Protein Α-glucosidase Research Articles

Revealing the potential hypoglycaemic ingredients of Terminalia chebula Retz. by spectrum–effect relationship combining molecular docking and experimental validation

Terminalia chebula Retz. is commonly used in the treatment of diabetes, but its specific ingredients and hypoglycaemic mechanisms remain unclear. In this study, spectrum-effect relationships between common peaks of fingerprint and DPPH, ABTS, PTP1B, α-glucosidase, were used to screen six compounds as the potential hypoglycemic ingredients. Molecular docking studies were conducted on chebulagic acid, chebulinic acid and punicalagin, which were identified by reference standard, revealing the potent in teractions between these bioactive substances and the PTP1B, α-glucosidase protein. Additionally, the cellular level results showed that punicalagin displayed stronger inhibition of PTP1B and α-glucosidase, with IC50 values of 0.0236 and 0.335 μg/mL, respectively, while improving glucose consumption and intracellular glycogen content of insult-resistant L6 muscle cell, and the hypoglycemic effect was achieved by activating the PI3K/AKT signaling pathway. This study demonstrated that T. chebula has the potential to become a hypoglycemic functional food, and offers a strategy for characterization hypoglycemic ingredients.

Two tetrahydroxyterpenoids and a flavonoid from Xylocarpus moluccensis M.Roem. and their α-glucosidase inhibitory and antioxidant capacity

Context: Scientific verification of the anti-hyperglycemic potential of Kayu sarampa (Xylocarpus moluccensis), which is popularly used for diabetic medication in North Sulawesi, Indonesia, is strongly important to conduct to avoid inappropriate medication that might cause worse conditions. Aims: To investigate the anti-hyperglycemic potential of X. moluccensis stem bark ethyl acetate extract and isolated compounds through the α-glucosidase enzyme inhibitory and antioxidant capacity determination. Methods: The active compound was isolated from ethyl acetate extract of X. moluccensis stem bark. The structures of those compounds were elucidated by infrared spectroscopy, liquid chromatography–mass spectrometry, and nuclear magnetic resonance spectroscopies. To discover the anti-hyperglycemic potency, α-glucosidase enzyme inhibition assay, antioxidant assay (DPPH and FRAP), and in silico study were performed. Results: Three isolated compounds were obtained and characterized as two tetrahydroxyterpenoids compounds, namely xyloccensin E (1) and ruageanin D (2), and one flavonoid compound, namely 3,5,7,3ʹ,4ʹ-pentahidroxyflavan (catechin) (3). Compounds 1 and 3 inhibited the α-glucosidase enzyme with IC50 values of 118.60 and 55.19 µg/mL, respectively, with a competitive inhibition mechanism. This is also in line with in silico findings, and both compounds showed good binding affinity of α-glucosidase protein, which indicated their anti-hyperglycemic activity potential by inhibiting α-glucosidase enzyme. Moreover, compounds 1 and 3 showed antioxidant capacity through the DPPH method with an IC50 value of 54.69 and 2.87 µg/mL. In addition, 100 µg/mL of compounds 1 and 3 also exhibited antioxidant capacity through the FRAP method with values of 66.35 and 213.82 µmol Fe2+/g, respectively. Conclusions: The X. moluccensis stem bark ethyl acetate extract, and isolated compounds exhibit α-glucosidase enzyme inhibitory activity and antioxidant capacity, which confirms its potency as an alternative medication for hyperglycemia issues.

α-Glucosidase Inhibitory Phytochemical Components of Chinese Endemic Plant Whitfordiodendron filipes var. tomentosum.

