Potent Α-glycosidase Inhibitors Research Articles

Dauresorcinols A and B, two pairs of merosesquiterpenoid enantiomers with new carbon skeletons from Rhododendron dauricum

Five pairs of new merosesquiterpenoid enantiomers, named dauresorcinols A−E (1−5), were isolated from the leaves of Rhododendron dauricum. Their structures were elucidated by comprehensive spectroscopic data analysis, quantum chemical calculations, Rh2(OCOCF3)4-induced ECD, and single-crystal X-ray diffraction analysis. Dauresorcinols A (1) and B (2) possess two new merosesquiterpene skeletons bearing an unprecedented 2,6,7,10,14-pentamethyl-11-oxatetracyclo[8.8.0.02,7.012,17]octadecane and a caged 15-isohexyl-1,5,15-trimethyl-2,10-dioxatetracyclo[7.4.1.111,14.03,8]pentadecane motif, respectively. Plausible biosynthetic pathways of 1−5 are proposed involving key oxa-electrocyclization and Wagner−Meerwein rearrangement reactions. (+)/(−)-1 and 3−5 showed potent α-glucosidase inhibitory activity, 3 to 22 times stronger than acarbose, an antidiabetic drug targeting α-glucosidase. Docking results provide a basis to design and develop merosesquiterpenoids as potent α-glycosidase inhibitors.

In silico and in vitro studies of thiosemicarbazone-indole hybrid compounds as potent α-glycosidase inhibitors

It is essential to study α-glucosidase enzyme (EC 3.2.1.20) inhibitors because of their physiological role as well as their clinical relevance. In previous research, a novel series of thiosemicarbazone-indole hybrid compounds were synthesized and reported. In the current research, α-glucosidase inhibitory activity of the derivatives was evaluated and then in silico studies were carried out on screened compounds. All derivatives exhibited a magnificent α-glucosidase inhibitory activity (IC50 = 27.0 ± 1.0–97.4 ± 1.5 µM) toward the acarbose as reference drug (IC50 = 750.0 ± 1.5 µM). Compound 1i having phenyl ring at the thiosemicarbazone moiety and the trimethoxymethyl substituent at phenyl moiety of C2 position of indole ring was the most potent compound (IC50 = 27.0 ± 1.0 µM) among other compounds. A kinetic study of 1i revealed that is a competitive inhibitor against α-glucosidase. Moreover, the molecular docking studies established that screened derivatives interacted with the essential amino acids in the active site. Finally, based on the molecular dynamics simulations and free binding energy calculations, complexes 1d, 1i and 1k with α-glucosidase showed a good stability in the active site. Van der Waals and electrostatic interactions also exhibited the most contributions to the stability of these complexes. Moreover, all the screened compounds showed agreeable ADME properties for oral bio-availability, and good drug-likeness.

Design and synthesis of phenoxymethybenzoimidazole incorporating different aryl thiazole-triazole acetamide derivatives as α-glycosidase inhibitors.

A novel series of phenoxymethybenzoimidazole derivatives (9a-n) were rationally designed, synthesized, and evaluated for their α-glycosidase inhibitory activity. All tested compounds displayed promising α-glycosidase inhibitory potential with IC50 values in the range of 6.31 to 49.89 μM compared to standard drug acarbose (IC50 = 750.0 ± 10.0 μM). Enzyme kinetic studies on 9c, 9g, and 9m as the most potent compounds revealed that these compounds were uncompetitive inhibitors into α-glycosidase. Docking studies confirmed the important role of benzoimidazole and triazole rings of the synthesized compounds to fit properly into the α-glycosidase active site. This study showed that this scaffold can be considered as a highly potent α-glycosidase inhibitor. Supplementary InformationThe online version contains supplementary material available at 10.1007/s11030-021-10310-7.

Recent Progress in the Construction of Natural De-O-Sulfonated Sulfonium Sugars with Antidiabetic Activities.

