Asecosteroid (/ˈsɛkoʊˌstɛrɔɪd/) is a type of steroid with a "broken" ring. The word secosteroid derives from the Latin verb secare meaning "to cut",[2]: 241 and 'steroid'. Secosteroids are described as a subclass of steroids under the IUPAC nomenclature.[1]: §3S-1 [3] Some sources instead describe them as compounds derived from steroids.[4]
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.).[1]: §3S-8
The prototypical secosteroid is cholecalciferol (vitamin D3).[5] Its IUPAC systematic is "(5Z,7E)-(3S)-9,10-secocholestra-5,7,10(19)-trien-3-ol".[1]: §3S-8
Some nonsteroidal estrogens, like doisynolic acid (cleaved on the D ring)[6] and allenolic acid,[citation needed] are also secosteroids or secosteroid-like compounds.
A compound derived from a steroid in which there has been a ring cleavage.
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Steroid classification
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| C17 |
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| C18 |
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| C19 |
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| C20 |
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| C21 |
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| C23 |
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| C24 |
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| C27 |
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| Functional group |
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| Elements removed |
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| Elements replaced |
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