Whitfordiodendron filipes var. tomentosum is an endemic plant in China. There have been no chemical or pharmacological studies of this plant reported before. In the current research, eight triterpenes and two steroids were obtained. Their structures were established by the analysis of NMR data and comparison with those reported in the literature. These ten structurally diverse compounds comprised five distinct carbon frameworks with different functionalities. The chemotaxonomic significance of these secondary metabolites was discussed, disclosing the common components between the variant W. filipes var. tomentosum and the species W. filipe. Evaluation of α-glucosidase inhibitory activities of these isolates disclosed that compounds 1, 2, 4, and 6 exhibited significant α-glucosidase inhibitory activities (IC50 = 16.6-19.2 μM), which were close in value to the positive control acarbose (IC50 = 11.5 μM). Moreover, the binding modes between the biologically active compounds 1, 2, 4, and 6 and the α-glucosidase protein were preliminarily studied using molecular docking. This study not only showed the chemical and biological profile of the plant W. filipes var. tomentosum but also revealed that these components could be developed as hypoglycemic lead compounds.

Novel sulfonamide derivatives as multitarget antidiabetic agents: design, synthesis, and biological evaluation.

A series of new sulfonamide derivatives connected through an imine linker to five or seven membered heterocycles were designed and synthesized. All synthesized derivatives were characterized using a variety of spectroscopic methods, including IR, 1HNMR, and 13CNMR. In vitro α-glucosidase and α-amylase inhibition activities, as well as glucose uptake were assessed for each of the synthesized compounds. Four sulfonamide derivatives namely 3a, 3b, 3h and 6 showed excellent inhibitory potential against α-glucosidase with IC50 values of 19.39, 25.12, 25.57 and 22.02 μM, respectively. They were 1.05- to 1.39-fold more potent than acarbose. Sulfonamide derivatives 3g, 3i and 7 (EC50 values of 1.29, 21.38 and 19.03 μM, respectively) exhibited significant glucose uptake activity that were 1.62- to 27-fold more potent than berberine. Both α-glucosidase protein (PDB: 2QMJ) and α-amylase (PDB: 1XCW) complexed with acarbose were adopted for docking investigations for the most active synthesized compounds. The docked compounds were able to inhabit the same space as the acarviosin ring of acarbose. The docking of the most active compounds showed an analogous binding with the active site of α-glucosidase as acarbose. The superior activity of the synthesized compounds against α-glucosidase enzyme than α-amylase enzyme can be rationalized by the weak interaction with the α-amylase. The physiochemical parameters of all synthesized compounds were aligned with Lipinski's rule of five.

Design, synthesis, biological evaluations and in silico studies of N-substituted 2,4-thiazolidinedione derivatives as potential a-glucosidase inhibitors

Diabetes mellitus is considered as one of the principal global health urgencies of the twenty first century. In the present investigation, novel N-substituted 2,4-thiazolidinedione derivatives were designed, synthesized, and characterized by spectral techniques. All the newly synthesized N-substituted 2,4-thiazolidinedione derivatives were tested for in vitro α-glucosidase inhibitory activities and compounds A-12 and A-14 were found to be the most potent which were further subjected to in-vivo disaccharide loading test. The most potent compound was also found to be non-toxic in cytotoxicity studies. Further, docking studies were carried out to investigate the binding mode and key interactions with amino acid residues of α-glucosidase. Molecular dynamic simulations studies for the compounds acarbose, A2, A12, and A14 were done with α-glucosidase protein. Further, ΔG was calculated for acarbose, A2, A12, and A14. In silico studies and absorption, distribution, metabolism, excretion (ADME) prediction studies were also executed to establish the ‘druggable’ pharmacokinetic profiles. Here, we have developed novel N-substituted TZD analogues with different alkyl groups as α-glucosidase inhibitors.Communicated by Ramaswamy H. Sarma

Chemical Composition, Anti-α-Glucosidase Activity, and Molecular Modelling Studies of Cleistocalyx operculatus Essential Oil

