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Some point mutations in β-glucocerebrosidase cause either improper folding or instability of this protein, resulting in Gaucher disease. Pharmacological chaperones bind to the mutant enzyme and stabilize this enzyme; thus, pharmacological chaperone therapy was proposed as a potential treatment for Gaucher disease. The binding affinities of α-1-C-alkyl 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) derivatives, which act as pharmacological chaperones for β-glucocerebrosidase, abruptly increased upon elongation of their alkyl chain. In this study, the primary causes of such an increase in binding affinity were analyzed using protein–ligand docking and molecular dynamics simulations. We found that the activity cliff between α-1-C-heptyl-DAB and α-1-C-octyl-DAB was due to the shape and size of the hydrophobic binding site accommodating the alkyl chains, and that the interaction with this hydrophobic site controlled the binding affinity of the ligands well. Furthermore, based on the aromatic/hydrophobic properties of the binding site, a 7-(tetralin-2-yl)-heptyl-DAB compound was designed and synthesized. This compound had significantly enhanced activity. The design strategy in consideration of aromatic interactions in the hydrophobic pocket was useful for generating effective pharmacological chaperones for the treatment of Gaucher disease.

There is reason to believe that diabetic neuropathy may be related to the accumulation of sorbitol in nerve tissue through an aldose reductase pathway from glucose. Short-term treatment with aldose reductase inhibitors improves nerve conduction in subjects with diabetes, but the effects of long-term treatment on the neuropathologic changes of diabetic neuropathy are unknown. To determine whether more prolonged aldose reductase inhibition reverses the underlying lesions that accompany symptomatic diabetic peripheral polyneuropathy, we performed a randomized, placebo-controlled, double-blind trial of the investigational aldose reductase inhibitor sorbinil (250 mg per day). Sural-nerve biopsy specimens obtained at base line and after one year from 16 diabetic patients with neuropathy were analyzed morphometrically in detail and compared with selected electrophysiologic and clinical indexes. In contrast to patients who received placebo, the 10 sorbinil-treated patients had a decrease of 41.8±8.0 percent in nerve sorbitol content (P<0.01) and a 3.8-fold increase in the percentage of regenerating myelinated nerve fibers (P<0.001), reflected by a 33 percent increase in the number of myelinated fibers per unit of cross-sectional area of nerve (P = 0.04). They also had quantitative improvement in terms of the degree of paranodal demyelination, segmental demyelination, and myelin wrinkling. The increase in the number of fibers was accompanied by electrophysiologic and clinical evidence of improved nerve function. We conclude that sorbinil, as a metabolic intervention targeted against a specific biochemical consequence of hyperglycemia, can improve the neuropathologic lesions of diabetic neuropathy. (N Engl J Med 1988; 319:548–55.) THE distal symmetric polyneuropathy that accompanies diabetes mellitus is by far the most common form of peripheral neuropathy in the Western world 1 , 2 and is a major contributor to the overall morbidity associated with diabetes. 3 Although this condition is presumed to reflect a complex interplay among metabolic factors related to hyperglycemia, 1 2 3 4 5 6 7 8 microvascular abnormalities, 1 , 9 10 11 and unidentified independent genetic and environmental variables, its exact pathogenesis remains controversial. 1 , 5 , 6 Effective and specific treatment continues to elude the efforts of both clinicians and investigators in the field. 5 , 12 Investigators searching for specific consequences of hyperglycemia that might initiate or accelerate the development of chronic complications of diabetes, . . .

To assess the potential role of polyol-pathway activity in diabetic neuropathy, we measured the effects of sorbinil — a potent inhibitor of the key polyol-pathway enzyme aldose reductase — on nerve conduction velocity in 39 stable diabetics in a randomized, double-blind, cross-over trial. During nine weeks of treatment with sorbinil (250 mg per day), nerve conduction velocity was greater than during a nine-week placebo period for all three nerves tested: the peroneal motor nerve (mean increase [±S.E.M.], 0.70±0.24 m per second, P<0.008), the median motor nerve (mean increase, 0.66±0.27, P<0.005), and the median sensory nerve (mean increase, 1.16±0.50, P<0.035). Conduction velocity for all three nerves declined significantly within three weeks after cessation of the drug. These effects of sorbinil were not related to glycemic control, which was constant during the study. Although the effect of sorbinil in improving nerve conduction velocity in diabetics was small, the findings suggest that polyol-pathway activity contributes to slowed nerve conduction in diabetics. The clinical applicability of these observations remains to be determined, but they encourage further exploration of this approach to the treatment or prevention of diabetic neuropathy. (N Engl J Med. 1983; 308:119–25.) THERE is a growing body of evidence to suggest that the impairment of nerve conduction velocity that has been observed in patients with diabetes mellitus is related to the abnormal metabolic state of these patients 1 , 2 and, in particular, to the degree of their hyperglycemia. 3 4 5 As a result of the activity of enzymes of the polyol pathway, an accumulation of sorbitol and fructose in proportion to the degree of hyperglycemia present has been observed in the peripheral nerves of diabetic animals and of some human beings. 6 7 8 9 Administration of an inhibitor of aldose reductase, the rate-limiting first enzyme of the polyol pathway, . . .

