Modifications of hydrophobicity, in vitro adherence and cellular aggregation of Streptococcus mutans by Helichrysum italicum extract

Aims: The purpose of the present study was to examine whether sublethal concentrations of Helichrysum italicum extract could affect some of the cariogenic properties of Streptococcus mutans. Methods and Results: We studied the antibacterial activity of H. italicum (ethanolic extract) against oral streptococci (Strep. mutans ATCC 35668, Strep. salivarius ATCC 13419 and Strep. sanguis ATCC 10556) and its influence on cell-surface hydrophobicity, in vitro sucrose-dependent adherence to glass surface and cellular aggregation of Strep. mutans. The results indicate that all streptococci were susceptible to ethanolic extract with minimum inhibitory concentration (MIC) values of 31.25-62.50 mug ml(-1). Sub-MIC concentrations of H. italicum (7.81-31.25 mug ml(-1)) reduced the hydrophobicity and the adherence (almost 90%) to glass surface of Strep. mutans. The aggregation in the presence of dextran T2000 was also affected. Conclusion: The inhibitory activity of H. italicum extract on Strep. mutans is worthy of further study. Significance and Impact of the Study: There is considerable interest in the use of natural compounds as alternative methods to control undesirable micro-organisms.