Unlocking the Potential of Glutinol: Structural Diversification and Antifungal Activity against Phytopathogenic <i>Fusarium</i> Strains

Unlike most common pentacyclic plant triterpenes, glutinol has a methyl group at position C-9 and a Δ₅ double bond. At the same time, it lacks a methyl at C-10. These features significantly modify its chemical behavior compared to other triterpenes, particularly under oxidative conditions. Although the isolation of glutinol from various plant species has been documented, its chemistry remains largely unexplored. In this study, glutinol was isolated from the bark of <i>Balfourodendron riedelianum</i> as a starting material for top-down strategies of structural diversification, which included ring fusion, oxidation, aromatization, and ring cleavage reactions. Glutinol, together with a library of 22 derivatives, was evaluated for antifungal activity against three phytopathogenic <i>Fusarium</i> strains, <i>F. solani</i>, <i>F. graminearum</i>, and <i>F. tucumaniae</i>. Some of the derivatives displayed antifungal activity; in particular, compound <b>12</b>, featuring a triazine ring, displayed the best fungicidal properties against <i>F. solani</i> and <i>F. graminearum</i>, while the ring B cleavage product <b>23</b> showed the best activity against <i>F. tucumaniae</i>. This study highlights the potential of glutinol as a scaffold for structural diversification, and these results may contribute to the design of novel fungicidal agents against phytopathogenic strains.