Hiroyuki Inouye

Biosynthesis of shikonin in callus cultures of Lithospermum erythrorhizon

Abstract Administration of various supposed precursors to the callus cultures of Lithospermum erythrorhizon grown on the Linsmaier—Skoog medium supplemented with IAA and kinetin established that the constituent shikonin is formed via shikimic acid, p-hydroxybenzoic acid, m-geranyl-p-hydroxybenzoic acid and geranylhydroquinone. In a strain of callus culture lacking the capacity to synthesize shikonin and in callus cultures which have had this capacity but lost it due to cultivation on a medium supplemented with 2,4-D, substances up to m-geranyl-p-hydroxybenzoic acid in the biosynthetic sequence have been detected. Although illumination with white light also arrested shikonin production, traces of pigment were still formed presumably because light did not reach the innermost part of the callus cultures.

Biosynthesis of anthraquinones and related compounds in Galium mollugo cell suspension cultures

Abstract From Galium mollugo cell suspension cultures, 1,4-dihydroxy-3-prenyl-2-naphtholic acid methyl ester diglucoside was isolated along with anthraquinones and mollugin. Production of the diglucoside was much increased by administering 2-succinylbenzoate to the cultures. The incorporation of 2-succinylbenzoate into lucidin-3-primeveroside, mollugin and the diglucoside in the mode so far proposed for rubiaceous anthraquinones was verified by administration of 13C-labelled 2-succinylbenzoate to the cell cultures.

A naphthoquinone and a lignan from the wood of Kigelia pinnata

Abstract A new naphthoquinone, kigelinone, and a new lignan, kigeliol, together with six known constituents including lapachol and dehydro-α- lapachone, were isolated from the wood of Kigelia pinnata . On the basis of spectral data and chemical degradations, kigelinone was characterized as 2-(1-hydroxyethyl)-8-hydroxy-naphtho[2,3-b]furano-4,9-dione and kigeliol as (2 S ,6 S )-bis(3,4-methylenedioxyphenyl)- 3,7- dioxabicyclo[3.3.0]octan-1 R ,5 R -diol or its enantiomer.

Two new iridoid glucosides from Mussaenda parviflora and Mussaenda shikokiana

Abstract From the leaves of Mussaenda parviflora , two new iridoid glucosides, mussaenoside and shanzhiside methyl ester were isolated and their structures e

Studies on monoterpene glucosides and related natural products. XXXI. Gas chromatography and gas chromatography-mass spectrometry of iridoid and secoiridoid glucosides.

A total of 33 iridoid and secoiridoid glucosides were detected by gas chromatography on several columns such as OV-1 or OV-17. Representative glucosides were then subjected to gas chromatography-mass spectrometry, giving some characteristic peaks that permitted the discrimination of both types of glucosides from other compounds in most instances. The successful detection of both types of glucosides in several plant extracts showed the applicability of this combination of methods to small amounts of plant materials.

Chemotaxonomic studies of rubiaceous plants containing iridoid Glycosides

Abstract Thirty-five species of rubiaceous plants have been examined for their iridoids by gas chromatography and/or gas chromatography-mass spectrometry and in some cases by isolation of the glycosides. The results, combined with data from other studies, suggest that these plants can be classified into three groups: (i) subfamily Ixoroideae, members of which contain gardenoside, geniposide and ixoroside; (ii) subfamily Rubioideae, all of which contain asperuloside and/or deacetylasperulosidic acid; (iii) subfamilies Cinchonoideae and Antirheoideae which contain loganin, secoiridoids, and/or indole alkaloids biosynthesized via the latter two glucosides. From this chemotaxonomic point of view, some doubt is thrown on the taxonomic position of Wendlandia formosana and plants of Mussaenda, two taxa currently placed in the Cinchonoideae but chemically allied to Ixoroideae.

Two new iridoid glucosides from Gardenia jasminoides fruits

Abstract From the fruits of Gardenia jasminoides which have been employed as Chinese crude drug “Shan-zhii”, two further new iridoid glucosides, gardoside (8,10-dehydrologanic acid) and scandoside methyl ester have been isolated and their structures have been established.

Two new iridoid glucosides from Ixora chinensis

Abstract From leaves and twigs of Ixora chinensis, two new iridoid glucosides, ixoroside (1) and ixoside (7,8-dehydroforsythide) (2) along with known geniposidic acid (3) have been isolated and their structures have been established.

Mechanism for iridane skeleton formation in the biosynthesis of secologanin and indole alkaloids in Lonicera tatarica, Catharanthus roseus and suspension cultures of Rauwolfia serpentina

Abstract Feeding experiments of various 3H-, 2H- and 13C-labelled compounds to plants of Lonicera tatarica, and Catharanthus roseus (hybrid) and to suspension cultures of Rauwolfia serpentina corroborated that secologanin, vindoline, ajmaline and vomilenine in these plants and cultured cells are biosynthesized via cyclization of 10-oxogeranial/10-oxoneral to iridodial in the same way as secologanin and vindoline in plants of L. morrowii and C. roseus. Therefore, this cyclization mechanism seems to be common in plants containing secoiridoids and indole alkaloids.

Two quinones from callus cultures of Echium lycopsis

Abstract Two new quinones, echinone and echinofuran, have been isolated from callus cultures of Echium lycopsis along with several acyl esters of shikonin. The structures of both quinones have been established by spectroscopic methods and by chemical degradations.