Secosteroid

{{Short description|Class of chemicals derived from steroids}}

{{nodisplay-span|1={{r|n1=IUPAC-IUB|r1={{cite web | url = http://www.chem.qmul.ac.uk/sbcs/iupac/steroid/ | title = The Nomenclature of Steroids | author = Moss GP and the Working Party of the IUPAC-IUB Joint Commission on Biochemical Nomenclature | publisher = Queen Mary University of London}} also available as {{cite journal | journal = Pure Appl. Chem. | volume = 61 | issue = 10 | pages = 1786f | year = 1989 | title = Nomenclature of Steroids (Recommendations 1989) | author = Moss GP | doi = 10.1351/pac198961101783| quote = | doi-access = free }}}}}}

File:Cholecalciferol-numbered.svg, an example of a 9,10-secosteroid. IUPAC-approved carbon numbering and ring labeling is shown in the picture. Since secosteroids are derived from steroids, they retain the same labeling system as steroids.

{{r|n1=IUPAC-IUB|loc1=§3S-8|a1=#^{a b c} Chapters [https://iupac.qmul.ac.uk/steroid/3S089.html 3S-8 "Ring fission" and 3S-9 "Vitamin D group"]|link-id=L1a}}]]

Image:Trimethyl steroid-nomenclature.svg

A secosteroid ({{IPAc-en|'|s|ɛ|k|oʊ|,|s|t|ɛ|r|ɔɪ|d}}) is a type of steroid with a "broken" ring. The word secosteroid derives from the Latin verb secare meaning "to cut",{{cite book | author = Ayers D | title = Bioscientific Terminology | year = 1972 | publisher = University of Arizona Press | location = Tucson | url = https://books.google.com/books?id=CTwh-QaifQkC | isbn = 978-0-8165-0305-6 }}{{rp|241}} and 'steroid'. Secosteroids are described as a subclass of steroids under the IUPAC nomenclature.{{r|n1=IUPAC-IUB|loc1=§3S-1|a1=#^ (esp. 3S-1.4, incl. note 4) "Steroids are compounds possessing the skeleton of cyclopenta[a]phenanthrene or a skeleton derived therefrom by one or more bond scissions or ring expansions or contractions."|link-id=L2}}{{cite book |author1=Hill RA |author2=Makin HL |author3=Kirk DN |author4=Murphy GM | title = Dictionary of Steroids | date = 1991 | publisher = Chapman & Hall | location = London | isbn = 978-0-412-27060-4 | edition = 1st }} Some sources instead describe them as compounds derived from steroids.{{cite web | url = http://medical-dictionary.thefreedictionary.com/secosteroid | title = Definition of secosteroid | publisher = TheFreeDictionary.com | work = Farlex Partner Medical Dictionary | quote = A compound derived from a steroid in which there has been a ring cleavage. }}

Types or subclasses of secosteroids are defined by the carbon atoms of the parent steroid skeleton where the ring cleavage has taken place. For example, 9,10-secosteroids are derived from cleavage of the bond between carbon atoms C9 and C10 of the steroid B-ring (similarly 5,6-secosteroids, 13,14-secosteroids, etc.).{{r|n1=IUPAC-IUB|loc1=§3S-8|link-id=L1c}}

The prototypical secosteroid is cholecalciferol (vitamin D₃).{{cite journal | author = Hanson JR | title = Steroids: partial synthesis in medicinal chemistry | journal = Nat Prod Rep | volume = 27 | issue = 6 | pages = 887–99 | year = 2010 | pmid = 20424788 | doi = 10.1039/c001262a }} Its IUPAC systematic is "(5Z,7E)-(3S)-9,10-secocholestra-5,7,10(19)-trien-3-ol".{{r|n1=IUPAC-IUB|loc1=§3S-8|link-id=L1b}}

Some nonsteroidal estrogens, like doisynolic acid (cleaved on the D ring){{cite journal |last1=Meyers |first1=CY |last2=Kolb |first2=VM |last3=Gass |first3=GH |last4=Rao |first4=BR |last5=Roos |first5=CF |last6=Dandliker |first6=WB |title=Doisynolic-type acids--uterotropically potent estrogens which compete poorly with estradiol for cytosolic estradiol receptors. |journal=Journal of Steroid Biochemistry |date=October 1988 |volume=31 |issue=4A |pages=393–404 |doi=10.1016/0022-4731(88)90307-x |pmid=3172773}} and allenolic acid,{{citation needed|date=June 2022}} are also secosteroids or secosteroid-like compounds.