A group of sulfonium salts equipped with a polyhydroxylated side-chain structure have been isolated and identified as potent α-glycosidase inhibitors. Consequently, they have become an attractive target in diverse research disciplines, including organic synthesis, drug discovery, and chemical biology. To this end, the development of practical and effective synthetic strategies, especially for more bioactive de-O-sulfonated sulfonium salts, is a significant research area in organic synthesis. An ideal synthetic methodology should provide easily accessible intermediates with high chemical stability for the key coupling reaction to diastereoselectively construct the sulfonium cation center. This minireview summarizes recently developed strategies applied in the construction of natural de-O-sulfonated sulfonium sugars: 1) acid-catalyzed de-O-sulfonation of sulfonium sulfate inner salts, 2) a coupling reaction between side-chain fragments containing leaving groups and a thiosugar, 3) a coupling reaction between side-chain fragments containing epoxide structures and a thiosugar, and 4) a two-step sequential SN 2 nucleophilic substitution between side-chain fragments containing thiol groups and a diiodide derivative.

Screening and identification of potent α-glycosidase inhibitors from Gardenia jasminoides Ellis

The α-glycosidase inhibition assay is used to examine the inhibition activity of traditional Chinese medicines through extraction with methanol. The α-glycosidase inhibition activity of the isolated compounds is measured by α-glycosidase inhibition assay and compared with Acarbose. Molecular docking is implemented to study the interaction between isolated compounds and CtMGAM (maltase–glucoamylase-C) or NtMGAM (maltase–glucoamylase-N). Compared with those of Acarbose, the methanol extract of Gardenia jasminoides Ellis has a higher activity to inhibit α-glycosidase among the 74 traditional Chinese medicines. Geniposide and Gardenoside, isolated compounds from Gardenia jasminoides Ellis, have better inhibition activity (IC50 values of 0.35 and 0.46 mg/ml, respectively) than Acarbose (IC50 values of 0.75 mg/ml). The molecular docking results show that Geniposide and Gardenoside have specific binding affinities with CtMGAM and can be considered comparable to those of Acarbose. Our findings illuminate the possible anti-diabetic mechanism of Gardenia jasminoides Ellis and support its use for the treatment of diabetes.

Short and Diastereoselective Total Synthesis of the Polyhydroxylated Pyrrolidine LAB-1: A Potent α-Glycosidase Inhibitor

We described herein a total synthesis of 1,4-dideoxy-1,4-imino-l-arabinitol [(2S,3S,4S)-2-(hydroxymethyl)pyrrolidine-3,4-diol, LAB-1], a polyhydroxylated pyrrolidine, which has been demonstrated to be a selective and potent α-glycosidase inhibitor. The main features of our approach are its shortness, efficiency, and simplicity. The total synthesis was accomplished in 6 steps with an overall yield of 12%, starting from a chiral optically active Morita–Baylis–Hillman (MBH) adduct prepared (without epimerization), from Garner’s aldehyde. As far as we know, this is the first report describing the total synthesis of this biologically active pyrrolidine by exploring the synthetic versatility of a MBH adduct.

Determination of 1-deoxynojirimycin in the Larvae of the Silkworm, Bombyx mori, by High-Performance Liquid Chromatography

1-Deoxynojirimycin, known to be one of the most potent α-glycosidase inhibitors, has been used as an antihyperglycemia agent. In this study, a rapid method for the determination of 1-deoxynojirimycin in the larvae of the silkworm, Bombyx mori was established, using high-performance liquid chromatography equipped with fluorescence detection after derivatization with 9-fluorenylmethyl chloroformate. The 1-deoxynojirimycin was efficiently extracted from the larvae using 0.05 mol/L hydrochloric acid, vortexing for 15 s at room temperature, followed by sonication for 30 min. The linear dynamic range extended from 0.7 to 28 µg/mL (r = 0.9999). The average recovery of the 1-deoxynojirimycin was 104% with a relative standard deviation of 3.30%. The limit of detection was 0.05 µg/mL at a signal-to-noise ratio of 3. There were high concentrations of 1-deoxynojirimycin in the larvae, reaching 0.50% of total body mass in the gluttonous stage of the third instar and significant variation in the fifth instar, suggests that the larvae may be a valuable source of 1-deoxynojirimycin for the treatment of carbohydrate-mediated disorders.

