ネジキLyonia ovalifolia DRUDE var.elliptica HAND.-MAZZ.の成分研究(第9報) : Lyoniol-A(Lyoniatoxin)の構造その1

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Lyoniol-A (I), the main component of the toxic principles of Lyonia ovalifolia var. elliptica, was identified as lyoniatoxin.^<5)> The structure of lyoniol-A (lyoniatoxin) was concluded as (I) through the reactions shown in Fig. 3 and from the physical data of the reaction products. Alkaline hydrolysis of I gave deacetyllyoniol-A, a pentahydric alcohol, which was proved to be identical with lyoniol-B (II), a minor constituent. II formed monoacetonide (IV) which did not react with chromic acid. Thus, the remaining three hydroxyl groups must be tertiary. II consumed one mole of sodium periodate but I did not. Chromic acid oxidation of I gave a monoketone (III), which was believed to be a six or more membered cyclic ketone from its IR spectrum. These results and nuclear magnetic resonance (NMR) data of I, II, and III suggested that I has a partial structure of 〓C-CH (OAc)-CH (OH)-C〓. Lithium aluminum hydride reduction of I or II gave dihydrolyoniol-B (V), which was derived to its triacetate (VI) with acetic anhydride and pyridine. These reactions suggested that I has an epoxide ring in its molecule and the epoxide group was reduced to an alcoholic group. When V was treated with p-toluenesulfonic acid in acetone, dihydrolyoniol-B acetonide (VII), dihydrolyoniol-B anhydroacetonide-I (VIII), and dihydrolyoniol-B anhydroacetonide-II (IX) were produced. VII afforded monoacetate on mild acetylation. Chromic acid oxidation of IX gave a cyclopentanone derivative X. Thus, the epoxide ring must be situated in the cyclopentane ring. Because of a close relationship between the plant source and similarity in biological activity, lyoniol-A seems to have the same carbon skeleton and a very similar stereostructure as grayanotoxin-I^<8)> and rhodojaponin-II.^<9)> Thus, the structure of lyoniol-A should be represented by formula I. From the coupling constant of C_6-H and C_7-H, and specu lation about stereo models, it was concluded that C_6-H and C_7-H are trans and, therefore, the C_7-hydroxyl group must be in α-configuration. The structures of IX and VIII were assumed to be △^<10,20>-ene-6,7-acetonide (20-terminal methylene protones) and △^<15,16>-ene-6,7-acetonide (allyl coupling of 17-methyl), respectively.
公益社団法人日本薬学会の論文
1970-07-25

ネジキLyonia ovalifolia DRUDE var.elliptica HAND.-MAZZ.の成分研究(第9報) : Lyoniol-A(Lyoniatoxin)の構造その1

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