Product Overview

Androstenedione (androst-4-ene-3,17-dione, Δ⁴-androstenedione, CAS 63-05-8, C₁₉H₂₆O₂, MW 286.41 g/mol) is the central C19 steroid intermediate at the biosynthetic branch-point of androgens and estrogens — the immediate precursor to both testosterone (via 17β-hydroxysteroid dehydrogenase type 3/5, AKR1C3 — reduction of the C17 ketone to 17β-hydroxyl) and estrone (via aromatase, CYP19A1 — three-step A-ring aromatization with C19 methyl elimination as formate). Androstenedione is produced naturally in three human steroidogenic tissues: the adrenal cortex zona reticularis (ACTH-regulated, DHEA → androstenedione via 3β-HSD2), testicular Leydig cells (LH-regulated, progesterone → 17α-OH-progesterone → androstenedione via CYP17A1 17,20-lyase activity), and ovarian theca cells (same Δ⁴ pathway as testes). It functions as a weak androgen itself (binding androgen receptor with ~1/10 the affinity of testosterone) but is primarily a prohormone — its biological significance lies in its conversion to the potent androgens (testosterone, DHT) and estrogens (estrone, estradiol) in peripheral tissues expressing 17β-HSD and aromatase. UPOR Biotech’s androstenedione is produced via microbial biotransformation of phytosterols (β-sitosterol, campesterol, stigmasterol from non-GMO soy or pine tall oil) using Mycobacterium neoaurum or M. fortuitum engineered strains. The bacterium’s endogenous steroid catabolic pathway (cholesterol → androstenedione as the first committed intermediate before 9α-hydroxylation and A/B-ring degradation) has been genetically modified to knock out 9α-hydroxylase (kshA/kshB) and Δ¹-dehydrogenase (kstD) — preventing further degradation and accumulating androstenedione as the terminal product at 60-80% molar yield. This biotech route has completely supplanted the historical diosgenin chemical degradation route since the 1990s, providing a sustainable, plant-based, non-GMO supply chain that is independent of wild yam harvesting or petroleum-derived synthetic chemistry. After fermentation, androstenedione is extracted, purified via column chromatography and recrystallization to ≥99% HPLC purity, and lyophilized to a white crystalline powder.

As a specialized pharmaceutical intermediate manufacturer and supplier, UPOR Biotech provides androstenedione exclusively to DEA-registered (US Schedule III) and equivalent international regulatory-compliant pharmaceutical companies, contract manufacturing organizations (CMOs), and licensed research institutions for legitimate pharmaceutical production and research purposes. Androstenedione’s position as the central node in steroid API synthesis makes it the highest-volume steroid intermediate globally — serving as the starting material for the entire testosterone ester franchise (cypionate, enanthate, propionate, undecanoate), synthetic anabolic steroids (nandrolone, boldenone, stanozolol, oxandrolone, methenolone), combined oral contraceptive 19-nor progestins (norethindrone, levonorgestrel, desogestrel, gestodene), and estrogen APIs (estradiol, estradiol valerate/cypionate). GMP manufacturing and DMF Type II preparation support available for ANDA and 505(b)(2) filings. All purchasers must provide valid regulatory credentials before order acceptance.

Androstenedione vs DHEA vs Testosterone — The Steroidogenic Pathway Branch-Point: Why Androstenedione Is the Central C19 Intermediate Between the Δ⁵ and Δ⁴ Pathways

