Glucosylceramides impact cellulose deposition and cellulose synthase complex motility in Arabidopsis

Cellulose is an abundant component of plant cell wall matrices, and this para-crystalline polysaccharide is synthesized at the plasma membrane by motile Cellulose Synthase Complexes (CSCs). However, the factors that control CSC activity and motility are not fully resolved. In a targeted chemical screen, we identified the alkylated nojirimycin analog N-Dodecyl Deoxynojirimycin (ND-DNJ) as a small molecule that severely impacts Arabidopsis seedling growth. Previous work suggests that ND-DNJ-related compounds inhibit the biosynthesis of glucosylceramides (GlcCers), a class of glycosphingolipid associated with plant membranes. Our work uncovered major changes in the sphingolipidome of plants treated with ND-DNJ, including reductions in GlcCer abundance and altered acyl chain length distributions. Crystalline cellulose content was also reduced in ND-DNJ-treated plants as well as plants treated with the known GlcCer biosynthesis inhibitor N-[2-hydroxy-1-(4-morpholinylmethyl)-2-phenyl ethyl]-decanamide (PDMP) or plants containing a genetic disruption in GLUCOSYLCERAMIDE SYNTHASE (GCS), the enzyme responsible for sphingolipid glucosylation that results in GlcCer synthesis. Live-cell imaging revealed that CSC speed distributions were reduced upon treatment with ND-DNJ or PDMP, further suggesting an important relationship between glycosylated sphingolipid composition and CSC motility across the plasma membrane. These results indicate that multiple interventions compromising GlcCer biosynthesis disrupt cellulose deposition and CSC motility, suggesting that GlcCers regulate cellulose biosynthesis in plants.

Flow Cytometry-Based Assay to Detect Alpha Galactosidase Enzymatic Activity at the Cellular Level

BACKGROUND

Fabry disease is a progressive, X chromosome-linked lysosomal storage disorder with multiple organ dysfunction. Due to the absence or reduced activity of alpha-galactosidase A (AGAL), glycosphingolipids, primarily globotriaosyl-ceramide (Gb3), concentrate in cells. In heterozygous women, symptomatology is heterogenous and currently routinely used fluorometry-based assays measuring mean activity mostly fail to uncover AGAL dysfunction. The aim was the development of a flow cytometry assay to measure AGAL activity in individual cells.

METHODS

Conventional and multispectral imaging flow cytometry was used to detect AGAL activity. Specificity was validated using the GLA knockout (KO) Jurkat cell line and AGAL inhibitor 1-deoxygalactonojirimycin. The GLA KO cell line was generated via CRISPR-Cas9-based transfection, validated with exome sequencing, gene expression and substrate accumulation.

RESULTS

Flow cytometric detection of specific AGAL activity is feasible with fluorescently labelled Gb3. In the case of Jurkat cells, a substrate concentration of 2.83 nmol/mL and 6 h of incubation are required. Quenching of the aspecific exofacial binding of Gb3 with 20% trypan blue solution is necessary for the specific detection of lysosomal substrate accumulation.

CONCLUSION

A flow cytometry-based assay was developed for the quantitative detection of AGAL activity at the single-cell level, which may contribute to the diagnosis of Fabry patients.

Amphiphilic α-Peptoid-deoxynojirimycin Conjugate-based Multivalent Glycosidase Inhibitor for Hypoglycemic Effect and Fluorescence Imaging

Multivalent glycosidase inhibitors based on 1-deoxynojirimycin derivatives against α-glucosidases have been rapidly developed. Nonetheless, the mechanism based on self-assembled multivalent glucosidase inhibitors in living systems needs to be further studied. It remains to be determined whether the self-assembly possesses sufficient stability to endure transit through the small intestine and subsequently bind to the glycosidases located therein. In this paper, two amphiphilic compounds, 1-deoxynojirimycin and α-peptoid conjugates (LP-4DNJ-3C and LP-4DNJ-6C), were designed. Their self-assembling behaviors, multivalent α-glucosidase inhibition effect, and fluorescence imaging on living organs were studied. LP-4DNJ-6C exhibited better multivalent α-glucosidase inhibition activities in vitro. Moreover, the self-assembly of LP-4DNJ-6C could effectively form a complex with Nile red. The complex showed fluorescence quenching effect upon binding with α-glucosidases and exhibited potent fluorescence imaging in the small intestine. This result suggests that a multivalent hypoglycemic effect achieved through self-assembly in the intestine is a viable approach, enabling the rational design of multivalent hypoglycemic drugs.

1-Deoxynojirimycin containing Morus alba leaf-based food modulates the gut microbiome and expression of genes related to obesity

BACKGROUND

Obesity is a serious disease with an alarmingly high incidence that can lead to other complications in both humans and dogs. Similar to humans, obesity can cause metabolic diseases such as diabetes in dogs. Natural products may be the preferred intervention for metabolic diseases such as obesity. The compound 1-deoxynojirimycin, present in Morus leaves and other sources has antiobesity effects. The possible antiobesity effect of 1-deoxynojirimycin containing Morus alba leaf-based food was studied in healthy companion dogs (n = 46) visiting the veterinary clinic without a history of diseases. Body weight, body condition score (BCS), blood-related parameters, and other vital parameters of the dogs were studied. Whole-transcriptome of blood and gut microbiome analysis was also carried out to investigate the possible mechanisms of action and role of changes in the gut microbiome due to treatment.

RESULTS

After 90 days of treatment, a significant antiobesity effect of the treatment food was observed through the reduction of weight, BCS, and blood-related parameters. A whole-transcriptome study revealed differentially expressed target genes important in obesity and diabetes-related pathways such as MLXIPL, CREB3L1, EGR1, ACTA2, SERPINE1, NOTCH3, and CXCL8. Gut microbiome analysis also revealed a significant difference in alpha and beta-diversity parameters in the treatment group. Similarly, the microbiota known for their health-promoting effects such as Lactobacillus ruminis, and Weissella hellenica were abundant (increased) in the treatment group. The predicted functional pathways related to obesity were also differentially abundant between groups.

CONCLUSIONS

1-Deoxynojirimycin-containing treatment food have been shown to significantly improve obesity. The identified genes, pathways, and gut microbiome-related results may be pursued in further studies to develop 1-deoxynojirimycin-based products as candidates against obesity.

Mulberry leaf multi-components exert hypoglycemic effects through regulation of the PI-3K/Akt insulin signaling pathway in type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Phytochemicals have unique advantages in the treatment of diabetes due to their multi-target activity and low toxicity. Mulberry leaves, a traditional Chinese herbal medicine, have been used in the prevention and treatment of diabetes for centuries. The main active ingredients in mulberry leaves with regards to the hypoglycemic effect are 1-deoxynojirimycin, flavonoids, and polysaccharides. However, the combined hypoglycemic effects and mechanisms of mulberry leaf multi-components remain unclear.

AIM OF THE STUDY

This study explored the anti-diabetic effects of mulberry leaf multi-components (MMC) and the role of the PI-3K/Akt insulin signalling pathway in improving insulin resistance.

MATERIALS AND METHODS

The main chemical components of MMC were analyzed using the phenol-sulfuric acid method, aluminum nitrate-sodium nitrite method, and HPLC-ultraviolet/fluorescence detection method. The T2DM rat model was created via feeding a high-fat diet and peritoneal injection of streptozotocin. T2DM rats were divided into four groups: model, model plus metformin, model plus low-dose, and model plus high-dose MMC groups (100 and 200 mg/kg body weight/day, respectively), and plus normal group for a total of five groups. MMC was administered by oral gavage for six weeks. Fasting blood glucose and serum lipid profiles were measured using a glucometer and an automatic biochemistry analyzer, respectively. Serum insulin and adipocytokine levels were analyzed by ELISA. Hepatic glucose metabolizing enzyme activity was evaluated by ELISA and the double antibody sandwich method. Expression of PI-3K/Akt signalling pathway proteins was analyzed by RT-PCR and Western blotting.

RESULTS

Extracted 1-deoxynojirimycin, flavonoid, and polysaccharide purity was 70.40%, 52.34%, and 32.60%, respectively. These components were then mixed at a ratio of 1:6:8 to form MMC. MMC significantly reduced serum glucose, insulin, and lipid levels. In diabetic rats, MMC enhanced insulin sensitivity and alleviated inflammatory and oxidative damage by lowing adipocytokine levels and increasing anti-oxidative enzyme activity. Insulin resistance was also mitigated. MMC regulated the activity of key downstream enzymes of hepatic glucose metabolism via activating the expression of PI-3K, Akt, PDX-1, and GLUT4 at the mRNA and protein levels, thereby correcting hepatic glucolipid metabolism disorders and exerting a hypoglycemic effect.

CONCLUSION

MMC ameliorated hepatic glucolipid metabolism disorders and improved insulin resistance in T2DM rats by activating the PI-3K/Akt signaling pathway. These results highlight the multi-component, multi-target, and combined effects of MMC, and suggest it may be further developed as a hypoglycemic drug.

