Isolation, structure revision and stereochemistry of trichomycins A and B, aromatic analogues of amphotericin B.

Fungal infections pose an increasing global health threat, particularly to immunocompromised individuals. In response, the World Health Organization has prioritized the development of new antifungal agents. Among clinically used polyene macrolides, trichomycin remains structurally ambiguous despite decades since its discovery. This study presents an integrated re-assessment of the trichomycin complex focused on its two principal constituents using a combination of liquid chromatography-mass spectrometry (HPLC-DAD-ESI-MS), preparative-scale HPLC, two-dimensional NMR spectroscopy, and computational modeling. Four principal components were identified, including trichomycins A and B and their respective all-trans isomers, formed via light-induced isomerization. One-step prep-HPLC isolation enabled the purification of both trichomycins in analytically pure form. Detailed NMR analysis redefined the polyol fragment (C1-C14) of trichomycin A and confirmed structural consistency in trichomycin B. Absolute configurations of 13 stereocenters in each molecule were assigned by integrating experimental ³J coupling constants, ROE data, and molecular modeling, incorporating the generalized Karplus equation. The chromophore geometry was determined as 22E, 24E, 26E, 28Z, 30Z, 32E, 34E. By resolving key structural inconsistencies, this work lays the foundation for the rational derivatization of trichomycin and supports future efforts toward the development of novel polyene-based antifungal agents with improved pharmacological profiles.