# 17α-Ethynyl-3α-androstanediol

17α-Ethynyl-3α-androstanediol (developmental code names HE-3235, Apoptone), also known as 17α-ethynyl-5α-androstane-3α,17β-diol, is a synthetic androstane steroid and a 17α-substituted derivative of 3α-androstanediol which was never marketed. It was under development for the treatment of prostate cancer but was discontinued.
17α-Ethynyl-3α-androstanediol itself shows very low affinity for steroid receptors, including the ARTooltip androgen receptor, ERαTooltip estrogen receptor alpha, ERβTooltip estrogen receptor beta, PRTooltip progesterone receptor, and GRTooltip glucocorticoid receptor, and its mechanism of action is not well-characterized. It produces 5α-dihydroethisterone (5α-dihydro-17α-ethynyltestosterone), a ligand of several steroid hormone receptors, and 17α-ethynyl-3β-androstanediol, an estrogen, as active metabolites. These metabolites may contribute importantly to the biological activity of 17α-ethynyl-3α-androstanediol, with 17α-ethynyl-3α-androstanediol potentially serving as a prodrug.
vte Affinities of estrogen receptor ligands for the ERα and ERβ :
| Ligand | Other names | Relative binding affinities (RBA, %)$^a$ | Relative binding affinities (RBA, %)$^a$ | Absolute binding affinities (K$_i$, nM)$^a$ | Absolute binding affinities (K$_i$, nM)$^a$ | Action |
| Ligand | Other names | ERα | ERβ | ERα | ERβ | Action |
| Estradiol | E2; 17β-Estradiol | 100 | 100 | 0.115 (0.04–0.24) | 0.15 (0.10–2.08) | Estrogen |
| Estrone | E1; 17-Ketoestradiol | 16.39 (0.7–60) | 6.5 (1.36–52) | 0.445 (0.3–1.01) | 1.75 (0.35–9.24) | Estrogen |
| Estriol | E3; 16α-OH-17β-E2 | 12.65 (4.03–56) | 26 (14.0–44.6) | 0.45 (0.35–1.4) | 0.7 (0.63–0.7) | Estrogen |
| Estetrol | E4; 15α,16α-Di-OH-17β-E2 | 4.0 | 3.0 | 4.9 | 19 | Estrogen |
| Alfatradiol | 17α-Estradiol | 20.5 (7–80.1) | 8.195 (2–42) | 0.2–0.52 | 0.43–1.2 | Metabolite |
| 16-Epiestriol | 16β-Hydroxy-17β-estradiol | 7.795 (4.94–63) | 50 | ? | ? | Metabolite |
| 17-Epiestriol | 16α-Hydroxy-17α-estradiol | 55.45 (29–103) | 79–80 | ? | ? | Metabolite |
| 16,17-Epiestriol | 16β-Hydroxy-17α-estradiol | 1.0 | 13 | ? | ? | Metabolite |
| 2-Hydroxyestradiol | 2-OH-E2 | 22 (7–81) | 11–35 | 2.5 | 1.3 | Metabolite |
| 2-Methoxyestradiol | 2-MeO-E2 | 0.0027–2.0 | 1.0 | ? | ? | Metabolite |
| 4-Hydroxyestradiol | 4-OH-E2 | 13 (8–70) | 7–56 | 1.0 | 1.9 | Metabolite |
| 4-Methoxyestradiol | 4-MeO-E2 | 2.0 | 1.0 | ? | ? | Metabolite |
| 2-Hydroxyestrone | 2-OH-E1 | 2.0–4.0 | 0.2–0.4 | ? | ? | Metabolite |
| 2-Methoxyestrone | 2-MeO-E1 | <0.001–<1 | <1 | ? | ? | Metabolite |
| 4-Hydroxyestrone | 4-OH-E1 | 1.0–2.0 | 1.0 | ? | ? | Metabolite |
| 4-Methoxyestrone | 4-MeO-E1 | <1 | <1 | ? | ? | Metabolite |
| 16α-Hydroxyestrone | 16α-OH-E1; 17-Ketoestriol | 2.0–6.5 | 35 | ? | ? | Metabolite |
| 2-Hydroxyestriol | 2-OH-E3 | 2.0 | 1.0 | ? | ? | Metabolite |
| 4-Methoxyestriol | 4-MeO-E3 | 1.0 | 1.0 | ? | ? | Metabolite |
