Biocatalytic synthesis of 3,4,5,3′,5′-pentahydroxy-trans-stilbene from piceatannol by two-component flavin-dependent monooxygenase HpaBC

Abstract

HpaBC monooxygenase was previously reported to hydroxylate resveratrol to piceatannol. In this article, we report a novel catalytic activity of HpaBC for the synthesis of a pentahydroxylated stilbene. When Escherichia coli cells expressing HpaBC were incubated with resveratrol, the resulting piceatannol was further converted to a new product. This product was identified by mass spectrometry and NMR spectroscopy as a 5-hydroxylated piceatannol, 3,4,5,3′,5′-pentahydroxy-trans-stilbene (PHS), which is a reportedly valuable biologically active stilbene derivative. We attempted to produce PHS from piceatannol on a flask scale. After examining the effects of detergents and buffers on PHS production, E. coli cells expressing HpaBC efficiently hydroxylated piceatannol to PHS in a reaction mixture containing 1.5% (v/v) Tween 80 and 100 mM 3-morpholinopropanesulfonic acid-NaOH buffer at pH 7.5. Under the optimized conditions, the whole cells regioselectively hydroxylated piceatannol, and the production of PHS reached 6.9 mM (1.8 g L⁻¹) in 48 h.

Graphical abstract

HpaBC regioselectively hydroxylates piceatannol to 3,4,5,3′,5′-pentahydroxy-trans-stilbene, a valuable biologically active stilbene derivative.

Key words:

• HpaBC
• hydroxylation
• monooxygenase
• resveratrol
• stilbene

Notes

Abbreviations: HEPES, 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid; HPLC, high-performance liquid chromatography; MOPS, 3-morpholinopropanesulfonic acid; PHS, 3,4,5,3′,5′-pentahydroxy-trans-stilbene; Tris, tris(hydroxymethyl)aminomethane.