Biotransformation of Licochalcone A by transgenic crown galls of Panax quinquefolium

Abstract Licochalcone A, as main constituent of Chinese Gancao ( Glycyrrhiza inflate Bat), is responsible for the chemopreventive effect of the herbal. In order to get the bioactive modified molecules of Licochalcone A, it was biotransformed using transgenic crown galls of Panax quinquefolium to afford 9 products including a new alkaloid together with 8 known compounds. Their structures were elucidated by physicochemical and spectral methods as: methyl(12 S )-1-[(5-formylfuran-2-yl)methyl]-5-oxopyrrolidine-2-carboxylate ( 1 ), methyl(12 S )-1-[2-(furan-2-yl)-2-oxoethyl]-5-oxopyrrolidine-2-carboxylate ( 2 ), 5-hydroxymethyl-2-furfural ( 3 ), (S)-methylpyroglutamate ( 4 ), 4-hydroxy-2-methoxy-5-(2-methylbut-3-en-2-yl) benzaldehyde ( 5 ), 4-hydroxybenzoicacid ( 6 ), dibutyl phthalate ( 7 ), 3 β ,6 α ,12 β ,25-tetrahydroxy-(20 S ,24 R )-epoxy-dammarane ( 8 ), β -sitosterol ( 9 ). Among them, compounds 5 and 6 were transformed from Licochalcone A, while 1 – 4 and 8 were derived from the culture medium stimulated by the substrate. Furthermore, their cancer chemopreventive effect were tested by the assay of NQO1 (NAD(P)H: quinine oxidoreductase 1) inducing activities in Hepa 1c1c cells.