Formulation and Antimicrobial Activity of Toothpastes from Four Citrus Peel Extracts Combined with Surfactant

Oral infections like dental caries and periodontal diseases arise from bacterial imbalances in the oral microbiome. While conventional antimicrobials risk resistance and adverse effects, citrus peel extracts, rich in bioactive compounds, exhibit antibacterial properties. This study aimed to formulate and evaluate citrus-peel toothpaste containing commonly available anionic and non-ionic surfactants. Four citrus peel extracts (C. limonum, C. reticulata, C. aurantium, and C. sinensis) and three different surfactants (sodium lauryl sulphate [SLS], Poloxamer-407, and Poloxamer-188) were incorporated into six toothpaste formulations (TP1–TP6). These formulations were evaluated for some physical properties, including pH, foaming ability, cleaning ability, moisture content, abrasiveness, spreadability, extrudability, and stability. Additionally, their antibacterial activity was evaluated against various bacterial species, along with antifungal activity against a single fungal strain. The formulations met standard parameters, ensuring quality and physicochemical properties. Two formulations with SLS surfactants (TP1 and TP2) demonstrated strong antimicrobial effects. Staphylococcus aureus was the most sensitive to TP1 and TP2 (inhibition zones of 25 and 27 mm, respectively), followed by Proteus vulgaris (21 and 22 mm for TP1 and TP2, respectively). However, both formulations had no effect on Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. On the other hand, both TP1 and TP2 exhibited a high effect against Candida albicans when compared to voriconazole as a positive control. The citrus-peel toothpaste, combined with surfactants, offers a refreshing aroma and antimicrobial effects against Gram-positive and Gram-negative microorganisms. It could be a safer alternative to synthetic toothpaste, but further studies are needed to confirm its safety and in vivo efficacy.