Editing Steroid (section)

=== Naming convention ===
Almost all biologically relevant steroids can be presented as a derivative of a parent [[cholesterol]]-like [[hydrocarbon]] structure that serves as a [[Skeletal formula|skeleton]].<ref name=wj>{{cite journal |doi=10.15347/WJM/2023.003 |doi-access=free |title=Alternative androgen pathways |date=3 April 2023 | vauthors = Masiutin MM, Yadav MK |journal=WikiJournal of Medicine |volume=10 |pages=29 |s2cid=257943362 |url=https://upload.wikimedia.org/wikiversity/en/a/a7/Alternative_androgens_pathways.pdf}}{{Creative Commons text attribution notice|cc=by4|from this source=yes}}</ref><ref name="pmid2606099-skeleton">{{cite journal|year=1989|title=IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN). The nomenclature of steroids. Recommendations 1989|journal=Eur J Biochem|volume=186|issue=3|pages=430|doi=10.1111/j.1432-1033.1989.tb15228.x|pmid=2606099|quote=3S‐1.0. Definition of steroids and sterols. 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. Methyl groups are normally present at C-10 and C-13. An alkyl side chain may also be present at C-17. Sterols are steroids carrying a hydroxyl group at C-3 and most of the skeleton of cholestane.|quote-page=430}}</ref> These parent structures have specific names, such as [[pregnane]], [[androstane]], etc. The derivatives carry various [[functional group]]s called suffixes or prefixes after the respective numbers, indicating their position in the steroid nucleus.<ref name="pmid2606099-parent-elisions" /> There are widely used trivial steroid names of natural origin with significant biologic activity, such as [[progesterone]], [[testosterone]] or [[cortisol]]. Some of these names are defined in The Nomenclature of Steroids.<ref name="pmid2606099-trivial">{{cite journal | vauthors =  | title = IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN). The nomenclature of steroids. Recommendations 1989, chapter 3S-4.9 | journal = European Journal of Biochemistry | volume = 186 | issue = 3 | pages = 429–458 | date = December 1989 | pmid = 2606099 | doi = 10.1111/j.1432-1033.1989.tb15228.x | url = https://iupac.qmul.ac.uk/steroid/3S04b.html#3S49 | quote = 3S‐4.9. Trivial names of important steroids Examples of trivial names retained for important steroid derivatives, these being mostly natural compounds of significant biological activity, are given in Table 2 | access-date = 19 February 2024 | archive-date = 19 February 2024 | archive-url = https://web.archive.org/web/20240219010052/https://iupac.qmul.ac.uk/steroid/3S04b.html#3S49 | url-status = live | url-access = subscription }}</ref> These trivial names can also be used as a base to derive new names, however, by adding prefixes only rather than suffixes, e.g., the steroid [[17α-hydroxyprogesterone]] has a [[hydroxy group]] (-OH) at position 17 of the steroid nucleus comparing to progesterone.

