Abstract: The biotransformation of four 4-hydroxybenzen derivatives (1,4-benzenediol (compound 1), 4-hydroxybenzaldehyde (compound 2), 4-hydroxybenzyl alcohol (compound 3) and 4-hydroxybenzoic acid (compound 4)) by the hairy root cultures of Polygonum multiflorum Thunb. as a new biocatalyst was investigated. It was found that the substrates were transformed to their corresponding glucosides, 4-hydroxyphenyl β-D-glucopyranoside (arbutin, compound 1a), 4-hydroxymethylphenyl β-D-glucopyranoside (gastrodin, compounds 2a, 3a) and 4-carboxyphenyl α-Dglucopyranoside (compound 4a), respectively. In the meantime, the hairy roots of P. multiflorum were able to stereoselectively and regioselectively glucosylate phenolic hydroxyl groups of compounds 1–4, but the cultures could not glucosylate the aldehyde group of compound 2 or the benzylic hydroxyl group of compound 3, and no glucosyl esterification of carboxyl groups of compound 4 was detected. On the other hand, the result also showed that the hairy roots of P. multiflorum were able to reduce the 4-hydroxybenzaldehyde to its corresponding alcohol. This is the first report that substrate 4 has been converted into its α-D-glucopyranoside by a plant biotransformation system.

Key words: 4-hydroxybenzen derivatives, arbutin, biotransformation, gastrodin, hairy root cultures, Polygonum multiflorum.