Validation of a highly sensitive HaloTag-based assay to evaluate the potency of a novel class of allosteric β-Galactosidase correctors

Site-directed Enzyme Enhancement Therapy (SEE-Tx®) technology is a disease-agnostic drug discovery tool that can be applied to any protein target of interest with a known three-dimensional structure. We used this proprietary technology to identify and characterize the therapeutic potential of structurally targeted allosteric regulators (STARs) of the lysosomal hydrolase β-galactosidase (β-Gal), which is deficient due to gene mutations in galactosidase beta 1 (GLB1)-related lysosomal storage disorders (LSDs). The biochemical HaloTag cleavage assay was used to monitor the delivery of wildtype (WT) β-Gal and four disease-related β-Gal variants (p.Ile51Thr, p.Arg59His, p.Arg201Cys and p.Trp273Leu) in the presence and absence of two identified STAR compounds. In addition, the ability of STARs to reduce toxic substrate was assessed in a canine fibroblast cell model. In contrast to the competitive pharmacological chaperone N-nonyl-deoxygalactonojirimycin (NN-DGJ), the two identified STAR compounds stabilized and substantially enhanced the lysosomal transport of wildtype enzyme and disease-causing β-Gal variants. In addition, the two STAR compounds reduced the intracellular accumulation of exogenous GM1 ganglioside, an effect not observed with the competitive chaperone NN-DGJ. This proof-of-concept study demonstrates that the SEE-Tx® platform is a rapid and cost-effective drug discovery tool for identifying STARs for the treatment of LSDs. In addition, the HaloTag assay developed in our lab has proved valuable in investigating the effect of STARs in promoting enzyme transport and lysosomal delivery. Automatization and upscaling of this assay would be beneficial for screening STARs as part of the drug discovery process.

Structure-Based Design of Potent Iminosugar Inhibitors of Endoplasmic Reticulum α-Glucosidase I with Anti-SARS-CoV-2 Activity

Enveloped viruses depend on the host endoplasmic reticulum (ER) quality control (QC) machinery for proper glycoprotein folding. The endoplasmic reticulum quality control (ERQC) enzyme α-glucosidase I (α-GluI) is an attractive target for developing broad-spectrum antivirals. We synthesized 28 inhibitors designed to interact with all four subsites of the α-GluI active site. These inhibitors are derivatives of the iminosugars 1-deoxynojirimycin (1-DNJ) and valiolamine. Crystal structures of ER α-GluI bound to 25 1-DNJ and three valiolamine derivatives revealed the basis for inhibitory potency. We established the structure-activity relationship (SAR) and used the Site Identification by Ligand Competitive Saturation (SILCS) method to develop a model for predicting α-GluI inhibition. We screened the compounds against SARS-CoV-2 in vitro to identify those with greater antiviral activity than the benchmark α-glucosidase inhibitor UV-4. These host-targeting compounds are candidates for investigation in animal models of SARS-CoV-2 and for testing against other viruses that rely on ERQC for correct glycoprotein folding.

Curcumin Has Beneficial Effects on Lysosomal Alpha-Galactosidase: Potential Implications for the Cure of Fabry Disease

Fabry disease is a lysosomal storage disease caused by mutations in the GLA gene that encodes alpha-galactosidase (AGAL). The disease causes abnormal globotriaosylceramide (Gb3) storage in the lysosomes. Variants responsible for the genotypic spectrum of Fabry disease include mutations that abolish enzymatic activity and those that cause protein instability. The latter can be successfully treated with small molecules that either bind and stabilize AGAL or indirectly improve its cellular activity. This paper describes the first attempt to reposition curcumin, a nutraceutical, to treat Fabry disease. We tested the efficacy of curcumin in a cell model and found an improvement in AGAL activity for 80% of the tested mutant genotypes (four out of five tested). The fold-increase was dependent on the mutant and ranged from 1.4 to 2.2. We produced evidence that supports a co-chaperone role for curcumin when administered with AGAL pharmacological chaperones (1-deoxygalactonojirimycin and galactose). The combined treatment with curcumin and either pharmacological chaperone was beneficial for four out of five tested mutants and showed fold-increases ranging from 1.1 to 2.3 for DGJ and from 1.1 to 2.8 for galactose. Finally, we tested a long-term treatment on one mutant (L300F) and detected an improvement in Gb3 clearance and lysosomal markers (LAMP-1 and GAA). Altogether, our findings confirmed the necessity of personalized therapies for Fabry patients and paved the way to further studies and trials of treatments for Fabry disease.

Chalcone-1-Deoxynojirimycin Heterozygote Reduced the Blood Glucose Concentration and Alleviated the Adverse Symptoms and Intestinal Flora Disorder of Diabetes Mellitus Rats

Chalcone-1-deoxynojirimycin heterozygote (DC-5), a novel compound which was designed and synthesized in our laboratory for diabetes treatment, showed an extremely strong in vitro inhibitory activity on α-glucosidase in our previous studies. In the current research, its potential in vivo anti-diabetic effects were further investigated by integration detection and the analysis of blood glucose concentration, blood biochemical parameters, tissue section and gut microbiota of the diabetic rats. The results indicated that oral administration of DC-5 significantly reduced the fasting blood glucose and postprandial blood glucose, both in diabetic and normal rats; meanwhile, it alleviated the adverse symptoms of elevated blood lipid level and lipid metabolism disorder in diabetic rats. Furthermore, DC-5 effectively decreased the organ coefficient and alleviated the pathological changes of the liver, kidney and small intestine of the diabetic rats at the same time. Moreover, the results of 16S rDNA gene sequencing analysis suggested that DC-5 significantly increased the ratio of Firmicutes to Bacteroidetes and improved the disorder of gut microbiota in diabetic rats. In conclusion, DC-5 displayed a good therapeutic effect on the diabetic rats, and therefore had a good application prospect in hypoglycemic drugs and foods.

Screening, cloning and functional characterization of key methyltransferase genes involved in the methylation step of 1-deoxynojirimycin alkaloids biosynthesis in mulberry leaves

The novel C-methyltransferase, MaMT1, could catalyze the conversion of piperidine to 2-methylpiperidine, which may be involved in the methylation step of DNJ biosynthesis in mulberry leaves. Mulberry (Morus alba L.) is a worldwide crop with medicinal, feeding and nutritional value, and 1-deoxynojirimycin ((2R, 3R, 4R, 5S)-2-hydroxymethyl-3, 4, 5-trihydroxypiperidine, DNJ) alkaloid, a potent α-glucosidase inhibitor, is its main active ingredient. Our previous researches clarified the biosynthetic pathway of DNJ from lysine to Δ¹-piperideine, but its downstream pathway is unclear. Herein, eight differential methyltransferases (MTs) genes were screened from transcriptome profiles of mulberry leaves with significant differences in DNJ content (P < 0.01). Subsequently, MaMT1 (OM140666) and MaMT2 (OM140667) were hypothesized as candidate genes related to DNJ biosynthesis by correlation analysis of genes expression levels and DNJ content of mulberry leaves at different dates. Functional characterization of MaMT1 and MaMT2 were performed by cloning, prokaryotic expression and enzymatic reaction in vitro, and it showed that MaMT1 protein could catalyze the conversion of piperidine to 2-methylpiperidine. Moreover, molecular docking confirmed the interaction of MaMT1 protein with piperidine and S-adenosyl-L-methionine (SAM), indicating that MaMT1 had C-methyltransferase activity, while MaMT2 did not. The above results suggested that MaMT1 may be involved in the methylation step of DNJ alkaloid biosynthesis in mulberry leaves, which is a breakthrough in the analysis of DNJ alkaloid biosynthetic pathway. It is worth mentioning that the novel MaMT1, annotated as serine hydroxymethyltransferase, could rely on SAM to perform C-methyltransferase function. Therefore, our findings contribute new insights into the research of DNJ alkaloid biosynthesis and C-methyltransferase family.

Effect of 1-Deoxynojirimycin on insulin resistance in prediabetic mice based on next-generation sequencing and intestinal microbiota study

ETHNOPHARMACOLOGICAL RELEVANCE

1-Deoxynojirimycin (DNJ), the major alkaloid in Morus alba L., is the main effective constituent in "Mulberry twig Alkaloids Tablets" launched in China in 2020. Prediabetes, characterized by insulin resistance, is regarded as the key period for reversing Type 2 diabetes mellitus (T2DM) through lifestyle intervention and glucose-lowering drugs. Besides the excellent activity as an α-glucosidase inhibitor, DNJ also improves insulin sensitivity in T2DM murine models, yet the mechanism is still unclear. Besides, the pharmaceutical effect of DNJ on prediabetes is also undocumented.

AIM OF THE STUDY

The aim of this study was to investigate the pharmaceutical effect of DNJ on high-fat and streptozotocin (STZ)-induced prediabetes mice, and to elucidate the mechanism of insulin resistance ameliorated by DNJ.

MATERIALS AND METHODS

Oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were performed to detect blood glucose level and insulin sensitivity in mice. The levels of circulating lipopolysaccharide (LPS), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) in the plasma of mice were measured by limulus reagent and enzyme-linked immunosorbent assay (ELISA), respectively. Next-generation sequencing (NGS) and intestinal microbiota sequencing were used to screen the alterations in the transcriptome of liver tissues and to assess the differences in intestinal flora composition, respectively. Expression of cytokine signaling pathway inhibitor 3 (SOCS3), insulin receptor substrate (IRS1), p-IRS1 (Tyr896), occludin, and toll like receptor 4 (TLR4)/NF-κB signaling pathway were confirmed by western blotting.

RESULTS

Our study revealed that DNJ decreased the blood glucose level and improve insulin sensitivity in prediabetic mice. DNJ significantly reduced the relative risk of T2DM in prediabetic mice by approximately 83.7%. Mechanistically, DNJ treatment suppressed the circulating levels of LPS, IL-6, and TNF-α in plasma and decreased the inflammatory infiltration in liver and colon tissues. DNJ-treatment increased the abundance of Akkermansia, Bifidobacterium, and Lactobacillus, and decreased the abundance of Enterococcaceae and Lachnospiraceae. Moreover, DNJ suppressed the expression of SOCS3 and the activity of TLR4/NF-κB signaling pathway, meanwhile improving the expression of occludin and the ratio of p-IRS1 (Tyr896)/IRS1.

