Evaluation of the antibacterial effects of aqueous and ethanolic leaf extracts ofAloysia Citriodora(Lemon verbena) on Streptococcus mutans and Streptococcus sobrinus.
BACKGROUND
TheAloysia citriodoraplant from the family ofVerbenaceaehas many uses in traditional medicine. The aim of the current study was to determine the effects of the aqueous and ethanolic extracts ofA. citriodoraonStreptococcus mutansandStreptococcus sobrinus, which cause tooth decay.


METHODS
This 2016 study was performed on standardized strains ofS. mutansPTCC1683 andS. sobrinusPTCC1601 and clinical isolates. Twenty clinical samples were obtained from the dental caries of children admitted to the pediatric ward at the Faculty of Dentistry of Babol University of Medical Sciences (Babol, Iran). The aqueous and ethanolic extracts ofA. citriodoraleaves were prepared in several concentrations ranging from 625-20,000 μg/ml. These concentrations of the extracts were applied to the bacteria by disk diffusion, agar well diffusion, and macrotube dilution. The antibacterial effects of amoxicillin and chlorhexidine digluconate 0.2% (CHX) were also carried out. Data were analyzed by SPSS version 18 software using independent-samples t-test.


RESULTS
Streptococcus spp.was successfully isolated from nine out of 20 (45%) specimens. Of the 9 positive samples cultured, 8 (88.8%) were S. mutans and 1 was S. sobrinus (11.2%). No inhibitory zone was observed around the disks and wells containing all concentrations ofA. citriodoraextracts. The minimum concentrations for inhibition of growth (MIC) resulted in turbidity in all tubes and were negative except for the control tubes. Inhibition zones were observed for amoxicillin and CHX disks (p< 0.001).


CONCLUSIONS
This study found that all studied bacteria were resistant to both types of the extracts; therefore, they are not a suggested replacement for chemical agents in mouthwash. It also shown that CHX is less effective than amoxicillin.
Postgraduate Student, Faculty of Dentistry, Babol University of Medical Sciences, Babol, Iran.
Faranak
F
Shafiee
Department of Pharmacology and Toxicology, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran.
Ali Akbar
AA
Moghadamnia
Department of Laboratory Sciences, Paramedical Faculty, Babol University of Medical Sciences, Babol, Iran.
Zahra
Z
Shahandeh
Department of Laboratory Sciences, Paramedical Faculty, Babol University of Medical Sciences, Babol, Iran.
Farhnaz
F
Sadighian
Dental Materials Research Center, Department of Pediatrics, Faculty of Dentistry, Babol University of Medical Sciences, Babol, Iran.
Effat
E
Khodadadi
A. citriodora; Amoxicillin; Chlorhexidine digluconate (CHX); S. mutans; S. sobrinus