Table 17.

P450 27B1

Properties	References
Natural substrates: 25-Hydroxyvitamin D3, 27-hydroxyvitamin D3, 24-oxo-,25-hydroxyvitamin D3, 25-hydroxy-3-epi-vitamin D3, 24(R),25-dihydroxyvitamin D3, 20,24-, 20,25-, and 20,26-dihydroxyvitamin D3	(Inouye and Sakaki 2001; Maas et al. 2001; Sakaki et al. 2005; Tang et al. 2013; Pan et al. 2016)
Function: 25-Hydroxyvitamin D3 1α-hydroxylase (Figs. 18, 20), synthesizes 1α,25-dihydroxyvitamin D3, the active form of vitamin D3, 24(R),25-dihydroxyvitamin D3 1α-hydroxylation
Inhibition: Decreased plasma 1α,25-dihydroxyvitamin D levels
Inhibitors: (Schuster, Egger, Nussbaumer, et al. 2003)
Drugs:
Azole drugs a (ketoconazole, liarozole) (Frizen and Zhegin 1976; Schuster et al. 2001; Bruno and Njar 2007)
Efavirenz b (Ellfolk et al. 2009; Wegler et al. 2016)
Ritonavir, indinavir, nelfinavir c (Cozzolino et al. 2003)
Natural compounds:
17α,20-Dihydroxyvitamin D3 b (Tang et al. 2013)
1α,25-Dihydroxyvitamin D3 b (Bland et al. 1999; Xie et al. 2002; Pascussi et al. 2005; Avila et al. 2007; Lechner et al. 2007; Wietrzyk 2007; Wu et al. 2007; Ellfolk et al. 2009)
Genistein c (Farhan and Cross 2002; Farhan et al. 2003)
Physiological compounds:
Short hairpin RNA c ((Wu et al. 2007)
Thyroid hormones c (Kozai et al. 2013)
Physiological condition and illnesses:
Breast cancer d (Zhalehjoo et al. 2017)
Other compounds:
Azoles a ((R)-VID400 weak inhibitor) (Xie et al. 2002; Schuster, Egger, Reddy, et al. 2003; Bruno and Njar 2007)
8-Bromo cAMP c (Avila et al. 2004)
Calcium b (high concentrations) (Bland et al. 1999)
Imidazoles a (e.g. SDZ-88357, SDZ 89–443, SDZ 284971, SDZ 284814, (R)- SDZ 287871, (R)-SDZ 286907, SDZ 283251, (S)- SDZ 285428, (R)-VAB636) (Schuster et al. 2001; Schuster, Egger, Nussbaumer, et al. 2003; Schuster et al. 2006)
Pyridine compounds a (Schuster, Egger, Nussbaumer, et al. 2003)
Induction: Increased production of 1,25-dihydroxyvitamin D3
Inducers:
Drugs:
Raloxifene d (Somjen et al. 2005)
Ritonavir, dexamethasone d (Wegler et al. 2016)
Natural compounds:
Carboxy biochainin A, genistein d (Somjen et al. 2005; Lechner et al. 2006; Somjen et al. 2007)
25-Hydroxyvitamin D3, femarelle, daidzein d (Somjen et al. 2017)
Forskolin e (Bland et al. 1999)
Physiological compounds:
5α-Dihydrotestosterone d (Somjen et al. 2007)
17β-Estradiol d (Lechner et al. 2006)
Parathyroid hormone d (Somjen et al. 2005; Somjen et al. 2007)
Spironolactone d (Alesutan et al. 2013)
Physiological condition and illnesses:
Colonic inflammation e (Du et al. 2017)
Psoriasis e (Sumantran et al. 2016)
Non-small cell lung cancer d (Ge et al. 2017)
Other compounds:
Calcium e (low concentrations) (Bland et al. 1999)

Footnotes:

^aCompetitive inhibition, ligand binding

^bGene downregulated/suppressed

^cReduced/suppressed mRNA and/or protein level/expression and activity

^dIncreased transcription/mRNA/protein expression/levels /and/or catalytic activity

^eUp-regulation of biosynthesis, increased expression of protein