Mohinder S. Kang

A potent inhibitor of β-N-acetylglucosaminidases: 6-acetamido-6-deoxycastanospermine

Abstract A facile synthesis of 6-acetamido-6-deoxycastanospermine ( 4 ) is described. The target compound inhibits mammalian β- N -acetylglucosaminidases at or below 1 μM.

Synthesis of polyhydroxylated indolizidine and quinolizidine compounds : potent inhibitors of α-glucosidase I

Abstract Polyhydroxylated indolizidine 6a and quinolizidine 6b were synthesized from a common precursor, iminoheptitol 8 . The target compounds are potent inhibitors of the glycoprotein trimming enzyme--α-glucosidase I.

Inhibition of Glycoprotein Processing and HIV Replication by Castanospermine Analogues

Inhibitors of glycoprotein processing enzymes have been shown to have activity against HIV. Several analogues of the known glucosidase I inhibitor, castanospermine (CAST), were synthesized and evaluated for their inhibitory effect on glucosidases and for antiviral activity against Moloney murine leukemia virus (MOLV) and HIV-1. The most effective analogue was 6-O-butanoyl CAST (B-CAST, MDL 28,574) with an IC50 of 0.05 micrograms/mL against MOLV. A correlation between inhibition of glucosidase I and MOLV replication was observed. This analogue was further evaluated against HIV-induced syncytial formation in HeLa T4+ cells and against productive infection in JM cells infected with HIV 1 (GB8 strain). B-CAST showed an IC50 of 0.3 micrograms/mL in the HeLa T4+ assay, compared to CAST at 11 micrograms/mL. The compound also was more potent (IC50:0.15 micrograms/mL) than CAST (4-6 micrograms/mL) in JM cells. The antiretroviral activity of B-CAST was further confirmed in Friend leukemia virus (FLV) infection in mice. B-CAST showed equivalent activity to AZT and was more potent than CAST in inhibiting FLV-induced splenomegaly in mice. The data presented herein suggest the potential of these novel glucosidase inhibitors as anti-HIV agents.

A simple and rapid microplate assay for glycoprotein-processing glycosidases

A simple and convenient microplate assay for glycosidases involved in the glycoprotein-processing reactions is described. The assay is based on specific binding of high-mannose-type oligosaccharide substrates to concanavalin A-Sepharose, while monosaccharides liberated by enzymatic hydrolysis do not bind to concanavalin A-Sepharose. By the use of radiolabeled substrates [( 3H]glucose for glucosidases and [3H]mannose for mannosidases), the radioactivity in the liberated monosaccharides can be determined as a measure of the enzymatic activity. This principle was employed earlier for developing assays for glycosidases previously reported (B. Saunier et al. (1982) J. Biol. Chem. 257, 14155-14161; T. Szumilo and A. D. Elbein (1985) Anal. Biochem. 151, 32-40). These authors have reported the separation of substrate from the product by concanavalin A-Sepharose column chromatography. This procedure is handicapped by the fact that it cannot be used for a large number of samples and is time consuming. We have simplified this procedure and adapted it to the use of a microplate (96-well plate). This would help in processing a large number of samples in a short time. In this report we show that the assay is comparable to the column assay previously reported. It is linear with time and enzyme concentration and shows expected kinetics with castanospermine, a known inhibitor of alpha-glucosidase I.