Background: Previous studies have shown antiviral, antibacterial, and anti-inflammatory activity of alkaline extract of the leaves of Sasa senanensis Rehder (SE). In order to manufacture an SE-containing toothpaste for combating oral diseases, we investigated the possible interaction between the candidate ingredients of toothpaste: SE, isopropyl methylphenol (IPMP, antibacterial agent) and charcoal prepared from Sasa senanensis Rehder.
Materials and methods: Cell viability of mock-infected, HIV-infected and UV-irradiated cells was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Superoxide radical scavenging activity was determined by electron-spin resonance spectroscopy. Antibacterial activity against Porphyromonas gingivalis 381 and Streptococcus mutans ATCC25175 was determined by the turbidity assay.
Results: Exposure to less than 50% SE or less than 0.31 mM IPMP for 10 min scarcely damaged human cultured gingival and periodontal ligament fibroblasts. Both SE and IPMP showed bi-modal action, stimulating the bacterial growth at lower concentrations, but synergistically inhibiting it at higher concentrations. Addition of extremely high concentrations of charcoal enhanced both anti-HIV and anti-UV activity of SE.
Conclusion: Practically, addition of charcoal may not be recommendable, since one or two orders higher concentrations of charcoal as compared with SE, are required to achieve the synergistic effect for anti-HIV and anti-UV activity. Rather, addition of about one tenth of the amount of IPMP may be recommendable for enhancing the antibacterial activity.