The efficacy of treatment with an aldose reductase inhibitor (1,3-dioxo-1 H-benz-de-isoquinoline-2(3H)-acetic acid, AY-22,284, Alrestatin) on peripheral nerve function in diabetic polyneuropathy was assessed. Thirty patients with long-standing diabetes and slight to moderate neuropathy participated in the double-blind placebo trial. Clinical examination, sensory threshold determinations for vibratory, tactile and thermal stimuli, conduction velocity measurements and studies of automatic function were performed to evaluate the treatment. Significant differences favouring Alrestatin over placebo were found for many of the measured variables, whereas no changes occurred on placebo. The apparent improvement of neuropathy occurred despite persisting hyperglycaemia. The results indicate that aldose reductase inhibitor treatment may be of value in diabetic polyneuropathy, and provide support for the sorbitol pathway hypothesis of diabetic polyneuropathy.

Unsporulated oocysts of the protozoan parasite Eimeria tenella contain high levels of mannitol, which is thought to be the principal energy source for the process of sporulation. Biosynthesis and utilization of this sugar alcohol occurs via a metabolic pathway known as the mannitol cycle. Here, results are presented that suggest that 3-nitrophenyl disulfide (nitrophenide, Megasul™), an anticoccidial drug commercially used in the 1950s, inhibits mannitol-1-phosphate dehydrogenase (M1PDH), which catalyzes the committed enzymatic step in the mannitol cycle. Treatment of E. tenella-infected chickens with nitrophenide resulted in a 90% reduction in oocyst shedding. The remaining oocysts displayed significant morphological abnormalities and were largely incapable of further development. Nitrophenide treatment did not affect parasite asexual reproduction, suggesting specificity for the sexual stage of the life cycle. Isolated oocysts from chickens treated with nitrophenide exhibited a dose-dependent reduction in mannitol, suggesting in vivo inhibition of parasite mannitol biosynthesis. Nitrophenide-mediated inhibition of M1PDH was observed in vitro using purified native enzyme. Moreover, M1PDH activity immunoprecipitated from E. tenella-infected cecal tissues was significantly lower in nitrophenide-treated compared with untreated chickens. Western blot analysis and immunohistochemistry showed that parasites from nitrophenide-treated and untreated chickens contained similar enzyme levels. These data suggest that nitrophenide blocks parasite development at the sexual stages by targeting M1PDH. Thus, targeting of the mannitol cycle with drugs could provide an avenue for controlling the spread of E. tenella in commercial production facilities by preventing oocyst shedding.

Carbon-13 nuclear magnetic resonance spectroscopy has been used in the study of glucose metabolism, specifically aldose reductase inhibition, in intact rabbit lenses maintained in organ culture. This technique provides an effective method of screening potential inhibitors of aldose reductase under conditions that more closely approximate in vivo conditions than do earlier methods. The aspirin substitutes acetaminophen and ibuprofen were studied as aldose reductase inhibitors and were found to be effective in reducing sorbitol accumulation in lenses exposed to high glucose stress. Results of this work with various inhibitors of aldose reductase are discussed in terms of lens metabolism and implications regarding diabetic complications such as cataract formation.

Upon addition of NADP+, the rose bengal-sensitized photoinactivation of D-erythrulose reductase from beef liver is prevented to a remarkable extent. Adenosine 2',5'-diphosphate (2',5'-ADP) also has a protective effect, but to a lesser extent. On the other hand, 2'-AMP markedly enhances the photoinactivation. Other nucleotides which have no 2'-phosphoryl group, such as NAD+, 3'-AMP, 5'-AMP, ADP, and NMN, are ineffective. Further, only 2'-AMP derivatives (NADP+, 2',5'-ADP, and 2'-AMP) among these nucleotides were found to be potent competitive inhibitors of the enzyme with small Ki's (6--13 muM). Photooxidation of some methionine residues in the enzyme is prevented by the addition of NADP+ and accelerated in the presence of 2'-AMP. Photooxidation products(s) of 2'-AMP derivatives have no effect upon the enzymatic activity. Although NADP+ and 2'-AMP induce detectable conformational changes of the enzyme, the changes are not characteristic to the compounds. Based on these observations, we present a possible action mechanism of 2'-AMP derivatives on the photoinactivation of D-erythrulose reductase.Upon addition of NADP+, the rose bengal-sensitized photoinactivation of D-erythrulose reductase from beef liver is prevented to a remarkable extent. Adenosine 2',5'-diphosphate (2',5'-ADP) also has a protective effect, but to a lesser extent. On the other hand, 2'-AMP markedly enhances the photoinactivation. Other nucleotides which have no 2'-phosphoryl group, such as NAD+, 3'-AMP, 5'-AMP, ADP, and NMN, are ineffective. Further, only 2'-AMP derivatives (NADP+, 2',5'-ADP, and 2'-AMP) among these nucleotides were found to be potent competitive inhibitors of the enzyme with small Ki's (6--13 muM). Photooxidation of some methionine residues in the enzyme is prevented by the addition of NADP+ and accelerated in the presence of 2'-AMP. Photooxidation products(s) of 2'-AMP derivatives have no effect upon the enzymatic activity. Although NADP+ and 2'-AMP induce detectable conformational changes of the enzyme, the changes are not characteristic to the compounds. Based on these observations, we present a possible action mechanism of 2'-AMP derivatives on the photoinactivation of D-erythrulose reductase.

