Antimicrob Agents Chemother. 2021 Jan 19:AAC.01628-20. doi: 10.1128/AAC.01628-20. Online ahead of print.
There is an increasing need for novel drugs and new strategies for the therapy of invasive candidiasis. This study aimed to develop and characterize liposome-based nanoparticles of carvacrol, cinnamaldehyde, citral or thymol with anti-Candida activities. Dioctadecyldimethylammonium bromide- and monoolein-based liposomes in a 1:2 molar ratio were prepared using a lipid-film hydration method. Liposomes were assembled with equal volumes of liposomal stock dispersion and stock solutions of carvacrol, cinnamaldehyde, citral or thymol in dimethyl sulfoxide. Cytotoxicity was tested on RAW 264.7 macrophages. In vitro antifungal activity of liposomes with phytocompounds was evaluated according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) methodology using clinical isolates of Candida albicans, Candida auris, Candida dubliniensis and Candida tropicalis Finally, the ability of macrophage cells to kill Candida after the addition of phytocompounds and their nanoparticles was determined. Nanoparticles with 64 μg/ml of cinnamaldehyde, 256 μg/ml of citral and 128 μg/ml of thymol had the best characteristics among the formulations tested. Highest encapsulation efficiencies were achieved with citral (78 to 83%) and carvacrol (66 to 71%) liposomes. Carvacrol and thymol in liposome-based nanoparticles were non-toxic regardless of the concentration. Moreover, carvacrol and thymol maintained their antifungal activity after encapsulation and there was a significant reduction (∼ 41%) of yeast survival when macrophages were incubated with carvacrol or thymol liposomes. In conclusion, carvacrol and thymol liposomes possess high stability, low cytotoxicity, and antifungal activity that acts synergistically with macrophages.