Shinichi Uesato

Fungal metabolites. Part 3. Structural elucidation of antibiotic peptides, trichosporin-B-IIIb, -IIIc, -IVb, -IVc, -IVd, -VIa and -VIb from Trichoderma polysporum. Application of fast-atom bombardment mass spectrometry/mass spectrometry to peptides containing a unique Aib–Pro peptide bond

Trichosporin-B-IIIb, -IIIc, -IVb, -IVc, -IVd, -VIa and -VIb are components of an antibiotic peptide mixture produced by Trichoderma polysporum. Each component was purified by reversed-phase high-performance liquid chromatography (HPLC). The amino acid sequences of these peptides, which have an unstable peptide bond, Aib–Pro, were elucidated by fast-atom bombardment mass spectrometry (FAB MS) and fast-atom bombardment mass spectrometry/mass spectrometry (FAB MS/MS) with the help of NMR spectroscopy. The molecular weights of these peptides were all ca. 2000 and the structures were very similar.

Iridoids from Galium mollugo

Abstract From Galium mollugo, two new iridoids, gardenosidic acid and 10-hydroxymorroniside as well as 10-hydroxyloganin have been isolated, along with seven known iridoids, secogalioside, asperuloside, asperulosidic acid, daphylloside, monotropein, scandoside and scandoside methyl ester. 10-Hydroxyloganin, a compound which was previously considered to be the key biosynthetic intermediate of secoiridoids, was obtained for the first time from a natural source.

Biosynthesis of iridoid glucosides in Galium mollugo, G. spurium var. Echinospermon and Deutzia crenata. Intermediacy of deoxyloganic acid, loganin and iridodial glucoside☆

Abstract Administration of 2H-labelled compounds to Galium mollugo, G. spurium var. echinospermon and Deutzia crenata established that deoxyloganic acid is a precursor of asperuloside, geniposidic acid and secogalioside in G. mollugo as well as asperuloside in G. spurium, while iridodial glucoside is a precursor of deutzioside in D. crenata. Additionally, the intermediacy of loganic acid in the biosynthesis of the iridoid and secoiridoid glucosides in the Galium plants was reconfirmed.

Three new secoiridoid glucosides from Eustoma russellianum

Abstract Three new secoiridoid glucosides, eustomoside, eustoside and eustomorusside, have been isolated along with three known glucosides, sweroside, swertiamarin and gentiopicroside, as well as one unknown glycoside from Eustoma russellianum.

Absolute structure of gibboside, an iridoid glucoside from Patrinia gibbosa

Abstract A new iridoid glucoside, gibboside, was isolated from the root of Patrinia gibbosa, together with three known glucosides, patrinoside, valerosidate and adoxoside. Based on spectroscopic and X-ray crystallographic studies, the absolute structure of the new iridoid glucoside was determined as (4R,4aS,6S,7R,7aS)-6-β- d -glucopyranosyl-7-hydroxymethyl-4-methyl-1,4,4a,7a-tetrahydrocyclopenta[e]pyran-3-one.

Absolute structure of nepetaside, a new iridoid glucoside from Nepeta cataria

Abstract Besides an earlier reported 1,5,9-epideoxyloganic acid, a new iridoid glucoside, nepetaside, has been isolated from the aerial part of Nepeta cataria . Its absolute structure has been elucidated based on NMR spectroscopy and chemical conversions.

Biosynthetic pathway of iridoid glucosides in Gardenia jasminoides f. grandiflora cell suspension cultures after iridodial cation formation

Administration of 2H- or 13C-labeled monoterpenes to Gardenia jasminoides f. grandiflora cell suspension cultures demonstrated that iridoid glucosides of the suspension cultures are biosynthesized, after iridodial cation formation from 10-oxocitral (3), via 8-epiiridodial (13), 8-epiiridotrial (14), boschnaloside (8-epiiridotrial glucoside) (12) and dehydroiridotrial glucoside (8). In addition, the coexistence of a route via iridodial cation (4), dehydroiridodial (6), dehydroiridotrial (15) and dehydroiridotrial glucoside (8) is conceivable.

Intermediacy of iridodial in the biosynthesis of some iridoid glucosides

Abstract Administration of MVA-[2- 14 C] to Lamium applexicaule and Deutzia crenata as well as of 11-hydroxyiridodial glucoside-[10- 3 H] and 7-deoxyloganic acid-[10- 3 H] to the former plant suggested that, in contrast to secoiridoid-indole alkaloids, iridoid glucosides such as ipolamiide, lamiide, lamioside, deutzioside and scabroside in these plants are biosynthesized via iridodial. Iridodial as a precursor for the biosynthesis of asperuloside was also suggested from the results of the administration of MVA-[2- 14 C] to Galium spurium var. echinospermon .

Four iridoids from Randia canthioides

Abstract Four new iridoids, 10-dehydrogardenoside, dimeric 10-dehydrogardenoside, randioside and deacetylasperulosidic acid methyl ester aglycone, have been isolated together with three known iridoid glucosides, gardenoside, deacetylasperulosidic acid methyl ester and scandoside methyl ester, from Randia canthioides. It is conceivable that dimeric 10-dehydrogardenoside could be an artefact formed during the isolation process.

A novel type secoiridoid glucoside, hydrangenoside a from Hydrangea macrophylla

Abstract Hydrangenoside A, isolated along with its three congeners from Hydrangea macrophylla, was proved to have a novel type of structure which is thought to be biosynthesized through an aldol-type condensation of secologanin with a unit formed by the shikimate-malonate route followed by decarboxylation.