10-methoxycanthin-6-one

Taylor (5) reviewed some of the canthin-6-one alkaloids such as canthin-6-one (1), 4-methylthiocanthin-6-one (6), 5-methoxycanthin-6-one... 

Hydroxycanthin-6-one (16) has been isolated from the root bark of Simarouba amara (34) and from cell cultures of A. altissima 12,15). Since its UV spectrum was similar to that of 5-methoxycanthin-6-one (25), Lassak et al. (34) assumed it to be 4- or 5-hydroxycanthin-6-one. The prominent peak at M -56 (mlz 180, M -2CO) in the mass spectrum supported structure 16 having an OH adjacent to the carbonyl group. The final confirmation of structure 16 was made through direct comparison of methylated 16 with authentic 7. 

Methoxycanthin-6-one (7) has been found in the bark (stem, root, branch, and sapling) and leaves of Pentaceras australis (35). This compound has also been found in three species of Rutaceae including P. australis, five species of Simaroubaceae, and one species of Caryophyl-laceae. The number of species of plants containing 7 is second only to those containing 1. Readers are referred to Volume 3 (p. 249) of this treatise for its structure (5). 

Roxb., the root bark of which contains several antileukaemic simaroubolides, together with four canthine derivatives canthin-6-one (15a), 1-methoxycanthin-6-one (15b), 5-methoxycanthin-6-one (15c), and 8-hydroxycanthin-6-one (15d). Of these, the first three were already known, but the fourth is new. 

Ailanthus altissima is a tall deciduous tree of Chinese origin. A study of the wood extractives has revealed the presence of three alkaloids canthin-6-one, can-thin-6-one-3-oxide, and l-methoxycanthin-6-one (118). Another member of the same family, Simarouba amara, contains 5-hydroxycanthine-6-one (93). The root bark of Ailanthus excelsa contains four canthine derivatives canthin-6-one, 1 -methoxycanthin-6-one, 5-methoxycanthin-6-one, and 8-hydroxanthin-6-one (27). 

Other constituents include two additional quassinoids, quassimarin and simalikalactone D, isolated from Q. amara, P-sitosterol and P-sitostenone 1.8% thiamine (inP. excelsa)-, and alkaloids of the P-carboline type including canthin-6-one, 5-methoxycanthin-6-one, 4-methoxy-5-hydroxycanthin-6-one, and A-methyl-1-vinyl-P-carboline (list and horhammer willaman and Schubert). Jamaican quassia is reported to contain no tannin (martestdale). 

Canthin-6-ones. From Pentaceras australis, three optically inactive coloured alkaloids were isolated. The structure of canthin-6-one followed from its analytical data, physical properties and potassium permanganate oxidation to j8-carboline-l-carboxylic acid and synthesis from 5-methoxycanthin-6-one vide infra). (Chart 10.2). 

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