Hardening Reaction of Alkenylcatechol Derivatives by Laccase from Pycnoporus Coccineus

" The relationship between the hardening reaction of alkenylcatechol derivatives by laccase and the stereo structure of the side chain double bond has been studied considering the former as an urushiol analogue. We synthesized several kinds of catechol devivatives with a C18-alkenyl side chain at 4-position of the catechol ring. The side chain of these compounds have different numbers of double bonds having different configurations. The hardening reaction of these catechol derivatives by laccase from Pycnoporus coccineus was carried out in the presence of polysaccharides and glycoproteins,in order to measure the drying time and the viscoelastic behavior of the dried films. Hardening was observed for the dienylcatechol derivative having cis double bonds at C-9',C-12' yielding the films which showed ideal dynamic viscoelasticity. On the other hand,such films were not obtained in the case of dienylcatechol having a mixture of geometrical isomers,72% of which were trans isomers. We suggest that the methylene-interrupted cis double bond pair can be crosslinked to a greater extenent than the trans-ones by the laccase."