Junkichi Iwasa

A regioselective, stereoselective synthesis of a diacylglycerophosphocholine hydroperoxide by use of lipoxygenase and lipase

1-Stearoyl-2-[13′-(S)-hydroperoxy-(9′Z, 11′E)-octadecadienoyl]-sn-glycero-3-phosphocholine (11) was synthesized without contamination by any regio- and stereo-chemical isomers by a combination of lipoxygenase-catalysed peroxidation, lipase-catalysed stearoylation, and dicyclohexyl carbodiimide-mediated (DCC) esterification.

Notes: A Plant Growth Regulator from Vernonia auriculifera (Asteraceae)

Abstract From the methanolic extract of fresh leaves of the Kenyan Vemonia auriculifera Hiern., a lettuce seeds growth regulator was isolated and identified as 8-desacylvernodalol (1) by spectroscopic analysis.

Syntheses of Cholesteryl 13-Hydroperoxyoctadecadienoate and Its Derivative with Lipoxygenase

Syntheses of Cholesteryl 13Hydroperoxyoctadecadienoate and Its Derivative with Lipoxygenase Naomichi Baba, Shoichi Tahara, Shuhei Nakajima, Junkichi Iwasa, Takao Kaneko & Mitsuyoshi Matsuo To cite this article: Naomichi Baba, Shoichi Tahara, Shuhei Nakajima, Junkichi Iwasa, Takao Kaneko & Mitsuyoshi Matsuo (1992) Syntheses of Cholesteryl 13Hydroperoxyoctadecadienoate and Its Derivative with Lipoxygenase, Bioscience, Biotechnology, and Biochemistry, 56:3, 540-540, DOI: 10.1271/bbb.56.540 To link to this article: http://dx.doi.org/10.1271/bbb.56.540

Synthesis of the Photoaffinity-labeled Grayanotoxins for Studying the Gating Mechanism of Na Channel.

Grayanotoxin loosely binds to the neurotoxin receptor site 2 on Na channels. 14R-N-[4-(1-Azi-2, 2, 2-triftuoroethyl)]benzyliminograyanotoxane-3β, 5, 6β, 16-tetraol (4) and 17-N-[4-(1-azi-2, 2, 2-triftuoroethyl)]- benzyliminograyanotox-15-ene-3β, 5, 6β, 14R-tetraol (5) were synthesized and applied intracellularly to squid axons. On UV irradiation, their membrane potential produced by a dose of 4 or 5 rose to higher level than that in the dark. However, in the case of 5, even when the axons were internally perfused with toxin-free solution after the dose, the potential level did not fall in contrast to 4. It suggested that 5 covalently bound to the receptor involved in the gating mechanism of Na channels.

Studies on the Active Principles of Leucothoe grayana MAX

Amides, IVa and IVb, which were derived from Grayanotoxin-II reacted very easily under a mild acidic condition to give a product, the structure of which has been established to be Va.