Kuniro Tsuji

BREVETOXIN B1, A NEW POLYETHER MARINE TOXIN FROM THE NEW ZEALAND SHELLFISH, AUSTROVENUS STUTCHBURYI

Abstract A new polyether marine toxin, brevetoxin B 1 , was isolated from a methanol extract of the New Zealand shellfish, Austrovenus stutchburyi , by chromatography on columns of SiO 2 , ODS, and LH-20, followed by reverse-phase HPLC and its structure was elucidated by comparison of its spectral data with those of brevetoxins B and use of NMR techniques.

Comutagenic actions of norharman derivatives with 4-dimethylaminoazobenzene and related compounds

Summary 4-Dimethylaminoazobenzene is only a weak mutagen on Salmonella typhimurium strains TA100 and TA98, although it is a fairly strong carcinogen. Norharman, which is present in tobacco smoke and tryptophan pyrolysate, enhanced the mutagenicity of 4-dimethylaminoazobenzene on strain TA98 about 40-fold. Norharman alone had no mutagenic activity on TA98 and so it is a ‘Comutagen’. The mutagenicities of 4-methylaminoazobenzene, 3′-methyl-4-dimethylaminoazobenzene, 4-aminoazobenzene and 4′-methoxycarbonyl- N -hydroxy-4-methylaminoazobenzene were all potentiated by norharman. Presence of a metabolic activation system was essential for comutagenic action of norharman with these compounds. Dihydronorharman, tetrahydronorharman, 9-methyl- β -carboline, harman and tetrahydroharman did not enhance the mutagenicity of 4-dimethylaminoazobenzene.

Isolation and structure determination of a new marine toxin, neosurugatoxin, from the Japanese Ivory Shell, .

A new toxin, named neosurugatoxin, was isolated from the toxic Japanese Ivory Shell and its structure was determined by X-ray crystallographic analysis.

Furan fatty acid as an anti-inflammatory component from the green-lipped mussel Perna canaliculus

A lipid extract of Perna canaliculus (New Zealand green-lipped mussel) has reportedly displayed anti-inflammatory effects in animal models and in human controlled studies. However, the anti-inflammatory lipid components have not been investigated in detail due to the instability of the lipid extract, which has made the identification of the distinct active components a formidable task. Considering the instability of the active component, we carefully fractionated a lipid extract of Perna canaliculus (Lyprinol) and detected furan fatty acids (F-acids). These naturally but rarely detected fatty acids show potent radical-scavenging ability and are essential constituents of plants and algae. Based on these data, it has been proposed that F-acids could be potential antioxidants, which may contribute to the protective properties of fish and fish oil diets against chronic inflammatory diseases. However, to date, in vivo data to support the hypothesis have not been obtained, presumably due to the limited availability of F-acids. To confirm the in vivo anti-inflammatory effect of F-acids in comparison with that of eicosapentaenoic acid (EPA), we developed a semisynthetic preparation and examined its anti-inflammatory activity in a rat model of adjuvant-induced arthritis. Indeed, the F-acid ethyl ester exhibited more potent anti-inflammatory activity than that of the EPA ethyl ester. We report on the in vivo activity of F-acids, confirming that the lipid extract of the green-lipped mussel includes an unstable fatty acid that is more effective than EPA.

Implication of brevetoxin B1 and PbTx-3 in neurotoxic shellfish poisoning in New Zealand by isolation and quantitative determination with liquid chromatography-tandem mass spectrometry

Brevetoxin B1 (BTX-B1) was isolated from Austrovenus stutchburyi following the 1992-1993 outbreak of neurotoxic shellfish poisoning (NSP) in New Zealand. We report here the first isolation of PbTx-3 from the same shellfish and the development of a procedure for quantitative determination of PbTx-3 and BTX-B1. PbTx-3 was isolated by chromatography on columns of SiO2, ODS, and LH-20, followed by reverse-phase HPLCs. In mass spectrometry (MS) with an electrospray ionization (ESI) interface operating in the positive or negative ion mode, the abundant protonated ion [M+H]+ of PbTx-3 (m/z 897) and the de-sodiated ion [M-Na]- of BTX-B1 (m/z 1016) were generated, respectively. These served as precursor ions for collision-induced dissociation, and the product ions of m/z 725 from PbTx-3 and m/z 80 from BTX-B1 were identified, allowing unambiguous confirmation of these toxins by selected reaction monitoring liquid chromatography-tandem mass spectrometry (SRM LC-MS/MS) analysis. The determination limits were 0.4 and 2 ng/g for BTX-B1 and PbTx-3 at a signal-to-noise ratio of five, respectively. This LC-MS/MS method was successfully applied to determine BTX-B1 and PbTx-3 in the NSP-associated toxic shellfish. BTX-B1 was found in both A. stutchburyi and Perna canaliculus, but not in Crassostrea gigas, while PbTx-3 was found in all three.

