Interaction of preservatives with macromolecules. Part II. Cellulose derivatives

Abstract

Antibacterial activities of chlorocresol, methyl-p-hydroxybenzoate and phenoxyethanol against Pseudomonas aeruginosa were studied in the presence of different concentrations of methylcellulose, sodium carboxymethylcellulose and hydroxypropylmethylcellulose. All the three cellulose derivatives reduced the activities of the preservatives to varying degrees. The activity of chlorocresol was considerably inhibited by sodium carboxymethylcellulose and hydroxypropylmethylcellulose, while hydroxypropylmethylcellulose caused the maximum suppression of the activity of methyl-p-hydroxybenzoate. The activity of phenoxyethanol was markedly reduced by each of the three cellulose derivatives. Interaction of the preservative with cellulose derivative and subsequent reduction in the availability of preservative to the bacterial cells was found to be the predominant mechanism involved in the reduction of activities of chlorocresol by methylcellulose and of methyl-p-hydroxybenzoate by sodium carboxymethylcellulose. Physical shielding of the bacterial cells from the action of preservative was the primary cause for the lower activities of chlorocresol in the presence of sodium carboxymethylcellulose and phenoxyethanol in the presence of all the three cellulose derivatives. The reduced activities of chlorocresol by hydroxypropylmethylcellulose and of methyl-p-hydroxybenzoate by methylcellulose and hydroxypropylmethylcellulose are attributed to both mechanisms of inactivation. © 1995.