Seiichiro Ogawa

Chemical chaperone therapy for brain pathology in GM1-gangliosidosis

We synthesized a galactose derivative, N-octyl-4-epi-β-valienamine (NOEV), for a molecular therapy (chemical chaperone therapy) of a human neurogenetic disease, β-galactosidosis (GM1-gangliosidosis and Morquio B disease). It is a potent inhibitor of lysosomal β-galactosidase in vitro. Addition of NOEV in the culture medium restored mutant enzyme activity in cultured human or murine fibroblasts at low intracellular concentrations, resulting in a marked decrease of intracellular substrate storage. Short-term oral administration of NOEV to a model mouse of juvenile GM1-gangliosidosis, expressing a mutant enzyme protein R201C, resulted in significant enhancement of the enzyme activity in the brain and other tissues. Immunohistochemical stain revealed a decrease in the amount of GM1 and GA1 in neuronal cells in the fronto-temporal cerebral cortex and brainstem. However, mass biochemical analysis did not show the substrate reduction observed histochemically in these limited areas in the brain probably because of the brief duration of this investigation. Chemical chaperone therapy may be useful for certain patients with β-galactosidosis and potentially other lysosomal storage diseases with central nervous system involvement.

Chemistry of Carba-Sugars (Pseudo-Sugars) and their Derivatives

Publisher Summary This chapter focuses on the chemistry of carbahexopyranoses and their derivatives. The first three carbasugars were synthesized by McCasland and coworkers. Two other carbasugars were prepared from myo -inositol and the remaining eleven carbasugars have been synthesized from the Diels–Alder adduct of furan and acrylic acid. Fifteen enantiomers have been synthesized among the thirty-two carbasugars theoretically predicted. D -Fructose is the sweetest sugar known in naturally occurring carbohydrates and its intense sweetness is produced only by β- D -fructopyranose. Carbaglycosylamines [2,3,4-trihydroxy-5-(hydroxymethyl)-1-cyclohexylamine] and related compounds are well known to exist as the components of antibiotic validamycin complex and carbaoligosaccharidic alpha amylase inhibitor. Carbadisaccharides are carbocyclic analogs of true disaccharides in which one or both of the hexose or pentose residues is(are) replaced with a carbasugar. Besides sweetness, a carbasugar may have biological activity owing to its structurally close resemblance to a true sugar. The chemistry of carba-sugars is a newly opened area ofchemistry and the biological effects of these compounds have not been well studied, except for (1) the equisweetness of D-carba-glucose, D-carba-galactose, and D-carba- fructose with the respective true sugars, (2) the antibiotic activity of α-D- carba-galactose, and (3) the inhibition of a D-glucose-stimulated insulin release by D-carba-glucose.

Synthesis of potent β-D-glucocerebrosidase inhibitors: N-alkyl-β-valienamines

Six homologous derivatives (N-butyl3a, hexyl 3b, octyl 3c, decyl 3d, tetradecyl 3e and stearyl 3f) of β-valienamine were synthesized. All have been shown to be potent and specific inhibitors of β-glucocerebrosidase, and to have no potency against glucosylceramide synthase (mouse liver microsomes). Among them, the N-octyl derivative possesses the strongest activity (IC50 3 × 10−8 M), being almost 10-fold more potent compared to the unsaturated 5a-carba-glucosylceramide 1. Compounds 3b and 3c are also moderate inhibitors of α-glucosidase (Bakers yeast).

Stereoselective total synthesis of (+)-lycoricidine

Abstract The stereoselective total synthesis of the title compound starting from D-glucose is described. The key steps in this synthesis are Ferrier rearrangement to construct the optically active cyclohexenone (C-ring), and Pd-catalyzed intramolecular Heck reaction to build the phenanthridone skeleton.