The three C19 steroid hormones form an interconnected metabolic network — understanding their relationships is essential for pharmaceutical intermediate sourcing. DHEA (Dehydroepiandrosterone, Δ⁵ pathway) — the most abundant circulating steroid (sulfated as DHEA-S at μM concentrations). Produced in the adrenal zona reticularis from 17α-OH-pregnenolone via CYP17A1 17,20-lyase. DHEA is the Δ⁵ precursor: it must be converted to androstenedione (via 3β-HSD2) before entering the testosterone/estrogen pathway. DHEA itself has negligible androgen receptor binding — it is a pure prohormone. Pharmaceutical use: DHEA is the starting material for 17α-alkylated androgens. Androstenedione — the crossroads molecule. It sits at the intersection of the Δ⁵ (DHEA → androstenedione) and Δ⁴ (progesterone → 17α-OH-progesterone → androstenedione) pathways. It is the immediate precursor to BOTH testosterone and estrone — making it the most versatile starting material for steroid API synthesis. The C17 ketone (C=O) provides a chemical handle for selective reduction (to 17β-OH testosterone) or modification (ethynylation → 17α-ethynyl steroids for oral contraceptives). The C3 ketone + Δ⁴ double bond provides the characteristic α,β-unsaturated ketone chromophore (UV λmax 240 nm). Testosterone — the terminal potent androgen. Produced from androstenedione by 17β-HSD3 in Leydig cells. Testosterone is the active hormone (not a prohormone) — it binds androgen receptor directly (Kd ~0.5 nM) and is converted to the more potent DHT by 5α-reductase in target tissues. For pharmaceutical synthesis, androstenedione is the preferred starting material: it is produced in the highest fermentation yield (60-80% from phytosterols vs ~40% for testosterone via the same route), has the most chemical versatility (C17 ketone enables diverse derivatization), and is the most cost-effective steroid scaffold ($/kg).

Technical Specifications

PropertySpecification
Product NameAndrostenedione (4-Androstene-3,17-dione) — Pharma Intermediate Grade
Common Name / SynonymsAndrost-4-ene-3,17-dione; 4-Androstene-3,17-dione; Δ⁴-Androstenedione; Andro; 4-Androstenedione; SKF 2170; NSC 12165
CAS Number63-05-8
EINECS200-554-5
Molecular FormulaC₁₉H₂₆O₂
Molecular Weight286.41 g/mol
Chemical ClassC19 Steroid — Androstane Series (10β,13β-dimethyl-gonane skeleton). Δ⁴-3-keto steroid. Prohormone / Pharmaceutical Intermediate.
Source / ProductionMicrobial biotransformation of phytosterols (β-sitosterol, campesterol, stigmasterol from non-GMO soy or pine tall oil) → Mycobacterium neoaurum / M. fortuitum (kshA/B⁻, kstD⁻ mutant) fermentation → extraction → chromatography → crystallization
Biosynthetic Position — Key DifferentiatorCentral branch-point C19 intermediate: immediate precursor to testosterone (via 17β-HSD) and estrone (via aromatase CYP19A1). Connects the Δ⁵ (DHEA→androstenedione) and Δ⁴ (progesterone→androstenedione) steroidogenic pathways.
AppearanceWhite to off-white crystalline powder; odorless