In this study, chemical components, α-glucosidase inhibitory activities, and molecular modelling studies of the essential oil extracted from the Cleistocalyx operculatus leaves were investigated. In total, thirty compounds were identified using GC/MS, representing 98.3% of the oil. Of these, the two most dominant constituents of the essential oil were determined as (Z)-β-ocimene (30.4%) and allo-ocimene (31.6%). The α-glucosidase inhibitory experiments indicated that the essential oil exhibited potent α-glucosidase inhibitory activities, with IC50 values of 61.82 ± 3.91 µg/mL. For further investigation into inhibitory mechanisms, molecular docking simulations were performed to investigate structural interactions between two dominant constituents and the α-glucosidase protein. The simulation revealed that allo-ocimene (31.6%) and (Z)-β-ocimene (30.4%) have protein binding affinities of −5.358 and −5.330 kcal/mol, respectively. Moreover, molecular dynamic simulation indicated that the complexes of two compounds and the target protein were stable over 100 ns. Overall, these findings suggest that the essential oil of C. operculatus leaves could be a natural source of potential α-glucosidase inhibitors.

In-vitro antidiabetic activity, theoretical investigation by DFT and molecular docking of mono oxo vanadyl (IV) azomethine macromolecule

Prospective antidiabetic applicant [VO(IV)HBDB] was synthesized qualitatively and rapidly, spending HBDB of the mode N, N′-bis (2-hydroxy benzylidene)-1,2-diaminobenzene/Salophen a well familiar Schiff base with myriad property. Interesting and valuable details of physical and electronic properties, band gap energy, electronic configuration, and NLO possessions of the complex were reported. The complex consent with extraordinary NLO property accords with first-order hyperpolarizability. The impressiveness of the monooxo Vanadyl complex is elevated further by biological applications. The antibacterial evaluation accounts that [VO(IV)HBDB] shows greater activity than HBDB. DPPH scavenging report demonstrates that [VO(IV)HBDB] exhibits greater antioxidant potential than standard assay. Subsequently, in-vitro antidiabetic activity with α-glucosidase enzyme was also excellent. Molecular docking with α-glucosidase protein of PDB id: 3 WY1 illustrates greater binding energy of about −12.3 kcal/mol defined for [VO(IV)HBDB] than HBDB roughly −7.6 kcal/mol with more amino acid binding residues. The above-disclosed findings of HBDB and its complex firmly sustenance the biochemists and pharmacological field.

Prediction of α-Glucosidase Inhibitory Activity of LC-ESI-TQ-MS/MS-Identified Compounds from Tradescantia pallida Leaves.

Diabetes is a chronic disease that leads to abnormal carbohydrate digestion and hyperglycemia. The long-term use of marketed drugs results in secondary infections and side effects that demand safe and natural substitutes for synthetic drugs. The objective of this study is to evaluate the antidiabetic potential of compounds from the leaves of Tradescantia pallida. Thirteen phenolic compounds were identified from the ethyl acetate fraction of leaves of Tradescantia pallida using liquid chromatography-mass spectrometry. The compounds were then studied for the type of interactions between polyphenols and human α-glucosidase protein using molecular docking analysis. Prime Molecular Mechanics/Generalized Born Surface Area (MM-GBSA) calculations were performed to measure the binding free energies responsible for the formation of ligand-protein complexes. The compounds were further investigated for the thermodynamic constraints under a specified biological environment using molecular dynamic simulations. The flexibility of the ligand-protein systems was verified by Root Mean Square Deviation (RMSD), Root Mean Square Fluctuation (RMSF) and molecular interactions. The results authenticated the antidiabetic potential of polyphenols identified from the leaves of Tradescantia pallida. Our investigations could be helpful in the design of safe antidiabetic agents, but further in vitro and in vivo investigations are required.

