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Abstract

Our previous study highlighted the antimicrobial activity evaluation of Nigella sativa seed oil extract that was obtained from supercritical fluid extraction using carbon dioxide (SCFE-CO 2 ) on Gram positive pathogenic bacteria. The aim of this study was to formulate oil-in-water (o/w) emulsion of previous N. sativa seed oil extract and to investigate its antimicrobial activity against Streptococcus mutans and Streptococcus sanguis as the most common causative bacteria of dental caries. Oil-in-water emulsion containing 10% N. sativa seed oil extract (DLBS1355) exhibited good inhibition activity on both S. mutans and S. sanguis. Time-kill assay and biofilm inhibition assay were conducted using emulsion with 0.5% N. sativa seed oil extract content. The results showed bactericidal and biofilm inhibition activities on both tested bacteria. Antimicrobial activity of the emulsion was found higher on S. sanguis than S. mutans. Results of the present study showed that emulsification process did not significantly affect the antimicrobial activity of N. sativa seed oil extract and the formulated N. sativa oil-in-water emulsion could further be used as an antimicrobial agent against dental cariogenic bacteria.