Skip to main content
. 2021 Aug 23;22(16):9097. doi: 10.3390/ijms22169097

Figure 1.

Figure 1

Noncanonical pathways of vitamin D3 and lumisterol (L3) activation (reprinted from [61] with the permission from Springer). D3, L3, and 7-DHC are substrates for CYP11A1 that produces the corresponding hydroxyderivatives. In the case of L3 and 7-DHC, the side chain can be cleaved by CYP11A1 to produce 7DHP or pL that can be further metabolized by steroidogenic enzymes (ES). In the skin, UVB acting on 5,7-dienes can lead to the production of D3, L3, and T3 derivatives with a full-length side chain and pD, pL, and pT derivatives with a shortened side chain. While the cut-off for UVC/UVB is 280 nm, we show the range of 290–315 nm because wavelengths below 290 nm are filtered by the ozone layer and no additional pre-D3 is produced above 315 nm [170]. 7DHC, 7-dehydrocholesterol; 7DHP, 7-dehydropregnenolone; pD, preganacalciferol; pL, preganalumisterol; D3, vitamin D3; L3, lumisterol; T3, tachysterol; OH, hydroxyl group; number before OH, carbon number with OH; number in subscripts after (OH), number of hydroxyl groups.