<!-- https://www.merriam-webster.com/grammar/em-dash-en-dash-how-to-use -->The letters α and β<ref name="pmid2606099-rs">{{cite journal | vauthors = | title = IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN). The nomenclature of steroids. Recommendations 1989, chapter 3S-1.4 | journal = European Journal of Biochemistry | volume = 186 | issue = 3 | pages = 429–458 | date = December 1989 | pmid = 2606099 | doi = 10.1111/j.1432-1033.1989.tb15228.x | quote = 3S‐1.4. Orientation of projection formulae. When the rings of a steroid are denoted as projections onto the plane of the paper, the formula is normally to be oriented as in 2a. An atom or group attached to a ring depicted as in the orientation 2a is termed α (alpha) if it lies below the plane of the paper or β (beta) if it lies above the plane of the paper. | quote-page = 431 }}</ref> denote absolute [[stereochemistry]] at [[Stereocenter|chiral centers]]—a specific nomenclature distinct from the [[R/S convention]]<ref name="norc-rs">{{cite book| vauthors = Favre HA, Powell WH |title=Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013|publisher=The Royal Society of Chemistry|year=2014|isbn=978-0-85404-182-4|doi=10.1039/9781849733069|chapter=P-91|quote-page=868|quote=P‐91.2.1.1 Cahn-Ingold-Prelog (CIP) stereodescriptors. Some stereodescriptors described in the Cahn-Ingold-Prelog (CIP) priority system, called ‘CIP stereodescriptors’, are recommended to specify the configuration of organic compounds, as described and exemplified in this Chapter and applied in Chapters P‐1 through P‐8, and in the nomenclature of natural products in Chapter P-10. The following stereodescriptors are used as preferred stereodescriptors (see P‐92.1.2): (a) ‘R’ and ‘S’, to designate the absolute configuration of tetracoordinate (quadriligant) chirality centers;}}</ref> of organic chemistry to denote absolute configuration of functional groups, known as [[Cahn–Ingold–Prelog priority rules]]. The R/S convention assigns priorities to substituents on a chiral center based on their atomic number. The highest priority group is assigned to the atom with the highest atomic number, and the lowest priority group is assigned to the atom with the lowest atomic number. The molecule is then oriented so that the lowest priority group points away from the viewer, and the remaining three groups are arranged in order of decreasing priority around the chiral center. If this arrangement is clockwise, it is assigned an R configuration; if it is counterclockwise, it is assigned an S configuration.<ref>{{cite web | url=https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Book%3A_Organic_Chemistry_with_a_Biological_Emphasis_v2.0_%28Soderberg%29/03%3A_Conformations_and_Stereochemistry/3.05%3A_Naming_chiral_centers-_the_R_and_S_system | title=3.5: Naming chiral centers- the R and S system | date=11 August 2018 | access-date=16 October 2023 | archive-date=1 November 2023 | archive-url=https://web.archive.org/web/20231101155825/https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Book:_Organic_Chemistry_with_a_Biological_Emphasis_v2.0_(Soderberg)/03:_Conformations_and_Stereochemistry/3.05:_Naming_chiral_centers-_the_R_and_S_system | url-status=live }}</ref> In contrast, steroid nomenclature uses α and β to denote stereochemistry at chiral centers. The α and β designations are based on the orientation of substituents relative to each other in a specific ring system. In general, α refers to a substituent that is oriented towards the plane of the ring system, while β refers to a substituent that is oriented away from the plane of the ring system. In steroids drawn from the standard perspective used in this paper, α-bonds are depicted on figures as dashed wedges and β-bonds as solid wedges.<ref name=wj/>

The name "[[11-Deoxycortisol|11-deoxycortisol]]" is an example of a derived name that uses cortisol as a parent structure without an [[oxygen]] [[atom]] (hence "deoxy") attached to position 11 (as a part of a hydroxy group).<ref name=wj/><ref name="norc-deoxy">{{cite book| vauthors = Favre HA, Powell WH |title=Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013|publisher=The Royal Society of Chemistry|year=2014|isbn=978-0-85404-182-4|doi=10.1039/9781849733069|chapter=P-13.8.1.1|quote-page=66|quote=P‐13.8.1.1 The prefix ‘de’ (not ‘des’), followed by the name of a group or atom (other than hydrogen), denotes removal (or loss) of that group and addition of the necessary hydrogen atoms, i.e., exchange of that group with hydrogen atoms. As an exception, ‘deoxy’, when applied to hydroxy compounds, denotes the removal of an oxygen atom from an –OH group with the reconnection of the hydrogen atom. ‘Deoxy’ is extensively used as a subtractive prefix in carbohydrate nomenclature (see P‐102.5.3).}}</ref>  The numbering of positions of [[carbon]] atoms in the steroid nucleus is set in a template found in the Nomenclature of Steroids<ref name="pmid2606099-numbering">{{cite journal|year=1989|title=IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN). The nomenclature of steroids. Recommendations 1989|journal=Eur J Biochem|volume=186|issue=3|pages=430|doi=10.1111/j.1432-1033.1989.tb15228.x|pmid=2606099|quote=3S-1.1. Numbering and ring letters. Steroids are numbered and rings are lettered as in formula 1|quote-page=430}}</ref> that is used regardless of whether an atom is present in the steroid in question.<ref name=wj/>

