Carbohydrate-hydrolyzing Enzymes Research Articles

Phytochemical Constituents and Biological Activities of the Unexplored Plant Rhinanthus angustifolius subsp. grandiflorus

In the present study, a total of 12 extracts of Rhinanthus angustifolius subsp. grandiflorus, an understudied hemiparasitic species, were obtained using different extraction techniques, namely, homogenizer-assisted extraction (HAE), maceration (MAC), soxhlet (SOX), infusion, and solvents (ethyl acetate, methanol, ethanol, and water), and were evaluated for their in vitro antioxidant and enzyme-inhibiting properties. Additionally, untargeted profiling based on high-resolution mass spectrometry targeted different phytochemical classes, namely, polyphenols, terpenoids, and alkaloids. The highest total phenolic and flavonoid contents were detected using methanol as the extraction solvent. Multivariate statistics following the untargeted profiling revealed that the extraction solvent had a hierarchically higher impact than the extraction method when considering the recovery of bioactive compounds. The methanolic extracts displayed the highest radical-scavenging antioxidant capacity, as provided by CUPRAC and FRAP assays. On the other hand, the water extracts (MAC and HAE) and the infusion extract showed the highest activity as metal chelators (25.66–27.51 mg EDTAE/g). Similarly, the water extract obtained by HAE and the infusion extract revealed the highest phosphomolybdenum activity (3.92 ± 0.14 and 3.71 ± 0.01 mmol TE/g, respectively). The different extracts also exhibited different enzyme inhibition potentials. For instance, HAE and MAC ethanolic extracts inhibited only α-amylase (0.69 ± 0.01 and 0.70 ± 0.01 mmol ACAE/g), while all the other extracts showed a dual inhibition against both carbohydrate-hydrolyzing enzymes tested (i.e., α-amylase: 0.07–0.69 mmol ACAE/g; α-glucosidase: 0.03–1.30 mmol ACAE/g). Nevertheless, the other extracts inhibited acetyl-, butyryl-cholinesterases, or both; MAC–water extract displayed no inhibition against the enzymes. Additionally, all the studied extracts were found to inhibit tyrosinase, ranging from 10.62 to 52.80 mg KAE/g. In general, the water extracts showed weaker inhibition towards the enzymes than the other extracts. This study demonstrated that R. angustifolius is an excellent source of natural antioxidants and enzyme inhibitors that could be further investigated and exploited for pharmaceutical purposes.

Investigation of Total Polyphenol Content, Antioxidant Activity, and Carbohydrate-hydrolyzing Enzyme Inhibition of Yacon Leaves among Four Domestic Cultivars and a Peru Line for over Four Years

Investigation of Total Polyphenol Content, Antioxidant Activity, and Carbohydrate-hydrolyzing Enzyme Inhibition of Yacon Leaves among Four Domestic Cultivars and a Peru Line for over Four Years

Chemical composition, antioxidant and enzyme inhibitory properties of Ajuga parviflora Benth.

Leaves of Ajuga parviflora Benth. (Lamiaceae) are widely used for treating hyperglycemia in the Himalayas' foothills of India. Hydroalcoholic and hexane leaf extracts of A. parviflora were evaluated for their inhibitory potential against carbohydrate-hydrolyzing enzymes linked with hyperglycemia (α-amylase and α-glucosidase) and the effect of extracts on glucose uptake by the yeast cells by in-vitro means. Additionally, antioxidant capacities of both extracts were tested and chemical compositions were also studied by gas chromatography-mass spectrometry (GC-MS). For estimation of the antioxidant capacities, total phenolic content (TPC), total flavonoid content (TFC), 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS •+ ) scavenging activities, Fe 3+ and MO(V) reducing assay were determined. GC-MS analysis revealed various biologically active compounds in which oleic acid , phytol and palmitic acid are present in both the extracts. The TPC and TFC contents were found higher in hydroalcoholic extract than hexane extract. The IC 50 value of both hydroalcoholic and hexane extracts exhibited significant potency for DPPH (113.13 ± 1.4 and 206.8 ± 9.43 μg/mL) and ABTS (156.67 ± 6.76 and 128.2 ± 1.71 μg/mL) as well as for α-amylase (103.55 ± 2.5 and 116.34 ± 2.08 μg/mL) and α-glucosidase (61.38 ± 0.25 and 74.76 ± 0.29 μg/mL) respectively. Both extracts showed a remarkable improvement in the rate of glucose uptake into yeast cells. These findings indicate that A. parviflora leaf possesses antidiabetic and antioxidant properties which justify its traditional antidiabetic use. Based on our findings, we suggest that A. parviflora might be used as an effective phytopharmaceutical in the management of type II diabetes. • Ajuga parviflora Benth. is used in folk medicine for treating hyperglycaemia in India. • Potential of extracts are evaluated by antioxidant, enzyme inhibitory properties and their chemical composition. • Oleic acid, phytol, palmitic acid like biologically active components were present in both extracts. • Extracts exhibited promising antioxidant and inhibitory action against α-amylase and α-glucosidase. • This type of study on A. parviflora is being reported for the first time.

