA1c), and increase in the insulin level. PDBW improved the glucose tolerance, insulin sensitivity and lipid profiles. Furthermore, PDBW inhibited the mRNA levels of key gluconeogenic enzymes [phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase)] in liver. PDBW also promoted glycogen synthesis by raising the liver glycogen content, decreasing the phosphorylation of glycogen synthase (GS) and increasing the phosphorylation of glycogen synthase kinase3β (GSK3β). Besides, PDBW induced the activation of protein kinase B (Akt) and AMP-activated protein kinase (AMPK), which might explain changes in the phosphorylation of above enzymes. In summary, PDBW supplementation ameliorates metabolic disorders in a HFD/STZ diabetic mouse model, suggesting the potential application of PDBW in prevention and amelioration of type 2 diabetes.

A review on structure, extraction, and biological activities of polysaccharides isolated from Cyclocarya paliurus (Batalin) Iljinskaja

Cyclocarya paliurus is essential and only living specie of the genus Cyclocarya Iljinskaja. The leaves of this plant have been extensively used as food in the form of tea and green vegetable. Many compounds have been isolated from this plant, and their useful aspects explored, including the polysaccharides. Studies conducted on leaves show that different methods of extraction have been used, as well as a combination of different techniques that have been applied to isolate polysaccharides from the leaves. Their structure has been elucidated because the activity of polysaccharides mainly depends upon their composition. It has been reported that different activities exhibited by the isolated crude, purified as well as modified polysaccharides include, anticancer, anti-inflammatory, antioxidant, antimicrobial, anti-hyperlipidemic and anti-diabetic activities. In some studies, a comparison of crude extract, as well as purified polysaccharide, has been performed. In this review, we have summarized all the available literature available on the methods of extraction, structure, and biological activities of polysaccharides from the leaves of C. paliurus and indicated the potential research areas that should be focused on future studies. We believe that this review will provide an up to date knowledge regarding polysaccharides of C. paliurus for the researchers.

Predicting associations among drugs, targets and diseases by tensor decomposition for drug repositioning

BACKGROUND

Development of new drugs is a time-consuming and costly process, and the cost is still increasing in recent years. However, the number of drugs approved by FDA every year per dollar spent on development is declining. Drug repositioning, which aims to find new use of existing drugs, attracts attention of pharmaceutical researchers due to its high efficiency. A variety of computational methods for drug repositioning have been proposed based on machine learning approaches, network-based approaches, matrix decomposition approaches, etc. RESULTS: We propose a novel computational method for drug repositioning. We construct and decompose three-dimensional tensors, which consist of the associations among drugs, targets and diseases, to derive latent factors reflecting the functional patterns of the three kinds of entities. The proposed method outperforms several baseline methods in recovering missing associations. Most of the top predictions are validated by literature search and computational docking. Latent factors are used to cluster the drugs, targets and diseases into functional groups. Topological Data Analysis (TDA) is applied to investigate the properties of the clusters. We find that the latent factors are able to capture the functional patterns and underlying molecular mechanisms of drugs, targets and diseases. In addition, we focus on repurposing drugs for cancer and discover not only new therapeutic use but also adverse effects of the drugs. In the in-depth study of associations among the clusters of drugs, targets and cancer subtypes, we find there exist strong associations between particular clusters.

CONCLUSIONS

The proposed method is able to recover missing associations, discover new predictions and uncover functional clusters of drugs, targets and diseases. The clustering of drugs, targets and diseases, as well as the associations among the clusters, provides a new guiding framework for drug repositioning.

Clinical and genetic predictors of diabetes drug's response

Diabetes is a major health problem worldwide. Glycemic control is the main goal in the management of type 2 diabetes. While many anti-diabetic drugs and guidelines are available, almost half of diabetic patients do not reach their treatment goal and develop complications. The glucose-lowering response to anti-diabetic drug differs significantly between individuals. Relatively little is known about the factors that might underlie this response. The identification of predictors of response to anti-diabetic drugs is essential for treatment personalization. Unfortunately, the evidence on predictors of drugs response in type 2 diabetes is scarce. Only a few trials were designed for specific groups of patients (e.g. patients with renal impairment or older patients), while subgroup analyses of larger trials are frequently unreported. Physicians need help in picking the drug which provides the maximal benefit, with minimal side effects, in the right dose, for a specific patient, using an omics-based approach besides the phenotypic characteristics.

