Laccase‐Catalyzed Dimerization of Piceid, a Resveratrol Glucoside, and its Further Enzymatic Elaboration

Abstract

Thel accase-catalyzed oxidation of piceid, the 3-b-d-glucopyranosyl derivative of the stilbenic phytoalexin resveratrol, allowed isolation of the corresponding b-5 like trans-dehydrodimer in good yield (45%) avoiding chromatography.T his compound was then submitted to the action of as mall library of commercially available hydrolases. While the cellulase from Trichoderma viride was able to fully hydrolyze the diglycosylated dimer to give the corresponding b-5 like trans-dehydrodimero fr esveratrol, the bglucosidase from almonds allowed the isolationo f am onoglycosylated intermediate in reasonable yield. Thed iastereoisomers and the enantiomers of the isolated dimeric products were separated using as emipreparative chiral column. Theb asic antioxidant properties of these new dimers have been determined.

Studies on the Laccase‐Catalyzed Oxidation of 4‐Hydroxy‐Chalcones

“…As expected, the samples corresponding to the two equivalent peaks showed identical NMR spectra and opposite values of optical rotation power ([α] D =−163° and [α] D =+163° for Peak 1 and Peak 2, respectively). Their CD spectra were, as expected, specular (Figure ) and, by analogy with previous literature reports, allowed us to tentatively assign the absolute configuration to the stereogenic carbons of the two enantiomers: 2 R ,3 R for the less retained peak ( 3 a , Peak 1) and 2 S ,3 S for the more retained one ( 3 b , Peak 2).…”

“…As shown in Scheme 3, this structure is generated (as previously observed with other vinylic [4] and stilbenic [5,6] derivatives) by the combination of radical III and radical II, followed by rearrangement and ring closure.…”

“…In conclusion, the laccase‐catalyzed oxidation of 4‐hydroxy‐chalcones allowed the isolation of new derivatives possessing the 2,3‐dihydrobenzofuran skeleton. Specifically, the pure enantiomers of the 2,3‐disubstituted trans diasteroisomers could be isolated by semipreparative HPLC with a chiral column, following a protocol previously exploited to purify the oxidized products obtained from hydroxystilbenes, The biological activities of these new compounds, for instance their ability to act as activators or inhibitors of the Heat shock protein Hsp90, deserve to be investigated and the results will be reported in due course.…”

“…In previous investigations we have shown that laccases can be exploited for the preparative scale oxidation of substituted vinyl phenols [4] and polyhydroxy-stilbenes, [5] the main isolated products being the corresponding DHB derivatives (Scheme 1, part A).…”

Biocatalysis with Laccases: An Updated Overview

“…Finally, 2,3-DHBs (i, β-5 type dimers in lignin framework) can be selectively obtained from ad hoc designed substrates. In these molecules, R' is a "spectator group" (i.e., hydrogen, alkyl chains, protected phenols) and the R substituent is either an alkyl or an aryl group [27,110,[112][113][114][115].…”