Tetsuro Shingu

Fumiquinazolines, novel metabolites of a fungus isolated from a saltfish

Abstract Fumiquinazolines A, B and C, exhibiting moderate cytotoxicity, were isolated from the mycelium of a strain of Aspergillus fumigatus which existed in the gastrointestinal tract of the saltwater fish Pseudolabrus japonicus . Their structures were elucidated by spectroscopic and X-ray diffraction analyses and chemical evidence.

Triterpenes of Poria cocos

Abstract Four lanostane triterpenes and four novel 3,4- seco -lanostane triterpenes were isolated from the surface layer of Poria cocos . 3β-Hydroxylanosta-7,9(11),24-trien-21-oic acid, trametenolic acid, dehydroeburicoic acid and eburicoic acid were isolated by HPLC after treatment with N -chloromethylphthalimide. Four novel 3,4- seco -lanostanes: poricoic acid C, D, DM and AM were isolated by HPLC methods. Their structures are, respectively, 3,4- seco -lanosta-4(28),7,9(11),24(31)-tetraen-3,21-dioic acid and 16α,25-dihydroxy-3,4- seco -lanosta-4(28),7,9(11),24(31)-tetraen-3,21-dioic acid, 16α,25-dihydroxy-3,4- seco -lanosta-4(28),7,9(11),24(31)-tetraen-3,21-dioic acid 3-methyl ester and 16α-hydroxy-3,4- seco -lanosta-4(28),7,9(11),24(31)-tetraen-3,21-dioic acid 3-methyl ester, from spectroscopic evidence.

Potent cytotoxic metabolites from a Leptosphaeria species. Structure determination and conformational analysis

Abstract New cytotoxic epipolysulfanyldioxopiperazine dimers, leptosins K (4), K1 (5) and K2 (6), have been isolated from a strain of Leptosphaeria sp. originally isolated from the marine alga Sargassum tortile. Their stereostructures, with a different configuration from that of leptosins A-C, have been elucidated by spectral and X-ray analyses and some chemical transformations. X-Ray and NMR and NOE spectral analyses of 4 revealed that it exists in a mixture of four conformers, of which two each closely resemble, in a single crystal, and in a single conformer in solution. NOE experiments of 5 and 6 demonstrated that they exist in a mixture of two conformers slowly exchanging in CDCl3.

Triterpenes from the surface layer of Poria cocos

Abstract The surface layer of Poria cocos has yielded five new triterpenes; two of the lanostane type and three of the 3,4-secolanostane type. The structures of these compounds were elucidated mainly by two-dimensional NMR techniques.

Isolation of lanostane-type triterpene acids having an acetoxyl group from sclerotia of Poria cocos

Abstract The separation of lanostane-type triterpene acids carrying an acetoxyl group from sclerotia of Poria cocos (hoelen) was effectively achieved by means of preparative HPLC of the phthalimidomethyl esters followed by selective hydrolysis of the phthalimidomethyl ester groupings. By this method, three new triterpene acids were isolated together with pachymic and dehydropachymic acids, which are characteristic compounds of hoelen. The structures of three new compounds were determined to be 3- o -acetyl-16α-hydroxydehydrotrametenolic acid, and 3-epidehydropachymic acid, respectively, based on spectroscopic evidence.

Liquidambin, an ellagitannin from Liquidambar formosana

Abstract A new ellagitannin, named liquidambin, which could be biogenetically closely correlated with casuarinin and pedunculagin, has been isolated from the leaves of Liquidambar formosana . Its structure was determined as 5- O -galloyl-2,3,4,6-di- O -(S)-hexahydroxydiphenoyl- d -glucose. The structural equilibration due to hydration of the aldehyde group of the glucose core in this tannin was shown from its 1 H and 13 C NMR spectra.

Die absolute konfiguration von valerosidatum und von didrovaltratum

Zusammenfassung Es wird die absolute Konfiguration von Valerosidatum (1), einem Iridoid-Glucosid aus Valeriana wallichii D. C. und V. officinalis L. und von Didrovaltratum (5), einem Valeportriat aus den gleichen Pflanzen, durch chemische Korrelation mit Asperulosid bewiesen.

Triterpenoids from Poria cocos

Abstract Two new triterpenoids, poricoic acid A and B were isolated from the surface layer of Poria cocos . The structures of poricoic acid A and B were elucidated to be 16α-hyroxy-3,4-secolanosta-4(28),7,9(11),24(31)-tetraen-3,21-dioic acid, and 16α-hydroxy-3,4-secolanosta-4(28),7,9(11),24-tetraen-3,21-dioic acid, respectively.

Agrimoniin and potentillin, an ellagitannin dimer and monomer having an α-glucose core

Potentillin (3), which has an α-glucosyl linkage, and its dimer, agrimoniin (1) have been isolated from Agrimonia pilosa ledeb. and Potentilla kleiniana Wight et Arnott., and their structures elucidated.

A lanostane triterpenoid from Poria cocos

Abstract The dehydro derivative of pachymic acid was isolated from the sclerotium of Poria cocos . Its structure has been shown to be 3β-acetyloxy-16α-hydroxylanosta-7,9(11), 24(31)-trien-21-oic acid.