<i>Psidium guajava</i> L. hydroethanolic extract as endodontic irrigant: phytochemical analysis, antioxidant activity, antimicrobial action and biocompatibility

The soluble solids content in the extract was 3.35%. Using the quercetin standard curve, the total flavonoid concentration was 0.130 ± 0.110 mg/mL. In addition, using standard curve for phenolic acids, the total phenolic concentration was 1.770 ± 1.540 mg/mL. HPLC analysis revealed peaks of rutin, quercetin and kaempferol as major flavonoids in the <i>P. guajava</i> L. extract. The extract demonstrated notable antioxidant activity, with an IC₅₀ value of 10.39 µg/mL. The MMC values ranged 1.04-8.37 mg/mL. The extract at 8.37 mg/mL was effective in reducing the biofilms of standard and clinical strains of <i>E. faecalis</i> and <i>C. albicans</i> after 10 min. Cytotoxicity analysis revealed that all tested concentrations exhibited relatively low toxicity toward HaCaT cells. Genotoxicity assessment <i>via</i> the micronucleus assay indicated minimal DNA damage at all tested concentrations. Overall, <i>P. guajava</i> L. hydroethanolic extract at 8.37 mg/mL is the most effective concentration in reducing the biofilm of the standard and clinical strains of <i>E. faecalis</i> and <i>C. albicans</i>, while maintaining biocompatibility with HaCaT cultures.