Synthesis, Characterization, Hirshfeld Surface Analysis, Crystal Structure and Molecular Modeling Studies of 1-(4-(Methoxy(phenyl)methyl)-2-methylphenoxy)butan-2-one Derivative as a Novel α-Glucosidase Inhibitor

The crystal compound was synthesized and characterized using conventional analytical techniques. The compound C19H21O3 crystallizes in a monoclinic crystal system with the space group P21/c. The crystal structure is stabilized by C-H…O interactions. The structure is further reinforced by π-π interactions. During in vitro inhibition of α-glucosidase, the crystal compound exhibited a significant inhibition of the enzyme (IC50: 10.30 ± 0.25 µg/mL) in comparison with the control, acarbose (IC50: 12.00 ± 0.10 µg/mL). Molecular docking studies were carried out for the crystal compound with the α-glucosidase protein model, which demonstrated that the crystal molecule has a good binding affinity (−10.8 kcal/mol) compared with that of acarbose (−8.2 kcal/mol). The molecular dynamics simulations and binding free energy calculations depicted the stability of the crystal molecule throughout the simulation period (100 ns). Further, a Hirshfeld analysis was carried out in order to understand the packing pattern and intermolecular interactions. The energy difference between the frontier molecular orbitals (FMO) was 4.95 eV.

Surface display of novel transglycosylating α-glucosidase from Aspergillus neoniger on Pichia pastoris for synthesis of isomaltooligosaccharides

In the present study, α-glucosidase gene of Aspergillus neoniger, agdA, was fused with glycosylphosphatidylinositol (GPI)-anchored glycoprotein gene of Pichia pastoris, GCW61 at its C-terminus for functional expression in Pichia pastoris X-33. The expression of this chimeric gene was induced using methanol, and the protein was displayed on the surface of X-33 strain with cell pellet activity of 4.65 U/gDCW. The surface display of recombinant α-glucosidase was confirmed using immunofluorescence microscopy and flow cytometry. The strain displaying α-glucosidase protein was also cultivated in bioreactor using fed-batch cultivation to obtain a maximum activity of 0.158 U/gDCW and with cell density of 45.35 gDCW/L. These cells were later used as whole-cell biocatalysts (20 g wet cell weight/L) for production of isomaltooligosaccharides (IMOs) using 250 g/L of maltose as substrate. The IMO mixture contains isomaltose, panose, maltotetraose, isomaltotriose and three other higher DP oligosaccharides with a net yield of 0.4 g/g maltose. Amongst these, the panose yield was observed to be highest (0.25 g panose/ g maltose). Here we establish that the surface display of novel transglycosylating α-glucosidase on Pichia pastoris using GCW61p as an anchor protein can be used as whole-cell biocatalysts for synthesis of isomaltooligosaccharides.

Two pairs of undescribed enantiomers isolated from the fungus Penicillium griseofulvum

Two pairs of undescribed enantiomers including a 2,5-diketopiperazine namely (±)-janthinolide G and a related analogue (±)-janthinolide H, were isolated from the crude extract of the fungus Penicillium griseofulvum together with five known compounds. Both two structures were determined by spectroscopic method and HRESIMS, whereas absolute stereochemistry was elucidated by using theoretical NMR calculation and ECD calculation. Janthinolide G is the first example of 2,5-diketopiperazine enantiomers with a cleavage diketopiperazine ring and comprises a terminal oxime group rarely seen in natural products. Biological screening of selected compounds found that 4 and 7 both exhibited weak α-glucosidase inhibitory effects, and a potential correlation was afforded by docking studies of α-glucosidase protein (PDB: 3TOP) and bioactive molecules. The plausible biosynthetic pathways of two unreported isolates are proposed here.

α-Glucosidase inhibitory activity of cannabidiol, tetrahydrocannabinol and standardized cannabinoid extracts from Cannabissativa