| Estradiol sulfate | E2S; Estradiol 3-sulfate | <1 | <1 | ? | ? | Metabolite |
| Estradiol disulfate | Estradiol 3,17β-disulfate | 0.0004 | ? | ? | ? | Metabolite |
| Estradiol 3-glucuronide | E2-3G | 0.0079 | ? | ? | ? | Metabolite |
| Estradiol 17β-glucuronide | E2-17G | 0.0015 | ? | ? | ? | Metabolite |
| Estradiol 3-gluc. 17β-sulfate | E2-3G-17S | 0.0001 | ? | ? | ? | Metabolite |
| Estrone sulfate | E1S; Estrone 3-sulfate | <1 | <1 | >10 | >10 | Metabolite |
| Estradiol benzoate | EB; Estradiol 3-benzoate | 10 | ? | ? | ? | Estrogen |
| Estradiol 17β-benzoate | E2-17B | 11.3 | 32.6 | ? | ? | Estrogen |
| Estrone methyl ether | Estrone 3-methyl ether | 0.145 | ? | ? | ? | Estrogen |
| ent-Estradiol | 1-Estradiol | 1.31–12.34 | 9.44–80.07 | ? | ? | Estrogen |
| Equilin | 7-Dehydroestrone | 13 (4.0–28.9) | 13.0–49 | 0.79 | 0.36 | Estrogen |
| Equilenin | 6,8-Didehydroestrone | 2.0–15 | 7.0–20 | 0.64 | 0.62 | Estrogen |
| 17β-Dihydroequilin | 7-Dehydro-17β-estradiol | 7.9–113 | 7.9–108 | 0.09 | 0.17 | Estrogen |
| 17α-Dihydroequilin | 7-Dehydro-17α-estradiol | 18.6 (18–41) | 14–32 | 0.24 | 0.57 | Estrogen |
| 17β-Dihydroequilenin | 6,8-Didehydro-17β-estradiol | 35–68 | 90–100 | 0.15 | 0.20 | Estrogen |
| 17α-Dihydroequilenin | 6,8-Didehydro-17α-estradiol | 20 | 49 | 0.50 | 0.37 | Estrogen |
| Δ$^8$-Estradiol | 8,9-Dehydro-17β-estradiol | 68 | 72 | 0.15 | 0.25 | Estrogen |
| Δ$^8$-Estrone | 8,9-Dehydroestrone | 19 | 32 | 0.52 | 0.57 | Estrogen |
| Ethinylestradiol | EE; 17α-Ethynyl-17β-E2 | 120.9 (68.8–480) | 44.4 (2.0–144) | 0.02–0.05 | 0.29–0.81 | Estrogen |
| Mestranol | EE 3-methyl ether | ? | 2.5 | ? | ? | Estrogen |
| Moxestrol | RU-2858; 11β-Methoxy-EE | 35–43 | 5–20 | 0.5 | 2.6 | Estrogen |
| Methylestradiol | 17α-Methyl-17β-estradiol | 70 | 44 | ? | ? | Estrogen |
| Diethylstilbestrol | DES; Stilbestrol | 129.5 (89.1–468) | 219.63 (61.2–295) | 0.04 | 0.05 | Estrogen |
| Hexestrol | Dihydrodiethylstilbestrol | 153.6 (31–302) | 60–234 | 0.06 | 0.06 | Estrogen |
| Dienestrol | Dehydrostilbestrol | 37 (20.4–223) | 56–404 | 0.05 | 0.03 | Estrogen |
| Benzestrol (B2) | – | 114 | ? | ? | ? | Estrogen |
| Chlorotrianisene | TACE | 1.74 | ? | 15.30 | ? | Estrogen |
| Triphenylethylene | TPE | 0.074 | ? | ? | ? | Estrogen |
| Triphenylbromoethylene | TPBE | 2.69 | ? | ? | ? | Estrogen |
| Tamoxifen | ICI-46,474 | 3 (0.1–47) | 3.33 (0.28–6) | 3.4–9.69 | 2.5 | SERM |
| Afimoxifene | 4-Hydroxytamoxifen; 4-OHT | 100.1 (1.7–257) | 10 (0.98–339) | 2.3 (0.1–3.61) | 0.04–4.8 | SERM |
| Toremifene | 4-Chlorotamoxifen; 4-CT | ? | ? | 7.14–20.3 | 15.4 | SERM |
| Clomifene | MRL-41 | 25 (19.2–37.2) | 12 | 0.9 | 1.2 | SERM |
| Cyclofenil | F-6066; Sexovid | 151–152 | 243 | ? | ? | SERM |
| Nafoxidine | U-11,000A | 30.9–44 | 16 | 0.3 | 0.8 | SERM |
| Raloxifene | – | 41.2 (7.8–69) | 5.34 (0.54–16) | 0.188–0.52 | 20.2 | SERM |
| Arzoxifene | LY-353,381 | ? | ? | 0.179 | ? | SERM |
