Effects of various antiplaque agents on fructosyltransferase activity in solution and immobilized onto hydroxyapatite

Fructosyltransferases (FTFs) are extracellular enzymes which synthesize fructans from sucrose. Cell free FTFs are found in the dental plaque biofilm as well as in saliva. Fructans play an important role in the progression of dental caries, mainly by serving as an extracellular nutrition reservoir for bacteria. The objective of the present study was to compare the effects of several antiplaque agents on the synthesis of fructans by FTF immobilized on hydroxyapatite (HA) or in solution. The effect of chlorhexidine, cetylpyridinium chloride, sodium lauryl sulfate and Tween on FTF activity was tested using radioactive assays. Their effect on fructan structure was tested using circular dichrosim-optical rotative dispersion (CD-ORD) analysis and Fourier transform infrared (FT-IR) spectroscopy. Our results show that the antiplaque agents tested had an inhibitory effect on FTF activity both in the immobilized phase and in solution, although the inhibitory effect was more pronounced in solution. Structural changes in fructans, due to the presence of the antiplque agents, were recorded as additional C-H or O-H bands demonstrated in FT-IR analysis. However, non-significant changes in peak location were detected in CD-ORD spectrum between fructans synthesized in solution and on HA surfaces, and after treatment with the different antiplaque agents. Our study shows that several antiplaque agents may affect FTF activity and the synthesis of fructans by FTF, immobilized on hydroxyapatite or in solution.