[[Saturated and unsaturated compounds|Unsaturated]] carbons (generally, ones that are part of a double bond) in the steroid nucleus are indicated by changing -ane to -ene.<ref name="pmid2606099-unsaturation">{{cite journal |title=IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN). The nomenclature of steroids. Recommendations 1989 |journal=Eur J Biochem |date=1989 |volume=186 |issue=3 |pages=436–437 |doi=10.1111/j.1432-1033.1989.tb15228.x |pmid=2606099 |quote-page=436-437|quote=3S‐2.5 Unsaturation. Unsaturation is indicated by changing -ane to -ene, -adiene, -yne etc., or -an- to -en-, -adien-, -yn- etc. Examples: Androst-5-ene, not 5-androstene; 5α-Cholest-6-ene; 5β-Cholesta-7,9(11)-diene; 5α-Cholest-6-en-3β-ol. Notes. 1) It is now recommended that the locant of a double bond is always adjacent to the syllable designating the unsaturation.[...] 3) The use of Δ (Greek capital delta) character is not recommended to designate unsaturation in individual names. It may be used, however, in generic terms, like ‘Δ<sup>5</sup>-steroids’}}</ref> This change was traditionally done in the parent name, adding a prefix to denote the position, with or without Δ (Greek capital delta) which designates unsaturation, for example, 4-pregnene-11β,17α-diol-3,20-dione (also Δ<sup>4</sup>-pregnene-11β,17α-diol-3,20-dione) or [[4-androstene-3,11-17-trione|4-androstene-3,11,17-trione]] (also Δ<sup>4</sup>-androstene-3,11,17-trione). However, the Nomenclature of Steroids recommends the [[locant]] of a double bond to be always adjacent to the syllable designating the unsaturation, therefore, having it as a suffix rather than a prefix, and without the use of the Δ character, i.e. pregn-4-ene-11β,17α-diol-3,20-dione or [[Androst-4-ene-3,11-17-trione|androst-4-ene-3,11,17-trione]]. The double bond is designated by the lower-numbered carbon atom, i.e. "Δ<sup>4</sup>-" or "4-ene" means the double bond between positions 4 and 5. The saturation of carbons of a parent steroid can be done by adding "dihydro-" prefix,<ref name="norc">{{cite book| vauthors = Favre HA, Powell WH |title=Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013|publisher=The Royal Society of Chemistry|year=2014|isbn=978-0-85404-182-4|doi=10.1039/9781849733069|chapter=P-3|quote=P-31.2.2 General methodology. ‘Hydro’ and ‘dehydro’ prefixes are associated with hydrogenation and dehydrogenation, respectively, of a double bond; thus, multiplying prefixes of even values, as ‘di’, ‘tetra’, etc. are used to indicate the saturation of double bond(s), for example ‘dihydro’, ‘tetrahydro’; or creation of double (or triple) bonds, as ‘didehydro’, etc. In names, they are placed immediately at the front of the name of the parent hydride and in front of any nondetachable prefixes. Indicated hydrogen atoms have priority over ‘hydro‘ prefixes for low locants. If indicated hydrogen atoms are present in a name, the ‘hydro‘ prefixes precede them.}}</ref> i.e., a saturation of carbons 4 and 5 of testosterone with two [[hydrogen]] atoms is 4,5α-dihydrotestosterone or 4,5β-dihydrotestosterone. Generally, when there is no ambiguity, one number of a hydrogen position from a steroid with a saturated bond may be omitted, leaving only the position of the second hydrogen atom, e.g., [[5α-dihydrotestosterone]] or [[5β-Dihydrotestosterone|5β-dihydrotestosterone]]. The Δ<sup>5</sup>-steroids are those with a double bond between carbons 5 and 6 and the Δ<sup>4</sup> steroids are those with a double bond between carbons 4 and 5.<ref name="pmid21051590">{{cite journal |vauthors=Miller WL, Auchus RJ |title=The molecular biology, biochemistry, and physiology of human steroidogenesis and its disorders |journal=Endocr Rev |volume=32 |issue=1 |pages=81–151 |date=February 2011 |pmid=21051590 |pmc=3365799 |doi=10.1210/er.2010-0013}}</ref><ref name="pmid2606099-unsaturation"/>

The abbreviations like "[[Progesterone|P4]]" for [[progesterone]] and "[[Androstenedione|A4]]" for [[androstenedione]] for refer to Δ<sup>4</sup>-steroids, while "[[Pregnenolone|P5]]" for [[pregnenolone]] and "[[Androstenediol|A5]]" for [[androstenediol]] refer to Δ<sup>5</sup>-steroids.<ref name=wj/>

