Inhibitory Potential of Artificial Saliva Containing Vanillin against Biofilm Formation of Candida

Abstract

Saliva plays a crucial role in oral health. Reduced salivary flow (hyposalivation) and xerostomia (dry mouth) are commonly found in many groups of patients, such as cancer patients with head and neck radiotherapy, patients taking medications with antisialogogic effects, diabetic patients, autoimmune patients, and the elderly. When salivary function is diminished, there is more risk of patients to develop opportunistic infections. One of therapeutic methods to restore lost or improve existing functions of natural saliva is the use of saliva substitutes. Several types of salivary substitutes have been developed to simulate human saliva as well as having antimicrobial property. Vanillin, an extensive flavor and aromatic component used worldwide, has been revealed to have antimicrobial potential against many types of bacteria yeasts and molds. The objective of this study was to evaluate the antimicrobial potential of vanillin-incorporated artificial saliva against biofilm formation of Candida. Artificial saliva containing different concentrations of vanillin (8, 4, 2, 1, 0.5 and 0.25 mg/mL) was prepared. Candida albicans ATCC 10231 and a clinical strain isolated from oral lesion of patient were used in this study. The Candida biofilm formation assay was performed on a 96-well plate by adding 150 μl 107colony forming unit (CFU)/ml of each Candida suspension and 50 μl of artificial saliva and incubated at 37°C in shaking incubator for 24 h. The vital Candida in biofilm formed on the bottom surface of microwell was determined by WST-8 microbial viability assay kit (Dojindo, USA). Artificial saliva without vanillin was used as a control. All tests were done in triplicate and repeated three times. Kruskal-Wallis and Dunn’ tests were used as statistical analysis. It was found that in the presence of vanillin (at concentrations > 0.5 mg/mL) the amount of vital biofilm formation of both strains of C. albicans was significantly reduced (31-56%) compared with a control. The suppressive activity was not different between both strains of Candida. Similarly, dose dependent effects were found except at 2 mg/mL and 1 mg/mL. The result was conformed to the previous study of our group that the incorporation of vanillin to surgical obturator resin could reduce the Candida biofilm formation to nearly 46-54%. The mechanisms of antifungal property of vanillin had been demonstrated to be the induction of oxidative stress, and an interference of metabolic pathways. In conclusion, artificial saliva containing vanillin exhibited a distinct inhibitory effect on biofilm formation of C. albicans as demonstrated in the present study. Attention is required for further studies to implement vanillin added artificial saliva to be used as a productive saliva substitute for the prevention or treatment of Candida infection.