Assay (HPLC)≥99.0% total androstenedione (HPLC, C18 column, UV detection at 240 nm, external standard method — anhydrous basis)
Related SteroidsTestosterone ≤0.3%; DHEA ≤0.1%; Androsta-1,4-diene-3,17-dione (ADD) ≤0.5%; 11β-Hydroxyandrostenedione ≤0.2%; 5α-Androstane-3,17-dione ≤0.1%; Any single unknown ≤0.1%; Total impurities ≤1.0%
Identification — Melting Point173-175°C (capillary method, USP <741> Class Ia)
Identification — Specific Optical Rotation[α]D²⁰ = +195° to +205° (c=1.0, absolute ethanol, 10 cm cell)
Identification — UV-Visλmax = 240 ± 1 nm (ethanol); ε = 16,200 M⁻¹cm⁻¹ (α,β-unsaturated ketone π→π* transition — Δ⁴-3-keto chromophore)
Identification — FTIRCharacteristic bands: C17 ketone C=O 1738 cm⁻¹, C3 conjugated ketone C=O 1660 cm⁻¹, C=C stretch 1615 cm⁻¹ (Δ⁴), CH₃/CH₂ bend 1450/1375 cm⁻¹, C-O stretch 1230 cm⁻¹
Identification — GC-MSMolecular ion [M]⁺· m/z 286; base peak m/z 244 [M−42, loss of CH₂=C=O (ketene) from D-ring fragmentation]; fragment ions m/z 271 [M−15, CH₃], 228, 201, 147, 124, 91
Identification — ¹H-NMR (CDCl₃, 400 MHz)δ 0.92 (s, 3H, H-18), 1.20 (s, 3H, H-19), 5.75 (s, 1H, H-4 — vinyl proton of α,β-unsaturated ketone)
Loss on Drying≤0.5% (105°C, 2 hours, USP <731>)
Residue on Ignition≤0.1% (USP <281>)
SolubilityPractically insoluble in water; freely soluble in chloroform, dichloromethane, acetone; soluble in ethanol (~5 mg/mL), ethyl acetate; slightly soluble in hexane
Heavy Metals (Total)≤10 ppm (as Pb, USP <231>)
Elemental ImpuritiesPb ≤2 ppm; As ≤1 ppm; Hg ≤1 ppm; Cd ≤1 ppm (USP <232> / ICH Q3D)
Microbial LimitsTAMC ≤100 CFU/g; TYMC ≤10 CFU/g (USP <61> / EP <2.6.12>); Pathogens — Absent in 10 g (USP <62>)
Residual SolventsUSP <467> / EP <5.4> / ICH Q3C Class 3 compliant; ethanol ≤5000 ppm; acetone ≤5000 ppm; ethyl acetate ≤5000 ppm; Class 1 solvents — not detected
Regulatory StatusUS DEA Schedule III Controlled Substance (21 CFR 1308.13). Supply exclusively to DEA-registered/licensed pharmaceutical manufacturers, CMOs, and research institutions. Export requires DEA export permit or equivalent national controlled substances authorization.
Grade / StandardsPharma Intermediate Grade ≥99% HPLC; GMP (ICH Q7) manufacturing available; DMF Type II preparation support available
CertificationsISO 9001:2015, FDA Facility Registration, HALAL, KOSHER, Non-GMO, BSE/TSE-Free (microbial-derived — no animal/plant tissue)
Packaging100 g / 500 g / 1 kg amber glass bottles with PTFE-lined cap, nitrogen-flushed; 5 kg / 10 kg aluminum foil bags in HDPE drums, nitrogen headspace, tamper-evident seal (controlled substance security packaging)
Storage2-8°C recommended; tightly sealed in original nitrogen-flushed container; protect from light (Δ⁴-3-keto susceptible to photochemical [2+2] cycloaddition); controlled substance secure storage (DEA 21 CFR 1301.75 compliant)
Shelf Life3 years from date of manufacture under recommended storage conditions; stability verified at 3/6/12/24/36 months by HPLC purity, melting point, and related steroids profile