Two major cannabinoids of cannabis, namely cannabidiol (CBD) and tetrahydrocannabinol (THC) have been reportedly used as alternative medicine for diabetes treatment in both pre-clinical and clinical research. However, their mechanisms of action still remain unclear. Therefore, this study aimed to evaluate the α-glucosidase inhibitory activity of THC, CBD and the standardized cannabinoid extracts. Based on in silico studies, THC generated hydrogen bonding and Van der Waals interactions, while CBD exhibited only Van der Waals interactions with functional residues of target α-glucosidase protein, with good binding energies of −7.5 and −6.9 kcal/mol, respectively. In addition, both of them showed excellent pharmacokinetic profiles with minor toxicity in terms of tumorigenic and reproductive effects. In addition, the enzyme based in vitro assay on α-glucosidase revealed that THC and CBD exhibited good inhibitory activity, with the IC50 values of 3.0 ± 0.37 and 5.5 ± 0.28 μg/ml, respectively. These were better than the standard drug, acarbose (IC50 of 488.6 ± 10.23 μg/ml). Furthermore, two standardized cannabinoid extracts, SCE-I (C. sativa leaf extract) and SCE-II (C. sativa inflorescence extract) exhibited stronger inhibitory activity than THC and CBD, with the IC50 values of 1.2 ± 0.62 and 0.16 ± 0.01 μg/ml, respectively. The present study provides the first evidence that the standardized cannabinoid extracts containing THC and CBD have greater potential than CBD and THC in application as an α-glucosidase inhibitor.

Study of Molecular Docking of Alkaloid Derivative Compounds from Stem Karamunting (Rhodomyrtus tomentosa)Against α-Glucosidase Enzymes

Karamunting plant (Rhodomyrtus tomentosa) is a traditional medicinal plant. The leaves, roots, stems, and fruits of Karamunting have been identified, and their biological activities are antioxidants, antibacterial, antidiabetic, anti-inflammatory, and anticancer that contained alkaloids, tannins, and flavonoids. The types of alkaloids found in karamunting stems are homolycorine, ismine, lycorine, maritidine and tazetine. This study aims to determine the binding score of alkaloid-derived compounds with protein α-glucosidase and determine the protein's active site bound to the ligand. The method used in this research is Protein-Ligand ANT-System (PLANTS). The results showed that the anchoring score of homolycorine was -60.83 kcal/mol, ismine -64.42 kcal/mol, lycorine -71.20 kcal/mol, maritidine -61.82 kcal/mol, and tazetine -65.02 kcal/mol. The active sites used for binding are Glu526, Gly555, and Pro556. The average score for anchoring alkaloid-derived compounds with protein α-glucosidase is 83.84%. This number indicates that karamunting stems can be used as antidiabetic.

A new biological prospective for the 2-phenylbenzofurans as inhibitors of α-glucosidase and of the islet amyloid polypeptide formation

In this study, we have investigated a series of hydroxylated 2-phenylbenzofurans compounds for their inhibitory activity against α-amylase and α-glucosidase activity.Inhibitors of carbohydrate degrading enzymes seem to have an important role as antidiabetic drugs.Diabetes mellitus is a wide-spread metabolic disease characterized by elevated levels of blood glucose. The most common is type 2 diabetes, which can lead to severe complications. Since the aggregates of islet amyloid polypeptide (IAPP) are common in diabetic patients, the effect of compounds to inhibit amyloid fibril formation was also determined.All the compounds assayed showed to be more active against α-glucosidase. Compound 16 showed the lowest IC50 value of the series, and it is found to be 167 times more active than acarbose, the reference compound. The enzymatic activity assays showed that compound 16 acts as a mixed-type inhibitor of α-glucosidase. Furthermore, compound 16 displayed effective inhibition of IAPP aggregation and it manifested no significant cytotoxicity.To predict the binding of compound 16 to IAPP and α-glucosidase protein complexes, molecular docking studies were performed.Altogether, our results support that the 2-phenylbenzofuran derivatives could represent a promising candidate for developing molecules able to modulate multiple targets involved in diabetes mellitus disorder.