Effects of BTI320 on Glycemic Control in Patients with Type 2 Diabetes

Background/Purpose: Treatment of Type 2 diabetes (T2D) remains an unmet need, particularly a medication with low toxicity. BTI320 (SugarDown®) is fractionated galactomannan with inhibitory activity on carbohydratehydrolyzing enzymes. The primary objective of this study was to investigate the efficacy and safety of BTI320 on glycemic control in T2D. Subjects/Methods: This was a double-blind, placebo-controlled, multi-center study in 60 T2D adults. Subjects ingested 4 g BTI320 or placebo 10 minutes before meals 3 times daily for 12 weeks. The primary endpoint was the change from Baseline to Week 12 in 2-hr post-prandial glucose (PPG) AUC between groups. Results/Conclusion: A consistent trend was observed in favor of BTI320 vs. placebo in change from Baseline at Week 12 in 2-hr PPG AUC (-795.00 vs. -228.75 mg/dL*min), HbA1c (-0.7% vs. +1.1%), lipids, weight/BMI, and blood pressure. At Week 12, BTI320 had more subjects with stable glucose levels (84.6% vs. 79.2%). According to CGM, the BTI320 group had more subjects with stable glucose levels (84.6 vs. 79.2%) and BTI320 subjects experienced relative hypoglycemia for shorter duration than placebo consistently across all visits. No differences were observed in AE profiles between groups. BTI320 was proven to be efficacious and safe in T2D. This study is registered at ClinicalTrials.gov (NCT03655535).

Inhibition Mechanism of α-Amylase/α-Glucosidase by Silibinin, Its Synergism with Acarbose, and the Effect of Milk Proteins.

As a natural flavonolignan, silibinin is reported to possess multiple biological activities, while the inhibitory potential of silibinin on carbohydrate-hydrolyzing enzymes is still unclear. Therefore, in this study, the inhibitory effect and underlying mechanism of silibinin against α-amylase/α-glucosidase were investigated. The results indicated that silibinin showed a strong inhibitory efficiency against α-amylase/α-glucosidase in noncompetitive manners and exhibited synergistic inhibition against α-glucosidase with acarbose. However, interestingly, the inhibitory effect of silibinin was significantly hindered in various milk protein-rich environments, but this phenomenon disappeared after simulated gastrointestinal digestion of milk proteins in vitro. Furthermore, silibinin could combine with the inactive site of α-amylase/α-glucosidase and change the microenvironment and secondary structure of the enzymes, thereby influencing the catalytic efficiency of enzymes. This research suggested that silibinin could be used as a novel carbohydrate-hydrolyzing enzyme inhibitor, and milk beverages rich in silibinin had the potential for further application in antidiabetic dietary or medicine.

Bioassay-Guided Isolation and Structure Elucidation of Bioactive Phytoconstituents with Inhibitory Activity against Carbohydrate-Hydrolyzing Enzymes from the Aerial Parts of Premna odorata Blanco

