P063 Research on antifungal activity of a new azoles compound, YZJT-1903
Authors: Zhu Shuo , Li Wanqian , Wu Hao , Lu Hui , Jiang Yuanying 
Published: September 2022

Abstract

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM

Objectives
Fluconazole is widely used to treat invasive fungal infections, but the fluconazole resistance of pathogenic fungi undermines its antifungal efficacy. Although voriconazole has a good anti-Aspergillus fumigatus activity, it is not a first-line drug for treating infections caused by Candida and Cryptococcus species. To meet the demand for new azoles, in our previous studies, we identified a new azoles compound, YZJT-1903 (Fig. 1e), and found that YZJT-1903 has a longer in vivo half-life (˃10 days in rat) and a wider therapeutic window than voriconazole, indicating that YZJT-1903 is a promising azoles compound to treat invasive fungal infections. In this study, we further investigated antifungal activity of YZJT-1903 compared with fluconazole and voriconazole.

Methods
We investigated the antifungal spectrum of YZJT-1903 and minimum inhibitory concentration (MIC) and accumulative antifungal percentage of YZJT-1903 against various pathogenic fungi using microbroth dilution method. We quantitatively analyzed the inhibitory effect of YZJT-1903 on fungal growth by the Time-Growth Curve assay. Mutation Preventative Concentration (MPC) was carried out to verify the antifungal potential of YZJT-1903. Sterols of plasma membrane were extracted and the composition was analyzed through Gas Chromatograph-Mass Spectrometer (GC-MS) to verify the classical action mechanism of azoles.

Results
Our MIC assay results demonstrated that YZJT-1903 has a broad antifungal spectrum and can significantly inhibit the growth of A. fumigatus, Cryptococcus neoformans, Cryptococcus gatti, and Candida species (such as Candida albicans, C. tropicalis, C. parapsilosis, C. glabrata, C. guilliermondii, and C. auris) (Fig. 1a). We found that the antifungal activity of YZJT-1903 is equivalent to that of voriconazole, but superior to that of fluconazole (Fig. 1a). Accumulative antifungal percentage can directly reflect this relationship quantitatively among YZJT-1903, fluconazole, and voriconazole due to the curve of YZJT-1903 has no significance with voriconazole (Fig. 1b). YZJT-1903 (0.25 μg/ml) has similar inhibitory effect to voriconazole (0.25 μg/ml) on the growth of C. albicans and C. neoformans, but has the best inhibitory effect on C. auris [compared with voriconazole (0.25 μg/ml), and fluconazole (0.25 μg/ml)] (Fig. 1c). MPC of YZJT-1903 in C. neoformans is as low as 0.25 μg/ml which means YZJT-1903 at low concentration can already prevent the drug-resistant mutation of strains, therefore, avoid the occurrence of resistance in Cryptococcus spp. (Fig. 1d). Extraction of sterols showed that the fungal cell treated with YZJT-1903 at 0.063 μg/ml have completely no detectable ergosterol which is similar to the group of fluconazole at 4 μg/ml, and the group of voriconazole at 0.031 μg/ml (Fig. 2). This result gave a hint that maybe the property of YZJT-1903 is more similar to voriconazole which may matter with the structure of these two compounds. We found that feeding exogenous 100 μm ergosterol counteracted the antifungal activity of YZJT-1903, indicating that YZJT-1903 has an antifungal activity by inhibiting the synthesis of ergosterol.

Conclusion
Our study demonstrates that YZJT-1903 has a potent antifungal activity, which will contribute to addressing devastating global invasive fungal infections caused by Candida and Cryptococcus species.