ergosterooli

Ergosterol is a sterol that is a key component of fungal cell membranes, where it helps regulate fluidity and permeability. It is the principal sterol in many fungi and is not found in significant amounts in plants or animals.

Chemically, ergosterol is a 28-carbon sterol with a hydroxyl group at the C-3 position and a characteristic set of double bonds (ergosta-5,7,22-trien-3β-ol). It is assembled by the fungal mevalonate pathway, through steps that convert acetyl-CoA to squalene, then to lanosterol, and finally to ergosterol via a series of demethylation and reduction reactions. The biosynthetic pathway is a common target of antifungal drugs, particularly azoles that inhibit lanosterol 14α-demethylase (ERG11).

Functionally, ergosterol maintains membrane structure and integrity in fungi, supporting proper membrane protein function and allowing adaptation to environmental stresses. Its presence is essential for viability in many fungal species, making the sterol a selective target for antifungal therapy. Drugs such as amphotericin B interact with ergosterol to form pores in membranes, while azoles disrupt ergosterol synthesis, increasing membrane permeability and impairing growth. Resistance can arise through reduced ergosterol content, mutations in pathway enzymes, or increased efflux of drugs.

In addition to its biological role, ergosterol can be converted to ergocalciferol (vitamin D2) upon UV exposure. Analytical measurement of ergosterol serves as a biomarker for fungal biomass in environmental and food studies, typically using HPLC or GC after lipid extraction.