Biotransformation of Paeonol and Emodin by Transgenic Crown Galls of Panax quinquefolium

Two aromatic substrates, paeonol (1) and emodin (2), were biotransformed by using transgenic crown galls of Panax quinquefolium. Four biotransformed products (3-6) were isolated and identified by physicochemical and spectral methods. A beta-glucoside (3, 73.2% of biotransformation yield) and a 1-(2,4-dimethoxyphenyl)- ethanone (4, 8.03%) were isolated from the suspension cultures after 7-day incubation of substrate 1. Upon administration of substrate 2, another beta-glucoside [emodin-6-O-beta-d-glucopyranoside (5), 19.2%] and a hydroxylated derivative, citreorosein (6, 54.6%), were also obtained. The results demonstrate that transgenic crown galls of P. quinquefolium have the capacities to catalyze glycosylation, hydroxylation, and methylation reactions in the plant cells on those aromatic compounds.