CONCLUSIONS

DNJ effectively ameliorates glucose and lipid metabolism in prediabetic mice, and decreased the relative risk of progression into T2DM from prediabetes. The suppressed immune responses play essential roles in the improvement of insulin resistance by DNJ treatment. In conclusion, DNJ from Morus alba L. is a promising alternative agent in T2DM prevention.

Drug Repositioning for Fabry Disease: Acetylsalicylic Acid Potentiates the Stabilization of Lysosomal Alpha-Galactosidase by Pharmacological Chaperones

Fabry disease is caused by a deficiency of lysosomal alpha galactosidase and has a very large genotypic and phenotypic spectrum. Some patients who carry hypomorphic mutations can benefit from oral therapy with a pharmacological chaperone. The drug requires a very precise regimen because it is a reversible inhibitor of alpha-galactosidase. We looked for molecules that can potentiate this pharmacological chaperone, among drugs that have already been approved for other diseases. We tested candidate molecules in fibroblasts derived from a patient carrying a large deletion in the gene GLA, which were stably transfected with a plasmid expressing hypomorphic mutants. In our cell model, three drugs were able to potentiate the action of the pharmacological chaperone. We focused our attention on one of them, acetylsalicylic acid. We expect that acetylsalicylic acid can be used in synergy with the Fabry disease pharmacological chaperone and prolong its stabilizing effect on alpha-galactosidase.

N-Hydroxyethyl-1-Deoxynojirimycin (Miglitol) Restores the Counterregulatory Response to Hypoglycemia Following Antecedent Hypoglycemia

Antecedent hypoglycemia suppresses the counterregulatory responses to subsequent hypoglycemic episodes, which can be prevented by normalizing portal-mesenteric vein (PMV) glycemia alone during the antecedent bout. Since the sodium-glucose transporter 3 receptor has been implicated in PMV glucosensing, we hypothesized that PMV infusion of the sodium-glucose cotransporter 3 receptor agonist N-hydroxyethyl-1-deoxynojirimycin (miglitol) would rescue the sympathoadrenal response to subsequent hypoglycemia. Rats underwent hyperinsulinemic-hypoglycemic clamps on 2 consecutive days without miglitol infusion (antecedent hypoglycemia without miglitol [HYPO]) or with miglitol infused upstream in the PMV, perfusing the glucosensors, or adjacent to the liver, bypassing PMV glucosensors, on day 1 or day 2. Control animals underwent day 1 euglycemic clamps, followed by hypoglycemic clamps on day 2. Peak epinephrine (EPI) responses for HYPO on day 2 were significantly blunted when compared with controls. Miglitol infusion on day 1 proved ineffective in restoring the EPI response following antecedent hypoglycemia, but day 2 miglitol infusion restored EPI responses to control levels. As norepinephrine and glucagon demonstrated similar responses, day 2 administration of miglitol effectively restored the counterregulatory response following antecedent hypoglycemia. In subsequent experiments, we demonstrate similar results with reduced miglitol infusion doses, approaching those currently prescribed for type 2 diabetes (correcting for rodent size), as well as the efficacy of oral miglitol administration in restoring the counterregulatory responses following antecedent hypoglycemia.

Chaperone Therapy in Fabry Disease

Fabry disease is an X-linked lysosomal multisystem storage disorder induced by a mutation in the alpha-galactosidase A (GLA) gene. Reduced activity or deficiency of alpha-galactosidase A (AGAL) leads to escalating storage of intracellular globotriaosylceramide (GL-3) in numerous organs, including the kidneys, heart and nerve system. The established treatment for 20 years is intravenous enzyme replacement therapy. Lately, oral chaperone therapy was introduced and is a therapeutic alternative in patients with amenable mutations. Early starting of therapy is essential for long-term improvement. This review describes chaperone therapy in Fabry disease.

α-Glucosidase Inhibitory Activity of Fermented Okara Broth Started with the Strain Bacillus amyloliquefaciens SY07

In this work, a new strain of Bacillus amyloliquefaciens SY07 isolated from a traditional fermented soybean food was reported to possess remarkable α-glucosidase inhibitor-producing ability. Different culture media were applied for the proliferation of B. amyloliquefaciens SY07, and it was found that fermented okara broth presented the highest α-glucosidase inhibitory activity, while Luria-Bertani medium showed a negative effect. The extract from fermented okara broth acted in a dose-dependent manner to inhibit α-glucosidase activity, with an IC50 value of 0.454 mg/mL, and main inhibitors in the fermentation extract presented a reversible, uncompetitive pattern according to Lineweaver-Burk plots. Moreover, 1-deoxynojirimycin, a recognized α-glucosidase inhibitor, was found in the extract. Results indicated that B. amyloliquefaciens SY07 could utilize okara, a by-product from the soy processing industry, to generate α-glucosidase inhibitors effectively, and be regarded as a novel excellent microbial candidate for safe, economical production of potential functional foods or ingredients with hypoglycemic effect.

Chemometric evaluation of functional components and anti-quorum sensing activity of mulberry leaves from Indian cultivars: a potential contribution to the food industry

BACKGROUND

Potential use of many native, easily available vegetal materials for human consumption and value addition is not well recognized. Mulberry, being a traditional industrial crop rich in nutrients and nutraceuticals can be of great importance for the food industry. However, mulberry leaves are mainly being utilized in sericulture and are not exploited for their functional components. Thus, the selection of promising mulberry cultivars, rich in bioactive compounds, like resveratrol and 1-deoxynojirimycin, increase their potential use in functional foods.

RESULTS

Chlorogenic acid, myricetin and kaempferol were the major polyphenols present in the nine selected cultivars, in the range 0.001-0.086, 0.003-0.079 and 0.003-0.163 g kg^-1 fresh weight (FW), respectively. Protocatechuic acid, epicatechin and rutin were predominantly present in cultivars V-1, G-2 and ML (0.103, 0.080 and 0.121 g kg^-1 FW, respectively). Similarly, resveratrol and 1-deoxynojirimycin were highest in cultivars ML and K-2 (0.078 and 0.079 g kg^-1 FW, respectively). Leaf extracts of cultivars G-2 and ML were able to effectively inhibit the violacein production with 64.08% and 70.04%, respectively at the concentration of 6 mg mL^-1 presumably due to a higher content of polyphenols. Chemometric evaluation of chromatographic data showed the intraspecific variability and secondary metabolite co-existence in different cultivars.

CONCLUSIONS

Considering phytoconstituents, cultivars G-2, ML, K-2 and V-1 could contribute efficiently to the rational utilization of mulberry in agro-food industries. Furthermore, cultivars G-2 and ML leaves can be a new source of quorum sensing inhibitory agents. © 2021 Society of Chemical Industry.

Pathogen-induced inflammation is attenuated by the iminosugar MON-DNJ via modulation of the unfolded protein response

Sepsis is a life-threatening condition involving a dysregulated immune response to infectious agents that cause injury to host tissues and organs. Current treatments are limited to early administration of antibiotics and supportive care. While appealing, the strategy of targeted inhibition of individual molecules in the inflammatory cascade has not proved beneficial. Non-targeted, systemic immunosuppression with steroids has shown limited efficacy and raises concern for secondary infection. Iminosugars are a class of small molecule glycomimetics with distinct inhibition profiles for glycan processing enzymes based on stereochemistry. Inhibition of host endoplasmic reticulum resident glycoprotein processing enzymes has demonstrated efficacy as a broad-spectrum antiviral strategy, but limited consideration has been given to the effects on host glycoprotein production and consequent disruption of signalling cascades. This work demonstrates that iminosugars inhibit dengue virus, bacterial lipopolysaccharide and fungal antigen-stimulated cytokine responses in human macrophages. In spite of decreased inflammatory mediator production, viral replication is suppressed in the presence of iminosugar. Transcriptome analysis reveals the key interaction of pathogen-induced endoplasmic reticulum stress, the resulting unfolded protein response and inflammation. Our work shows that iminosugars modulate these interactions. Based on these findings, we propose a new therapeutic role for iminosugars as treatment for sepsis-related inflammatory disorders associated with excess cytokine secretion.

Dual-Targeting Antiproliferation Hybrids Derived from 1-Deoxynojirimycin and Kaempferol Induce MCF-7 Cell Apoptosis through the Mitochondria-Mediated Pathway

1-Deoxynojirimycin, an α-glucosidase inhibitor, possesses various biological activities such as antitumor, antidiabetic, and antiviral effects. However, the application of 1-deoxynojirimycin is restricted by its poor lipophilicity and low bioavailability. In this study, three 1-deoxynojirimycin derivatives (8-10) comprising 1-deoxynojirimycin and kaempferol were designed and synthesized to modify their pharmacokinetics and improve their antitumor efficacy. Among them, compound 10, a conjugate of 1-deoxynojirimycin and kaempferol linked through an undecane chain, exhibited excellent lipophilicity, antiproliferative effects, and α-glucosidase inhibitory activity. Compared with 1-deoxynojirimycin, kaempferol, and their combination, compound 10 downregulated cyclooxygenase-2 (COX-2) expression, arrested the cell cycle at the S phase, induced cellular apoptosis, and inhibited the migration of MCF-7 cells. Moreover, further investigation indicated that compound 10 induced MCF-7 cell apoptosis through a mitochondrial-mediated pathway via the loss of mitochondrial membrane potential. This led to increasing intracellular levels of reactive oxygen species (ROS) and Ca²⁺, the downregulation of Bcl-2 expression, and the upregulation of Bax levels.

