What molecule am I?
Silodosin1 is a drug used for treating benign prostatic hyperplasia (BPH), an expansion of the prostate gland that can occur in men over 40 years old. It first appeared in the literature in 1995 under the experimental name KMD-3213, when Katsushi Shibata and co-workers at National Children's Medical Research Center (Tokyo) described it as an α1a-adrenoceptor-selective antagonist that could identify high and low affinity sites in human liver and prostate.
The following year, J. B. Bremner, B. Coban, and R. Griffith at the University of Wollongong (Australia) used molecular modeling software to develop pharmacophore models for α1A and α1B adrenergic receptors, including silosin, for the purpose of treating BPH. They found that “The critical structural feature for selectivity between the α1A and α1B adrenergic receptor sites is the distance between the basic nitrogen atom and the center of an aromatic ring system.” Silosin was among the molecules that qualified for developing BPH antagonists.
Ten years later, Japan approved silosin for treating BPH. Kissei Pharmaceutical of Matsumoto, Japan, one of the companies that first marketed silosin, sold the North American rights to the drug in 2004 to Watson Pharmaceuticals (now part of Abbvie, North Chicago, IL). It was approved by the US Food and Drug Administration in 2008.
Last year, Vishal Singh at Sun Pharmaceutical Industries (Mumbai) and colleagues there and at Hakim Sanaullah Specialist Hospital (Sopore, India) published “A comprehensive review of the clinical evidence on the efficacy, effectiveness, and safety of silodosin for the treatment of [BPH]”. They examined the results of 23 clinical trials and observational studies from 2014 to 2024 and concluded that silodosin is efficacious for its purpose, is well tolerated, and has minimal adverse cardiovascular effects.
1. SciFinder name: 1H-indole-7-carboxamide, 2,3-dihydro-1-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)propyl]-.
Silodosin hazard information
| Hazard class* | GHS code and hazard statement | |
|---|---|---|
| Acute toxicity, oral, category 4 | H302—harmful if swallowed |  |
| Specific target organ toxicity, repeated exposure, category 2 | H373—May cause damage to organs (liver) through prolonged or repeated exposure |  |
*Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms.
Molecules from the Journals
Hinckdentine A1 is an alkaloid that occurs in the marine bryozoan2 Hincksinoflustra denticulata. Its discovery was reported in 1987 by A. J. Blackman at the University of Tasmania (Australia) and colleagues at the University of Sydney and Siipakorn University (Nakorn Pathom, Thailand), who used spectral analysis and X-ray crystallography to identify it.
Thirty years later (2018), Jieping Zhu and co-workers at the École Polytechnique Fédérale de Lausanne (Écublens, Switzerland) reported an enantioselective total synthesis of hinckdentine A. A key step in the synthetic procedure was the heteroannulation of an in situ–generated aryne with an α-amino imide. This past April, Daler Baidilov. Pavel K. Elkin, and Viresh H. Rawal* at the University of Chicago, with all due credit to Zhu et al., described a concise, five-step total synthesis of the molecule in 34% overall yield beginning from indolo[1,2-c]quinazoline3.
Tris(pentafluorophenyl)borane4 [(C6F5)3B], completely fluorinated triphenylborane5, is a Lewis acid that is frequently used as a catalyst in organic reactions. It was first reported in 1963–64 by A. G Massey* and A. J. Park at the University of London, who prepared it from boron trichloride6 and pentafluorophenyllithium7. They noted that it was a thermally stable strong receptor toward Lewis bases such as ammonia, trimethylamine, triphenylphosphine, and pyridine.
Since (C6F5)3B became available, its major use has been as a catalyst or cocatalyst for polymerization reactions. In 1992, for example, Xinmim Yang, Charlotte L. Stern, and Tobin J. Marks* at Northwestern University (Evanston, IL) described the use of (C6F5)3B to prepare the more complex catalyst [Cp’2ZrH][(C6F5)3BH] and demonstrated its use for polymerizing ethylene and propylene.
In recent years, the versatility of (C6F5)3B has continued to be shown. Last year, Gowri Sankar Redipalli and colleagues at Gandhi Institute of Technology and Management (Visakhapatnam) and KG Reddy College of Engineering and Technology (Hyderabad, both in India) reported that (C6F5)3B is a reusable catalyst for hydroalkylating styrenes with 1, 3-dicarbonyl compounds. Most recently, in April, Masayuki Wasa and collaborators at Scripps Research (Jupiter, FL) and Boston College (Chestnut Hill, MA) described the use of (C6F5)3B to chemically tag bioactive N-alkylamines. The compound, along with a Brønsted base, converts the alkylamines to enamines that undergo conjugate addition to maleimide-based tagging agents to provide β-substituted amine derivatives that contain various bioconjugation handles.
1. CAS Reg. No. 112663-91-9.
2. Bryozoans, or “moss animals”, are microscopic aquatic
invertebrates.
3. CAS Reg. No. 239-43-0.
4. CAS Reg. No. 1109-15-5.
5. CAS Reg. No. 960-71-4.
6. CAS Reg. No. 10294-34-5.
7. CAS Reg. No. 1076-44-4.
Molecules from the Journals
MOTW briefly describes noteworthy molecules that appeared in recent ACS journal articles. See this week's edition.
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Silodosin fast facts
| CAS Reg. No. | 160970-54-7 |
| Empirical formula | C25H32F3N3O4 |
| Molar mass | 495.54 g/mol |
| Appearance | White to pale yellow crystals or powder |
| Melting point | 105–109 °C (dec.) |
| Water solubility | <1 g/L |
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