| Lasofoxifene | CP-336,156 | 10.2–166 | 19.0 | 0.229 | ? | SERM |
| Ormeloxifene | Centchroman | ? | ? | 0.313 | ? | SERM |
| Levormeloxifene | 6720-CDRI; NNC-460,020 | 1.55 | 1.88 | ? | ? | SERM |
| Ospemifene | Deaminohydroxytoremifene | 0.82–2.63 | 0.59–1.22 | ? | ? | SERM |
| Bazedoxifene | – | ? | ? | 0.053 | ? | SERM |
| Etacstil | GW-5638 | 4.30 | 11.5 | ? | ? | SERM |
| ICI-164,384 | – | 63.5 (3.70–97.7) | 166 | 0.2 | 0.08 | Antiestrogen |
| Fulvestrant | ICI-182,780 | 43.5 (9.4–325) | 21.65 (2.05–40.5) | 0.42 | 1.3 | Antiestrogen |
| Propylpyrazoletriol | PPT | 49 (10.0–89.1) | 0.12 | 0.40 | 92.8 | ERα agonist |
| 16α-LE2 | 16α-Lactone-17β-estradiol | 14.6–57 | 0.089 | 0.27 | 131 | ERα agonist |
| 16α-Iodo-E2 | 16α-Iodo-17β-estradiol | 30.2 | 2.30 | ? | ? | ERα agonist |
| Methylpiperidinopyrazole | MPP | 11 | 0.05 | ? | ? | ERα antagonist |
| Diarylpropionitrile | DPN | 0.12–0.25 | 6.6–18 | 32.4 | 1.7 | ERβ agonist |
| 8β-VE2 | 8β-Vinyl-17β-estradiol | 0.35 | 22.0–83 | 12.9 | 0.50 | ERβ agonist |
| Prinaberel | ERB-041; WAY-202,041 | 0.27 | 67–72 | ? | ? | ERβ agonist |
| ERB-196 | WAY-202,196 | ? | 180 | ? | ? | ERβ agonist |
| Erteberel | SERBA-1; LY-500,307 | ? | ? | 2.68 | 0.19 | ERβ agonist |
| SERBA-2 | – | ? | ? | 14.5 | 1.54 | ERβ agonist |
| Coumestrol | – | 9.225 (0.0117–94) | 64.125 (0.41–185) | 0.14–80.0 | 0.07–27.0 | Xenoestrogen |
| Genistein | – | 0.445 (0.0012–16) | 33.42 (0.86–87) | 2.6–126 | 0.3–12.8 | Xenoestrogen |
| Equol | – | 0.2–0.287 | 0.85 (0.10–2.85) | ? | ? | Xenoestrogen |
| Daidzein | – | 0.07 (0.0018–9.3) | 0.7865 (0.04–17.1) | 2.0 | 85.3 | Xenoestrogen |
| Biochanin A | – | 0.04 (0.022–0.15) | 0.6225 (0.010–1.2) | 174 | 8.9 | Xenoestrogen |
| Kaempferol | – | 0.07 (0.029–0.10) | 2.2 (0.002–3.00) | ? | ? | Xenoestrogen |
| Naringenin | – | 0.0054 (<0.001–0.01) | 0.15 (0.11–0.33) | ? | ? | Xenoestrogen |
| 8-Prenylnaringenin | 8-PN | 4.4 | ? | ? | ? | Xenoestrogen |
| Quercetin | – | <0.001–0.01 | 0.002–0.040 | ? | ? | Xenoestrogen |
| Ipriflavone | – | <0.01 | <0.01 | ? | ? | Xenoestrogen |
| Miroestrol | – | 0.39 | ? | ? | ? | Xenoestrogen |
| Deoxymiroestrol | – | 2.0 | ? | ? | ? | Xenoestrogen |
| β-Sitosterol | – | <0.001–0.0875 | <0.001–0.016 | ? | ? | Xenoestrogen |
| Resveratrol | – | <0.001–0.0032 | ? | ? | ? | Xenoestrogen |
| α-Zearalenol | – | 48 (13–52.5) | ? | ? | ? | Xenoestrogen |
| β-Zearalenol | – | 0.6 (0.032–13) | ? | ? | ? | Xenoestrogen |
| Zeranol | α-Zearalanol | 48–111 | ? | ? | ? | Xenoestrogen |
| Taleranol | β-Zearalanol | 16 (13–17.8) | 14 | 0.8 | 0.9 | Xenoestrogen |
| Zearalenone | ZEN | 7.68 (2.04–28) | 9.45 (2.43–31.5) | ? | ? | Xenoestrogen |
| Zearalanone | ZAN | 0.51 | ? | ? | ? | Xenoestrogen |
| Bisphenol A | BPA | 0.0315 (0.008–1.0) | 0.135 (0.002–4.23) | 195 | 35 | Xenoestrogen |
| Endosulfan | EDS | <0.001–<0.01 | <0.01 | ? | ? | Xenoestrogen |
| Kepone | Chlordecone | 0.0069–0.2 | ? | ? | ? | Xenoestrogen |
