Phytosphingosine disrupts dual-species oral biofilms and attenuates LPS-induced pro-inflammatory responses in human gingival fibroblasts

Oral biofilms are major etiological factors in dental caries and periodontitis and are often resistant to conventional anti-microbial therapies, particularly in mixed-species communities. Phytosphingosine (PHS), a naturally occurring bioactive sphingolipid, has demonstrated anti-microbial activity against several pathogens; however, its effects on mixed-species oral biofilms and inflammatory responses remain unclear. This study investigated the in vitro anti-microbial, anti-biofilm, and immunomodulatory activities of PHS against Streptococcus mutans and Aggregatibacter actinomycetemcomitans in single- and dual-species biofilms. Confocal laser scanning microscopy revealed a significant reduction in biofilm matrix formation in both single- and dual-species biofilms treated with PHS compared with untreated controls (P < 0.001). Cytotoxicity analysis demonstrated that cell viability remained above 90% following exposure to 5 µg/ml PHS for 24 h. Furthermore, PHS pretreatment significantly attenuated LPS-induced IL-6 and TNF-α production (P < 0.001). Collectively, these findings suggest that PHS is a promising dual-function agent with anti-microbial and anti-inflammatory properties and may have potential as an adjunctive therapeutic strategy for biofilm-associated oral diseases.