Abstract: Background: This study aimed to isolate the bioactive components from the aerial parts of Premna odorata Blanco and to evaluate the hypoglycemic potentials of the crude extracts, sub-fractions and final isolate. Materials and Methods: The plant material underwent a series of enzyme assay-guided isolation and purification having the fractions assayed for inhibitory activity against α-amylase using 3,5-dinitrosalicylic acid (DNS) colorimetric method for each stage. H.1 isolate was tested for α-amylase and α-glucosidase inhibitory activity and glucose uptake by yeast cells. Phytochemical characterization and 1H and 13C NMR spectral analysis were done for the structure elucidation of H.1. Results: In vitro amylase studies revealed that at 100 μg/mL concentrations, hexane crude extract, fraction F (20%/80% and 10%/90% n-hexane/dichloromethane fractions) and F.3 (10:1 v/v petroleum ether/ethyl acetate sub-fraction) exhibited 34.38±0.116%, 71.86± 4.909% and 42.16±1.257% inhibition against α-amylase (at 1000 μg/mL concentration), respectively. H.1 isolate exerted significant inhibition (p < 0.05) of 55.99± 2.202% and 72.43±3.988% against α-amylase and α-glucosidase enzyme (both at 1000 μg/ mL concentration), respectively and significant glucose uptake of 13.85± 0.368%. The purified isolate was spectroscopically confirmed as a 5:1 mixture of β- sitosterol (H.1a) and stigmasterol (H.1b). Conclusion: The compounds have significant inhibitory activity against carbohydrate-hydrolyzing enzymes and may be potentially developed as adjuvant pharmacotherapy for type 2 diabetes. Key words: Premna odorata, α-amylase, α-glucosidase, Bioassay, Hyperglycemia, Inhibition.

A GH13 α-glucosidase from Weissella cibaria uncommonly acts on short-chain maltooligosaccharides.

α-Glucosidase (EC 3.2.1.20) is a carbohydrate-hydrolyzing enzyme which generally cleaves α-1,4-glycosidic bonds of oligosaccharides and starch from the nonreducing ends. In this study, the novel α-glucosidase from Weissella cibaria BBK-1 (WcAG) was biochemically and structurally characterized. WcAG belongs to glycoside hydrolase family 13 (GH13) and to the neopullanase subfamily. It exhibits distinct hydrolytic activity towards the α-1,4 linkages of short-chain oligosaccharides from the reducing end. The enzyme prefers to hydrolyse maltotriose and acarbose, while it cannot hydrolyse cyclic oligosaccharides and polysaccharides. In addition, WcAG can cleave pullulan hydrolysates and strongly exhibits transglycosylation activity in the presence of maltose. Size-exclusion chromatography and X-ray crystal structures revealed that WcAG forms a homodimer in which the N-terminal domain of one monomer is orientated in proximity to the catalytic domain of another, creating the substrate-binding groove. Crystal structures of WcAG in complexes with maltose, maltotriose and acarbose revealed a remarkable enzyme active site with accessible +2, +1 and -1 subsites, along with an Arg-Glu gate (Arg176-Glu296) in front of the active site. The -2 and -3 subsites were blocked by Met119 and Asn120 from the N-terminal domain of a different subunit, resulting in an extremely restricted substrate preference.

Evaluating the Inhibitory Effects of Dichloromethane and Methanol Extracts of Salvia macilenta and Salvia officinalis on the Diabetes Marker Enzyme, Alpha-Glucosidase: An Approach for the Treatment of Diabetes

Background: Diabetes mellitus is believed to be the most serious metabolic disease. One of the treatments for diabetes is to delay glucose uptake by inhibiting carbohydrate-hydrolyzing enzymes. Alpha-glucosidase inhibitors delay glucose uptake. Objectives: The present study was conducted aiming to evaluate the efficacy of Salvia extracts in inhibiting diabetes marker enzymes and their effects on the treatment of diabetes. Methods: This experimental study was performed in vitro. The studied plants included Salvia macilenta and Salvia officinalis. The inhibitory effects of their dichloromethane and methanol extracts were also investigated. After calculating the percentage of inhibition and IC50, Km and Vmax using GraphPad Prism 7 were also calculated. The statistical analysis was performed employing GraphPad Instat 3 software. Results: The results herein showed that the greatest inhibitory effect on alpha-glucosidase belonged to the methanol extract of S. macilenta with IC50 = 8.73 ± 0.26 mg/mL compared to that of acarbose with IC50 = 8.82 ± 0.14 mg/mL as a standard. The IC50 of dichloromethane extract of S. officinalis was 8.95 ± 0.23 mg/mL. Conclusions: The extracts had significant inhibitory effects on alpha-glucosidase. However, methanol extract of S. macilenta and dichloromethane extract of S. officinalis demonstrated the greatest inhibitory effects on alpha-glucosidase compared to acarbose as a standard.

Pressurized Hot Liquid Extraction with 15% v/v Glycerol-Water as An Effective Environment-Friendly Process to Obtain Durvillaea incurvata and Lessonia spicata Phlorotannin Extracts with Antioxidant and Antihyperglycemic Potential.