Crosstalk between gut microbiota and antidiabetic drug action

Type 2 diabetes (T2D) is a disorder characterized by chronic inflated blood glucose levels (hyperglycemia), at first due to insulin resistance and unregulated insulin secretion but with tendency towards global spreading. The gut microbiota is recognized to have an influence on T2D, although surveys have not formed a clear overview to date. Because of the interactions between gut microbiota and host homeostasis, intestinal bacteria are believed to play a large role in various diseases, including metabolic syndrome, obesity and associated disease. In this review, we highlight the animal and human studies which have elucidated the roles of metformin, α-glucosidase inhibitors, glucagon-like peptide-1 agonists, peroxisome proliferator-activated receptors γ agonists, inhibitors of dipeptidyl peptidase-4, sodium/glucose cotransporter inhibitors, and other less studied medications on gut microbiota. This review is dedicated to one of the most widespread diseases, T2D, and the currently used antidiabetic drugs and most promising new findings. In general, the gut microbiota has been shown to have an influence on host metabolism, food consumption, satiety, glucose homoeostasis, and weight gain. Altered intestinal microbiota composition has been noticed in cardiovascular diseases, colon cancer, rheumatoid arthritis, T2D, and obesity. Therefore, the main effect of antidiabetic drugs is on the microbiome composition, basically increasing the short-chain fatty acids-producing bacteria, responsible for losing weight and suppressing inflammation.

Effects of metformin, acarbose, and sitagliptin monotherapy on gut microbiota in Zucker diabetic fatty rats

OBJECTIVE

Recent studies have demonstrated that gut microbiota was closely related to metabolic disorders such as type 2 diabetes. Oral antidiabetic medications including metformin, acarbose and sitagliptin lowered blood glucose levels via acting on the gastrointestinal tract. The aim of the study was to observe the comparisons among those medications on gut microbiota composition.

RESEARCH DESIGN AND METHODS

Zucker diabetic fatty rats (n=32) were randomly divided into four groups, and had respectively gastric administration of normal saline (control), metformin (215.15 mg/kg/day), acarbose (32.27 mg/kg/day), or sitagliptin (10.76 mg/kg/day) for 4 weeks. Blood glucose levels were measured during an intragastric starch tolerance test after the treatments. 16S rRNA gene sequencing was used to access the microbiota in the fecal samples.

RESULTS

Metformin, acarbose, and sitagliptin monotherapy effectively decreased fasting and postprandial blood glucose levels (p<0.001). Acarbose group displayed specific cluster and enterotype mainly composed by Ruminococcus 2 while Lactobacillus was the dominant bacterium in the enterotype of the other three groups. The relative abundance of genera Ruminococcus 2 and Bifidobacterium was dramatically higher in acarbose group. Metformin and sitagliptin increased the relative abundance of genus Lactobacillus. Metagenomic prediction showed that the functional profiles of carbohydrate metabolism were enriched in acarbose group.

CONCLUSIONS

Metformin, acarbose and sitagliptin exerted different effects on the composition of gut microbiota and selectively increased the beneficial bacteria. Supplementation with specific probiotics may further improve the hypoglycemic effects of the antidiabetic drugs.

Identification of α-glucosidase inhibitors from cyclocarya paliurus tea leaves using UF-UPLC-Q/TOF-MS/MS and molecular docking

11 potential α-glucosidase inhibitors in leaves of Cyclocarya paliurus were quickly identified by UF-UPLC-Q/TOF-MS/MS, and their inhibitory activities were verified in vitro and in vivo, as well as docked with homology model.