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 μg ml−1. Sub‐MIC concentrations of H. italicum (7·81–31·25 μg 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.