7-dehydro Cholesterol

7-dehydro Cholesterol (CAS No.: 434-16-2) is an endogenous sterol intermediate that functions as an immediate precursor in the terminal step of cholesterol biosynthesis and as a provitamin for vitamin D3 formation upon ultraviolet B irradiation. In mammalian systems, it is enzymatically reduced to cholesterol by 3β-hydroxysterol-Δ7-reductase (DHCR7), and disruption of this step leads to its accumulation, as observed in Smith-Lemli-Opitz syndrome, thereby linking it to neurodevelopmental abnormalities and altered lipid homeostasis. Upon UVB exposure, 7-dehydrocholesterol undergoes photochemical conversion to vitamin D3, a critical regulator of calcium and phosphate balance, bone metabolism, and immune function, making it highly relevant for studies of photobiology and endocrine signaling. Additionally, it is particularly susceptible to free radical-mediated oxidation, generating bioactive oxysterols implicated in oxidative stress and disease pathogenesis. As a research tool, 7-dehydrocholesterol is widely used to investigate cholesterol biosynthetic pathways, DHCR7-associated metabolic disorders, and mechanisms of vitamin D synthesis in skin models and engineered tissues. In vitro and in vivo studies typically employ concentration ranges tailored to specific experimental systems, often spanning low micromolar levels, to probe pathway modulation, lipid metabolism, and UV-induced biochemical responses.