P062 Identification of Octenidine (dihydrochloride) inhibiting fungal filamentation by the repurposing approach

Abstract

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PMObjectivesHyphal formation is an important virulence factor of opportunistic pathogenic fungi and plays a vital role in invasive fungal infections. Therefore, hyphae can act as a specific target against invasive fungal infections and it is a new attempt to focus on identification of compounds inhibiting hyphal growth. Amphotericin B has potent inhibitory effect on the growth of hyphae, but its high toxicity limits its clinical use. To address this question, we performed a high-throughput screen of an FDA-approved compound library (HY-L022, MCE®) to identify compounds with mycelial inhibitory function.MethodsWe performed a high-throughput screen of an FDA-approved compounds library to identify potentially novel compounds for inhibiting hyphal growth and used amphotericin B (1.56 μm) as a positive control drug. The screening schematic is shown in Figure 1a. Firstly, we investigated the mycelial inhibitory activity of each compound at 100 μm in RPMI 1640 medium with Candida albicans SN152 strain. Secondly, micro checkboard dilution method was applied to determine the minimum hyphae-inhibiting concentration of compounds. The compound being included in the next round could inhibit the hyphal formation when its concentration was ≤12.5 μm. Lastly, we expanded medium to YPD containing 10% FBS, YPD containing 5 mm N-acetylglucosamine (GlcNAc), and Spider medium. The final Candidate compound was determined due to its minimum hyphae-inhibiting concentration was ≤3.125 μm in four mediums.ResultsWe screened a library of FDA-approved compound and identified 117 Candidate compounds that inhibit hyphal growth (≤100 μm). We excluded 14 compounds with known antifungal activity, and finally 103 compounds were included in the next step of mycelial inhibitory activity screening (Fig. 1a). We further identified that 14 of 103 Candidate compounds (red square) could significantly inhibit the growth of mycelium at a concentration not higher than 12.5 μm in RPMI 1640 medium (Fig. 1b). We then expanded the types of media that induce mycelial growth (such as YPD medium with 10% FBS, YPD medium with 5 mm GlcNAc, and Spider medium) and used amphotericin B (1.56 μm) as a positive control drug and found that Octenidine (dihydrochloride) still has a significant inhibitory effect on mycelial growth in various mycelial induction media when it is as low as 3.125 μm (Figs. 2a and b).ConclusionOur study demonstrates that Octenidine (dihydrochloride) has a potent hyphal inhibitory activity and is helpful to open the way for the development of new antifungal therapeutics targeting filamentous formation.