Brown seaweed phlorotannins have shown the potential to promote several health benefits. Durvillaea incurvata and Lessonia spicata—species that are widely distributed in central and southern Chile—were investigated to obtain phlorotannin extracts with antioxidant and antihyperglycemic potential. The use of an environmentally friendly and food-grade glycerol-based pressurized hot liquid extraction (PHLE) process (15% v/v glycerol water) was assessed for the first time to obtain phlorotannins. Multiple effects were analyzed, including the effect of the species, harvesting area (Las Cruces and Niebla), and anatomical part (holdfast, stipe, and frond) on the extracts’ polyphenol content (TPC), antioxidant capacity (AC), and carbohydrate-hydrolyzing enzyme—α-glucosidase and α-amylase—inhibitory activity. Contaminants, such as mannitol, heavy metals (As, Cd, Pb, Hg, and Sn), and 5-hydroxymethylfurfural (HMF), were also determined. The anatomical part used demonstrated a significant impact on the extracts’ TPC and AC, with holdfasts showing the highest values (TPC: 95 ± 24 mg phloroglucinol equivalents/g dry extract; DPPH: 400 ± 140 μmol Trolox equivalents/g dry extract; ORAC: 560 ± 130 μmol TE/g dry extract). Accordingly, holdfast extracts presented the most potent α-glucosidase inhibition, with D. incurvata from Niebla showing an activity equivalent to fifteen times that of acarbose. Only one frond and stipe extract showed significant α-glucosidase inhibitory capacity. No α-amylase inhibition was found in any extract. Although no HMF was detected, potentially hazardous cadmium levels (over the French limit) and substantial mannitol concentrations—reaching up to 50% of the extract dry weight—were found in most seaweed samples and extracts. Therefore, further purification steps are suggested if food or pharmaceutical applications are intended for the seaweed PHLE extracts obtained in this study.

PH Changes Have a Profound Effect on Gene Expression, Hydrolytic Enzyme Production, and Dimorphism in Saccharomycopsis fibuligera.

Saccharomycopsis fibuligera is an amylolytic yeast that plays an important role within nuruk (a traditional Korean fermentation starter) used for the production of makgeolli (Korean rice wine), which is characterized by high acidity. However, the effect of pH change (neutral to acidic) on the yeast cell to hyphal transition and carbohydrate-hydrolyzing enzyme activities for S. fibuligera has not been investigated yet. In this study, S. fibuligera strains were cultured under the different pH conditions, and the effect on the enzyme production and gene expression were investigated. An acidic pH induced a hyphal transition from yeast cell of S. fibuligera KPH12 and the hybrid strain KJJ81. In addition, both strains showed a gradual decrease in the ability to degrade starch and cellulose as the pH went down. Furthermore, a transcriptome analysis demonstrated that the pH decline caused global expression changes in genes, which were classified into five clusters. Among the differentially expressed genes (DEGs) under acidic pH, the downregulated genes were involved in protein synthesis, carbon metabolism, and RIM101 and cAMP-PKA signaling transduction pathways for the yeast-hyphal transition. A decrease in pH induced a dimorphic lifestyle switch from yeast cell formation to hyphal growth in S. fibuligera and caused a decrease in carbohydrate hydrolyzing enzyme production, as well as marked changes in the expression of genes related to enzyme production and pH adaptation. This study will help to elucidate the mechanism of adaptation of S. fibuligera to acidification that occur during the fermentation process of makgeolli using nuruk.

The potential of chalcone-capped gold nanoparticles for the management of diabetes mellitus

Searching for new natural bioactive capping agents represent an urgent priority in the green synthesis of metal nanoparticles. Additionaly, the biosaftey of metal nanparticles is a major concern especially in medical applications. Recently, the use of pharmacollogicaly active natural products as capping agents has been deployed to avoid toxic effects during the nanoparticles preparation and to enhance their drugability compared with convential drugs. Helichrysum foetidum is a South African medicinal plant used in folk medicine for the treatment of different human pathologies, and it is known to contain a variety of bioactive compounds. Herein, the total extract and two pure chalcones, helichrysetin and helichrysin, isolated from the same plant were successfully used to synthesize quasi-monodispersed gold nanoparticles in the size range of 2–12 nm. The bio-evaluation of samples indicated that the AuNP/capping agent conjugates are biostable, and have different biological profiles from the total extract/pure compounds. The enzymatic inhibition assays showed significant inhibition by the total extract, helichrysetin and their gold nanoparticles. Interestingly, a similar activity was observed for glucose uptake in HEK293 treated cells. On the other hand, all the tested samples relatively demonstrated no cytotoxicity when tested against the HaCaT keratinocytes. In conclusion, the study demonstrated potential enhancement of glucose uptake in mammalian kidney cells, and inhibition of carbohydrate-hydrolysing enzymes by green synthesized gold nanoparticles of H. foetidum. It also provides a therapeutic appraisal of AuNPs/chalcones conjugate towards the development of antidiabetes drugs derived from H. foetidum and its gold nanoparticles.

