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Sterols are a subgroup of steroids with a hydroxyl group at the 3-position of the A-ring. [10] They are amphipathic lipids synthesized from acetyl-coenzyme A via the HMG-CoA reductase pathway. The overall molecule is quite flat. The hydroxyl group on the A ring is polar. The rest of the aliphatic chain is non-polar.
The Marker degradation is a three-step synthetic route in steroid chemistry developed by American chemist Russell Earl Marker in 1938–1940. It is used for the production of cortisone and mammalian sex hormones (progesterone, estradiol, etc.) from plant steroids, and established Mexico as a world center for steroid production in the years immediately after World War II. [1]
Major secosteroid subclasses are defined by the steroid carbon atoms where this scission has taken place. For instance, the prototypical secosteroid cholecalciferol, vitamin D 3 (shown), is in the 9,10-secosteroid subclass and derives from the cleavage of carbon atoms C-9 and C-10 of the steroid B-ring; 5,6-secosteroids and 13,14-steroids are ...
A secosteroid (/ ˈ s ɛ k oʊ ˌ 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", [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 ...
DNA uses the deoxynucleotides C, G, A, and T, while RNA uses the ribonucleotides (which have an extra hydroxyl(OH) group on the pentose ring) C, G, A, and U. Modified bases are fairly common (such as with methyl groups on the base ring), as found in ribosomal RNA or transfer RNAs or for discriminating the new from old strands of DNA after ...
Dexamethasone is based on the cortisol structure but differs at three positions (extra double bond in the A-ring between carbons 1 and 2 and addition of a 9-α-fluoro group and a 16-α-methyl substituent). A variety of synthetic glucocorticoids, some far more potent than cortisol, have been created for therapeutic use.
These ring substructures include cycloalkanes, aromatics, and other ring types. They come in sizes of three atoms and upward, and in combinations of linkages that include tethering (such as in biaryls), fusing (edge-to-edge, such as in anthracene and steroids), links via a single atom (such as in spiro compounds), bridged compounds, and ...
However, the four-ring structure of a steroid is quite expensive to replicate using direct synthetic methods. In 1938–1940, American chemist Russell Earl Marker developed the process known as Marker degradation , which converts diosgenin from Mexican Dioscorea yams into 16-dehydropregnenolone acetate , which has a four-ring structure and can ...