Steroids: Videos & Practice Problems

Steroids are non-hydrolyzable lipids characterized by a tetracyclic structure, consisting of three cyclohexane rings and one cyclopentane ring. Their stereochemistry typically features trans configurations at ring junctions, with angular methyl groups in beta positions. Steroid hormones, including sex hormones like androgens and estrogens, regulate various physiological functions. Adrenocortical hormones, such as glucocorticoids and mineralocorticoids, manage glucose metabolism and electrolyte balance, respectively. Understanding these structures and functions is crucial for grasping their biological significance.

Steroids Concept 1

Steroids are a class of non-hydrolyzable lipids characterized by their unique structure based on the Androstane framework. The Androstane molecule is tetra cyclic, consisting of four fused rings: three cyclohexane rings and one cyclopentane ring, along with two methyl groups. This structural arrangement is crucial for the function of steroids, which include important biological molecules such as cholesterol and steroid hormones.

In the steroid structure, the rings are labeled as A, B, C, and D in alphabetical order. The methyl groups are specifically located at carbon positions 10 and 13, which are designated as carbons 19 and 18, respectively. Understanding this basic steroid structure is essential for further exploration of its derivatives and biological roles.

Steroids Example 1

Cholesterol is classified as a lipid due to its hydrophobic nature and structural characteristics, but it does not undergo saponification with aqueous base. Saponification is a chemical reaction that typically involves the hydrolysis of fats or oils, which are triglycerides, into glycerol and fatty acid salts. This process specifically targets ester linkages present in fatty acid esters.

Cholesterol, however, is not a fatty acid ester; it is a sterol, which means it has a distinct structure that does not include the ester bonds necessary for saponification. The primary function of saponification is to cleave these ester linkages, resulting in the formation of glycerol and fatty acid salts. Since cholesterol lacks these ester linkages, it does not undergo the saponification process.

Additionally, while cholesterol can be hydrolyzed under acidic conditions, this does not relate to its inability to undergo saponification. The stability of the steroid skeleton, including the alkyl side chain at carbon number 17, contributes to its non-polar characteristics but does not influence its reactivity in the context of saponification. Therefore, the key takeaway is that cholesterol's structure as a sterol, rather than a fatty acid ester, is the reason it does not participate in saponification reactions.

Drostanolone propionate is a synthetic androgen that has been used to treat breast cancer. Number the carbon atoms with groups in red.

In this exercise, we focus on the numbering of carbon atoms in a synthetic androgen molecule, which is significant in the treatment of breast cancer. The structure of the steroid is essential for understanding its chemical properties and biological activity. We begin by identifying the carbon atoms, starting from position 1 and progressing sequentially through the molecule.

As we number the carbon atoms, we observe the following sequence: Carbon 1, Carbon 2, Carbon 3, and so forth, up to Carbon 19. The numbering is guided by the structure's shading, which helps indicate the progression through the steroid framework. Specifically, we note that:

• Carbon 2 is associated with a methyl group.
• Carbon 3 features a carbonyl group, which is a key functional group in organic chemistry, represented as R-C(=O)-R'.
• Carbon 17 is involved in an ester linkage, which is crucial for the molecule's reactivity and interaction with biological systems.

Thus, the carbon atoms of interest, highlighted in red, are Carbon 2, Carbon 3, and Carbon 17. Understanding the positioning and functional groups attached to these carbons is vital for comprehending the molecule's overall structure and its implications in medicinal chemistry.

Steroids Concept 2

In the study of decalin molecules, it is essential to understand the structural differences between cis and trans fused ring systems. The cis configuration features both hydrogen atoms oriented in the same direction, typically represented as both being "up" in a molecular diagram. This is depicted with wedge bonds, indicating that the hydrogens are on the same side of the ring. Conversely, the trans configuration has one hydrogen atom pointing "up" and the other "down," illustrated with a wedge for the upward hydrogen and a dash for the downward hydrogen.