Inhibition by neurosurugatoxin of nicotine-induced antinociception

We have found a selective inhibition of nicotine-induced antinociception in mice by neosurugatoxin (NSTX, 0.4-3.8 nmol/kg), a neurotoxin with a high affinity for ganglionic nicotinic receptors (ED50 = 0.65 nmol/kg). The toxin also reduced specific [3H]nicotine binding in mouse brain membranes (IC50 = 95 nM). The anti-nicotinic activity of NSTX was markedly greater than that of mecamylamine and pempidine. These data indicate that NSTX may block functional nicotinic cholinoceptors possibly in the central nervous system.

Reduction in mutagenicity of cigarette smoke condensate by added sugars

The effects of adding sugars to high- and low-tar cigarettes on the mutagenicity of their smoke condensates were studied using Salmonella typhimurium TA100 and TA98 with and without metabolic activation. The sugars tested were glucose, fructose, galactose, sorbitol, sucrose and lactose. The lowest mutagenicities observed with these sugars per mg of smoke condensate assayed on TA98 with metabolic activation were 37% (high-tar cigarettes) and 22% (low-tar cigaretts) of that of smoke condensate from untreated cigarettes. Addition of sugars increased the total amounts of smoke condensates, but the mutagenicities of the total condensates were also decreased by all the sugars, the lowest values being 35% (high-tar cigarettes) and 36% (low-tar cigarettes) of that of smoke condensates from cigarettes without added sugar. On assay with TA100 with metabolic activation, decreases in both specific and total mutangenicities of condensates of high-tar cigarettes were observed with all the sugars tested except galactose and sucrose. Treatment with glucose, fructose or sorbitol decreased the specific mutagenicity of condensates of low-tar cigarettes and glucose and fructose reduced also their total mutagenicity. The effects of added sugars were more marked when assayed on TA98 than on TA100 and of the sugars tested fructose and sorbitol had the greatest effects. Addition of sugars had no effect of the mutagenicity of cigarette-smoke condensate without metabolic activation.

Structure-activity relationship study on α1 adrenergic receptor antagonists from beer.

Hordatine A and aperidine have been previously isolated from beer as active ingredients, which bind to muscarinic M3 receptor. In addition, these compounds have exhibited antagonist activity against the alpha1A adrenoceptor. Although the relative structures of these two molecules have previously been determined, the absolute stereochemistry was unclear. Hence, to elucidate the absolute stereochemistry of natural hordatine A, we synthesized each enantiomer of hordatine A and aperidine from optically pure dehydrodi-p-coumaric acid. Several additional related compounds were also synthesized for structure-activity relationship studies. Chiral column HPLC analysis demonstrated that the absolute stereochemistry of natural hordatine A is (2S,3S), while based on the isomerization mechanism, the stereochemistry of aperidine is (2R,3S). The alpha1A adrenoceptor binding activity of (2R,3R)-hordatine A is the most potent among the enantiomeric pairs of hordatines and aperidines. Furthermore, the related, synthetic compound, (2R,3R)-methyl benzofurancarboxylate exhibits antagonist activity against the alpha1A adrenoceptor at a lower concentration than that of hordatine A.

止血に用いられる生薬の有効成分に関する研究(第10報)熱処理止血生薬の止血効果

The effect of heat treatment on the anti-hemorrhagic action of seven hemostatic herbs employed especially after parching in order to work effectively as an anti-hemorrhagic agent in traditional Chinese medicine, was examined. It was found that the anti-hemorrhagic activities of the following 5 herbs are apparently increased by parching: Kaika (Sophorae immaturus Flos), Renbo.(Nelumnbins Receptaculum), Gusetsu (Nelumnbins Rhizomatis Nodus), Chiyu (Sanguisorbae Radix) and Gaiyou (Artemisiae argyi Folium).

Isolation and structure determination of a new marine neurotoxin from the New Zealand shellfish, Austrovenus stutchburyi

A new marine neurotoxin was isolated from a water extract of the New Zealand shellfish, Austrovenus stutchburyi, by chromatography on columns of Sephadex G-15 and LH-20, followed by reverse-phase HPLC. It was identified as (4-methoxycarbonylbutyl)trimethyl-ammonium chloride, and this was confirmed by synthesis.