| o,p'-DDT | – | 0.0073–0.4 | ? | ? | ? | Xenoestrogen |
| p,p'-DDT | – | 0.03 | ? | ? | ? | Xenoestrogen |
| Methoxychlor | p,p'-Dimethoxy-DDT | 0.01 (<0.001–0.02) | 0.01–0.13 | ? | ? | Xenoestrogen |
| HPTE | Hydroxychlor; p,p'-OH-DDT | 1.2–1.7 | ? | ? | ? | Xenoestrogen |
| Testosterone | T; 4-Androstenolone | <0.0001–<0.01 | <0.002–0.040 | >5000 | >5000 | Androgen |
| Dihydrotestosterone | DHT; 5α-Androstanolone | 0.01 (<0.001–0.05) | 0.0059–0.17 | 221–>5000 | 73–1688 | Androgen |
| Nandrolone | 19-Nortestosterone; 19-NT | 0.01 | 0.23 | 765 | 53 | Androgen |
| Dehydroepiandrosterone | DHEA; Prasterone | 0.038 (<0.001–0.04) | 0.019–0.07 | 245–1053 | 163–515 | Androgen |
| 5-Androstenediol | A5; Androstenediol | 6 | 17 | 3.6 | 0.9 | Androgen |
| 4-Androstenediol | – | 0.5 | 0.6 | 23 | 19 | Androgen |
| 4-Androstenedione | A4; Androstenedione | <0.01 | <0.01 | >10000 | >10000 | Androgen |
| 3α-Androstanediol | 3α-Adiol | 0.07 | 0.3 | 260 | 48 | Androgen |
| 3β-Androstanediol | 3β-Adiol | 3 | 7 | 6 | 2 | Androgen |
| Androstanedione | 5α-Androstanedione | <0.01 | <0.01 | >10000 | >10000 | Androgen |
| Etiocholanedione | 5β-Androstanedione | <0.01 | <0.01 | >10000 | >10000 | Androgen |
| Methyltestosterone | 17α-Methyltestosterone | <0.0001 | ? | ? | ? | Androgen |
| Ethinyl-3α-androstanediol | 17α-Ethynyl-3α-adiol | 4.0 | <0.07 | ? | ? | Estrogen |
| Ethinyl-3β-androstanediol | 17α-Ethynyl-3β-adiol | 50 | 5.6 | ? | ? | Estrogen |
| Progesterone | P4; 4-Pregnenedione | <0.001–0.6 | <0.001–0.010 | ? | ? | Progestogen |
| Norethisterone | NET; 17α-Ethynyl-19-NT | 0.085 (0.0015–<0.1) | 0.1 (0.01–0.3) | 152 | 1084 | Progestogen |
| Norethynodrel | 5(10)-Norethisterone | 0.5 (0.3–0.7) | <0.1–0.22 | 14 | 53 | Progestogen |
| Tibolone | 7α-Methylnorethynodrel | 0.5 (0.45–2.0) | 0.2–0.076 | ? | ? | Progestogen |
| Δ$^4$-Tibolone | 7α-Methylnorethisterone | 0.069–<0.1 | 0.027–<0.1 | ? | ? | Progestogen |
| 3α-Hydroxytibolone | – | 2.5 (1.06–5.0) | 0.6–0.8 | ? | ? | Progestogen |
| 3β-Hydroxytibolone | – | 1.6 (0.75–1.9) | 0.070–0.1 | ? | ? | Progestogen |
| Footnotes: $^a$ = (1) Binding affinity values are of the format "median (range)" (# (#–#)), "range" (#–#), or "value" (#) depending on the values available. The full sets of values within the ranges can be found in the Wiki code. (2) Binding affinities were determined via displacement studies in a variety of in-vitro systems with labeled estradiol and human ERα and ERβ proteins (except the ERβ values from Kuiper et al. (1997), which are rat ERβ). Sources: See template page. |||||||
Analogues of 17α-ethynyl-3α-androstanediol include 17α-ethynyl-3β-androstanediol, ethinylandrostenediol (17α-ethynyl-5-androstenediol), ethandrostate (17α-ethynyl-5-androstenediol 3β-cyclohexanepropionate), ethinylestradiol (17α-ethynylestradiol), ethisterone (17α-ethynyltestosterone), and 5α-dihydroethisterone (17α-ethynyldihydrotestosterone).