Blood glucose lowering, glycaemic index, carbohydrate-hydrolysing enzyme inhibitory activities of potential functional food from plantain, soy-cake, rice-bran and oat-bran flour blends

Blood glucose lowering, glycaemic index, carbohydrate-hydrolysing enzyme inhibitory activities of potential functional food from plantain, soy-cake, rice-bran and oat-bran flour blends

Bound Polyphenols from Insoluble Dietary Fiber of Defatted Rice Bran by Solid-State Fermentation with Trichoderma viride: Profile, Activity, and Release Mechanism

This study is aimed at exploring the release of bound polyphenols (BP) from insoluble dietary fiber (IDF) and its mechanism by solid-state fermentation (SSF) via Trichoderma viride. The results indicated that BP released by SSF (5.55 mg GAE/g DW) was significantly higher than by alkaline hydrolysis. In addition, 39 polyphenols and catabolites were detected, and the related biotransformation pathways were speculated. Quantitative analysis showed that SSF released more ferulic acid, p-coumaric acid, and organic acids, which led to advances in antioxidant, α-amylase, and α-glucosidase inhibitory activities. Furthermore, structural characteristics (scanning electron microscopy, X-ray diffraction, thermos gravimetric analysis, and Fourier transform infrared spectroscopy) and dynamic changes of carbohydrate-hydrolyzing enzymes indicated that the destruction of hemicellulose and the secretion of xylanase were vital for releasing BP. Overall, this study demonstrated that SSF was beneficial to release BP from IDF, which could provide insight into utilizing agricultural byproducts in a more natural and economical way.

The Effect of Processing of Hempseed on Protein Recovery and Emulsification Properties.

The effect of carbohydrate-hydrolysing enzyme blend with or without supercritical CO2 (SFE) defatting on pretreat hempseed meal, hempseeds, peeled hempseeds, hempseed protein powder, and germinated hempseeds was determined. The raw materials and recovered fractions from the treatments were subjected to gel electrophoresis, and their emulsion capacity, activity, and stability as well as colour (CIE L∗a∗b∗ values) were determined. The highest protein contents, 65% (w/w dm), were detected in soluble fractions prepared from germinated, defatted hempseeds followed by soluble fractions of peeled, defatted hempseed, 55% (w/w dm). The gel electrophoresis showed quite similar protein profiles for all samples; however, the edestin content was lower in the germinated samples than in the others. Enzyme treatment and SFE did not have a significant effect on the emulsion properties. Germinated samples demonstrated a higher ability to stabilise emulsions (15-20%) than other pretreated samples. On the other hand, hempseed meal samples had lower emulsification activity and stability values compared to the other samples. The colour of the sample solutions varied from light to dark with a brown to yellowish colour, and PHS samples showed overall higher L∗ values. In conclusion, germination and peeling in combination with defatting are promising methods to produce functional protein concentrates with efficient emulsion stability and activity as well as a mild colour for food applications.

Potentials of synthesised Lessertia montana zinc oxide nanoparticles on free radicals-mediated oxidative stress and carbohydrate-hydrolysing enzymes

The study evaluated the effects of green absorbed zinc oxide nanostructures on oxidative stress-mediated free radicals and carbohydrate-hydrolysing enzymes. The synthesised Lessertia montana zinc oxide nanoparticles were characterised using different spectroscopic, microscopic, and diffraction techniques. The activity of L. montana ZnONPs against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid (ABTS), metal chelating assay, alpha-amylase and alphaglucosidase were determined using standard methods. L. montana ZnONPs were stable nanoparticles (NPs), appeared cubical (predominantly) in shape, and in nanometre range sizes. The synthesised NPs are very active (p &lt; 0.05) against DPPH and alpha-glucosidase (0.120 and 0.037 g/L, respectively) when compared with other samples and controls, quercetin (0.349 g/L) and acarbose (0.065 g/L). However, their interaction with quercetin revealed a good ABTS (0.093 g/L) scavenging and an excellent metal chelating (0.027 g/L) effect compared to other samples. The mode of inhibition of alpha-amylase and alpha-glucosidase enzymes by L. montana ZnONPs was competitive and non-competitive, respectively. The study outcomes revealed that the synthesised ZnONPs possessed the potential to mitigate oxidative stress and diabetes in vitro.

