P-Nitrophenyl-a-D-glucopyranosides

T. Nishio, W. Hakamata, A. Kimura, S. Chiba, A. Takatsuki, R. Kawachi, and T. Oku, Glycon specificity profiling of a-glucosidases using monodeoxy and mono-O-methyl derivatives of p-nitrophenyl a-D-glucopyranoside, Carbohydr. Res., 337 (2002) 629-634. 

Fig. 10.9. Electrochromatograms of p-nitrophenyl-a-D-glucopyranosides and malto-oligosaccharides. Column, 200 (270) mm x 100 pm i.d. packed with ODS mobile phase (a), 5 mM NaH2PC>4, pH 6.0-water-acetonitrile 45 45 10 (v/v/v) (b), 5 mM NaH2P04, pH 6.0-water-acetonitrile 42.5 42.5 15 (v/v/v) (c), 5 mil/ NaFfePCU, pH 6.0-water-acetonitrile 40 40 10 (v/v/v). Voltage, 20 kV detection, UV at 254 nm 18°C. Peak identification 1, p-nitrophenyl-a-D-glucopyranoside 2, p-nitrophenyl-a-D-maltoside 3, p-nitrophenyl-a-D-maltotrioside 4, p-nitrophenyl-a-D-maltotctraoside 5, p-nitrophenyl-a-D-maltopentaoside Reproduced with permission from Yang and El Rassi [39].

Key + = hydrolyzed — = not hydrolyzed = slow hydrolysis. 6 Methyl a-D-glucopyranoside. c p-Nitrophenyl a-D-glucopyranoside. Phenyl a-D-glucopyranoside. 

A somewhat different mechanism involving participation from the 2-oxyanion has been proposed from the observation that p-nitrophenyl a-D-glucopyranoside is cleaved 105 times faster than the corresponding phenyl glucopyranoside in 3.9 molar aqueous KOH at 60 °C, suggesting initial nucleophilic attack by 0-2 on the aryl group. 

More recently, it was shown that the biotransformation of oleanolic acid (30), with F. Uni afforded, in low amoxmts, two oxidative metabolites, 2a,3p-dihydroxy-olean-12-en-28-oic acid (50) and 2a,3p,lip-trihydroxy-olean-12-en-28-oic acid (51) [52]. The structures (Figure 28.12) were characterized on the basis of spectroscopic studies. Metabolites exhibited a potent inhibition of a-glucosidase from Saccharomyces sp. using p-nitrophenyl a-D-glucopyranoside as a substrate. 

Phenyl a-D- and (3-L- glucopyranosides and their acetates (102 1-7) were prepared and hydrolyzed by yeast (X-glucosidase [104]. 2-Chloromethyl-4-nitrophenyl a-D-glucopyranoside (102 1) showed the most potent inhibitory activity in this series. The 2-chloromethyl-phenyl derivative (102 6) which had no nitro group in the benzene ring, and the 2-chloromethyl-4-nitrophenyl P-L-glucopyranoside (102 7), in which the... 

A 4-nitrophenyl a-D-glucopyranoside-hydrolysing a-D-glucosidase of a thermophile, Bacillus thermoglucosidius, has been purified to an electrophoreti-cally homogeneous state (see p. 458). " ... 

Potato tuber a-D-glucosidase (p/ 4.7, mol. wt. 1.2 x 10 , pH optimum 6.5—7.0, Km 0.21 mM for 4-nitrophenyl a-D-glucopyranoside) has been shown to act on maltose and malto-oligosaccharides. The enzyme exhibited trans-glucosidase activity. 

An Aspergillus niger a-glucosidase catalyses the slow hydrolsys of -D-glucopyranosyl fluoride which competitively inhibits the hydrolysis of p-nitrophenyl a-0-glucopyranoside and thus binds at the same site as do substrates of the en me. ... 

It is of interest that reaction of methyl, benzyl, and p-nitrophenyl 2-acetamido-4,6-0-benzylidene-2-deoxy-/3-D-glucopyranosides, and also the corresponding methyl a-D-glucopyranoside derivative, with ( )-2-chloropropionic acid gave, in preponderant yields, the respective 3-0-(D-l-carboxyethyl) derivatives257 only from the last-mentioned reaction was a significant amount of the 3-0-(L-l-carboxy-ethyl) derivative isolated. 

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