A new cytotoxic compound from a water extract of corn.

A new cytotoxic compound 2 was isolated from a water extract of corn germ. Structural elucidation by spectroscopic data and chemical evidence fully substantiated 2 to be 11 (E)-10-oxo-11-octadecen-13-olide. Compound 2 exhibited considerably strong cytotoxic activity against various cell lines with IC50 of 0.

Synthesis of (E)-δ-hydroxy-β,γ-dehydroα-amino acids, a new class of vinylglycines by the rearrangement ofβ acetoxyallylglycine derivatives.

The efficient synthesis ofδ-hydroxy-β,γ-dehydroα-amino acids (1) was achieved by the hybrid process, in which the Pd(II)-assisted rear-rangement ofβ-acetoxyallylglycine ester (6) afforded the corresponding (E)-δ-acetoxyvinylglycine derivatives (7) in a moderate yield. The chemo- and stereo-selective hydrolysis of7 was accomplished by the use of microbial lipase (Amano PS) to afford the allylic alcohol (8), which was transformed into1 in two step sequence.

Effects of Sugar Acids on the Functions of Ribulose Bisphosphate Carboxylase/Oxygenase: Differentiation of Two Different Ligand-binding Modes of the Catalytic Sites.

The effects of sugar acids on the kinetics and the protein conformation of ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) were examined to differentiate the ligand-binding modes of the catalytic sites. D-Glucarate, L-glucarate, and mucate inhibited the carboxylase activity of RuBisCO competitively with respect to ribulose 1,5-bisphosphate. Their inhibition constants were 2.

Stereoselective synthesis of marine antibiotic (-)-malyngolide and its stereoisomers.

A convenient synthetic method for the marine antibiotic (-)-malyngolide and its stereoisomers was accomplished from a chiral alpha-alkoxyketone (4), which was readily available as a chiron. Chiral quaternary carbon synthons (5a) and (5b) as the key intermediates were constructed by the chelation controlled addition of Grignard reagent to 4. The diastereomeric mixture of 5a and 5b was readily transformed into a separable mixture of lactones (7a) and (7b), each of which could be easily separated by silica-gel column chromatography.