Effects of ultrasound-assisted extraction (UAE), high voltage electric field (HVEF), high pressure processing (HPP), and combined methods (HVEF+UAE and HPP+UAE) on Gac leaves extraction

Emerging processing technologies and their combinations might be promising approaches to overcome the limitations of the conventional extraction method (CEM). In this study, ultrasonic-assisted extraction (UAE, 150 W, 20 min), high voltage electric field (HVEF, 4000 kV m−1 min), and high-pressure processing (HPP, 300 MPa, 3 min) were used in comparison with the CEM to extract Gac leaves (Momordica cochinchinensis Spreng). Besides, two innovative combined methods, i.e., HVU (HVEF+UAE) and HPU (HPP+UAE), were proposed and investigated. Total phenolic content (TPC), total flavonoid content (TFC), total chlorophyll content (TCC), SOD-like capacity, and carbohydrate-hydrolyzing enzyme inhibition of the extracts were measured. Also, polyphenolic compounds were identified by HPLC and the most contributors in the dataset were assessed by principal component analysis (PCA). Gac leaves extract was found to be a source of valuable bioactive compounds with antioxidant activity and hypoglycemic effects that can help with postprandial hyperglycemia management. Vanillic acid and myricetin had the most contributions to α-glucosidase and α-amylase inhibition ability. Combined emerging technologies (HVU and HPU) were superior to other methods due to the highest values of TPC (5200 mg GAE/100 g DW), TFC (620 mg QE/100 g DW), SOD-like activity (12,100 U/g DW), and inhibitory effects of α-glucosidase (38%, IC50 value of 20.5 mg/mL) and α-amylase (42%, IC50 value of 16.5 mg/mL).

Ultrasound-assisted extraction of Gac (Momordica cochinchinensis Spreng.) leaves: Effect of maturity stage on phytochemicals and carbohydrate-hydrolyzing enzymes inhibitory activity

Although phytochemical contents of Gac fruit have been extensively analyzed, information about the bioactive compounds and valorization of Gac leaves is limited. In this study, Gac (Momordica cochinchinensis Spreng.) leaves at different maturity stages (young: YL, mature: ML and old: OL leaves) were extracted during a 20 min of 150-W sonication process. Color, phytochemicals, antioxidant activity, and inhibitory effects against carbohydrate-hydrolyzing enzymes were assessed by colorimetric, high-performance liquid chromatography, and spectrophotometric methods, respectively. Results indicated a decrease in L* (lightness) and an increase in a* (greenness–redness) during maturation of leaves. The YL extract had the highest contents of phytochemicals with 4897.01 (mg gallic acid equivalent [GAE] per 100 gram dried weight [DW]), total phenolics, 592.81 (mg querce-tin [QE]/100 g DW), total flavonoids, 34.77% ?-amylase inhibitory activity, and 40.21% ?-glucosidase inhibitory activity. Myricetin (43%), vitexin (22%), and esculetin (11%) were the major bioactive compounds detected in YL extract. Also, the superoxide dismutase (SOD)-like capacity of the extract decreased from 11,599.96 to 3,999.63 U/g DW during the transformation of YL to OL. Extract of Gac leaves was found to be a potential ingredient for food preservation and supplementation that could reduce postprandial hyperglycemia.