The 25 human bitter taste receptors (hTAS2Rs) are responsible for detecting bitter molecules present in food, and they also play several physiological and pathological roles in extraoral compartments. Therefore, understanding their ligand specificity is important both for food research and for pharmacological applications. Here we provide a molecular insight into the exquisite molecular recognition of bitter β-glycopyranosides by one of the members of this receptor subclass, hTAS2R16. Most of its agonists have in common the presence of a β-glycopyranose unit along with an extremely structurally diverse aglycon moiety. This poses the question of how hTAS2R16 can recognize such a large number of “bitter sugars”. By means of hybrid molecular mechanics/coarse grained molecular dynamics simulations, here we show that the three hTAS2R16 agonists salicin, arbutin and phenyl-β-D-glucopyranoside interact with the receptor through a previously unrecognized dual binding mode. Such mechanism may offer a seamless way to fit different aglycons inside the binding cavity, while maintaining the sugar bound, similar to the strategy used by several carbohydrate-binding lectins. Our prediction is validated a posteriori by comparison with mutagenesis data and also rationalizes a wealth of structure-activity relationship data. Therefore, our findings not only provide a deeper molecular characterization of the binding determinants for the three ligands studied here, but also give insights applicable to other hTAS2R16 agonists. Together with our results for other hTAS2Rs, this study paves the way to improve our overall understanding of the structural determinants of ligand specificity in bitter taste receptors.

The re-emergence of tuberculosis in recent years led the World Health Organization (WHO) to launch the Stop TB Strategy program. Beside repurposing the existing drugs and exploring novel molecular combinations, an essential step to face the burden of tuberculosis will be to develop new drugs by identifying vulnerable bacterial targets. Recent studies have focused on decaprenylphosphoryl- d -ribose oxidase (DprE1) of Mycobacterium tuberculosis , an essential enzyme involved in cell wall metabolism, for which new promising molecules have proved efficacy as antitubercular agents. This review summarizes the state of the art concerning DprE1 in terms of structure, enzymatic activity and inhibitors. This enzyme is emerging as one of the most vulnerable target in M. tuberculosis .

Gastric ulcer (GU) is a prevalent digestive system disease, yet effective treatment methods remain limited. D-mannose, a monosaccharide isolated from Bletilla striata polysaccharides, has been demonstrated to exhibit significant antioxidant potential in previous studies. Prior investigations have not addressed the therapeutic implications of this compound in preventing alcohol-induced gastric epithelial disruptions. This scientific inquiry is designed to investigate the gastroprotective attributes and antioxidant activity of D-mannose in mitigating alcohol-related gastric ulceration. An ethanol-induced GU mouse model was established using absolute ethanol. The protective effects and antioxidant activity of different doses of D-mannose (40%, 20% w/v) on gastric tissues were evaluated through morphological observation, pathological staining, and biochemical analysis. Complementarily, computational methodologies encompassing network pharmacological analysis and molecular interaction modeling were utilized to anticipate potential therapeutic mechanisms of D-mannose in gastric ulcer management, subsequently validated through comprehensive experimental investigations in biological systems. D-mannose significantly reduced the ulcer index and pathological scores in gastric tissues, alleviating the damage induced by absolute ethanol. D-mannose markedly increased the activity of antioxidant enzymes, including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT), while reducing the production of reactive oxygen species (ROS) and malondialdehyde (MDA), thereby enhancing the antioxidant capacity of gastric tissues. Bioinformatics predictions identified HSP90 as the key target for the therapeutic effect of D-mannose on GU. Molecular biology experiments confirmed that D-mannose significantly activated the expression of HSP90 and the downstream Nrf2/HO-1 pathway-related genes and proteins. Similarly, in vitro experiments demonstrated that D-mannose activated key genes and proteins in the HSP90/Nrf2/HO-1 pathway, counteracting oxidative stress damage to gastric epithelial cells induced by absolute ethanol. D-mannose enhances the antioxidant capacity of gastric tissues by activating key molecules in the HSP90/Nrf2/HO-1 pathway, thereby exerting a protective effect on the stomach.