Itsuo Ichimoto

An Efficient Synthesis of p -Boronophenylalanine and Its Homologues by the Reaction of Ethyl Isocyanoacetate with a p -Formylbenzeneboronic Acid Derivative

p-Boronophenylalanine (BPA) and its related compounds are worthwhile synthetic targets due to their proven and potential biological activities, particularly with respect to the boron-neutron capture therapy (BNCT) for metastatic melanomas and other tumors. The first synthesis of BPA was achieved by the alkylation of diethyl aminoacetomalonate with p-bromomethylbenzeneboronic acid and subsequent hydrolysis; however, the overall yield was not satisfactory.1) On the other hand, we have developed efficint synthetic routes of nonproteinous amino acids which possess specific functional groups on their side chain using ethyl isocyanoacetate as a synthon.2) These results prompt us to explore a more convenient and practical synthetic route to BPA and its homologues. In this paper, we describe a simple and efficient synthesis of D,L-BPA and p-boronophenylserine (BPS), a new analogue of BPA, via the short routes shown in the schemes.

An Efficient Synthetic Method for (±)-Malyngolide and Its Optical Resolution

A convenient synthetic method for (±)-malyngolide (1), an antibiotic from the marine bluegreen alga Lyngbya majuscula GOMONT, is described. The compound (±)-1 was synthesized from 2-methylglutaric ...

Electrophoretic study of the interaction of p-boronophenylserine with carboxylic acids by the three-spot method

The electrophoretic behaviour of p-dihydroxyborylphenylserine (BPS) was studied by spotting a sample solution at three different positions on the support (a pure cellulose paper). Electrophoretic migration of BPS was carried out using organic di- and tricarboxylic acid supporting solutions. A strong interaction between BPS and oxalic or citric acid was observed by paper electrophoresis. This interaction could be applied to isolation of BPS from a mixture of common amino acids. The separation of BPS from p-boronophenylalanine (BPA) could be made in sodium borate solution.

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 2.5 to 8.5 mM. The sugar acids induced such a change of the protein conformation of activated RuBisCO as is detected with a hydrophobic fluorescence probe. However, the change was not concerned with hysteresis of the enzyme. The sugar acids bound to· the catalytic sites retarded the release of activator CO2 from the sites in the absence of CO2. These characteristics of the sugar acids were quite similar to those of 6-phosphogluconate, but not of fructose bisphosphate or 3-phosphoglycerate. It is proposed that sugar phosphates that bind to the catalytic sites of RuBisCO could be divided into two groups on the basis of the modes of the binding to the sites.

Study of the Interaction of P-Boronophenylalanine and Its Analogs with Various Carboxylic Acids by Using Zone Electrophoresis

The chemical nature of a boron carrier in an aqueous solution plays an importnat role in its metabolism. The charge state and interaction of a compound can be determined by zone electrophoresis. We investigated the chemical state of p-boronophenylalanine (BPA), its related amino acids and p-boronophenylserine (BPS) using a “three-spot method” which was developed by Kitaoka1.