Gender-Specific Effects of Two Treatment Strategies in a Mouse Model of Niemann-Pick Disease Type C1

In a mouse model of Niemann-Pick disease type C1 (NPC1), a combination therapy (COMBI) of miglustat (MIGLU), the neurosteroid allopregnanolone (ALLO) and the cyclic oligosaccharide 2-hydroxypropyl-β-cyclodextrin (HPßCD) has previously resulted in, among other things, significantly improved motor function. The present study was designed to compare the therapeutic effects of the COMBI therapy with that of MIGLU or HPßCD alone on body and brain weight and the behavior of NPC1^−/− mice in a larger cohort, with special reference to gender differences. A total of 117 NPC1^−/− and 123 NPC1^+/+ mice underwent either COMBI, MIGLU only, HPßCD only, or vehicle treatment (Sham), or received no treatment at all (None). In male and female NPC1^−/− mice, all treatments led to decreased loss of body weight and, partly, brain weight. Concerning motor coordination, as revealed by the accelerod test, male NPC1^−/− mice benefited from COMBI treatment, whereas female mice benefited from COMBI, MIGLU, and HPßCD treatment. As seen in the open field test, the reduced locomotor activity of male and female NPC1^−/− mice was not significantly ameliorated in either treatment group. Our results suggest that in NPC1^−/− mice, each drug treatment scheme had a beneficial effect on at least some of the parameters evaluated compared with Sham-treated mice. Only in COMBI-treated male and female NPC^+/+ mice were drug effects seen in reduced body and brain weights. Upon COMBI treatment, the increased dosage of drugs necessary for anesthesia in Sham-treated male and female NPC1^−/− mice was almost completely reduced only in the female groups.

Study on the Synthesis and Biological Activities of N-Alkylated Deoxynojirimycin Derivatives with a Terminal Tertiary Amine

A series of N-alkylated deoxynojirimycin (DNJ) derivatives connected to a terminal tertiary amine at the alkyl chains of various lengths were prepared. These novel synthetic compounds were assessed for preliminary glucosidase inhibition and anticancer activities in vitro. Potent and selective inhibition was observed among them. Compound 7d (IC50 = 0.052 mM) showed improved and selective inhibitory activity against ?-glucosidase compared to DNJ (IC50 = 0.65 mM). In addition, analysis of the kinetics of enzyme inhibition by using Lineweaver-Burk plots indicated that 7d inhibited ?-glu-cosidase in a competitive manner, suggesting that 7d was expected to bind to the active site of ?-glucosidase. Compounds 8b and 8c were found to be moderate and selective inhibitors of ?-glucosidase. Nevertheless, none of compounds inhib-ited the growth of B16F10 melanoma cells.

Identification of Brain-Specific Treatment Effects in NPC1 Disease by Focusing on Cellular and Molecular Changes of Sphingosine-1-Phosphate Metabolism

Niemann-Pick type C1 (NPC1) is a lysosomal storage disorder, inherited as an autosomal-recessive trait. Mutations in the Npc1 gene result in malfunction of the NPC1 protein, leading to an accumulation of unesterified cholesterol and glycosphingolipids. Beside visceral symptoms like hepatosplenomegaly, severe neurological symptoms such as ataxia occur. Here, we analyzed the sphingosine-1-phosphate (S1P)/S1P receptor (S1PR) axis in different brain regions of Npc1^-/- mice and evaluated specific effects of treatment with 2-hydroxypropyl-β-cyclodextrin (HPβCD) together with the iminosugar miglustat. Using high-performance thin-layer chromatography (HPTLC), mass spectrometry, quantitative real-time PCR (qRT-PCR) and western blot analyses, we studied lipid metabolism in an NPC1 mouse model and human skin fibroblasts. Lipid analyses showed disrupted S1P metabolism in Npc1^-/- mice in all brain regions, together with distinct changes in S1pr3/S1PR3 and S1pr5/S1PR5 expression. Brains of Npc1^-/- mice showed only weak treatment effects. However, side effects of the treatment were observed in Npc1^+/+ mice. The S1P/S1PR axis seems to be involved in NPC1 pathology, showing only weak treatment effects in mouse brain. S1pr expression appears to be affected in human fibroblasts, induced pluripotent stem cells (iPSCs)-derived neural progenitor and neuronal differentiated cells. Nevertheless, treatment-induced side effects make examination of further treatment strategies indispensable.

Fabry disease genotype, phenotype, and migalastat amenability: Insights from a national cohort

Fabry disease (FD) is a rare X-linked lysosomal storage disorder caused by α-galactosidase A (α-Gal A) deficiency. The progressive accumulation of globotriaosylceramide results in life-threatening complications, including renal, cardiac, and cerebrovascular diseases. The pharmacological chaperone migalastat was recently approved as an alternative to enzyme replacement therapy in patients with amenable mutations. In this article, we investigate the proportion of amenable mutations, related to phenotype, in a population of adult patients with FD in Switzerland. This study included 170 adult patients (n = 64 males) from 46 independent pedigrees with 39 different identified mutations over the last 59 years. Overall, 68% had the classic phenotype and 48% fulfilled the current amenability criteria. Migalastat was stopped in 2/11 (18%) patients: the only male classic patient, because of lack of efficacy based on lyso-Gb3 levels, and one patient with a benign variant. In males, the achieved enzyme activities in peripheral leucocytes under migalastat treatment differed from the activities in HEK-cells after incubation with migalastat (eg, 33% in PL vs 41% HEK-cells for p.F113L; 43% in leucocytes vs 36% in HEK-cells for p.N215S, 24-30% in leucocytes vs 96% in HEK-cells for S238N). In this national cohort, we found a relatively high proportion of patients with amenable GLA mutations, which, however, had heterogeneous extent of amenability: the higher the residual α-Gal A activity, the higher the chaperone effect. Further studies are required to investigate the long-term benefits of migalastat therapy depending on the achieved enzyme activities in different amenable mutations.

The Iminosugar AMP-DNM Improves Satiety and Activates Brown Adipose Tissue Through GLP1

Obesity is taking on worldwide epidemic proportions, yet effective pharmacological agents with long-term efficacy remain unavailable. Previously, we designed the iminosugar N-adamantine-methyloxypentyl-deoxynojirimycin (AMP-DNM), which potently improves glucose homeostasis by lowering excessive glycosphingolipids. Here we show that AMP-DNM promotes satiety and activates brown adipose tissue (BAT) in obese rodents. Moreover, we demonstrate that the mechanism mediating these favorable actions depends on oral, but not central, administration of AMP-DNM, which ultimately stimulates systemic glucagon-like peptide 1 (GLP1) secretion. We evidence an essential role of brain GLP1 receptors (GLP1r), as AMP-DNM fails to promote satiety and activate BAT in mice lacking the brain GLP1r as well as in mice treated intracerebroventricularly with GLP1r antagonist exendin-9. In conclusion, AMP-DNM markedly ameliorates metabolic abnormalities in obese rodents by restoring satiety and activating BAT through central GLP1r, while improving glucose homeostasis by mechanisms independent of central GLP1r.

Inter-assay variability influences migalastat amenability assessments among Fabry disease variants

Fabry disease is a lysosomal storage disorder caused by mutations in the GLA gene that encodes for the lysosomal enzyme α-galactosidase A (α-Gal A). Reduced or absent α-Gal A activity leads to substrate accumulation and deleterious effects in multiple organs. Migalastat is a pharmacological chaperone that may stabilize the enzyme in specific GLA variants, considered amenable, assisting enzyme trafficking to lysosomes and thus increasing enzyme activity. Using a good laboratory practice (GLP)-validated human embryonic kidney cell (HEK)-based (GLP-HEK) amenability assay established during the clinical development of migalastat, approximately one-third of GLA variants are reported to be amenable to migalastat. On the basis of this biochemical amenability, migalastat is approved for use in patients with specific GLA variants. In this study, the reproducibility of the amenability assay was assessed by evaluation of 59 GLA variants for α-Gal A activity in the presence and absence of migalastat. As for the GLP-HEK assay, variants were considered amenable when there was both an absolute increase in enzyme activity of ≥3% wild-type and a relative increase in enzyme activity ≥1.2 fold over baseline following incubation with migalastat. Six of the 59 variants tested here did not match the classification of amenability reported using the GLP-HEK assay. Linear regression and Bland-Altman analyses, comparing data from all variants with and without migalastat, provided additional evidence for a lack of assay reproducibility. Data from the GLP-HEK assay (and the resulting classification of amenability) can determine treatment strategy and, ultimately, patient outcomes, so discrepancies between amenability assay data could be a cause for concern for physicians managing patients with Fabry disease.

