Viscosity of Carboxymethylcellulose, Hydroxyethylcellulose and Polyethylene Glycol and Their Effect on Salivary Enzymes

OBJECTIVES: Carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC) and polyethylene glycol (PEG) are commonly used polymers for oral health care products. This study aimed to identify the molecular weight (MW)-concentration combinations of these polymers with viscosities comparable to human whole saliva and to evaluate their influence on antimicrobial enzymatic activities. METHODS: ) for CMC and HEC (90 and 250 kDa) and PEG (1, 10, 20 and 35 kDa) at various concentrations. Their effects on hen egg-white lysozyme (HEWL), bovine lactoperoxidase (bLPO) and the glucose oxidase-peroxidase (GO-PO) system were examined. Human whole saliva was used for salivary enzyme source. The independent effects of polymer concentration and MW were also investigated. RESULTS: Seven MW-concentration combinations exhibited viscosities comparable to human whole saliva within physiological shear ranges. CMC inhibited HEWL activity but enhanced salivary lysozyme activity, whereas HEC and PEG enhanced both. All 3 polymers enhanced bLPO activity, but HEC and PEG decreased salivary peroxidase activity. All polymers inhibited the GO-PO activity. These effects were concentration-dependent, with most significant changes at concentrations well below those used in oral health care products. Polymers of higher MW resulted in greater inhibition of salivary peroxidase activity. CONCLUSIONS: CMC, HEC and PEG differentially affected antimicrobial enzymatic activities, with the direction and magnitude of effects dependent on polymer type, MW, concentration and enzyme source. CLINICAL RELEVANCE: These findings provide useful information for the formulation of polymers in oral health care products.