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.
Highlights
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Resveratrol (3,5,4′-trihydroxy-trans-stilbene) is the best-known hydroxystilbene. This compound has been shown to activate sirtuins, it may contribute to lifespan extension.4–6) Resveratrol has various health-benefiting properties including antioxidant, anticancer, and anti-inflammatory activities.7–9) piceatannol (3,4,3′,5′-tetrahydroxy-trans-stilbene) has recently attracted much attention.10–12) A recent report indicates that piceatannol and its metabolite, isorhapontigenin, induce expression of sirtuin 1 in THP-1 human monocytic cell line.10) In addition to having similar biological activities to resveratrol,10–12) piceatannol exerts positive effects on human dermal cells through the inhibition of melanogenesis and synthesis of collagen, and exhibits vasorelaxant effects in rat thoracic aorta.13,14) Interestingly, these effects of piceatannol are more pronounced than those of resveratrol.13,14) These beneficial properties of hydroxystilbenes encourage their use in health and functional foods, as well as in pharmaceuticals and cosmetics
Several monooxygenases including P450 monooxygenases and a tyrosinase have been reported to hydroxylate resveratrol to piceatannol.15,16) In addition, we recently found that the two-component flavindependent monooxygenase HpaBC from Pseudomonas aeruginosa has high activity for the hydroxylation of resveratrol to piceatannol (Fig. 1).17,18) HpaBC consists of a flavin-dependent monooxygenase (HpaB) and an NAD(P)H:flavin oxidoreductase (HpaC)
Summary
View supplementary material Submit your article to this journal View related articles Citing articles: 5 View citing articles. Several monooxygenases including P450 monooxygenases and a tyrosinase have been reported to hydroxylate resveratrol to piceatannol.15,16) In addition, we recently found that the two-component flavindependent monooxygenase HpaBC from Pseudomonas aeruginosa has high activity for the hydroxylation of resveratrol to piceatannol (Fig. 1).17,18) HpaBC consists of a flavin-dependent monooxygenase (HpaB) and an NAD(P)H:flavin oxidoreductase (HpaC) This monooxygenase physiologically functions as a 4-hydroxyphenylacetate 3-hydroxylase in the degradation pathway of 4-hydroxyphenylacetate.19–21) Recombinant cells expressing HpaBC enabled the regioselective hydroxylation of resveratrol to produce 23 mM (5.2 g L−1) piceatannol.18) HpaBC is useful practically because this monooxygenase can efficiently produce the rare and expensive compound piceatannol from resveratrol, which is relatively abundant and inexpensive. There have been no reports concerning monooxygenases that catalyze the hydroxylation of stilbene derivatives other than resveratrol
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