A Crude 1-DNJ Extract from Home Made Bombyx Batryticatus Inhibits Diabetic Cardiomyopathy-Associated Fibrosis in db/db Mice and Reduces Protein N-Glycosylation Levels

The traditional Chinese drug Bombyx Batryticatus (BB), which is also named the white stiff silkworm, has been widely used in Chinese clinics for thousands of years. It is famous for its antispasmodic and blood circulation-promoting effects. Cardiomyocyte hypertrophy, interstitial cell hyperplasia, and myocardial fibrosis are closely related to the N-glycosylation of key proteins. To examine the alterations of N-glycosylation that occur in diabetic myocardium during the early stage of the disease, and to clarify the therapeutic effect of 1-Deoxynojirimycin (1-DNJ) extracted from BB, we used the db/db (diabetic) mouse model and an approach based on hydrophilic chromatography solid-phase extraction integrated with an liquid Chromatograph Mass Spectrometer (LC-MS) identification strategy to perform a site-specific N-glycosylation analysis of left ventricular cardiomyocyte proteins. Advanced glycation end products (AGEs), hydroxyproline, connective tissue growth factor (CTGF), and other serum biochemical indicators were measured with enzyme-linked immunosorbent assays (ELISA). In addition, the α-1,6-fucosylation of N-glycans was profiled with lens culinaris agglutinin (LCA) lectin blots and fluorescein isothiocyanate (FITC)-labelled lectin affinity histochemistry. The results indicated that 1-DNJ administration obviously downregulated myocardium protein N-glycosylation in db/db mice. The expression levels of serum indicators and fibrosis-related cytokines were reduced significantly by 1-DNJ in a dose-dependent manner. The glycan α-1,6-fucosylation level of the db/db mouse myocardium was elevated, and the intervention effect of 1-DNJ administration on N-glycan α-1,6-fucosylation was significant. To verify this result, the well-known transforming growth factor-β (TGF-β)/Smad2/3 pathway was selected, and core α-1,6-fucosylated TGF-β receptor II (TGFR-βII) was analysed semi-quantitatively with western blotting. The result supported the conclusions obtained from LCA lectin affinity histochemistry and lectin blot analysis. The expression level of α-1,6-fucosyltransferase (FUT8) mRNA was also detected, and the results showed that 1-DNJ administration did not cause obvious inhibitory effects on FUT8 expression. Therefore, the mechanism of 1-DNJ for relieving diabetic cardiomyopathy (DCM)-associated fibrosis can be concluded as the inhibition of N-acetylglucosamine (N-GlcNAc) formation and the reduction of substrate concentration.

Comparative transcriptome analysis reveals significant metabolic alterations in eri-silkworm (Samia cynthia ricini) haemolymph in response to 1-deoxynojirimycin

Samia cynthia ricini (Lepidoptera: Saturniidae) is an important commercial silk-producing insect; however, in contrast to the silkworm, mulberry leaves are toxic to this insect because the leaves contain the component 1-deoxynojirimycin (DNJ). A transcriptomic analysis of eri-silkworm haemolymph was conducted to examine the genes related to different metabolic pathways and to elucidate the molecular mechanism underlying eri-silkworm haemolymph responses to DNJ. Eight hundred sixty-five differentially expressed genes (DEGs) were identified, among which 577 DEGs were up-regulated and 288 DEGs were down-regulated in the 2% DNJ group compared to control (ddH₂O) after 12h. Based on the results of the functional analysis, these DEGs were associated with ribosomes, glycolysis, N-glycan biosynthesis, and oxidative phosphorylation. In particular, according to the KEGG analysis, 138 DEGs were involved in energy metabolism, glycometabolism and lipid metabolism, and the changes in the expression of nine DEGs were confirmed by reverse transcription quantitative PCR (RT-qPCR). Thus, DNJ induced significant metabolic alterations in eri-silkworm haemolymph. These results will lay the foundation for research into the toxic effects of DNJ on eri-silkworm as a model and provide a reference for the exploitation of new drugs in humans.

Increased Regenerative Capacity of the Olfactory Epithelium in Niemann-Pick Disease Type C1

Niemann–Pick disease type C1 (NPC1) is a fatal neurovisceral lysosomal lipid storage disorder. The mutation of the NPC1 protein affects the homeostasis and transport of cholesterol and glycosphingolipids from late endosomes/lysosomes to the endoplasmic reticulum resulting in progressive neurodegeneration. Since olfactory impairment is one of the earliest symptoms in many neurodegenerative disorders, we focused on alterations of the olfactory epithelium in an NPC1 mouse model. Previous findings revealed severe morphological and immunohistochemical alterations in the olfactory system of NPC1^−/− mutant mice compared with healthy controls (NPC1^+/+). Based on immunohistochemical evaluation of the olfactory epithelium, we analyzed the impact of neurodegeneration in the olfactory epithelium of NPC1^−/− mice and observed considerable loss of mature olfactory receptor neurons as well as an increased number of proliferating and apoptotic cells. Additionally, after administration of two different therapy approaches using either a combination of miglustat, 2-hydroxypropyl-β-cyclodextrin (HPβCD) and allopregnanolone or a monotherapy with HPβCD, we recorded a remarkable reduction of morphological damages in NPC1^−/− mice and an up to four-fold increase of proliferating cells within the olfactory epithelium. Numbers of mature olfactory receptor neurons doubled after both therapy approaches. Interestingly, we also observed therapy-induced alterations in treated NPC1^+/+ controls. Thus, olfactory testing may provide useful information to monitor pharmacologic treatment approaches in human NPC1.

Metabolic changes in the midgut of Eri silkworm after Oral administration of 1-deoxynojirimycin: A 1H-NMR-based metabonomic study

1-deoxynojirimycin (DNJ) is a natural D-glucose analogue and has a strong physiological activity in inhibiting α-glucosidase in vivo. The antidiabetic effects of DNJ in mice or other mammals were extensively explored, but the physiological and toxic roles of DNJ in insects was seldom reported. In this study, the biological effects of DNJ were examined in midgut extracts of fourth-instar larvae of Eri silkworm (Samia cynthia ricini, Saturniidae). Based on nuclear magnetic resonance (NMR) metabonomics technology, we analyzed the alterations of glycometabolism, lipids, and energy metabolism pathways in the midgut of S. cynthia ricini caused by DNJ. Pattern recognition analysis (partial least square-discriminant analysis, PLS-DA) showed that four groups of latex, 0.25% DNJ, 0.5% DNJ and the mixture of 0.5% DNJ and latex (1:1) were distinctly different from the control group. Moreover, several metabolic pathways of DNJ-mediated modulation in the midgut were identified. Compared with the control group, alanine, succinate, glutamate, and fumarate concentrations decreased in three groups of 0.5% DNJ, latex, and the mixture, choline levels increased in two DNJ groups, and trehalose levels increased in all experimental groups. Therefore, these results suggest that DNJ modulated lipid metabolism by limiting the hydrolysis pathways of phospholipids metabolism. Additionally, DNJ has a potent negative effect on energy metabolism by inhibiting the hydrolysis of trehalose, glycolysis and the tricarboxylic acid (TCA) cycle. Overall, DNJ, as a single-ingredient, is an efficient substance for modulating lipid metabolism and inhibiting energy metabolism.

Metabolic Control of Tobacco Pollination by Sugars and Invertases

Pollination in flowering plants is initiated by germination of pollen grains on stigmas followed by fast growth of pollen tubes representing highly energy-consuming processes. The symplastic isolation of pollen grains and tubes requires import of Suc available in the apoplast. We show that the functional coupling of Suc cleavage by invertases and uptake of the released hexoses by monosaccharide transporters are critical for pollination in tobacco (Nicotiana tabacum). Transcript profiling, in situ hybridization, and immunolocalization of extracellular invertases and two monosaccharide transporters in vitro and in vivo support the functional coupling in supplying carbohydrates for pollen germination and tube growth evidenced by spatiotemporally coordinated expression. Detection of vacuolar invertases in maternal tissues by these approaches revealed metabolic cross talk between male and female tissues and supported the requirement for carbohydrate supply in transmitting tissue during pollination. Tissue-specific expression of an invertase inhibitor and addition of the chemical invertase inhibitor miglitol strongly reduced extracellular invertase activity and impaired pollen germination. Measurements of (competitive) uptake of labeled sugars identified two import pathways for exogenously available Suc into the germinating pollen operating in parallel: direct Suc uptake and via the hexoses after cleavage by extracellular invertase. Reduction of extracellular invertase activity in pollen decreases Suc uptake and severely compromises pollen germination. We further demonstrate that Glc as sole carbon source is sufficient for pollen germination, whereas Suc is supporting tube growth, revealing an important regulatory role of both the invertase substrate and products contributing to a potential metabolic and signaling-based multilayer regulation of pollination by carbohydrates.

Add-on therapy with anagliptin in Japanese patients with type-2 diabetes mellitus treated with metformin and miglitol can maintain higher concentrations of biologically active GLP-1/total GIP and a lower concentration of leptin

Metformin, α-glucosidase inhibitors (α-GIs), and dipeptidyl peptidase 4 inhibitors (DPP-4Is) reduce hyperglycemia without excessive insulin secretion, and enhance postprandial plasma concentration of glucagon-like peptide-1 (GLP-1) in type-2 diabetes mellitus (T2DM) patients. We assessed add-on therapeutic effects of DPP-4I anagliptin in Japanese T2DM patients treated with metformin, an α-GI miglitol, or both drugs on postprandial responses of GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), and on plasma concentration of the appetite-suppressing hormone leptin. Forty-two Japanese T2DM patients with inadequately controlled disease (HbA1c: 6.5%-8.0%) treated with metformin (n=14), miglitol (n=14) or a combination of the two drugs (n=14) received additional treatment with anagliptin (100mg, p.o., b.i.d.) for 52 weeks. We assessed glycemic control, postprandial responses of GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), and on plasma concentration of leptin in those patients. Add-on therapy with anagliptin for 52 weeks improved glycemic control and increased the area under the curve of biologically active GLP-1 concentration without altering obesity indicators. Total GIP concentration at 52 weeks was reduced by add-on therapy in groups treated with miglitol compared with those treated with metformin. Add-on therapy reduced leptin concentrations. Add-on therapy with anagliptin in Japanese T2DM patients treated with metformin and miglitol for 52 weeks improved glycemic control and enhanced postprandial concentrations of active GLP-1/total GIP, and reduce the leptin concentration.