The suffix -ol denotes a [[hydroxy group]], while the suffix -one denotes an oxo group. When two or three identical groups are attached to the base structure at different positions, the suffix is indicated as -diol or -triol for hydroxy, and -dione or -trione for oxo groups, respectively. For example, [[5α-Pregnane-3α,17α-diol-20-one|5α-pregnane-3α,17α-diol-20-one]] has a hydrogen atom at the 5α position (hence the "5α-" prefix), two hydroxy groups (-OH) at the 3α and 17α positions (hence "3α,17α-diol" suffix) and an oxo group (=O) at the position 20 (hence the "20-one" suffix). However, erroneous use of suffixes can be found, e.g., "5α-pregnan-17α-diol-3,11,20-trione"<ref name="google-pregnan17diol">{{cite web| url=https://scholar.google.com/scholar?&q=%225%CE%B1-pregnan-17%CE%B1-diol-3%2C11%2C20-trione%22| title=Google Scholar search results for "5α-pregnan-17α-diol-3,11,20-trione" that is an incorrect name| year=2022| access-date=1 October 2023| archive-date=6 October 2023| archive-url=https://web.archive.org/web/20231006203706/https://scholar.google.com/scholar?&q=%225%CE%B1-pregnan-17%CE%B1-diol-3%2C11%2C20-trione%22| url-status=live}}</ref> [''sic''] — since it has just one hydroxy group (at 17α) rather than two, then the suffix should be -ol, rather than -diol, so that the correct name to be "5α-pregnan-17α-ol-3,11,20-trione".

According to the rule set in the Nomenclature of Steroids, the terminal "e" in the parent structure name should be elided before the [[vowel]] (the presence or absence of a number does not affect such elision).<ref name=wj/><ref name="pmid2606099-parent-elisions">{{cite journal |title=IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN). The nomenclature of steroids. Recommendations 1989 |journal=Eur J Biochem |date=1989 |volume=186 |issue=3 |pages=429–458 |doi=10.1111/j.1432-1033.1989.tb15228.x |pmid=2606099|quote-page=441|quote=3S-4. FUNCTIONAL GROUPS. 3S-4.0. General. Nearly all biologically important steroids are derivatives of the parent hydrocarbons (cf. Table 1) carrying various functional groups. [...] Suffixes are added to the name of the saturated or unsaturated parent system (see 33-2.5), the terminal e of -ane, -ene, -yne, -adiene etc. being elided before a vowel (presence or absence of numerals has no effect on such elisions).}}</ref> This means, for instance, that if the suffix immediately appended to the parent structure name begins with a vowel, the trailing "e" is removed from that name. An example of such removal is "[[5α-Pregnan-17α-ol-3,20-dione|5α-pregnan-17α-ol-3,20-dione]]", where the last "e" of "[[pregnane]]" is dropped due to the vowel ("o") at the beginning of the suffix -ol. Some authors incorrectly use this rule, eliding the terminal "e" where it should be kept, or vice versa.<ref name="google-pregnane17ol">{{cite web| url=https://scholar.google.com/scholar?q=%225%CE%B1-pregnane-17%CE%B1-ol-3%2C20-dione%22| title=Google Scholar search results for "5α-pregnane-17α-ol-3,20-dione" that is an incorrect name| year=2022| access-date=1 October 2023| archive-date=7 October 2023| archive-url=https://web.archive.org/web/20231007002325/https://scholar.google.com/scholar?q=%225%CE%B1-pregnane-17%CE%B1-ol-3%2C20-dione%22| url-status=live}}</ref>