Investigation of the Anti-Diabetic Effects of Imperialine on Beta-TC6 Pancreatic and C2C12 Skeletal Muscle Cell Lines; A In Vitro Study

Introduction: Imperialine (Imp) is a steroidal alkaloid present as the main active constituent of medicinal herb, Fritillaria imperialis with many biological and therapeutic effects. However, it has not been investigated in vitro for hypoglycemic effects. Herein, the effects of Imp on cell survival, carbohydrate-hydrolyzing enzymes (alpha-amylase and alpha-glucosidase), glucose uptake ability, insulin secretion levels, advanced glycation end product (AGEs) include pentosidine, methylglyoxal, and 3-deoxyglucosone levels and the activity of glyoxalase I as the main factor for degradation of AGEs are examined. Materials and Methods: C2C12 skeletal muscle and beta-TC6 pancreatic cells incubated with Imp at concentrations of 0, 25, 50, 75, and 10 µg/ml, and the cells evaluated separately. The biological evaluations were based on ultraviolet-visible (UV/VIS) spectrophotometric and/or high-performance liquid chromatography (HPLC) methods. Results: Imperialine had considerable and dose-dependent effects on glucose uptake and insulin secretion (p <0.05). The highest levels of glucose uptake were achieved at a concentration of 100 µg/ml of Imp. Increased glycation index, cytotoxicity, and decreased glyoxalase I activity appeared mostly at the concentrations of 75 microgram/ml and higher. The studied alkaloid demonstrated a remarkable hypoglycemic effect by inhibition of alpha-amylase and alpha-glucosidase. Conclusions: Consequently, the results of the present study revealed possible hypoglycemic effects of Imp and it could be suggested for future studies in the treatment of diabetes mellitus.

α-Glucosidase and α-amylase inhibition, molecular modeling and pharmacokinetic studies of new quinazolinone-1,2,3-triazole-acetamide derivatives

In this study, a new series of quinazolinone-1,2,3-triazole-acetamide hybrids 8a–m, using by molecular hybridization of the potent α-glucosidase inhibitor pharmacophores, was designed and evaluated against carbohydrate-hydrolyzing enzymes α-glucosidase and α-amylase. All the synthesized compounds with IC50 values in the range of 45.3 ± 1.4 µM to 195.5 ± 4.7 µM were significantly more potent than standard inhibitor against α-glucosidase, while these compounds were not active against α-amylase in comparison to standard inhibitor. Representatively, compound 8a with IC50 = 45.3 ± 1.4 µM was around 17 times more potent than standard inhibitor acarbose (IC50 = 750.0 ± 12.5 µM). The inhibition kinetic analysis of the compound 8a indicated that this compound was a competitive α-glucosidase inhibitor. Molecular modeling analysis confirmed that the most potent inhibitors 8a and 8b well accommodated in the modeled α-glucosidase active site and it was also revealed that these compounds formed stable inhibitor–receptor complexes with the α-glucosidase in comparison to acarbose. In silico pharmacokinetic and toxicity of the most potent compounds were evaluated and obtained results were compared with acarbose. Furthermore, the most potent compounds were also evaluated against human normal cells and no cytotoxicity was observed.

Marsectohexol and other pregnane phytochemicals derived from Gongronema latifolium as α-amylase and α-glucosidase inhibitors: in vitro and molecular docking studies

This study employed in vitro and in silico techniques to screen isolated pregnane phytochemicals (P1–P4), as well as their source pregnane-rich chromatographic fractions, which were derived from Gongronema latifolium Benth (GLB), for their inhibitory potentials against α-amylase, α-glucosidase, and sucrase enzyme activities. The results show that, most pregnane-rich chromatographic fractions and isolated compounds exhibited good inhibitory activities against α-amylase, and α-glucosidase enzymes. Among the isolated compounds, marsectohexol (P2) is the most favourable structure that showed inhibition against α-amylase (IC50 = 3.712 µg/mL) when compared with the reference inhibitor, acarbose ((IC50 = 15.418 µg/mL). Based on negative and low value of ∆G (Gibb’s free energy), docking scores revealed that, marsectohexol has the highest binding affinity (− 8.8 kcal/mol) to human pancreatic α-amylase (HPA) as compared to the standard acarbose (− 8.1 kcal/mol). Marsectohexol and the other phytocompounds were also found to dock into the active site of HPA; interacting with key catalytic amino acid residues (ASP197, GLU233 and ASP300), which are known to involve in the nucleophilic, and the acid/base catalysis of the enzyme. Although, the pregnane phytocompounds have considerable high affinity binding to the human lysosomal α-glucosidase, they interacted with pockets other than the active site. In conclusion, at least, marsectohexol and three other constituent pregnane phytochemicals of GLB are potential inhibitors of the carbohydrate-hydrolyzing enzymes. These compounds may account for the anti-hyperglyceamic and antidiabetic potentials of this food herb.