Trans decalin is characterized by its greater rigidity and stability compared to cis decalin, which allows it to maintain a more planar structure, although it is not as planar as benzene. This rigidity in trans fused rings prevents them from undergoing ring flipping, a process that is possible in the more flexible cis fused rings.

Additionally, stereo descriptors play a crucial role in identifying the orientation of substituents on the decalin structure. In this context, the term "Beta" is used to denote the upward hydrogens in the cis configuration, while "Alpha" refers to the downward hydrogen. Understanding these distinctions is vital for grasping the chemical behavior and properties of decalin and its derivatives.

Steroids Concept 3

Steroid stereochemistry is characterized by specific features that define their structure and function. In steroids, the junctions between rings exhibit a trans configuration, particularly at the A-B and B-C junctions, which are almost always trans. This trans configuration is a common characteristic in nature for steroids.

Focusing on the angular methyl groups located at carbon positions 10 and 13, these groups are positioned in a beta orientation, meaning they project upwards and are in an axial position. Additionally, carbon number 3 may have a hydroxyl (OH) group, which can be either in an alpha or beta configuration. If present, the alkyl group at carbon number 17 is also in a beta orientation, but it is equatorial.

When visualizing the stereochemistry, the trans alpha-beta junction at carbon 3 can be represented with the OH group in a wedged position, indicating it is above the plane, while the hydrogen atom is shown as dashed, indicating it is below the plane. The methyl groups at carbons 10 and 13 are also depicted as beta and axial, meaning they are both above the plane of the steroid structure.

In chair conformation, the stereochemistry can be illustrated with specific orientations: the hydrogen atoms and substituents are arranged to reflect their axial or equatorial positions. For instance, in this conformation, the hydroxyl group and the two methyl groups are positioned upwards, while other hydrogen atoms may be shown as dashed, indicating they are oriented downwards.

Furthermore, it is important to note that all ring junctions in cholesterol maintain a trans configuration, contributing to the rigidity of the molecule. This rigidity is crucial for the structural integrity of cellular membranes, highlighting the functional significance of steroid stereochemistry in biological systems.

Steroids Example 2

In understanding the stereochemical characteristics of steroids, it is essential to recognize the significance of the cis configuration at the AB ring junction. This configuration influences the spatial arrangement of substituents on the steroid structure. In this case, the methyl groups attached to the steroid framework remain in a wedged position, indicating they are oriented above the plane of the ring system.

For the alkyl group located at carbon 17, it also adopts a wedged orientation, maintaining the stereochemical integrity of the molecule. When considering the hydrogen atoms attached to the steroid structure, their orientations vary: one hydrogen is represented as wedged, indicating it is above the plane, while another is dashed, showing it is below the plane. This alternating pattern continues with another hydrogen being wedged and the final hydrogen being dashed.

This careful depiction of the substituents illustrates the cis alpha-beta junction, which is crucial for accurately representing the three-dimensional conformation of the tetracyclic steroid structure. Understanding these stereochemical details is vital for predicting the biological activity and interactions of steroid compounds.

Steroids Concept 4

To draw the structure of testosterone, it is essential to understand the basic steroid skeleton, which consists of three cyclohexane rings and one cyclopentane ring. The first step involves sketching this skeleton and numbering the carbon atoms appropriately. The numbering starts from one end of the structure and continues sequentially through the rings, ensuring that all carbons are accounted for, from carbon 1 to carbon 17, with potential extensions for any alkyl groups.

Next, specific modifications must be made according to the provided information. For testosterone, two methyl groups need to be added at carbon 10 and carbon 13. These groups are represented using wedges to indicate their beta configuration, meaning they project upwards from the plane of the steroid skeleton.

Following the addition of the methyl groups, the hydrogen atoms at the junctions of the carbon atoms must be drawn. The convention is to use dashes for hydrogens that are in the alpha position (down) and wedges for those in the beta position (up). This step is crucial for accurately representing the stereochemistry of the molecule.

