Anticryptococcal Evaluation of the Allylimine 3H2: Modulation of Virulence Traits and Synergistic Action with Amphotericin B

The development of new antifungal scaffolds is critical for expanding therapeutic options against cryptococcosis. Here, we evaluated the allylimine 3H2 as a potential lead compound against Cryptococcus gattii. The allylimine 3H2 exhibited consistent in vitro activity with a geometric mean MIC of 7.5 μg mL–1 across 12 strains and showed a synergistic interaction with amphotericin B, with FICI values reaching 0.5. The compound impaired major virulence determinants, reducing capsule size, melanin synthesis, and laccase activity while altering the negative surface charge. In a murine model, 3H2 potentiated amphotericin B therapy, extending survival to over 100 days and markedly lowering fungal burden in both lungs and brain. Docking simulations supported interactions of 3H2 with targets involved in melanin biosynthesis and cell wall-associated processes. These findings highlight 3H2 as a promising scaffold for antifungal drug discovery and support its further optimization as a candidate for combination therapy against cryptococcosis.