Key Benefits — Androstenedione

Central Branch-Point Intermediate — Testosterone + Estrogen from One Scaffold

Androstenedione is the only steroid that serves as direct precursor to both androgens and estrogens. C17 ketone → 17β-OH testosterone (via stereoselective reduction). A-ring Δ⁴-3-keto → aromatization → estrone. One starting material enables the entire testosterone ester + estrogen API portfolio.

Dual Pathway

Sustainable Microbial Biotransformation — Plant Sterols, No Wild Yam Harvesting

Produced from non-GMO soy/pine phytosterols via Mycobacterium fermentation — completely sustainable, 60-80% molar yield. No diosgenin from wild Dioscorea (Mexican yam), no petroleum-derived chemical total synthesis. BSE/TSE-free, vegan-compatible supply chain.

Green Biotech

≥99% HPLC Purity — Full Related Steroids Profile with 0.1% Detection Limit

Pharma intermediate grade: total impurities ≤1.0% with individual related steroids (testosterone ≤0.3%, DHEA ≤0.1%, ADD ≤0.5%, 11β-OH-androstenedione ≤0.2%) verified by HPLC, GC-MS, and FTIR. GMP manufacturing and DMF Type II preparation support available for ANDA filings.

≥99% Purity

C17 Ketone Chemical Handle — Most Versatile Steroid Scaffold for Derivatization

The C17 carbonyl (C=O) is the key functional group for pharmaceutical derivatization: stereoselective NaBH₄ reduction → 17β-OH testosterone; K-selectride → 17β-OH with >95% stereoselectivity; ethynylation (acetylide) → 17α-ethynyl-17β-OH → oral contraceptive progestins (norethindrone, levonorgestrel). The most versatile steroid starting material.

C17 Handle

Applications

Testosterone API & Testosterone Ester Production

Androstenedione → stereoselective C17 reduction → testosterone → esterification → testosterone cypionate/enanthate/propionate/undecanoate APIs. The highest-volume pharmaceutical steroid synthesis route globally. GMP and DMF support available.

Synthetic Anabolic-Androgenic Steroid (AAS) Synthesis

Androstenedione → nandrolone (19-nortestosterone via Birch reduction), boldenone (ADD → 1-dehydrotestosterone), stanozolol, oxandrolone, methenolone. The starting scaffold for the entire 19-nor and 1-dehydro AAS families.

Combined Oral Contraceptive 19-Nor Progestins

Androstenedione → 17α-ethynylation → 19-nor removal (Birch reduction) → norethindrone, levonorgestrel, desogestrel, gestodene APIs. The foundational intermediate for the global contraceptive steroid market.

Estradiol & Estrogen API Manufacturing

Androstenedione → chemical or enzymatic aromatization (A-ring) → estrone → estradiol → estradiol valerate/cypionate/hemihydrate APIs. Used in hormone replacement therapy (HRT) and combined oral contraceptives.

Corticosteroid Precursor — Hydrocortisone Synthesis

Androstenedione → microbial 11β-hydroxylation (Curvularia lunata or Cochliobolus lunatus) → 11β-hydroxyandrostenedione → hydrocortisone (cortisol) and cortisone APIs via additional chemical steps.

Steroid Research & Analytical Reference Standards

≥99.5% HPLC androgynous reference standard grade for endocrinology research, steroid receptor binding assays, enzyme kinetic studies (17β-HSD, aromatase, 5α-reductase), and LC-MS/MS method development.

Frequently Asked Questions

Androstenedione (androst-4-ene-3,17-dione, CAS 63-05-8, C₁₉H₂₆O₂, MW 286.41 g/mol) is a C19 endogenous steroid hormone that serves as the central branch-point intermediate in androgen and estrogen biosynthesis. Produced in the adrenal zona reticularis (ACTH-regulated, via 3β-HSD2 conversion of DHEA), testicular Leydig cells (LH-regulated, via CYP17A1 17,20-lyase from 17α-OH-progesterone), and ovarian theca cells, androstenedione is the immediate precursor to two major hormone classes: (1) Testosterone — via 17β-hydroxysteroid dehydrogenase type 3/5 (17β-HSD3/5, also known as AKR1C3) which stereoselectively reduces the C17 ketone (C=O) to a 17β-hydroxyl (C-OH), producing testosterone. This is the committed step in androgen biosynthesis. (2) Estrone (E1) — via aromatase (CYP19A1), a cytochrome P450 enzyme complex located in the endoplasmic reticulum of granulosa cells (ovary), adipose tissue, placenta, and brain. Aromatase catalyzes three sequential NADPH-dependent hydroxylations at the C19 methyl group: C19 → 19-hydroxymethyl (−CH₂OH) → 19,19-dihydroxymethyl (−CH(OH)₂) → formate elimination (−CHO₂H) + aromatization of the A-ring (Δ⁴→aromatic with loss of C19). This is the committed step in estrogen biosynthesis. Androstenedione sits at the metabolic intersection of the Δ⁵ pathway (DHEA → androstenedione via 3β-HSD2) and Δ⁴ pathway (progesterone → 17α-OH-progesterone → androstenedione via CYP17A1). Its biological significance is as a prohormone — it is a weak androgen itself (~1/10 testosterone AR affinity) but is converted to potent androgens (testosterone, DHT) and estrogens (estrone, estradiol) in peripheral target tissues expressing 17β-HSD and aromatase.

