5β-Dihydroprogesterone (5β-DHP), also known as 5β-pregnan-3,20-dione, is an endogenous neurosteroid and an intermediate in the biosynthesis of pregnanolone and epipregnanolone from progesterone. It is synthesized from progesterone by the enzyme 5β-reductase. 5β-DHP has been found to act as a positive allosteric modulator of the GABAA receptor (albeit with an affinity for this receptor regarded as relatively low (in comparison to 3α-hydroxylated progesterone metabolites such as pregnanolone and allopregnanolone)) and also as a negative allosteric modulator of the GABAA-rho receptor. In accordance with the former action, it is reported to possess anesthetic, anxiolytic, and antinociceptive effects. 5β-DHP has been found to act as an agonist of the pregnane X receptor (PXR) as well (albeit weakly (EC50 >10,000 µM)), and has been found to regulate uterine contractility through activation of this receptor. Unlike 5α-dihydroprogesterone, 5β-DHP does not possess affinity for the progesterone receptor, and hence, is not a progestogen.

CAS：128-23-4
中文别名：
英文别名：5beta-Pregnan-3,20-dione;(5R,8R,9S,10S,13S,14S,17S)-17-acetyl-10,13-dimethyl-1,2,4,5,6,7,8,9,11,12,14,15,16,17-tetradecahydrocyclopenta[a]phenanthren-3-one;Pregnane-3,20-dione, (5β)-;3,20-Pregnanedione;5beta-Dihydroprogesterone;5beta-pregnane-3,20-dione;CI2;5b-pregnane-3,20-dione;
分子式：C21H32O2
分子量：316.478
精确质量：316.24
Psa：34.14
Logp：4.8034

密度：1.048g/cm3
沸点：429.2ºC at 760mmHg
闪点：160.3ºC
折射率：1.515
蒸汽压：1.43E-07mmHg at 25°C