Antibacterial effects of Nanyang Kiwifruit extract toothpaste on common oral pathogens

Tao Liu^1#, Hongmei Wang^2#, Hua Li³, Lidan Shi⁴, Panpan Meng³, Lin Feng^3*, Rui Xiao³*

¹Department of Stomatology, the Sixth Medical Center of PLA General Hospital, Beijing 100853, China

²Department of Stomatology, the First Hospital of the Southern Theater Command of the Navy, Zhanjiang 524000, China

³Department of Stomatology, the First Medical Center of PLA General Hospital, Beijing 100853, China

⁴Xinhua Hospital of Tongzhou District, Beijing 101122, China

# T.L. and H.W. contributed equally to this work.L.F. and R.X. were co-corresponding authors.

*Correspondence: Lin Feng; Email: fenglin4746@163.com. Rui Xiao; Email: xiao_rui0809@163.com.

Abstract

Objective Oral diseases exhibit a multifactorial etiology. Plant-derived antimicrobial agents have gained recognition in daily personal care because of their eco-friendly, natural, and biodegradable properties. This study aimed to investigate the antibacterial efficacy of Nanyang kiwifruit extract toothpaste against common oral pathogens, in comparison with four commercially available toothpastes, to identify effective strategies for controlling pathogenic microorganisms and preventing oral diseases.

Methods Five toothpaste formulations (grape probiotic, white, grape-flavored, peach-flavored, and kiwifruit extract) were prepared as gradient dilutions via two-fold serial dilution. Each dilution series was mixed 1:1 with standardized suspensions of Candida albicans, Staphylococcus aureus, Escherichia coli, or Proteus vulgaris (0.5×10⁶ CFU/ml), followed by overnight incubation at 37°C. Minimum inhibitory concentrations (MICs) were determined spectrophotometrically at OD600. Minimum bactericidal concentrations (MBCs) were subsequently assessed by plate spreading of 100 μl aliquots of the overnight cultures onto LB agar, with bactericidal activity confirmed as a ≥99.9% CFU reduction.

Results The kiwifruit extract toothpaste demonstrated comprehensive antibacterial activity against all four tested pathogens, exhibiting broader-spectrum inhibitory effects compared with commercial toothpastes.

Conclusion The Nanyang kiwifruit extract toothpaste demonstrated broad-spectrum antimicrobial activity against both bacterial and fungal pathogens, exhibiting superior efficacy and broader coverage compared with single-target commercial toothpastes. Its multi-pathogen inhibitory capacity addresses a critical limitation of conventional antibacterial toothpastes that primarily target specific microbial subsets, thereby providing greater microbial control for oral ecological balance.

Keywords: antimicrobial toothpaste, kiwifruit extract, MIC, MBC, oral microbiota