CYCLOPENTANEPERHYDROPHENANTHRENE: STRUCTURE AND IMPORTANCE - BIOLOGY - 2025

The cyclopentanoperhydrophenanthrene, estrane, steranes or gonane is a hydrocarbon consisting of several cyclic rings making up the central skeleton of cholesterol and hormone derivatives; in addition to some drugs and their derivatives. Plants and animals contain various compounds with cyclopentaneperhydrophenanthrene skeletons that have important functions in their life processes.

The pharmacological industry has been dedicated for decades to the investigation of the natural compounds of different organisms in search of active and effective ingredients for the development of drugs, pesticides and other chemical compounds.

Scheme of the four-ring polycyclic structure of Cyclopentaneperhydrophenanthrene (Source: NEUROtiker via Wikimedia Commons) In these investigations, some esters or acids of cyclopentaneperhydrophenanthrene have turned out to be useful as active principles of therapeutic agents that are used in combination with other substances for the treatment of certain types of pathologies and diseases.

Structure

Cyclopentaneperhydrophenanthrene is a four-ring polycyclic hydrocarbon that results from the condensation of a cyclopentane nucleus with a phenanthrene. This is considered a product of total saturation by hydrogenation of phenanthrene.

It is composed of 17 carbon atoms and some natural derivatives always have two methyl groups at carbons 10 and 13, which are known as angular methyls.

The cyclopentaneperhydrophenanthrene molecule, together with the angular methyls, has six asymmetric carbons (5.10; 8.9; 13.14), so the compound has at least 64 isomers.

However, most naturally occurring steroid derivatives differ only in the stereoisomerism of carbons 5 and 10.

Compounds derived from cyclopentaneperhydrophenanthrene possess a highly hydrophobic behavior, since they have a central nucleus of four interconnected cyclic rings that can function to repel water around them in aqueous media.

Occurrence in nature

Sterols: Cholesterol

The cyclic structure of cyclopentaneperhydrophenanthrene can be found in multiple compounds in nature.

Sterols are secondary alcoholic compounds whose main skeleton is the polycyclic ring of cyclopentaneperhydrophenanthrene. Among the best-studied sterols is cholesterol.

Structure of Cholesterol (Source: Chem Sim 2001 via Wikimedia Commons) Cholesterol is a solid alcohol of 27 carbon atoms found only in animals. It is derived from a molecule known as cholestene, which comes from cholestane, formed by a double bond between carbons 5 and 6 of cholestene.

This compound has a side chain at the 17-position carbon and an OH group at the 3-position carbon.

Steroids, vitamins, and steroid hormones such as progesterone, aldosterone, cortisol, and testosterone are derived from cholesterol. These hormones, despite presenting great variations between their structures, maintain the cyclopentaneperhydrophenanthrene molecule as their central skeleton.

Steroids

The basis of the steroid structure is the four-ring nucleus of the cyclopentaneperhydrophenanthrene molecule. Natural steroids in mammals are synthesized primarily in the sex organs, the adrenal glands, and the placenta, and all are derived from cholesterol.

Steroids are a varied group of compounds that generally have a hormonal character or are vitamins that have as substituent groups of the cyclopentaneperhydrophenanthrene skeleton to carbonyl groups, hydroxyl groups or hydrocarbon chains.

Steroids include vitamin D and its derivatives. Some scientists classify cholesterol as a steroid.

In the brain, glial cells possess all the cellular machinery to synthesize many neurosteroids necessary for their function in situ.

Steroid hormones

Steroid hormones are a large class of small lipophilic molecules that are synthesized in steroidogenic tissues and that act at their target sites to regulate a myriad of physiological functions of the endocrine system, including sexual and reproductive development.

Some steroid hormones are produced by cells of the adrenal cortex, the "thecal" cells of the ovary, and testicular Leydig cells. In the placenta, trophoblastic cells synthesize large amounts of progesterone and estrogen, both steroid hormones.

Structure of Testosterone Propionate (Source: Claudio Pistilli via Wikimedia Commons) Progesterone is a naturally occurring hormone that belongs to the family of progestin hormones. These promote the development of the ovaries in animals, so it is said that progesterone is the hormone responsible for secondary sexual development in the female sex.

Estrogens are hormones derived from estrano. These hormones are typical of the first half of the female sexual cycle and induce the formation of organs such as the breasts and ovaries.

Being steroid hormones, the structure of progesterone and estrogen consists of a central skeleton of cyclopentaneperhydrophenanthrene that varies only in ketone and oxygenated functional groups.

Presence in the industry

In the pharmaceutical industry, numerous drugs have been developed using the cyclic skeleton of cyclopentaneperhydrophenanthrene or cholesterol derivatives as their main structure.

Such is the case of levonorgestrel, a progestin used in contraceptive formulations and which has an activity 80 times more powerful than the body's natural progesterones. This drug has an androgenic effect, since it competes with testosterone to activate the progesterone transporter protein.

Levonorgestrel structure (Source: No machine-readable author provided. Ayacop assumed (based on copyright claims). Via Wikimedia Commons) Many corticosteroids such as cortisone, hydrocortisone and prednisone are currently used for the treatment of different inflammatory conditions, skin rashes, to the treatment of asthma and lupus. These compounds are synthetic steroids that mimic the effects of many hormones produced by the adrenal glands.

Dehydroepiandrosterone is a synthetic steroid hormone precursor to testosterone, marketed as a pre-hormonal nutritional supplement, commonly known as andros. As a curious fact, in 1998 the sales of this drug soared after the doping of Mark McGwire, who at the time was the holder of the record for home runs in major league baseball.

Importance

The importance of the cyclopentaneperhydrophenanthrene skeleton lies in its presence as a fundamental part of various molecules in nature.

Cholesterol is an important constituent of biological membranes and lipoproteins of an amphipathic nature. It is a precursor in the synthesis of vitamin D, steroid hormones and bile acids.

Vitamin D plays an important role in reducing the risk of chronic diseases, including various types of cancer, autoimmune diseases, and cardiovascular diseases. Humans acquire this compound through exposure to light or through food eaten in the diet.

Structure of Vitamin D (Source: Nwanneka123 via Wikimedia Commons) The processing of vitamin D is related to the levels of parathyroid hormone, so it is closely related to the body metabolism of humans.

Phytosterols are bioactive plant compounds analogous to cholesterol in animals that possess a four-ring molecular structure derived from cyclopentaneperhydrophenanthrene.

These compounds are present in plants and differ from each other by the number of carbon atoms and the nature of their side chain. Crude palm oil, which is widely used in various industries and among them in the food industry, is rich in this type of sterols.

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