Chemical chaperone therapy: clinical effect in murine GM1‐gangliosidosis

Certain low‐molecular‐weight substrate analogs act both as in vitro competitive inhibitors of lysosomal hydrolases and as intracellular enhancers (chemical chaperones) by stabilization of mutant proteins. In this study, we performed oral administration of a chaperone compound N‐octyl‐4‐epi‐β‐valienamine to GM1‐gangliosidosis model mice expressing R201C mutant human β‐galactosidase. A newly developed neurological scoring system was used for clinical assessment. N‐Octyl‐4‐epi‐β‐valienamine was delivered rapidly to the brain, increased β‐galactosidase activity, decreased ganglioside GM1, and prevented neurological deterioration within a few months. No adverse effect was observed during this experiment. N‐Octyl‐4‐epi‐β‐valienamine will be useful for chemical chaperone therapy of human GM1‐gangliosidosis. Ann Neurol 2007

Stereoselective total syntheses of (−)-desoxoprosopinine and (−)-desoxoprosophylline : palladium(O)-catalyzed intramolecular N-alkylation for the key piperidine ring formation

Abstract Intramolecular N -alkylation of D-glucose-derived substrate 21 E proceeded in an S N 2′ mode smoothly in the presence of a Pd(O)catalyst and n -Bu 4 NI. The major cyclization product, a 2,6-dialkylated piperidine 22 t , was effectively converted into the title alkaloids.

Stereoselective total synthesis of (+)-lactacystin from D-glucose

The chiral and stereoselective synthesis of (+)-lactacystin 1, the first non-protein neurotrophic factor having an α,α-disubstituted α-amino acid structure, is described. The highly functionalized γ-lactam portion possessing a tetra-substituted carbon with nitrogen in 1 was effectively constructed from d-glucose using allylic trichloroacetimidate rearrangement (Overman rearrangement) as the key reaction.

Chemical modification of the β-glucocerebrosidase inhibitor N-octyl-β-valienamine: Synthesis and biological evaluation of 4-epimeric and 4-O-(β-D-galactopyranosyl) derivatives

Abstract N-Octyl-β-valienemine (1), a potent β-glucocerebrosidase inhibitor, was chemically transformed into two biologically interesting compounds: the 4-epimer Figure 1 , Scheme 1 , β-galacto-type N-octyl-valienamine, and the 4-O-(β- d -galactopyranosyl) derivative 3 , a carba-lactosylceramide analogue. The former, interestingly, could be demonstrated to act as a very effective inhibitor (IC50=0.3 μM) of human β-galactosidase. The latter exhibited moderate inhibitory activity (IC50=20 μM) against β-glucocerebrosidase (mouse liver).

Total synthesis of bengamide E

The first total synthesis of bengamide E (1), a novel sponge-derived amino acid, is described. The side chain of bengamide E (2) possessing four contiguous chiral centers was prepared in a stereoselective manner starting from naturally abundant cyclitol, l-quebrachitol.

Chemical chaperone therapy: chaperone effect on mutant enzyme and cellular pathophysiology in β-galactosidase deficiency.

β‐Galactosidase deficiency is a group of lysosomal lipid storage disorders with an autosomal recessive trait. It causes two clinically different diseases, GM1‐gangliosidosis and Morquio B disease. It is caused by heterogeneous mutations in the GLB1 gene coding for the lysosomal acid β‐galactosidase. We have previously reported the chaperone effect of N‐octyl‐4‐epi‐β‐valienamine (NOEV) on mutant β‐galactosidase proteins. In this study, we performed genotype analyses of patients with β‐galactosidase deficiency and identified 46 mutation alleles including 9 novel mutations. We then examined the NOEV effect on mutant β‐galactosidase proteins by using six strains of patient‐derived skin fibroblast. We also performed mutagenesis to identify β‐galactosidase mutants that were responsive to NOEV and found that 22 out of 94 mutants were responsive. Computational structural analysis revealed the mode of interaction between human β‐galactosidase and NOEV. Moreover, we confirmed that NOEV reduced GM1 accumulation and ameliorated the impairments of lipid trafficking and protein degradation in β‐galactosidase deficient cells. These results provided further evidence to NOEV as a promising chaperone compound for β‐galactosidase deficiency. Hum Mutat 32:843–852, 2011.