Sumio Umezawa

Structures and syntheses of aminoglycoside antibiotics.

Publisher Summary This chapter discusses the structure and synthesis of aminoglycoside antibiotic. The chemistry of individual sugars present in antibiotic has been reviewed along with sugars contained of other antibiotics. The classification of aminoglycoside antibiotics has been based on common structural relationships, being divided into the seven groups discussed in the chapter. The modern instrumental techniques, particularly nuclear magnetic resonance (N.M.R.) spectroscopy, X-ray crystal-structure analysis, infrared (I.R.) spectroscopy, mass spectrometry (M.S.) are used. Studies on biochemical mechanisms of resistance to aminoglycoside antibiotics have revealed that they are enzymatically inactivated in several ways, and these mechanisms suggested that chemical modification of certain special groups of aminoglycoside molecules might lead to useful derivatives that would be active against resistant bacteria.

Studies on inhibitory effect of phosphoramidon and its analogs on thermolysin.

Abstract Phosphoramidon, N -(α- l -rhamnopyranosyloxyhydroxyphosphinyl)- l -leucyl- l -tryptophan, and its analog, N -phosphoryl- l -leucyl- l -tryptophan, inhibited thermolysin in a competitive manner and K i values were calculated to be 2.8 × 10 −8 and 2.0 × 10 −9 m , respectively. The l -rhamnose moiety in phosphoramidon was suggested to be not involved in inhibition of thermolysin. A phosphoramidon analog containing histidine instead of tryptophan showed weaker inhibition. Spectrophotometric titration based on difference ultraviolet absorption spectra of the enzyme-inhibitor complex showed equimolar binding of the inhibitor to the enzyme.

Synthesis of methyl 3-O- and 2-O-carbamoyl-α-D-mannopyranosides and carbamoyl-group migration between them

Abstract Methyl 3- O - and 2- O -carbamoyl-α- D -mannopyranosides, ( 2 and 3 ), were synthesized from methyl α- D -mannopyranoside via ammonolysis of a cyclic carbonate or a p -nitrophenoxycarbonate, as shown in Charts 1 and 2. Carbamoyl-group migration between the C-2 and C-3 hydroxyl groups, in methyl α- D -mannopyranoside under alkaline conditions, was also studied.

A novel cyclic lipoundecapeptide, pholipeptin, isolated from Pseudomonas sp.

An inhibitor of phosphatidylinositol-specific phospholipase C, pholipeptin, was purified from the culture broth of Pseudomonas sp. Structural determination by 2D NMR spectroscopy with addition of a small amount of trifluoroacetic acid revealed that it was a novel cyclic lipodepsipeptide (1) consisting of 11 amino acids and a 3-hydroxydecanoic acid moiety.