Antibacterial Effect of Sapindus mukorossi Aqueous Extract in Human Saliva—A Pilot Translational Study with an Ex Vivo Model

Abstract

Sapindus mukorrosi (Sm) seeds have been used in Chinese medicine for treating gingival disease, suggesting that Sm may modulate oral bacteria and alleviate gingival inflammation. However, the hydrophobicity of seed oil limits its use in the aqueous oral environment. Therefore, the artificial saliva-infused Sm seed aqueous extract (SMa) was developed and applied to our ex vivo model to test its anti-bacterial effect. Unstimulated whole saliva from seven patients with Stage III/IV, Grade C periodontitis was cultured for 8 h with or without SMa. The bacterial count was measured based on the optical density and bacterial DNA concentration. The salivary microbiome was sequenced via next-generation sequencing over the 16S rRNA gene V3-V4 hypervariable regions. The bacterial DNA concentration in the SMa group was significantly lower than the Without-SMa group after 6 to 8 h of culture. No significant difference in alpha and beta diversity was observed between the two groups. The relative abundance of Porphyromonas was reduced, while that of Veillonella was elevated in the SMa group compared to the Without-SMa group. The findings indicated that the antibacterial effects of SMa are manifested primarily through bacterial growth inhibition, with the minor modulation of specific taxa.