Antibacterial activity of hinokitiol against both antibiotic‐resistant and ‐susceptible pathogenic bacteria that predominate in the oral cavity and upper airways

• Published in: Microbiology and immunology 2019-06, Vol.63 (6), p.213-222
• Main Authors: Domon, Hisanori, Hiyoshi, Takumi, Maekawa, Tomoki, Yonezawa, Daisuke, Tamura, Hikaru, Kawabata, Shigetada, Yanagihara, Katsunori, Kimura, Osamu, Kunitomo, Eiji, Terao, Yutaka
• Format: Article
• Language: English
• Subjects: Aggregatibacter actinomycetemcomitans - drug effects; Anti-Bacterial Agents - pharmacology; Antibacterial activity; antibacterial agent; Antibiotics; Antifungal activity; Bacteria; Bacteria - classification; Bacteria - drug effects; Cell Line, Tumor - drug effects; Cell Survival - drug effects; Cytotoxicity; Endothelial cells; Epithelial cells; Epithelial Cells - drug effects; Essential oils; Fibroblasts; Fungicides; Fusobacterium nucleatum - drug effects; Gingiva; hinokitiol; Humans; Methicillin; Methicillin-Resistant Staphylococcus aureus - drug effects; Microbial Sensitivity Tests; Monoterpenes - pharmacology; Mouth - microbiology; Oral cavity; Pharynx; Porphyromonas gingivalis - drug effects; Prevotella intermedia - drug effects; Staphylococcus aureus - drug effects; Strains (organisms); Streptococcus infections; Streptococcus mutans - drug effects; Streptococcus pneumonia; Streptococcus pneumoniae; Streptococcus pneumoniae - drug effects; Streptococcus pyogenes - drug effects; Streptococcus sobrinus - drug effects; Tropolone - analogs & derivatives; Tropolone - pharmacology; Umbilical vein
• ISSN: 0385-5600; 1348-0421
• DOI: 10.1111/1348-0421.12688

Hinokitiol, a component of the essential oil isolated from Cupressaceae, possesses antibacterial and antifungal activities and has been used in oral care products. In this study, the antibacterial activities of hinokitiol toward various oral, nasal and nasopharyngeal pathogenic bacteria, including Streptococcus mutans, Streptococcus sobrinus, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Fusobacterium nucleatum, methicillin‐resistant and ‐susceptible Staphylococcus aureus, antibiotic‐resistant and ‐susceptible Streptococcus pneumoniae, and Streptococcus pyogenes were examined. Growth of all these bacterial strains was significantly inhibited by hinokitiol, minimal inhibitory concentrations of hinokitiol against S. mutans, S. sobrinus, P. gingivalis, P. intermedia, A. actinomycetemcomitans, F. nucleatum, methicillin‐resistant S. aureus, methicillin‐susceptible S. aureus, antibiotic‐resistant S. pneumoniae isolates, antibiotic‐susceptible S. pneumoniae, and S. pyogenes being 0.3, 1.0, 1.0, 30, 0.5, 50, 50, 30, 0.3–1.0, 0.5, and 0.3 μg/mL, respectively. Additionally, with the exception of P. gingivalis, hinokitiol exerted bactericidal effects against all bacterial strains 1 hr after exposure. Hinokitiol did not display any significant cytotoxicity toward the human gingival epithelial cell line Ca9‐22, pharyngeal epithelial cell line Detroit 562, human umbilical vein endothelial cells, or human gingival fibroblasts, with the exception of treatment with 500 μg/mL hinokitiol, which decreased numbers of viable Ca9‐22 cells and gingival fibroblasts by 13% and 12%, respectively. These results suggest that hinokitiol exhibits antibacterial activity against a broad spectrum of pathogenic bacteria and has low cytotoxicity towards human epithelial cells.