Discovery of Novel Coumarin Analogs against the α-Glucosidase Protein Target of Diabetes Mellitus: Pharmacophore-Based QSAR, Docking, and Molecular Dynamics Simulation Studies

Diabetes mellitus (DM) is a chronic metabolic disease, the third killer of mankind. The finding of potent drugs against diabetes remains challenging. In the present study, coumarin derivatives with known biological activity against diabetic protein have been used to predict functional groups’ positions on coumarin derivatives. α-Glucosidase is a brush border membrane-bound lysosomal enzyme from the hydrolase enzyme family. It plays an important role in the metabolism of glycoproteins. Inhibitors of lysosomal α-glucosidase can reduce postprandial hyperglycemia. Due to this, lysosomal α-glucosidase is a good therapeutic target for drugs. A total of 116 coumarin derivatives with IC50 values against lysosomal α-glucosidase were selected for a CADD (computer-aided drug design) approach to identify more potent drugs. Pharmacophore modeling and atom-based 3-QSAR of 116 active compounds against lysosomal α-glucosidase were performed and identified positions and types of groups to increase activity. We performed molecular docking of 116 coumarin derivatives against the lysosomal α-glucosidase enzyme, and three compounds (isorutarine, 10_, and 36) resulted in a docking score of −7.64, −7.12, and −6.86 kcal/mol. The molecular dynamics simulation of the above three molecules and protein complex performed for 100 ns supported the interaction stability of isorutarine, 10_, and 36 with the lysosomal binding site α-glucosidase.

Cloning and characterization of a recombinant α-glucosidase from Ensifer adhaerens NBRC 100388 and evaluation of its glucosyl transfer activity

Abstract Terpene alcohol glycosides are useful compounds in industry. An α-glucosidase gene from a strain of Ensifer adhaerens NBRC 100388 showing transglucosylation activity toward alkylalcohols, which belongs to the glycosides hydrolase family 13, was cloned and expressed in Escherichia coli BL21 (DE3). The molecular mass of the purified recombinant α-glucosidase protein was estimated to be 60 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This α-glucosidase from E. adhaerens NBRC 100388 (EaG) was able to hydrolyze maltose, maltotriose, maltotetraose, maltulose, sucrose, trehalose, ethyl α-D-glucoside, and p-nitrophenyl D-glucoside (p-NPG). The enzyme activity increased in the presence of NH4+ and K+ ions but was inhibited by Cu+ and Zn2+. The enzyme exhibited optimal activity with maltose at a pH of 7.5 and a temperature of 45 °C. The transglucosylation activity was observed not only for nerol, a primary alcohol, but also for 6-gingerol, a secondary alcohol, and (−)-linalool, a tertiary alcohol. The enantioselectivity for the glucosyl transfer toward the acceptor of (±)-linalool was 21.5% ee for the (−)-isomer. Thus, purified EaG can be used in the synthesis of pharmaceuticals, chemicals, and fragrances owing to its ability to catalyze the transglucosylation of tertiary alcohols.

Synthesis, molecular docking, α-glucosidase inhibition, and antioxidant activity studies of novel benzimidazole derivatives

A novel series of N-methyl/benzyl-substituted benzimidazolyl-linked para-substituted benzyl-based compounds containing 2,4-thiazolidinediones, dimethyl malonate (DMM), and diethyl malonate (DEM) 17–27 were designed, docked, synthesized, and evaluated for their antidiabetic activity studies. Structures of all the synthesized compounds were confirmed through 1H NMR, 13C NMR, FTIR, and mass spectrometry. Four targeted compounds (17–18 and 22–23) showed good inhibitory potential in the range of 4.10 ± 0.01 to 9.12 ± 0.06 µM. Furthermore, synthesized compounds 17–27 were evaluated for their antioxidant potential and compared with standard ascorbic acid and results showed that compound 18 (EC50 = 0.176 ± 0.002 mM) being the most active. Compounds 17–18 and 22–23 exhibited prominent antidiabetic as well as antioxidant activity. Compound 18 was considered a promising candidate for this series. The designed molecules were docked into α-glucosidase protein (PDB Code. 3TOP) to develop a correlation with the α-glucosidase inhibition studies and were also additionally docked into PPARγ proteins (PDB ID: 2PRG) with rosiglitazone (standard drug) to study their PPARγ binding affinity in comparison with rosiglitazone and to classify these compounds for their PPARγ agonistic behavior.