Minimal In Vivo Efficacy of Iminosugars in a Lethal Ebola Virus Guinea Pig Model

The antiviral properties of iminosugars have been reported previously in vitro and in small animal models against Ebola virus (EBOV); however, their effects have not been tested in larger animal models such as guinea pigs. We tested the iminosugars N-butyl-deoxynojirimycin (NB-DNJ) and N-(9-methoxynonyl)-1deoxynojirimycin (MON-DNJ) for safety in uninfected animals, and for antiviral efficacy in animals infected with a lethal dose of guinea pig adapted EBOV. 1850 mg/kg/day NB-DNJ and 120 mg/kg/day MON-DNJ administered intravenously, three times daily, caused no adverse effects and were well tolerated. A pilot study treating infected animals three times within an 8 hour period was promising with 1 of 4 infected NB-DNJ treated animals surviving and the remaining three showing improved clinical signs. MON-DNJ showed no protective effects when EBOV-infected guinea pigs were treated. On histopathological examination, animals treated with NB-DNJ had reduced lesion severity in liver and spleen. However, a second study, in which NB-DNJ was administered at equally-spaced 8 hour intervals, could not confirm drug-associated benefits. Neither was any antiviral effect of iminosugars detected in an EBOV glycoprotein pseudotyped virus assay. Overall, this study provides evidence that NB-DNJ and MON-DNJ do not protect guinea pigs from a lethal EBOV-infection at the dose levels and regimens tested. However, the one surviving animal and signs of improvements in three animals of the NB-DNJ treated cohort could indicate that NB-DNJ at these levels may have a marginal beneficial effect. Future work could be focused on the development of more potent iminosugars.

α-Glucosidase Inhibitors from the Marine-Derived Fungus Aspergillus flavipes HN4-13

Three new butenolide derivatives, flavipesolides A-C (1-3), along with 13 known compounds (4-13, aspulvinone Q, monochlorosulochrin, and dihydrogeodin), were isolated from the marine-derived Aspergillus flavipes HN4-13 from a Lianyungang coastal sediment sample. The structures were elucidated by spectroscopic evidence. Compounds 4-6 and 9 were noncompetitive α-glucosidase inhibitors with K_i/IC₅₀ values of 0.43/34, 2.1/37, 0.79/19, and 2.8/90 μM, respectively. Compounds 1-3, 8, 10, and 13 are mixed α-glucosidase inhibitors with K_i/IC₅₀ values of (2.5, 19)/44, (3.4, 14)/57, (9.2, 4.7)/95, (6.3, 5.5)/55, (1.4, 0.60)/9.9, and (2.5, 7.2)/33 μM, respectively (IC₅₀ 101 μM for acarbose and 79 μM for 1-deoxynojirimycin).

1-Deoxynojirimycin: Occurrence, Extraction, Chemistry, Oral Pharmacokinetics, Biological Activities and In Silico Target Fishing

1-Deoxynojirimycin (DNJ, C₆H13NO₄, 163.17 g/mol), an alkaloid azasugar or iminosugar, is a biologically active natural compound that exists in mulberry leaves and Commelina communis (dayflower) as well as from several bacterial strains such as Bacillus and Streptomyces species. Deoxynojirimycin possesses antihyperglycemic, anti-obesity, and antiviral features. Therefore, the aim of this detailed review article is to summarize the existing knowledge on occurrence, extraction, purification, determination, chemistry, and bioactivities of DNJ, so that researchers may use it to explore future perspectives of research on DNJ. Moreover, possible molecular targets of DNJ will also be investigated using suitable in silico approach.

Pharmacologic Treatment Assigned for Niemann Pick Type C1 Disease Partly Changes Behavioral Traits in Wild-Type Mice

Niemann-Pick Type C1 (NPC1) is an autosomal recessive inherited disorder characterized by accumulation of cholesterol and glycosphingolipids. Previously, we demonstrated that BALB/c-npc1nihNpc1-/- mice treated with miglustat, cyclodextrin and allopregnanolone generally performed better than untreated Npc1-/- animals. Unexpectedly, they also seemed to accomplish motor tests better than their sham-treated wild-type littermates. However, combination-treated mutant mice displayed worse cognition performance compared to sham-treated ones. To evaluate effects of these drugs in healthy BALB/c mice, we here analyzed pharmacologic effects on motor and cognitive behavior of wild-type mice. For combination treatment mice were injected with allopregnanolone/cyclodextrin weekly, starting at P7. Miglustat injections were performed daily from P10 till P23. Starting at P23, miglustat was embedded in the chow. Other mice were treated with miglustat only, or sham-treated. The battery of behavioral tests consisted of accelerod, Morris water maze, elevated plus maze, open field and hot-plate tests. Motor capabilities and spontaneous motor behavior were unaltered in both drug-treated groups. Miglustat-treated wild-type mice displayed impaired spatial learning compared to sham- and combination-treated mice. Both combination- and miglustat-treated mice showed enhanced anxiety in the elevated plus maze compared to sham-treated mice. Additionally, combination treatment as well as miglustat alone significantly reduced brain weight, whereas only combination treatment reduced body weight significantly. Our results suggest that allopregnanolone/cyclodextrin ameliorate most side effects of miglustat in wild-type mice.

α-Glucosidase Inhibitors Have a Prolonged Antiviral Effect against Hepatitis B Virus through the Sustained Inhibition of the Large and Middle Envelope Glycoproteins

Previous work has shown that the secretion of enveloped hepatitis B virus (HBV) DNA and the HBV middle envelope protein (MHBs) are sensitive to glucosidase inhibition. Here, it is shown that HBV DNA secretion remains depressed after the removal of the glucosidase inhibitor and long after glucosidase function returns to normal. For example, glycoprocessing and the secretion of α-1 anti-trypsin returned to normal within 3 h of the removal of the glucosidase inhibitor. In contrast, the secretion of HBV did not return to normal for more than 7 days after the removal of the inhibitor. Consistent with the inhibition of HBV virion secretion, the levels of HBV L and HBV M proteins were also reduced by treatment with the glucosidase inhibitor and remained reduced for 7 days after compound withdrawal. The implications of the prolonged antiviral effect against HBV and the use of glucosidase inhibitors as antiviral agents are discussed.

N-butyldeoxynojirimycin treatment restores the innate fear response and improves learning in mucopolysaccharidosis IIIA mice

Mucopolysaccharidosis IIIA is a heritable neurodegenerative disorder resulting from the dysfunction of the lysosomal hydrolase sulphamidase. This leads to the primary accumulation of the complex carbohydrate heparan sulphate in a wide range of tissues and the secondary neuronal storage of gangliosides GM2 and GM3 in the brain. GM2 storage is associated with CNS deterioration in the GM2 gangliosidosis group of lysosomal storage disorders and may also contribute to MPS CNS disease. N-butyldeoxynojirimycin, an inhibitor of ceramide glucosyltransferase activity and therefore of ganglioside synthesis, was administered to MPS IIIA mice both prior to maximal GM2 and GM3 accumulation (early treatment) and after the maximum level of ganglioside had accumulated in the brain (late treatment) to determine if behaviour was altered by ganglioside level. Ceramide glucosyltransferase activity was decreased in both treatment groups; however, brain ganglioside levels were only decreased in the late treatment group. Learning in the water cross maze was improved in both groups and the innate fear response was also restored in both groups. A reduction in the expression of inflammatory gene Ccl3 was observed in the early treatment group, while IL1β expression was reduced in both treatment groups. Thus, it appears that NB-DNJ elicits a transient decrease in brain ganglioside levels, some modulation of inflammatory cytokines and a functional improvement in behaviour that can be elicited both before and after overt neurological changes manifest.

SYNOPSIS

NB-DNJ improves learning and restores the innate fear response in MPS IIIA mice by decreasing ceramide glucosyltransferase activity and transiently reducing ganglioside storage and/or modulating inflammatory signals.

An Evaluation of 1-Deoxynojirimycin Oral Administration in Eri Silkworm through Fat Body Metabolomics Based on (1) H Nuclear Magnetic Resonance

1-Deoxynojirimycin (DNJ), the main hypoglycemic constituent in mulberry (Morus alba) latex, has been extensively researched. Although there is considerable interest in the biological effects of DNJ, the roles of 1-deoxynojirimycin (DNJ) in glycometabolism and energy metabolism in insects have received little attention. In this paper, (1)H nuclear magnetic resonance ((1)H NMR) based metabonomic was performed to study the effects of the oral supplementation of 0.25% DNJ, 0.5% DNJ, latex, and the mixture of 0.5% DNJ and latex (1 : 1) on the fat body glycometabolism and energy metabolism of the fourth-instar larvae of Eri silkworms, Samia cynthia ricini. Metabolic pattern recognition analysis (partial least square-discriminant analysis, PLS-DA) of fat body extracts indicated that the groups of 0.25% DNJ, 0.5% DNJ, latex, and the mixture of 0.5% DNJ and latex (1 : 1) were significantly different from the control group. Further, compared to the control group, the metabolites levels of lactate, trehalose, succinate, malate, and fumarate were remarkably changed in experimental groups, which were involved in glycolysis, hydrolysis of trehalose, and tricarboxylic acid (TCA) cycle. Our results indicate that DNJ has a positive impact on the reverse energy metabolism of Eri silkworms and metabonomic analysis based on NMR can be used as a tool to identify potential biomarkers.