Commercial androstenedione is produced exclusively via microbial biotransformation of phytosterols (plant sterols — β-sitosterol, campesterol, stigmasterol — extracted from non-GMO soybean oil deodorizer distillate or pine tall oil). The fermentation process uses genetically engineered Mycobacterium neoaurum or Mycobacterium fortuitum strains: (1) Phytosterol feedstock preparation — soy sterols are emulsified with surfactants (Tween 80, lecithin) and added to the fermentation medium at 5-20 g/L. (2) Bacterial steroid catabolism — Mycobacterium species naturally catabolize cholesterol/sterols as a carbon source. The pathway: phytosterol → side-chain β-oxidation (removal of C17 alkyl chain, analogous to fatty acid β-oxidation but using CYP125/CYP142 cytochrome P450s for terminal hydroxylation) → androstenedione (the first C19 intermediate). (3) Genetic knockout blocking further degradation — the bacterium would normally continue: androstenedione → 9α-hydroxyandrostenedione (via 9α-hydroxylase, kshA/kshB) → A/B-ring opening and complete mineralization to CO₂ + H₂O. Industrial production strains have kshA/kshB (9α-hydroxylase) and kstD (Δ¹-dehydrogenase, which produces ADD/boldenone precursor) knocked out — androstenedione accumulates as the terminal product at 60-80% molar conversion from phytosterols. (4) Downstream processing — fermentation broth extraction (ethyl acetate or toluene), solvent evaporation, silica gel chromatography (removal of residual phytosterols and other steroid byproducts), crystallization (acetone/hexane or ethanol/water), and vacuum drying to ≥99% HPLC purity. This biotech process has completely replaced the historical Marker degradation (diosgenin from Mexican yam → 16-DPA → androstenedione via multi-step chemical synthesis) since the 1980s-1990s. The entire process is sustainable (plant sterols are a byproduct of vegetable oil refining), BSE/TSE-free (no animal materials), and scalable to multi-ton production.

Androstenedione is the highest-volume steroid intermediate globally — an estimated 500+ metric tons of phytosterols are processed annually for androstenedione production, which feeds into five major pharmaceutical steroid families: (1) Testosterone and testosterone esters (cypionate, enanthate, propionate, undecanoate) — via stereoselective C17 ketone reduction (NaBH₄, K-selectride, or enzymatic 17β-HSD) → testosterone → esterification with the corresponding acid chloride/anhydride. This is the highest-volume steroid API route — testosterone replacement therapy market ~$2.5B globally. (2) Synthetic anabolic-androgenic steroids (AAS) — androstenedione → ADD (androsta-1,4-diene-3,17-dione, via Δ¹-dehydrogenation) → boldenone (1-dehydrotestosterone, selective NaBH₄ reduction of C17 ketone). Androstenedione → 19-norandrostenedione (via Birch reduction — Li/NH₃, removes C19 methyl) → nandrolone (19-nortestosterone). These serve as precursors for stanozolol, oxandrolone, methenolone, and numerous other AAS. (3) Combined oral contraceptive 19-nor progestins — androstenedione → 17α-ethynylation (lithium acetylide-ethylenediamine complex in THF/NH₃ → 17α-ethynyl-17β-hydroxy) → 19-nor removal (Birch reduction) → norethindrone. Further modification yields levonorgestrel (D-norgestrel enantiomer), desogestrel (3-deketo, 3-methylene), and gestodene (Δ¹⁵ double bond). These are the most prescribed contraceptive steroids globally. (4) Estrogen APIs — androstenedione → aromatization (chemical: CuBr₂/LiBr in acetonitrile, or enzymatic: recombinant human CYP19A1 + NADPH-P450 reductase in E. coli) → estrone → estradiol (NaBH₄ reduction of C17 ketone) → estradiol esters (valerate, cypionate). (5) Corticosteroids — androstenedione → 11β-hydroxyandrostenedione (Curvularia lunata fermentation, 11β-hydroxylation) → multi-step chemical synthesis → hydrocortisone (cortisol), cortisone, prednisolone (Δ¹-dehydrogenation). GMP manufacturing and DMF Type II preparation support available for ANDA and 505(b)(2) filings.

