Chemistry and biosynthesis of isoprenylated flavonoids from Japanese mulberry tree

Abstract

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 α, β-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 [1,3-13C2]- and [2-13C]-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 isoprenoidphenols, 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.

Molecular Characterization and Phylogenetic Analysis of Two Novel Regio-specific Flavonoid Prenyltransferases from Morus alba and Cudrania tricuspidata

“…In moraceous plants, many prenylated aromatic compounds, such as Diels-Alder-type adducts, flavonoids, 2-arylbenzofurans, xanthones, and stilbenes, have been identified, and their biological/pharmacological activities have been extensively studied (9,22,23). Of these compounds optically active DielsAlder-type adducts, which are characteristic mulberry constituents with promising biological activities, are attractive compounds from a biosynthetic point of view, and prenylation is a key biosynthetic step in their formation (8,9).…”

“…Of these compounds optically active DielsAlder-type adducts, which are characteristic mulberry constituents with promising biological activities, are attractive compounds from a biosynthetic point of view, and prenylation is a key biosynthetic step in their formation (8,9).…”

“…The prenylation reactions catalyzed by flavonoid prenyltransferases (FPTs) 2 have received particular attention and significantly contribute to the structural diversity and further modification of the prenylated flavonoids (7). For example, prenylation is a key step in the biosynthesis of diverse Diels-Alder-type adducts in mulberry trees (8,9). Consequently, intensive biochemical studies of FPTs * The study was supported by National Natural Science Foundation of China have been performed for more than two decades (10,11).…”

Phytoestrogens: Naturally Occurring, Hormonally Active Compounds in Our Diet

“…87 Besides hop products, a number of prenylated flavonoids have also been isolated from Japanese mulberry tree, Morus alba L. The fruits of mulberry trees are eaten, often dried or made into wine, but there are no reports if these sources of prenylated flavonoids exhibit any estrogenic activity. 88 Before 8PN was described as a hop ingredient, it was first isolated from another source and named 8-isopentenylnaringenin, which was found in a Thai crude drug, together with other prenylflavonoids. This traditional drug derives from the duramen of Anaxagorea luzonensis A.…”

Enhancement of the Tyrosinase Inhibitory Activity of Mori Cortex Radicis Extract by Biotransformation UsingLeuconostoc paramesenteroidesPR

“…[4][5][6] Botanical structures of the mulberry tree (Morus alba L.), including the fruit, leaves, and root bark, have been used widely for many years in traditional Oriental medicine to treat fever, protect the liver, remove sputum, improve eyesight, strengthen joints, facilitate the discharge of urine, and lower blood pressure. 7,8) The root bark of Morus alba L., Mori Cortex Radicis (MCR), is rich in phytochemicals such as 1-deoxynojirimycin, -aminobutyric acid, benzofuran derivatives, coumarins, and various flavonoids including hydroxystilbene derivatives. 9,10) Stilbene glucosides such as mulberroside A (MA), oxyresveratrol-2-O--D-glucopyranoside, and oxyresveratrol-3 0 -O--D-glucopyranoside comprise the main components of MCR aqueous extract 10,11) and are not found in Morus alba L. leaves or fruits, suggesting that there are significant differences in the components of the root bark, leaves, and fruits.…”