The Iminosugar UV-4 is a Broad Inhibitor of Influenza A and B Viruses ex Vivo and in Mice

Iminosugars that are competitive inhibitors of endoplasmic reticulum (ER) α-glucosidases have been demonstrated to have antiviral activity against a diverse set of viruses. A novel iminosugar, UV-4B, has recently been shown to provide protection against lethal infections with dengue and influenza A (H1N1) viruses in mice. In the current study, the breadth of activity of UV-4B against influenza was examined ex vivo and in vivo. Efficacy of UV-4B against influenza A and B viruses was shown in primary human bronchial epithelial cells, a principal target tissue for influenza. Efficacy of UV-4B against influenza A (H1N1 and H3N2 subtypes) and influenza B was demonstrated using multiple lethal mouse models with readouts including mortality and weight loss. Clinical trials are ongoing to demonstrate safety of UV-4B and future studies to evaluate antiviral activity against influenza in humans are planned.

1-Deoxynojirimycin Alleviates Liver Injury and Improves Hepatic Glucose Metabolism in db/db Mice

The present study investigated the effect of 1-Deoxynojirimycin (DNJ) on liver injury and hepatic glucose metabolism in db/db mice. Mice were divided into five groups: normal control, db/db control, DNJ-20 (DNJ 20 mg·kg⁻¹·day⁻¹), DNJ-40 (DNJ 40 mg·kg⁻¹·day⁻¹) and DNJ-80 (DNJ 80 mg·kg⁻¹·day⁻¹). All doses were treated intravenously by tail vein for four weeks. DNJ was observed to significantly reduce the levels of serum triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and liver TG, as well as activities of serum alanine aminotransferase (ALT), and aspartate transaminase (AST); DNJ also alleviated macrovesicular steatosis and decreased tumor necrosis factor α (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6) levels in liver tissue. Furthermore, DNJ treatment significantly increased hepatic glycogen content, the activities of hexokinase (HK), pyruvate kinase (PK) in liver tissue, and decreased the activities of glucose-6-phosphatase (G6Pase), glycogen phosphorylase (GP), and phosphoenolpyruvate carboxykinase (PEPCK). Moreover, DNJ increased the phosphorylation of phosphatidylinositol 3 kinase (PI3K) on p85, protein kinase B (PKB) on Ser473, glycogen synthase kinase 3β (GSK-3β) on Ser9, and inhibited phosphorylation of glycogen synthase (GS) on Ser645 in liver tissue of db/db mice. These results demonstrate that DNJ can increase hepatic insulin sensitivity via strengthening of the insulin-stimulated PKB/GSK-3β signal pathway and by modulating glucose metabolic enzymes in db/db mice. Moreover, DNJ also can improve lipid homeostasis and attenuate hepatic steatosis in db/db mice.

Inhibition of α-glucosidase activity by N-deoxynojirimycin analogs in several insect phloem sap feeders

Secondary metabolites and synthetic iminosugars that structurally resemble monosaccharides are potent inhibitors of α-glucosidase activity. The enzyme is core in cleaving sucrose in phloem feeding insects and it also plays a crucial role of reducing osmotic stress via the formation of oligosaccharides. Inhibition of hydrolysis by iminosugars should result in nutritional deficiencies and/or disruption of normal osmoregulation. Deoxynojirimycin (DNJ) and 2 N-alkylated analogs [N-butyl DNJ (NB-DNJ) and N-nonyl DNJ (NN-DNJ)] were the major iminosugars used throughout the study. The extensive experiments conducted with α-glucosidase of the whitefly Bemisia tabaci indicated the competitive nature of inhibition and that the hydrophilic DNJ is a potent inhibitor in comparison to the more hydrophobic NB-DNJ and NN-DNJ compounds. The same inhibitory pattern was observed with the psyllid Cacopsylla bidens α-glucosidase. In contrast to the above pattern, enzymes of the aphids, Myzus persicae and Aphis gossypii were more sensitive to the hydrophobic iminosugars as compared to DNJ. In vivo experiments in which adult B. tabaci were fed dietary iminosugars, show that the hydrophilic DNJ was far less toxic than the lipophilic NB-DNJ and NN-DNJ. It is proposed that this pattern is attributed to the better accessibility of the hydrophobic NN-DNJ to the α-glucosidase membrane-bound compartment in the midgut. Based on the inhibitory effects of certain polyhydroxy N-alkylated iminosugars, α-glucosidase of phloem feeding hemipterans could serve as an attractive target site for developing novel pest control agents.

1-Deoxynojirimycin Alleviates Insulin Resistance via Activation of Insulin Signaling PI3K/AKT Pathway in Skeletal Muscle of db/db Mice

1-Deoxynojirimycin (DNJ) is widely used for the treatment of diabetes mellitus as an inhibitor of intestinal α-glucosidase. However, there are few reports about its effect on insulin sensitivity improvement. The aim of the present study was to investigate whether DNJ decreased hyperglycemia by improving insulin sensitivity. An economical method was established to prepare large amounts of DNJ. Then, db/db mice were treated with DNJ intravenously (20, 40 and 80 mg·kg⁻¹·day⁻¹) for four weeks. Blood glucose and biochemical analyses were conducted to evaluate the therapeutic effects on hyperglycemia and the related molecular mechanisms in skeletal muscle were explored. DNJ significantly reduced body weight, blood glucose and serum insulin levels. DNJ treatment also improved glucose tolerance and insulin tolerance. Moreover, although expressions of total protein kinase B (AKT), phosphatidylinositol 3 kinase (PI3K), insulin receptor beta (IR-β), insulin receptor substrate-1 (IRS1) and glucose transporter 4 (GLUT4) in skeletal muscle were not affected, GLUT4 translocation and phosphorylation of Ser473-AKT, p85-PI3K, Tyr1361-IR-β and Tyr612-IRS1 were significantly increased by DNJ treatment. These results indicate that DNJ significantly improved insulin sensitivity via activating insulin signaling PI3K/AKT pathway in skeletal muscle of db/db mice.

Mulberry 1-Deoxynojirimycin Inhibits Adipogenesis by Repression of the ERK/PPARγ Signaling Pathway in Porcine Intramuscular Adipocytes

Intramuscular fat (IMF), which is modulated by adipogenensis of intramuscular adipocytes, plays a key role in pork quality associated with marbling, juiceness, and flavor. However, the regulatory mechanism of 1-deoxynojirimycin (DNJ) on adipogenesis is still unknown. Here, we found that both DNJ (2.0, 3.0, 4.0, 5.0, and 6.0 μM) and rosiglitazone (RSG; 0.1, 0.2, 0.3, 0.4, and 0.5 mM) had no effect on cell viability. Moreover, 4 μM DNJ significantly inhibited adipogenesis, whereas 0.4 mM RSG increased lipogenesis of porcine intramuscular adipocytes. Interestingly, DNJ sharply inhibited phosphorylation of extracellular regulated protein kinases 1/2 (ERK1/2), but did not change phosphorylation of AKT (protein kinase B) in intramuscular adipocytes. We further found that the inhibitory adipogenesis of DNJ was attenuated by RSG via up-regulation of PPARγ. On the basis of the above findings, we suggest that DNJ inhibited adipogenesis through the ERK/PPARγ signaling pathway in porcine intramuscular adipocytes.

A 1H-NMR Based Study on Hemolymph Metabolomics in Eri Silkworm after Oral Administration of 1-Deoxynojirimycin

We aimed to investigate whether 1-deoxynojirimycin (DNJ) modulates glycometabolism and has toxicity in Eri silkworm (Samia cynthia ricini, Saturniidae). In this paper, hemolymph metabolites were used to explore metabolic changes after oral administration of DNJ or mulberry latex and to characterize the biological function of DNJ at the metabolic and systemic levels. Hemolymph samples were collected from fourth-instar larvae of Eri silkworm and ex-vivo high-resolution 1H nuclear magnetic resonance (NMR) spectra were acquired from the collected hemolymph samples. Then the obtained spectra were analyzed by principal component analysis (PCA) and independent-samples t-test. Metabolic pattern recognition analysis of hemolymph samples indicated that the groups of 0.25% DNJ, latex, and the mixture of 0.5% DNJ and latex (1:1) were significantly different from the control group. Moreover, compared to the control group, the groups of 0.25% DNJ, latex, and the mixture of 0.5% DNJ and latex (1:1) showed the decreased levels of citrate, succinate, fumarate, malate, and glutamine in hemolymph, the groups of 0.25% DNJ and the mixture of 0.5% DNJ and latex (1:1) showed the increased levels of trehalose and lactate. In addition, mulberry leaves exude latex was highly toxic to Eri silkworm because rich unidentified high-molecular-weight factor (s) acted as toxic substances. In our results, latex caused 20 deaths among 50 fourth-instar larvae of Eri silkmoth, but DNJ or the mixture did not caused death. All these results suggest that DNJ has a positive impact on the reverse glycometabolism by modulating glycometabolism and inhibiting glucogenesis and energy metabolism. DNJ is a secure substance as a single-ingredient antidiabetic medicine due to its nontoxicity and bioactivity.

Glycosphingolipid synthesis inhibition limits osteoclast activation and myeloma bone disease

Glycosphingolipids (GSLs) are essential constituents of cell membranes and lipid rafts and can modulate signal transduction events. The contribution of GSLs in osteoclast (OC) activation and osteolytic bone diseases in malignancies such as the plasma cell dyscrasia multiple myeloma (MM) is not known. Here, we tested the hypothesis that pathological activation of OCs in MM requires de novo GSL synthesis and is further enhanced by myeloma cell-derived GSLs. Glucosylceramide synthase (GCS) inhibitors, including the clinically approved agent N-butyl-deoxynojirimycin (NB-DNJ), prevented OC development and activation by disrupting RANKL-induced localization of TRAF6 and c-SRC into lipid rafts and preventing nuclear accumulation of transcriptional activator NFATc1. GM3 was the prevailing GSL produced by patient-derived myeloma cells and MM cell lines, and exogenous addition of GM3 synergistically enhanced the ability of the pro-osteoclastogenic factors RANKL and insulin-like growth factor 1 (IGF-1) to induce osteoclastogenesis in precursors. In WT mice, administration of GM3 increased OC numbers and activity, an effect that was reversed by treatment with NB-DNJ. In a murine MM model, treatment with NB-DNJ markedly improved osteolytic bone disease symptoms. Together, these data demonstrate that both tumor-derived and de novo synthesized GSLs influence osteoclastogenesis and suggest that NB-DNJ may reduce pathological OC activation and bone destruction associated with MM.

