Chemistry and biosynthesis of isoprenylated flavonoids from Japanese mulberry tree.
Many isoprenylated flavonoids have been isolated from Japanese mulberry tree (Moraceae). Among them, kuwanons G (1) and H (2) were the first isolated active substances exhibiting a hypotensive effect. These compounds are considered to be formed through an enzymatic Diels-Alder type reaction between an isoprenyl portion of an isoprenylphenol as the diene and an alpha, beta-double bond of chalcone as the dienophile. The absolute configurations of these Diels-Alder type adducts were confirmed by three different methods. The stereochemistries of the adducts were consistent with those of ones in the Diels-Alder reaction involving exo- and endo-addition. Some strains of Morus alba callus tissues have a high productivity of mulberry Diels-Alder type adducts, such as chalcomoracin (3) and kuwanon J (4). The biosynthetic studies of the mulberry Diels-Alder type adducts have been carried out with the aid of the cell strain. Chalcomoracin (3) and kuwanon J (4) were proved to be enzymatic Diels-Alder type reaction products by the administration experiments with O-methylchalcone derivatives. Furthermore, for the isoprenoid biosynthesis of prenylflavonoids in Morus alba callus tissues by administration of [1,3-(13)C(2)]- and [2-(13)C]-glycerol, a novel way through the junction of glycolysis and pentose-phosphate cycle was proved. Two independent isoprenoid biosynthetic pathways, that for sterols and that for isoprenoid-phenols, operate in the Morus alba cell cultures. The former is susceptible to compactin (ML-236) and the latter resists to compactin in the cell cultures, respectively.
Nomura
Taro
T
Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan. hano@phar.toho-u.ac.jp
Hano
Yoshio
Y
Fukai
Toshio
T
D000959:Antihypertensive Agents / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D005419:Flavonoids / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification; D031625:Morus / Q000737:chemistry* / Q000378:metabolism*; D010427:Pentose Phosphate Pathway / Q000502:physiology; D054876:Prenylation; D014197:Trees / Q000737:chemistry* / Q000378:metabolism
D000959:Antihypertensive Agents; D005419:Flavonoids