Use of a deoxynojirimycin–fluorophore conjugate as a cell-specific imaging probe targeting α-glucosidase on cell membranes

Molecules designed for cell-specific imaging were studied, taking advantage of an enzyme-inhibitor interaction. 1-Deoxynojirimycin (DNJ) can be actively captured by cells which express the surface membrane protein α-glucosidase. New probes composed of DNJ for recognition linked to a fluorophore signal portion were prepared (DNJ-CF31, DNJ-Dans 2 and DNJ-DEAC 3). Docking simulations revealed that the inhibitors acarbose and miglitol and the inhibitor portion of the probes bind at the same position in the pocket of α-glucosidase (human-derived PDB: 3TON). The ability of probes 1-3 to detect the difference between HeLa cells (from human cervical cancer tissue), Neuro-2a cells (from a mouse neuroblastoma C1300 tumor), N1E-115 cells (from a mouse brain neuroblastoma C1300 tumor), A1 cells (from the astrocyte of a newborn mouse brain), and Caco-2 cells (from a human colon carcinoma) was evaluated, and cell-specific fluorescence imaging was possible for conjugate probes 1 and 2. Caco-2 cells treated with probes 1 and 2 showed blue and green fluorescence, respectively, from the cell membrane, and did not stain the Caco-2 cells inside. These results show that DNJ-CF31 and DNJ-Dans 2 recognize an α-glucosidase protein on the surface of Caco-2 cells. Probes 1 and 2 did not stain any part of the other cells. This cell-specific imaging strategy is applicable for a variety of therapeutic agents for many diseases.

Synthesis, in vitro and computational studies of 1,4-disubstituted 1,2,3-triazoles as potential α-glucosidase inhibitors

1,4-Disubstituted-1,2,3-triazoles were synthesized by Cu(I) catalyzed click reaction, where the azides, with electron donating and electron withdrawing groups acted as 1,3-dipoles and 1-ethynyl-1-cyclohexanol served as the terminal alkyne. These synthesized triazoles were subjected to enzymatic assay which showed promising activity against α-glucosidase; 1-(2-cyano-4-nitrophenyl)-4-(1-hydroxycyclohexyl)-1H-1,2,3-triazole 3m being the most active members of the library. Molecular docking studies of these triazoles with the homology-modeled α-glucosidase protein were also performed to delineate ligand-protein interactions at molecular level which suggested that Phe157, Arg312 and His279 are the major interacting residues in the biding site of the protein and may have a significant role in the inhibition of enzyme's function.

Suppression of α-glucosidase gene by RNA interference can increase resistance of Culex quinquefasciatus to Bacillus sphaericus binary toxin

Bacillus sphaericus binary toxin displays a specific toxicity towards Culex spp. larvae. Resistance of Culex quinquefasciatus to B. sphaericus is associated with the reduction or absence of 66-kDa α-glucosidase, a binary toxin receptor, in larval midgut microvilli. In this study, long double-stranded RNA (dsRNA) targeting the α-glucosidase gene was used to suppress the expression of α-glucosidase in Cx. quinquefasciatus larvae and the consequences of the suppression was investigated. Three sets of dsRNAs, dsGRi1, dsGRi2, and dsGRi3, which are homologous to distinct regions of α-glucosidase gene, were delivered to mosquito larva by feeding with dsRNA–chitosan particles. Reverse transcriptase-polymerase chain reaction results demonstrated that the expression of α-glucosidase mRNA was reduced by 43% in larvae fed with dsGRi3–chitosan, compared to those fed with dsgfp–chitosan particles. Western blot analysis revealed a 7–17% reduction of α-glucosidase protein expression in larvae fed with dsGRi–chitosan. Mortality rates of larvae that received dsRNAs–chitosan particles were only 45–62% compared to those that received dsgfp–chitosan particles. These results indicate that α-glucosidase is essential for the toxicity of B. sphaericus binary toxin to Cx. quinquefasciatus.