Distinct action of the α-glucosidase inhibitor miglitol on SGLT3, enteroendocrine cells, and GLP1 secretion

Oral ingestion of carbohydrate triggers glucagon-like peptide 1 (GLP1) secretion, but the molecular mechanism remains elusive. By measuring GLP1 concentrations in murine portal vein, we found that the ATP-sensitive K(+) (KATP) channel is not essential for glucose-induced GLP1 secretion from enteroendocrine L cells, while the sodium-glucose co-transporter 1 (SGLT1) is required, at least in the early phase (5 min) of secretion. By contrast, co-administration of the α-glucosidase inhibitor (α-GI) miglitol plus maltose evoked late-phase secretion in a glucose transporter 2-dependent manner. We found that GLP1 secretion induced by miglitol plus maltose was significantly higher than that by another α-GI, acarbose, plus maltose, despite the fact that acarbose inhibits maltase more potently than miglitol. As miglitol activates SGLT3, we compared the effects of miglitol on GLP1 secretion with those of acarbose, which failed to depolarize the Xenopus laevis oocytes expressing human SGLT3. Oral administration of miglitol activated duodenal enterochromaffin (EC) cells as assessed by immunostaining of phosphorylated calcium-calmodulin kinase 2 (phospho-CaMK2). In contrast, acarbose activated much fewer enteroendocrine cells, having only modest phospho-CaMK2 immunoreactivity. Single administration of miglitol triggered no GLP1 secretion, and GLP1 secretion by miglitol plus maltose was significantly attenuated by atropine pretreatment, suggesting regulation via vagal nerve. Thus, while α-GIs generally delay carbohydrate absorption and potentiate GLP1 secretion, miglitol also activates duodenal EC cells, possibly via SGLT3, and potentiates GLP1 secretion through the parasympathetic nervous system.

Isolation and SAR studies of bicyclic iminosugars from Castanospermum australe as glycosidase inhibitors

We report the isolation and structural determination of fourteen iminosugars, containing five pyrrolizidines and five indolizidines, from Castanospermum australe. The structure of a new alkaloid was elucidated by spectroscopic methods as 6,8-diepi-castanospermine (13). Our side-by-side comparison between bicyclic and corresponding monocyclic iminosugars revealed that inhibition potency and spectrum against each enzyme are clearly changed by their core structures. Castanospermine (10) and 1-deoxynojirimycin (DNJ) have a common d-gluco configuration, and they showed the expected similar inhibition potency and spectrum. In sharp contrast, 6-epi-castanospermine (12) and 1-deoxymannojirimycin (manno-DNJ) both have the d-manno configuration but the α-mannosidase inhibition of 6-epi-castanospermine (12) was much better than that of manno-DNJ. 6,8-Diepi-castanospermine (13) could be regarded as a bicyclic derivative of talo-DNJ, but it showed a complete loss of α-galactosidase A inhibition. This behavior against α-galactosidase A is similar to that observed for 1-epi-australine (6) and altro-DMDP.

Miglustat: a review of its use in Niemann-Pick disease type C

Miglustat (Zavesca®, Brazaves®), a small iminosugar molecule that reversibly inhibits glycosphingolipid synthesis, is the only disease-specific drug approved for the treatment of progressive neurological manifestations of Niemann-Pick disease type C (NP-C) in adult and paediatric patients. NP-C is a rare, autosomal-recessive lipid storage disorder characterized by impaired intracellular lipid trafficking and progressive neurological symptoms leading to premature death. In a randomized clinical trial, long-term extension studies and a retrospective observational cohort study, treatment with oral miglustat stabilized key neurological manifestations of NP-C (including horizontal saccadic eye movement peak velocity, ambulation, manipulation, language and swallowing) in paediatric and adult patients with the disease. The therapeutic effects of miglustat in stabilizing or slowing disease progression have been confirmed in other reports in the clinical experience setting. The primary tolerability issues associated with miglustat are mild to moderate gastrointestinal effects (e.g. diarrhoea, flatulence and abdominal pain/discomfort) and weight loss, which usually occur during initial therapy and are generally manageable. In the absence of a cure, miglustat is a valuable agent to reduce the progression of clinically relevant neurological symptoms in paediatric and adult patients with NP-C, which is considered a significant achievement in the treatment of this disease.

GBA2-encoded β-glucosidase activity is involved in the inflammatory response to Pseudomonas aeruginosa

Current anti-inflammatory strategies for the treatment of pulmonary disease in cystic fibrosis (CF) are limited; thus, there is continued interest in identifying additional molecular targets for therapeutic intervention. Given the emerging role of sphingolipids (SLs) in various respiratory disorders, including CF, drugs that selectively target the enzymes associated with SL metabolism are under development. Miglustat, a well-characterized iminosugar-based inhibitor of β-glucosidase 2 (GBA2), has shown promise in CF treatment because it reduces the inflammatory response to infection by P. aeruginosa and restores F508del-CFTR chloride channel activity. This study aimed to probe the molecular basis for the anti-inflammatory activity of miglustat by examining specifically the role of GBA2 following the infection of CF bronchial epithelial cells by P. aeruginosa. We also report the anti-inflammatory activity of another potent inhibitor of GBA2 activity, namely N-(5-adamantane-1-yl-methoxy)pentyl)-deoxynojirimycin (Genz-529648). In CF bronchial cells, inhibition of GBA2 by miglustat or Genz-529648 significantly reduced the induction of IL-8 mRNA levels and protein release following infection by P. aeruginosa. Hence, the present data demonstrate that the anti-inflammatory effects of miglustat and Genz-529648 are likely exerted through inhibition of GBA2.

The pharmacological chaperone AT2220 increases the specific activity and lysosomal delivery of mutant acid alpha-glucosidase, and promotes glycogen reduction in a transgenic mouse model of Pompe disease

Pompe disease is an inherited lysosomal storage disorder that results from a deficiency in acid α-glucosidase (GAA) activity due to mutations in the GAA gene. Pompe disease is characterized by accumulation of lysosomal glycogen primarily in heart and skeletal muscles, which leads to progressive muscle weakness. We have shown previously that the small molecule pharmacological chaperone AT2220 (1-deoxynojirimycin hydrochloride, duvoglustat hydrochloride) binds and stabilizes wild-type as well as multiple mutant forms of GAA, and can lead to higher cellular levels of GAA. In this study, we examined the effect of AT2220 on mutant GAA, in vitro and in vivo, with a primary focus on the endoplasmic reticulum (ER)-retained P545L mutant form of human GAA (P545L GAA). AT2220 increased the specific activity of P545L GAA toward both natural (glycogen) and artificial substrates in vitro. Incubation with AT2220 also increased the ER export, lysosomal delivery, proteolytic processing, and stability of P545L GAA. In a new transgenic mouse model of Pompe disease that expresses human P545L on a Gaa knockout background (Tg/KO) and is characterized by reduced GAA activity and elevated glycogen levels in disease-relevant tissues, daily oral administration of AT2220 for 4 weeks resulted in significant and dose-dependent increases in mature lysosomal GAA isoforms and GAA activity in heart and skeletal muscles. Importantly, oral administration of AT2220 also resulted in significant glycogen reduction in disease-relevant tissues. Compared to daily administration, less-frequent AT2220 administration, including repeated cycles of 4 or 5 days with AT2220 followed by 3 or 2 days without drug, respectively, resulted in even greater glycogen reductions. Collectively, these data indicate that AT2220 increases the specific activity, trafficking, and lysosomal stability of P545L GAA, leads to increased levels of mature GAA in lysosomes, and promotes glycogen reduction in situ. As such, AT2220 may warrant further evaluation as a treatment for Pompe disease.

Structural basis of pharmacological chaperoning for human β-galactosidase

GM1 gangliosidosis and Morquio B disease are autosomal recessive diseases caused by the defect in the lysosomal β-galactosidase (β-Gal), frequently related to misfolding and subsequent endoplasmic reticulum-associated degradation. Pharmacological chaperone (PC) therapy is a newly developed molecular therapeutic approach by using small molecule ligands of the mutant enzyme that are able to promote the correct folding and prevent endoplasmic reticulum-associated degradation and promote trafficking to the lysosome. In this report, we describe the enzymological properties of purified recombinant human β-Gal(WT) and two representative mutations in GM1 gangliosidosis Japanese patients, β-Gal(R201C) and β-Gal(I51T). We have also evaluated the PC effect of two competitive inhibitors of β-Gal. Moreover, we provide a detailed atomic view of the recognition mechanism of these compounds in comparison with two structurally related analogues. All compounds bind to the active site of β-Gal with the sugar-mimicking moiety making hydrogen bonds to active site residues. Moreover, the binding affinity, the enzyme selectivity, and the PC potential are strongly affected by the mono- or bicyclic structure of the core as well as the orientation, nature, and length of the exocyclic substituent. These results provide understanding on the mechanism of action of β-Gal selective chaperoning by newly developed PC compounds.