37 光学活性Diels-Alder型付加化合物の生合成研究(口頭発表の部)  [in Japanese] 37 BIOSYNTHETIC STUDIES ON OPTICALLY ACTIVE DIELS-ALDER TYPE ADDUCTS  [in Japanese]

Biosynthesis of the optically active Diels-Alder type adducts in the mulberry tree (Moraceae) has been examined by the administration of O-methylated precursory chalcones to Morus alba cell cultures. From the cell cultures incubated with 2,2',4'-trihydroxy-4-methoxychalcone (3), 3'-prenylated 3 (4), 4-O-methyl-kuwanon J (5), 4-O-methyl-kuwanon Q (6), 4,18"-di-O-methyl-kuwanon J (7), and 18"-O-methyl-chalcomoracin (8) were obtained. Furthermore, 12",16",18"-tri-O-methyl-chalcomoracin (11) was isolated from the cell cultures incubated with 2'-hydroxy-2,4,4'-trimethoxy-3'-prenylchalcone (10). These O-methylated Diels-Alder type adducts 5, 6, 7, 8, and 11 were optically active, and the patterns of their CD spectra were in good agreement with those of chalcomoracin (1) and kuwanon J (2). These results indicated that the O-methylchalcones 3 and 10 are incorporated into the biosynthetic pathway resulting in the formation of optically active adducts through a Diels-Alder type cycloaddition reaction of the α,β-double bond of the chalcone as a dienophile with the prenyl portion as a diene.