Evaluation of General Toxicity and Genotoxicity of the Silkworm Extract Powder

The silkworm extract powder contain 1-deoxynojirimycin (DNJ), a potent α-glycosidase inhibitor, has therapeutic potency against diabetes mellitus. Therefore, natural products containing DNJ from mulberry leaves and silkworm are consumed as health functional food. The present study was performed to evaluate the safety of the silkworm extract powder, a health food which containing the DNJ. The repeated toxicity studies and gentic toxicity studies of the silkworm extract powder were performed to obtain the data for new functional food approval in MFDS. The safety was evaluated by a single-dose oral toxicity study and a 90 day repeated-dose oral toxicity study in Sprague-Dawley rats. The silkworm extract powder was also evaluated for its mutagenic potential in a battery of genetic toxicity test: in vitro bacterial reverse mutation assay, in vitro chromosomal aberration test, and in vivo mouse bone marrow micronucleus assay. The results of the genetic toxicology assays were negative in all of the assays. The approximate lethal dose in single oral dose toxicity study was considered to be higher than 5000 mg/kg in rats. In the 90 day study, the dose levels were wet at 0, 500, 1000, 2000 mg/kg/day, and 10 animals/sex/dose were treated with oral gavage. The parameters that were monitored were clinical signs, body weights, food and water consumptions, ophthalmic examination, urinalysis, hematology, serum biochemistry, necropsy findings, organ weights, and histopathological examination. No adverse effects were observed after the 90 day administration of the silkworm extract powder. The No-Observed-Adverse-Effect-Level (NOAEL) of silkworm extract powder in the 90 day study was 2000 mg/kg/day in both sexes, and no target organ was identified.

Pharmacokinetic mechanism of enhancement by Radix Pueraria flavonoids on the hyperglycemic effects of Cortex Mori extract in rats

Ethnopharmacological relevanceDiabetes mellitus, characterized by abnormal blood glucose evaluation, is a serious chronic disease. In the treatment of the disease, α-glycosidase inhibitors play an important role for controlling the postprandial blood glucose level. Cortex Mori, a traditional Chinese herbal medicine, has a long history of use for the treatment of headaches, cough, edema and diabetes. Modern pharmacological studies have shown that the herb has beneficial effects on the suppression of postprandial blood glucose levels by inhibiting α-glycosidase activity in the small intestine. 1-Deoxynojirimycin (DNJ), the main active ingredient of this herb, is recognized as a potent α-glycosidase inhibitor. Our previous studies have shown that the hypoglycemic effect of Cortex Mori extract (CME) was significantly improved when giving CME in combination with Radix Pueraria flavonoids (RPF). In the present study, the pharmacokinetics and intestinal permeability of DNJ were comparatively investigated in rats after being given orally or by intestinal perfusion with CME alone or in CME–RPF pairs, to explore the mechanism of this synergistic effect. Materials and methodsThe role of RPF on the plasma and urine concentrations of DNJ from CME orally administered was investigated. Four groups of rats received a single oral dose of either CME or CME–RPF, at DNJ equivalent doses of 20 and 40mg/kg, respectively. After dosing, plasma and urine were collected and assayed by LC/MS/MS. In addition, another two groups of rats were used for small intestinal perfusion with CME or CME–RPF at DNJ concentration of 10µM. ResultsCompared to the data when dosing with CME alone, the Cmax of DNJ were decreased from 5.78 to 2.94µg/ml (p<0.05) and 10.66 to 5.35µg/ml (p<0.01); Tmax were delayed from 0.40 to 0.55h and 0.35 to 0.50h (p<0.05); and MRT were significantly prolonged from 1.14 to 1.72h (p<0.05) and 0.95 to 1.62h (p<0.01), after dosing with CME–RPF at DNJ doses of 20 and 40mg/kg, respectively. In addition, the urinary recovery of DNJ over the first 4h after dosing significantly decreased from 48.76% to 33.86%. Effective permeability (Peff) of DNJ was decreased from 7.53×10−3 to 3.09×10−3cm/s (p<0.05) when RPF was added to CME, when it was evaluated using the rat intestinal perfusion model. ConclusionsAll the above results demonstrate that RPF was able to suspend and delay the absorption of DNJ, but did not affect the total amount of DNJ in the body. The resulting higher concentration of DNJ in the small intestine produced a relatively stronger effect of depressing the elevation of the postprandial blood glucose level. These findings support the important role of RPF in the application of CME on blood glucose control.

