Synthesis and antifungal activity of ethers, alcohols, and iodohydrin derivatives of sclareol against phytopathogenic fungi in vitro.

This study synthesized 20 sclareol derivatives. The antifungal activities of these derivatives were evaluated in vitro against five phytopathogenic fungi using the mycelium growth rate method. Among all the tested compounds, compound 16 with one iodine atom and three hydroxyl groups displayed higher fungicidal activities against all the tested phytopathogenic fungi than precursor sclareol. Compound 16 also showed more pronounced antifungal activities against Curvularia lunata (IC50=12.09 µg/mL) and Alternaria brassicae (IC50=14.47 µg/mL) than the positive control, a commercial agricultural fungicide thiabendazole.