Androstenedione was legally marketed as a dietary supplement in the United States from 1996-2004 under the Dietary Supplement Health and Education Act (DSHEA) of 1994 — most notably by baseball player Mark McGwire during his record-breaking 1998 season (70 home runs, surpassing Roger Maris’s 1961 record). However, clinical studies demonstrated that oral androstenedione (100-300 mg/day) acutely increased serum testosterone by 30-60% within 2-4 hours of ingestion (Leder 2000 JAMA study) and significantly increased serum estradiol (via aromatization) — confirming its pharmacological activity as an anabolic steroid prohormone. The Anabolic Steroid Control Act of 2004 (Public Law 108-358, signed January 20, 2005) amended the Controlled Substances Act (21 USC 802) to add androstenedione and 57 other steroid-related compounds to Schedule III — the same controlled substance classification as ketamine, codeine, and anabolic steroids including testosterone. Current US regulatory status (DEA 21 CFR 1308.13): Schedule III Controlled Substance. Legitimate uses are LIMITED to: (1) licensed pharmaceutical manufacturing (DEA-registered manufacturer, 21 CFR 1301.13), (2) bona fide research (DEA researcher registration, 21 CFR 1301.18), (3) analytical reference standards (DEA exempt chemical preparation registration), and (4) export under DEA export permit (21 CFR 1312). Similar controlled status exists in most countries: UK (Misuse of Drugs Act 1971, Class C), Canada (CDSA Schedule IV), Australia (SUSMP Schedule 4 — Prescription Only Medicine), EU (varies by member state — generally prescription-only for pharmaceutical use). UPOR Biotech supplies androstenedione EXCLUSIVELY as a pharmaceutical intermediate to DEA-licensed or equivalent international regulatory-compliant entities. All purchasers MUST provide valid regulatory credentials before order acceptance. No sales to individuals or non-licensed entities under any circumstances.

Every shipment includes: COA (HPLC purity ≥99.0% total androstenedione; related steroids — testosterone ≤0.3%, DHEA ≤0.1%, ADD ≤0.5%, 11β-OH-androstenedione ≤0.2%, 5α-androstane-3,17-dione ≤0.1%, any single unknown ≤0.1%, total impurities ≤1.0%; heavy metals Pb ≤2 ppm/As ≤1 ppm/Hg ≤1 ppm/Cd ≤1 ppm; residual solvents USP <467>/ICH Q3C; microbial panel USP <61>/<62>), MSDS, HPLC Chromatogram (C18, UV 240 nm, signed and dated), GC-MS Purity Confirmation (EI, m/z 286 [M]⁺·, m/z 244 base peak — signed and dated), FTIR Spectrum (C=O 1738/1660 cm⁻¹, C=C 1615 cm⁻¹ verification), Melting Point Certificate (173-175°C, USP <741>), Specific Optical Rotation Certificate (+195° to +205°, c=1, ethanol), ¹H-NMR Spectrum (CDCl₃, 400 MHz — structural identity), Residual Solvent Analysis (GC-headspace), GMP Certificate (ICH Q7 — if applicable), DEA Schedule III Compliance Documentation (21 CFR 1308.13 — for US domestic shipments, DEA Form 222 or CSOS electronic order verification), Export Permit Documentation (DEA Form 236 / 486 — for international shipments), BSE/TSE-Free Statement (microbial-derived — no animal tissues), Non-GMO Statement, Allergen Statement, HALAL Certificate, KOSHER Certificate, ISO 9001:2015, FDA Facility Registration, Stability Data (25°C/60%RH 36-month real-time; 40°C/75%RH 6-month accelerated; HPLC purity + related steroids re-verified at 3/6/12/24/36 months), and Complete Lot Traceability from phytosterol feedstock batch to finished product. Free sample (1-5 g) available for qualified, DEA-licensed or regulatory-compliant entities only. MOQ: 100 g. All documents in English. Regulatory credentials required before quotation.