Production of the α-glycosidase inhibitor 1-deoxynojirimycin from Bacillus species

1-Deoxynojirimycin (DNJ), a potent α-glycosidase inhibitor, has therapeutic applications in treatments of HIV, Gaucher’s disease, and diabetes. DNJ has been extracted from natural sources (mulberry leaves) for therapeutic purposes; however, DNJ ingredients are in limited supply and are costly to obtain on a large scale. Since certain strains of Bacillus and Streptomyces species reportedly produce DNJ, they may serve as potential sources for high-yield DNJ production. In this study, we obtained evidence for a DNJ production in Bacillus subtilis DSM704 by hydrophilic interaction chromatography-tandem mass spectrometry. In addition, from a screen of 750 microorganisms, we identified additional Bacillus strains (Bacillus amyloliquefaciens AS385 and Bacillus subtilis B4) that produce DNJ in large quantities. Investigation of the effect of various culture conditions, using Bacillus subtilis DSM704 and the DNJ high-production Bacillus strains, provided evidence for the importance of sorbitol supplementation on the yield of the DNJ precursor, 2-amino-2-deoxy-D-mannitol, thereby increasing DNJ production. The role of sorbitol in increased DNJ production was supported by an observed increase in mRNA expression of the biosynthetic gene, gabT1. When Bacillus amyloliquefaciens AS385 was cultured in medium supplemented with sorbitol, extracellular DNJ concentration reached a maximum of 460mg/l of medium (equivalent to 9.20mg/g of freeze-dried medium), indicating that this strain can serve as a source for food- and drug-grade products. These findings not only lead to a further understanding of the DNJ biosynthetic pathway, but also suggest a method for microbial mass production of DNJ for therapeutic applications.

A novel gelatin crosslinking method retards release of mulberry 1-deoxynojirimycin providing a prolonged hypoglycaemic effect

Mulberry 1-deoxynojirimycin (DNJ), a potent α-glycosidase inhibitor, has therapeutic potency in the suppression of postprandial blood glucose levels thereby possibly preventing diabetes mellitus. However, DNJ has a relatively short half-life in vivo (about 2 h). Therefore, several doses of mulberry DNJ are required to achieve optimal therapeutic results. This study aimed to delay the release of mulberry DNJ with biodegradable matrices to maintain the intestinal DNJ concentration and prolong the hypoglycaemic effect in vivo. A novel, simple, and commercially viable method was adopted to develop DNJ-entrapped microspheres (DNJ-MSs). A higher extent of crosslinking and the larger sized DNJ-MS decreased the rate of mulberry DNJ release in vitro. Consequently, an in vivo study was performed in Wistar rats over a 6 h period. The area under curve (AUC) of rats with DNJ-MS was significantly increased, compared to animals dosed with mulberry powder (control). DNJ-MS suppressed postprandial glucose from sucrose administration at the initial and 3 h time points indicating a prolonged hypoglycaemic effect.

