Toyo Kaiya

A novel enzyme enantio-selectively synthesizes (R)salsolinol, a precursor of a dopaminergic neurotoxin, N-methyl(R)salsolinol.

In the human brain, only (R)enantiomer of 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline ((R)salsolinol) and N-methyl-salsolinol, a dopaminergic neurotoxin, were detected, suggesting their enzymatic biosynthesis. This paper reports the isolation and characterization of a novel enzyme, which enantio-selectively synthesizes (R)salsolinol from dopamine and acetaldehyde. Dopamine, acetaldehyde, formaldehyde and pyruvic acid were the substrates of this synthase, whereas N-methyldopamine, adrenaline, noradrenaline and L-DOPA were not. The possible function of this enzyme under physiological and pathological conditions in the brain is discussed.

6β-Hydroxyursolic acid and other triterpenoids of Enkianthus cernuus

Abstract From the leaves of Enkianthus cernuus forma rubens, a new triterpene, 6β-hydroxyursolic acid, was isolated together with several known compounds

Triterpenoids from enkianthus campanulatus

Abstract From the leaves of Enkianthus campanulatus were isolated three new triterpenes, 3-oxo-19,23,24-trihydroxyurs-12-en-28-oic acid, 3β,6β, 19,23-tetrahydroxyurs-12-en-28-oic acid and 3β,6β,23-trihydroxyurs-12-en-28-oic acid.

Terpenoids of Rhododendron japonicum

Abstract From Rhododendron japonicum were isolated two diterpene glucosides, pieroside B and grayanoside B, and two new triterpenes, 2α,3α,24-trihydroxy

Grayanotoxin-XVIII and grayanoside B, a new a-nor-b-homo-ent-kaurene and its glucoside from Leucothoe grayana

Abstract From Leucothoe grayana a new grayanoid (diterpene) and its glucoside have been isolated. The structures of these new natural compounds have been established by chemical and spectroscopic means and by correlation with a known compound.

Grayanoside A, a new diterpene glucoside from Leucothoe grayana

Abstract A new diterpenoid glucoside, grayanoside D, has been isolated from Leucothoe grayana . Its structure was elucidated by chemical and spectroscopic means and by correlation with grayanotoxin-XV to be 3- O -(β- D -glucopyranosyl)-(10S)-dihydrograyanotoxin-XV.

ELECTROPHILIC AMINATION OF ADENINES. FORMATION AND CHARACTERISTICS OF N-AMINOADENINES

Abstract Amination of adenine with H2N-O-SO3H in alkaline media afforded 1-, 3-, 7-and 9-aminoadenine isomers at a ratio of about 1:1:3:1. In neutral media, the product ratio of the isomers changed to about 3:1:1:0. These results were different from the regioselectivity obtained by methylation of adenine with dimethyl sulfate under similar conditions. Amination of adenine with dinitrophenoxyamine in DMF gave 1-aminoadenine as the main product and this regioselectivity was also different from that of methylation with cH3I. Chemical characteristics of these N-amino adenines are described. This paper is dedicated to Professor Emeritus Yoshihisa Mizuno of Hokkaido University on the occasion of his 75th birthday.

Electrophilic amination of imidazole moieties of 9-ethylguanine and 1-methylbenzimidazole derivatives and reactivities of N-aminated products

Abstract Electrophilic amination of four 9-ethylguanine derivatives and seven 1-methylbenzimidazole derivatives with 2,4-dinitrophenoxyamine was carried out. N-amination proceeded at the imidazole moiety of these compounds with pKas of more than 3.2. Treatment of these N-aminated derivatives with 0.1 N NaOH gave different results depending on their structures. Reactivity of the imidazole moiety to electrophilic amination and the reaction pathways of N-aminated compounds with alkaline treatment are discussed.

Structure-mutagenicity relationship among aminoquinolines, aza-analogues of naphthylamine, and their N-acetyl derivatives☆

The mutagenicity of 7 positional isomers of aminoquinolines (AQ) and their N-acetyl derivatives (AcAQ) was tested in Salmonella typhimurium TA100 and TA98 in the presence and absence of S9 mix. In a series of aminoquinolines, the order of mutagenic potency in the presence of S9 mix is: 5-AQ greater than 8-AQ greater than 7-AQ greater than 3-AQ greater than 2-AQ much greater than 4-AQ, 6-AQ. The alpha-positional isomers, 5-AQ and 8-AQ, are more mutagenic than the beta-isomer, 2-, 3-, 6-, 7-AQs. These results are in contrast to the finding that beta-naphthylamine is more mutagenic than alpha-naphthylamine. In a series of N-acetylaminoquinolines, the order of mutagenic potency in the presence of S9 mix is: 7-AcAQ greater than 6-AcAQ greater than 8-AcAQ much greater than all the others. It is suggested that the AQ and AcAQ series might exert their mutagenicity through different molecular mechanisms (i.e., metabolic activation) from each other. The rate of metabolic activation does not seem to be correlated with the mutagenic potency of the compounds. It is noteworthy that 7-AQ and 8-AQ are mutagenic in both the strains tested in the absence of S9 mix.

Reactions of 1-methylbenzimidazole derivatives with m-chloroperoxybenzoic acid

Oxidation of seven 1-methylbenzimidazole (MBI) derivatives (with pKas ranging from 1.6 to 6.0) was carried out with m-chloroperoxybenzoic acid and structures of the products formed were identified. (Condensed benzene moiety-hydroxylated)-2-(m-chlorobenzyloxy)-MBIs and 2-oxo-MBIs were obtained from MBIs with pKas of more than 5.6 and about 3.3, respectively.