The term "11-oxygenated" refers to the presence of an oxygen atom as an oxo (=O) or hydroxy (-OH) substituent at carbon 11. "Oxygenated" is consistently used within the chemistry of the steroids<ref name="chemster">{{cite journal| vauthors = Makin HL, Trafford DJ |year=1972|title=The chemistry of the steroids|journal=Clinics in Endocrinology and Metabolism|volume=1|issue=2|pages=333–360|doi=10.1016/S0300-595X(72)80024-0}}</ref> since the 1950s.<ref name="pmid13167092">{{cite journal | vauthors = Bongiovanni AM, Clayton GW | title = Simplified method for estimation of 11-oxygenated neutral 17-ketosteroids in urine of individuals with adrenocortical hyperplasia | journal = Proceedings of the Society for Experimental Biology and Medicine | volume = 85 | issue = 3 | pages = 428–429 | date = March 1954 | pmid = 13167092 | doi = 10.3181/00379727-85-20905 | s2cid = 8408420 }}</ref> Some studies use the term "11-oxyandrogens"<ref name="11oxyhs">{{cite journal| vauthors = Slaunwhite Jr WR, Neely L, Sandberg AA |year=1964|title=The metabolism of 11-Oxyandrogens in human subjects|journal=Steroids|volume=3|issue=4|pages=391–416|doi=10.1016/0039-128X(64)90003-0}}</ref><ref name="pmid35611324">{{cite journal | vauthors = Taylor AE, Ware MA, Breslow E, Pyle L, Severn C, Nadeau KJ, Chan CL, Kelsey MM, Cree-Green M | display-authors = 6 | title = 11-Oxyandrogens in Adolescents With Polycystic Ovary Syndrome | journal = Journal of the Endocrine Society | volume = 6 | issue = 7 | pages = bvac037 | date = July 2022 | pmid = 35611324 | pmc = 9123281 | doi = 10.1210/jendso/bvac037 | doi-access = free }}</ref> as an abbreviation for 11-oxygenated androgens, to emphasize that they all have an oxygen atom attached to carbon at position 11.<ref name="pmid32203405">{{cite journal | vauthors = Turcu AF, Rege J, Auchus RJ, Rainey WE | title = 11-Oxygenated androgens in health and disease | journal = Nature Reviews. Endocrinology | volume = 16 | issue = 5 | pages = 284–296 | date = May 2020 | pmid = 32203405 | pmc = 7881526 | doi = 10.1038/s41574-020-0336-x }}</ref><ref name="pmid33539964">{{cite journal | vauthors = Barnard L, du Toit T, Swart AC | title = Back where it belongs: 11β-hydroxyandrostenedione compels the re-assessment of C11-oxy androgens in steroidogenesis | journal = Molecular and Cellular Endocrinology | volume = 525 | pages = 111189 | date = April 2021 | pmid = 33539964 | doi = 10.1016/j.mce.2021.111189 | s2cid = 231776716 }}</ref> However, in chemical nomenclature, the prefix "oxy" is associated with ether functional groups, i.e., a [[Chemical compound|compound]] with an oxygen atom connected to two [[Alkyl group|alkyl]] or [[Aryl group|aryl]] groups (R-O-R),<ref name="norc-oxy">{{cite book| vauthors = Favre H, Powell W |title=Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013|publisher=The Royal Society of Chemistry|year=2014|isbn=978-0-85404-182-4|doi=10.1039/9781849733069|chapter=Appendix 2|quote-page=1112|quote=oxy* –O– P-15.3.1.2.1.1; P-63.2.2.1.1}}</ref> therefore, using "oxy" within the name of a steroid class may be misleading. One can find clear examples of "oxygenated" to refer to a broad class of organic molecules containing a variety of oxygen containing functional groups in other domains of organic chemistry,<ref name="Barrientos-2013">{{cite journal| vauthors = Barrientos EJ, Lapuerta M, Boehman AL |date=August 2013|title=Group additivity in soot formation for the example of C-5 oxygenated hydrocarbon fuels |journal=Combustion and Flame|language=en|volume=160|issue=8|pages=1484–1498|doi=10.1016/j.combustflame.2013.02.024|bibcode=2013CoFl..160.1484B }}</ref> and it is appropriate to use this convention.<ref name=wj/>

Even though "keto" is a standard prefix in organic chemistry, the 1989 recommendations of the Joint Commission on Biochemical Nomenclature discourage the application of the prefix "keto" for steroid names, and favor the prefix "oxo" (e.g., 11-oxo steroids rather than 11-keto steroids), because "keto" includes the carbon that is part of the steroid nucleus and the same carbon atom should not be specified twice.<ref name="pmid2606099-keto">{{cite journal|year=1989|title=IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN). The nomenclature of steroids. Recommendations 1989|journal=Eur J Biochem|volume=186|issue=3|pages=429–58|doi=10.1111/j.1432-1033.1989.tb15228.x|pmid=2606099|quote=The prefix oxo- should also be used in connection with generic terms, e.g., 17-oxo steroids. The term ‘17-keto steroids’, often used in the medical literature, is incorrect because C-17 is specified twice, as the term keto denotes C=O|quote-page=430}}</ref><ref name=wj/>