7‑hydroxycalamenene Effects on Secreted Aspartic Proteases Activity and Biofilm Formation of Candida spp.

Background: The 7‑hydroxycalamenenene‑rich essential oil (EO) obtained from the leaves of Croton cajucara (red morphotype) have been described as active against bacteria, protozoa, and fungi species. In this work, we aimed to evaluate the effectiveness of 7‑hydroxycalamenenene against Candida albicans and nonalbicans species. Materials and Methods: C. cajucara EO was obtained by hydrodistillation and its major compound, 7‑hydroxycalamenene, was purified using preparative column chromatography. The anti‑candidal activity was investigated by minimum inhibitory concentration (MIC) and secreted aspartic proteases (SAP) and biofilm inhibition assays. Results: 7‑hydroxycalamenene (98% purity) displayed anti‑candidal activity against all Candida species tested. Higher activity was observed against Candida dubliniensis, Candida parapsilosis and Candida albicans, showing MIC values ranging from 39.06 µg/ml to 78.12 µg/ml. The purified 7‑hydroxycalamenene was able to inhibit 58% of C. albicans ATCC 36801 SAP activity at MIC concentration (pH 7.0). However, 7‑hydroxycalamenene demonstrated poor inhibitory activity on C. albicans ATCC 10231 biofilm formation even at the highest concentration tested (2500 µg/ml). Conclusion: The bioactive potential of 7‑hydroxycalamenene against planktonic Candida spp. further supports its use for the development of antimicrobials with anti‑candidal activity.