Hiroo Aoki

Plant Growth Promoting Metabolites of Sclerotinia sclerotiorum: Part I. Isolation and Structures of Sclerotinin A and B

In the research on the plant growth regulators produced by phytopathogenic fungi, two active metabolites, sclerotinin A and B, in addition to sclerin have been isolated from the culture filtrate of S. sclerotiorum. Sclerotinin A and B have been shown to be 3,6,8-tri-hydroxy-3,4,5,7-tetramethyl-3,4-dihydroisocoumarin and 3,6,8-trihydroxy-3,5,7-trimethyl-3,4- dihydroisocoumarin, respectively.

Studies on Camellia sasanqua Thunb:Part II. Synthesis of Sasanquin

A glycoside “Sasanquin” ( = eugenol primeveroside), isolated by us from leaves of Camellia sasanqua, was synthesized. The glucoside linkage between eugenol and primeverose has been now confirmed as β-form.

Production of Melilotic Acid by Action of Taphrina wiesneri Studies on Hypertrophic Disease of Cherry (Genus Prunus):So-called "Witch's Broom" Caused by Taphrina wiesneri . Part III

The in vitro action of Taphrina wiesneri on coumarin and its related compounds were examined. Melilotic acid, which accumulates in larger amounts in infected cherry leaves than in healthy leaves, was produced from coumarin, 3,4-dihydrocoumarin, o-coumaric acid or o-coumaryl glucoside by the action of acetone-dried cells of the fungus. From the results it is suggested that in cherry plants infected with the fungus melilotic acid may be formed from these precursors contained as ordinary components in cherry leaves. Possible mechanisms of the conversion of coumarin to melilotic acid are also discussed.

Fluorescent Glycosides Accumulated in Taphrina wiesneri-infected Cherry Stems: Part I. Contents of Glycosides, and the Isolation and Identification of Gentisic Acid-5-β-d-glucosidePart II. Isolation and Characterization of FG-2, a New Gentisic Acid-glycoside

It was observed that three kinds of fluorescent glycosides (FG-1, FG-2, and FG-3) were more abundantly accumulated in Taphrina wiesneri-infected cherry (Prunus yedoensis) stems than in healthy ones. The contents of FG-1, FG-2, and FG-3 in infected stems were, respectively, 2.7, 7.2, and 4.3 times those in healthy stems. In dryed infected stems, FG-1, FG-2, and FG-3, amounted respectively to 0.005, 0.18, and 0.12% in the bark part; and to 0.003, 0.048, and 0.008% in the wood part.FG-1 was isolated in crystalline form, and was identified with gentisic acid-5-β-d-glucopyranoside by the comparison of its chemical and physical properties with those of synthesized gentisic acid-5- or 2-β-d-glucopyranoside.

Chemical Studies of Camellia Family: Part II. A New Glycoside “Sakakin” from Cleyera ochnaceae D. C. (Sakaki)

In the course of chemotaxonomical works of Camellia family, a new phenolic substance was found in the methanol extract of the young leaves of Cleyera ochnaceae D. C. This was named “Sakakin” which is a glycoside composed of orcinol and d-glucose. The structure was proved to be 3-hydroxy-5-β-d-glucopyranosidoxy-toluene, and has been confirmed by synthesis.