Determination of iminosugars in mulberry leaves and silkworms using hydrophilic interaction chromatography–tandem mass spectrometry

Mulberry 1-deoxynojirimycin (DNJ, a potent α-glycosidase inhibitor) has been investigated thoroughly for its analytical methods and therapeutic potential against diabetes, whereas little attention has been given to other iminosugars such as 2- O-α- d-galactopyranosyl–DNJ (GAL–DNJ) and fagomine. For instance, concentration and composition of these iminosugars in mulberry leaves as well as sericulture products have not been fully characterized due to lack of suitable analytical methods. Here we developed a simultaneous determination method for DNJ, GAL–DNJ, and fagomine using hydrophilic interaction chromatography (HILIC) with tandem mass spectrometry (MS/MS). When mulberry leaf extracts were subjected to HILIC–MS/MS with multiple reaction monitoring (MRM), individual iminosugars could be separated and detected. The developed method is sufficiently sensitive for determining iminosugars in mulberry leaves as well as silkworms, providing new information (e.g., different amounts of iminosugars in mulberry leaf varieties; high DNJ and low GAL–DNJ in the silkworm body, especially in the blood) that is useful for producing iminosugar-rich products for nutraceutical purposes.

Optimization of 1-Deoxynojirimycin Extraction from Mulberry Leaves by Using Response Surface Methodology

Mulberry 1-deoxynojirimycin (DNJ, a potent alpha-glycosidase inhibitor) has therapeutic potency against diabetes mellitus. However, the amount of DNJ in mulberry leaves is low (about 0.1%), and a more effective extraction method is needed. Ultrasound-assisted extraction (UAE) was applied in this study for mulberry DNJ extraction, and five factors, the percentage of ethanol in the extraction solvent (x(1)), ratio of the extraction solvent to mulberry sample (x(2)), ultrasonic power (x(3)), extraction temperature (x(4)) and extraction time (x(5)), were investigated by fractional factorial 2((5-1)) design (FFD) to obtain the optimum extraction efficiency (DNJ yield, Y(1)) and extraction productivity (total yield, Y(2)). The results showed that x(2), x(3) and x(5) had significant impact on Y(1) and Y(2), and were further optimized by response surface methodology (RSM). Under the optimized conditions (x(2), x(3) and x(5) of 7 ml/g, 180 W and 260 s, respectively), DNJ-enriched powder (0.8%) was produced with high extraction efficiency (98%) and productivity (20%), enabling this product to be used for nutraceutical purposes.

A Route to (2α,3β,4α)-(±)-2-(Hydroxymethyl)-3,4-pyrrolidinediol Based on the α-Silyloxyallylation of a Glycolaldehyde-Derived Nitrone

A protected form of title compound 6a, whose two enantiomers are known to be potent α-glycosidase inhibitors, was obtained through a five-step synthesis based on two thoroughly diastereo-controlled steps. An anti-selective α-silyloxyallylation of nitrone 9 afforded hydroxylamine 8a which, after O-silylation, was subjected to iodocyclisation to give 5-iodomethylisoxazolidine 7a as a single diastereoisomer. Displacement of iodide by mesylate and hydrogenolysis of mesylate 7b furnished 6b in 20 % overall yield starting from tert-butyldimethylsilyloxyacetaldehyde.

ChemInform Abstract: A New Route to Pyrrolidines: One‐Step Cyclization of 1,4‐Azido Alcohol. Synthesis of 1,4‐Dideoxy‐1,4‐imino‐L‐lyxitol.

AbstractD‐Ribonolactone (I) is converted to the protected derivative (IV) which is reduced to give the diol (V).

A New Route to Pyrrolidines: One-Step Cyclization of 1,4-Azido Alcohol Synthesis of 1,4-Dideoxy-1,4-Imino-L-Lyxitol

Several optically active 3,4-dihydroxy-2-hydroxymethyl pyrrolidines are potent α-glycosidase inhibitors; for example, 1,4-dideoxy-1,4-imino-D-lyxitol (1) is a powerful inhibitor of α-galactosidase.1 Furthermore, pyrrolidine 1 can be easily converted into the indolizidine alkaloid swainsonine to which it is structurally related.2 (-) Swainsonine exhibits α-D-mannosidase inhibitory activity and immunoregulatory activity. Certain swainsonine stereoisomers have glycosidase inhibitory activity as well, and therefore have attracted considerable interest.3 1,4-Dideoxy-1,4-imino-L-lyxitol (2) (enantiomer of 1) could be of biological interest. This communication describes the first synthesis of 2, starting from D-ribonolactone.