In vitro and in vivo effects of the combination of myricetin and miconazole nitrate incorporated to thermosensitive hydrogels, on C. albicans biofilms.

BACKGROUND

Candida albicans-related infections are common infections in clinic, among which biofilm-associated infections are most devastating and challenging to overcome. Myricetin (MY) is a plant-derived natural product with various pharmacological activities. Its anti-biofilm effect against C. albicans and its ability to increase the antifungal effect of miconazole nitrate (MN) were unclear and yet need to be explored.

HYPOTHESIS/PURPOSE: In this study the anti-biofilm effect of MY and its ability to increase the antifungal effect of MN were investigated in vitro and in vivo.

STUDY DESIGN AND

METHODS

MY or/and MN were incorporated into a thermosensitive hydrogel (TSH) of poloxamer. The safety of MY or/and MN loaded TSHs towards human umbilical vein endothelial cells (HUVEC) was evaluated by a MTT assay and the in vivo safety towards mice knees was confirmed by histopathological examination. The anti-biofilm effect of MY and its ability to increase the antifungal effect of MN were investigated in vitro with C. albicans ATCC 10231 by broth microdilution method, crystal violet staining and scanning electron microscopy (SEM), as well as in vivo in an established mouse model of periprosthetic joint infection (PJI) by SEM, histological analysis, microorganism culture and detection of the serum levels of interleukin-6 (IL-6). The mechanism of action of MY was analyzed by qRT-PCR assay with C. albicans SC5314.

RESULTS

Our results showed that MY and MN incorporated into TSHs exhibited good stability and safety, excellent temperature sensitivity and controlled drug release property. MY (5-640 µg/ml) exhibited no effect on C. albicans cell viability and MY (≥80 µg/ml) showed a significantly inhibitory effect on biofilm formation. MIC50 (the lowest concentrations of drugs resulting in 50% decrease of C. albicans growth) and MIC80 (the lowest concentrations of drugs resulting in 80% decrease of C. albicans growth) of MN were respectively decreased from 2 µg/ml to 0.5 µg/ml and from 4 µg/ml to 2 µg/ml when used in combination with MY (80 µg/ml). The mouse PJI was effectively prevented by MY and MN incorporated into TSH.

CONCLUSIONS

Local application of MY and MN incorporated into TSH might be useful for clinical biofilm-associated infections.