Biological characterization of Iranian walnut (Juglans regia) leaves

In recent years, emphasis has been placed on the use of natural materials in the control and treatment of various infections, as some chemically synthesized drugs have undesirable side effects. In this study, the ethanol extract of Iranian walnut leaves was examined for antibacterial activities on Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguinis, and Actinomyces viscosus using the microdilution method. Total phenols, flavonoids, and flavonols were also determined colorimetrically. The minimum inhibitory concentrations (MIC) for ethanolic extract ranged between 15.6 and 187.5 mg/mL and minimum bactericidal concentrations (MBC) ranged between 31.25 and 250 mg/mL. Total phenols were 410 +/- 14.43 mg/g gallic acid equivalent, and total flavonols and flavonoids were 270 +/- 22.33 and 330 +/- 12.21 mg/g rutin equivalent, respectively. These findings show that Iranian walnut leaves have antibacterial effects on the 4 examined bacteria and may be a suitable alternative remedy for protection and treatment of dental plaque due to these microorganisms.