Preliminary study on the inhibitory effect of seaweed Gracilaria verrucosa extract on biofilm formation of Candida albicans cultured from the saliva of a smoker

Abstract

Background: Candida albicans is an opportunistic fungus that might infect the oral cavity. Increased colony numbers of C. albicans in the mouth can be caused by multiple factors, such as smoking, weakened immune system, antibiotics use and immune-compromised condition. Smoking can increase expression of virulence factors of C. albicans and make it stronger. One virulence factor of C. albicans is biofilm formation. The ability of creating biofilm makes C. albicans more tolerant to commercial antifungal agents. The objective of this preliminary study was to examine the ability of the seaweed G. verrucosa extracts to inhibit the formation of biofilm by C. albicans isolated from the saliva of a smoker. Methods: The extract of G. verrucosa was prepared by maceration using 96% methanol and subjected for phytochemical analysis. C. albicans was isolated from the saliva of a smoker who voluntarily participated in the study after providing informed consent. In triplicate, the fungus was cultured in the growth medium containing increased concentrations of G. verrucosa (6.25, 12.5, 25, 50, 75 and 100% ).The same reaction using fluconazole 0.31 µg/ml C. albicans was prepared as positive control. Biofilm formation was accessed based on optical density of cell mixtures using an ELISA reader. The data obtained were subjected to Kruskal-Wallis test at a significance limit of 0.05. Results: Methanol extract of seaweed G. verrucosa contained three bio-active compounds namely steroids, terpenoid, and tannins. Inhibitory activity of seaweed extracts on C. albicans biofilm formation increased as their concentration increased. The highest inhibitory effect was recorded at fungus culture treated with seaweed concentration of 25% at 24 hours of time exposure. Conclusions: Seaweed G. verrucosa extract contained steroids, terpenoids and tannins that were able to effectively inhibit the formation of biofilm by C. albicans at the concentration of 25% after 24 hours of time exposure.