### Ergosterol: Definition, Functions, and Applications
#### Definition
Ergosterol is a sterol compound found in the cell membranes of fungi, yeast, and some protozoa. It serves a similar role to cholesterol in animal cells, providing structural integrity and fluidity to membranes. Its chemical formula is C28H44O.
#### Functions
1. **Membrane Stability**: Ergosterol is essential for maintaining the structure and function of fungal cell membranes.
2. **Precursor to Vitamin D2**: When exposed to UV light, ergosterol converts into vitamin D2 (ergocalciferol), which is vital for calcium absorption and bone health.
3. **Antifungal Target**: Ergosterol biosynthesis is a key target for antifungal drugs, as it is absent in human cells.
#### Applications
1. **Pharmaceuticals**: Used in the production of antifungal medications, such as azoles, which inhibit ergosterol synthesis.
2. **Nutraceuticals**: A source of vitamin D2, commonly used in dietary supplements and fortified foods.
3. **Research**: Studied for its role in fungal biology and as a biomarker for fungal growth.
4. **Cosmetics**: Incorporated into skincare products for its potential benefits in promoting skin health.
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