Toshie Minematsu

Absolute stereostructures of novel norcadinane- and trinoreudesmane-type sesquiterpenes with nitric oxide production inhibitory activity from Alpinia oxyphylla

Novel 14-norcadinane-type sesquiterpenes, oxyphyllenodiols A and B, and 11,12,13-trinoreudesmane-type sesquiterpenes, oxyphyllenones A and B, were isolated from the methanolic extract of kernels of Alpinia oxyphylla. The absolute stereostructures of these norsesquiterpenes were determined on the basis of physicochemical and chemical evidence. In addition, oxyphyllenodiol A and oxyphyllenone A were found to inhibit the NO production in lipopolysaccharide-activated macrophages.

Facile synthesis of de-O-sulfated salacinols: Revision of the structure of neosalacinol, a potent α-glucosidase inhibitor

Facile synthesis of de-O-sulfated salacinols (3) was developed by employing the coupling reaction of an epoxide, 1,2-anhydro-3,4-di-O-benzyl-D-erythritol (9) with 2,3,5-tri-O-benzyl-1,4-dideoxy-1,4-epithio-D-arabinitol (10) as the key reaction. The reported structure of a potent alpha-glucosidase inhibitor named neosalacinol (8), isolated recently from Ayurvedic medicine Salacia oblonga, was proved incorrect, and revised to be de-O-sulfated salacinol formate (3c) by comparison of the spectroscopic properties with those of the authentic specimen synthesized. Discrepancies and confusion in the literature concerning the NMR spectroscopic properties of salacinol (1) have also been clarified.

A facile preparation, the crystal structure, the chemical and electrochemical properties of [4-(dimethylamino)phenyl]-3-guaiazulenylmethylium tetrafluoroborate

Reaction of guaiazulene (1) with p-dimethylaminobenzaldehyde in methanol in the presence of tetrafluoroboric acid gives the title monocarbocation compound, [4-(dimethylamino)phenyl]-3-guaiazulenylmethylium tetrafluoroborate (2), in 90% yield. The title investigations of compound 2 compared with those of two other monocarbocations stabilized by a 3-guaiazulenyl group (i.e. phenyl-3-guaiazulenylmethyl and [4-(isopropyl)phenyl]-3-guaiazulenylmethyl cations) are reported.

The crystal structure and characteristic chemical property of 1,2-bis(3-guaiazulenylmethylium)benzene bishexafluorophosphate

Reaction of guaiazulene ( 1 ) with a 0.5 molar amount of phthalaldehyde in a mixed solvent of acetonitrile and diethyl ether in the presence of hexafluorophosphoric acid at 25°C under aerobic conditions rapidly gives the title dicarbocation compound, 1,2-bis(3-guaiazulenylmethylium)benzene bishexafluoro-phosphate ( 2 ) in 98% yield. Reduction of 2 with a large excess of NaBH 4 in a mixed solvent of acetonitrile and ethanol at 25°C quantitatively affords a unique intra -molecular cycloaddition compound 9 via the intermediate 8 . The crystal structure and characteristic chemical property of 2 are reported.

21α-hydroxy-3β-methoxyserrat-14-en-30-al and other triterpenoids from the cuticle of Picea jezoensis

Abstract A new methoxytriterpene aldehyde was isolated from the cuticle of the stem bark of Picea jezoensis Carr jezoensis , together with six known serratene triterpenoids, 3α-methoxyserrat-14-en-21β-ol, 3β-methoxyserrat-14-en-21β-ol, 29-nor-3β-methoxyserrat-14-en-21-one, 21-episerratenediol, serratenediol and 3β-methoxyserrat-14-en-21α,29-diol; the structure of the new compound was established to be 21α-hydroxy-3β-methoxyserrat-14-en-30-al on the basis of spectral evidence.

Isolation and characterization of new limonoid glycosides from Citrus unshiu peels.

Three limonoid glycosides were isolated from Citrus unshiu peels, and their structures were determined based on MS and NMR spectroscopic data as nomilinic acid 17-O-beta-D-glucopyranoside (1), methyl nomilinate 17-O-beta-D-glucopyranoside (2), and obacunone 17-O-beta-D-glucopyranoside (3). In particular, the location of the sugar moiety was clearly determined by the B/E constant linked scan FABMS method. No limonoid glycosides obtained here were found to have antitumor activity in NCI-H292 and EL-4 cell lines.

SYNTHESES AND EVALUATION AS GLYCOSIDASE INHIBITOR OF 1,5-DIDEOXY-1,5-IMINO-D-GLUCITOL ANALOGS OF SALACINOL, A POTENT α-GLUCOSIDASE INHIBITOR ISOLATED FROM AYURVEDIC MEDICINE, SALACIA RETICULATA

- N-Alkylated deoxynojirimycin (10) bearing the same alkyl chain as salacinol (1), a potent α-glucosidase inhibitor isolated from Ayurvedic traditional medicine, Salacia reticulata, was found to inhibit both rat intestinal maltase and sucrase as strong as 1, while 10 has been reported to be inactive against glucoamylase G2 from Aspergillus niger. Its O-desulfate (12) was also found active against these enzymes, and characteristic sulfate anion moiety of 1 was found not essential for the α-glucosidase inhibitory activity.

Bowl–shaped Cu(I) metallamacrocyclic ethylene and carbonyl adducts as structural analogues of organic calixarenes

Three novel Cu(I) metallacalixarenes with C(2)H(4) and CO legs, in which an anion is accommodated in the inside cavity, were self-assembled by anion templation and have been structurally characterized.

The Role of Arg114 at Subsites E and F in Reactions Catalyzed by Hen Egg-White Lysozyme

To understand better the role of subsites E and F in lysozyme-catalyzed reactions, mutant enzymes, in which Arg114, located on the right side of subsites E and F in hen egg-white lysozyme (HEL), was replaced with Lys, His, or Ala, were prepared. Replacement of Arg114 with His or Ala decreased hydrolytic activity toward an artificial substrate, glycol chitin, while replacement with Lys had little effect. Kinetic analysis with the substrate N-acetylglucosamine pentamer, (GlcNAc)5, revealed that the replacement for the Arg residue reduced the binding free energies of E-F sites and the rate constant of transglycosylation. The rate constant of transglycosylation for R114A was about half of that for the wild-type enzyme. 1H-NMR analysis of R114H and R114A indicated that the structural changes induced by the mutations were not restricted to the region surrounding Arg114, but rather extended to the aromatic side chains of Phe34 and Trp123, of which the signals are connected with each other through nuclear Overhauser effect (NOE) in the wild-type. We speculate that such a conformational change causes differences in substrate and acceptor binding at subsites E and F, lowering the efficiency of glycosyl transfer reaction of lysozyme.

Synthesis of 3- and 21-monosulfates of [2,2,3β,4,4-2H5]-tetrahydrocorticosteroids in the 5β-series as internal standards for mass spectrometry

The 3- and 21-monosulfates of pentadeuterated 5β-tetrahydrocorticosteroides were synthesized, starting from cortisol and 11-deoxycotisol. The principal reactions used were (1) perdeuteration of the methylene groups adjacent to the 3-oxo group of 17,20:20,21-bismethylendioxy-5β-3-ketosteroids with NaOD in CH(3)OD followed by stereoselective reduction with NaBD(4), (2) sulfation of hydroxy groups with sulfur trioxide-trimethylamine complex, and (3) removal of the 17,20:20,21-bismethylendioxy group with hydrogen fluoride. The labeled compounds can be used as internal standards in liquid chromatography/mass spectrometry assays for clinical and biochemical studies.