Development of an enzyme-enhancer system to improve laccase biological activities

Abstract

The present investigation reports an in-vitro study using combination of laccase and an enhancer capable of inhibiting the growth of pathogenic microorganisms, preventing biofilm formation, and whitening teeth. Laccase-cinnamic acid system remarkably inhibited the growth of Aggregatibacter actinomycetemcomitans, Candida albicans, S. aureus, and Streptococcus mutans whilst showed no significant effects on Gram-negative bacteria. Data presented that cinnamic acid (10 mM) with laccase (0.125 U ml−1) led to a maximum decrease of about 90%, in S. mutans biofilm formation. The confocal laser scanning microscopy showed considerable detachment of S. mutans cells from glass substratum. The combined laccase-cinnamic acid system could remove teeth discoloration caused by coffee. SEM of the teeth surface exhibited no damages such as surface cracking or fracture. Liquid chromatography-tandem mass spectrometry (LC-MS) and cyclic voltammetry (CV) studies showed that laccase can catalyze the one-electron oxidation of cinnamic acid to the respective radical. This radical can then undergo several fates, including recombination with another radical to form a dimeric species, dismutation of the radical back to cinnamic acid or decarboxylation to give various reduced oxygen species. Therefore, the redox potential values of phenolic monomers/oligomers are related with their biological activities.