Further modifications include adding a carbonyl group at carbon 3, which is a double-bonded oxygen (C=O). Additionally, a double bond must be established between carbons 4 and 5, necessitating the removal of a hydrogen atom from one of these carbons to maintain the tetravalency of carbon. Finally, a beta hydroxyl group (-OH) is added at carbon 17, also projecting upwards to reflect its beta configuration.

By integrating these features—carbonyl at C3, a double bond between C4 and C5, and a beta hydroxyl at C17—the final structure of testosterone is achieved, showcasing the importance of stereochemistry and functional groups in steroid chemistry.

Which one of the structures given below fulfills the given criteria?
1) Ketone at C3.
2) Double bond between C4 and C5.
3) An –OH group at C17 in β configuration.
4) A –CH₃ group at C17 in α configuration.

• A.
• B.
• C.
• D.

Answer: (B)

Draw the structure of metenolone from the information given below:
1) A –CH₃ group at C1.
2) A double bond between C1 and C2.
3) A ketone at C3.
4) An acetate group at C17 in β configuration.

To draw the structure of metal no loan, we start by constructing the tetracyclic framework characteristic of steroids, which consists of three cyclohexane rings. The numbering of the carbon atoms in the steroid structure is essential, and it proceeds as follows: 1 through 17.

According to the provided information, we need to incorporate specific functional groups into our structure. First, a methyl group is attached to carbon 1. Next, a double bond is present between carbons 12 and 13, which simplifies the stereochemistry for the methyl group at carbon 1, as it does not require additional stereochemical specification.

At carbon 3, we introduce a ketone functional group, represented by a carbonyl (C=O) group. Additionally, an acetate group is positioned at carbon 17 in the beta configuration. In this context, the beta configuration indicates that the acetate group is oriented in a wedged manner, which can be depicted as follows: the acetate group includes an oxygen atom bonded to a carbon atom.

To complete the structure, we must also consider the stereochemistry of other substituents. A methyl group is added at carbon 13, which is also represented in a wedged orientation. At carbon 10, we have a hydrogen atom that is dashed, indicating its orientation away from the viewer. Furthermore, we need to denote the alpha and beta hydrogens around carbon 10: the alpha hydrogen is positioned down, while the beta hydrogen is oriented up, with another alpha hydrogen also directed down.

This comprehensive approach allows us to accurately represent the complete structure of metal no loan, adhering to the specified criteria and the foundational skeletal structure of steroids.

Draw the structure of the product formed when fluoxymesterone undergoes reduction with LiAlH₄.

• A.
• B.
• C.
• D.

Answer: (B)

Steroids Concept 5

Hormones serve as essential chemical messengers that facilitate communication between different parts of the body. They can be categorized into two main groups: sex hormones and adrenocortical hormones. Sex hormones play a crucial role in controlling sexual characteristics and regulating muscle growth.

In males, the primary sex hormones are androgens, which are produced in the testes. These hormones are vital for sexual development and muscle growth, with testosterone being the most well-known androgen. In females, sex hormones include estrogens and progestins, both produced in the ovaries. Estrogens are responsible for sexual development in females, while progestins, such as progesterone, regulate the menstrual cycle and support pregnancy.

Estrogens are characterized by their unique structure, which includes an aromatic ring (referred to as ring A) and a notable absence of a methyl group at Carbon 10. This structural feature distinguishes estrogens from other steroid hormones. A helpful mnemonic to remember these relationships is: "Esters have aroma," linking estrogens with their aromatic structure, while androgens and progestins are also closely associated within the category of sex hormones.

Overall, understanding the functions and structures of these steroid hormones is essential for grasping their roles in human physiology and development.

Steroids Concept 6

Adrenocortical hormones, a crucial category of steroid hormones, play a significant role in regulating various physiological functions within the body. These hormones are primarily produced in the adrenal glands and can be classified into two main types: glucocorticoids and mineralocorticoids.

Glucocorticoids, such as cortisol, are essential for regulating glucose metabolism and reducing inflammation. They help maintain energy balance and support the body's response to stress. On the other hand, mineralocorticoids, with aldosterone as a key example, are vital for regulating the balance of sodium and potassium ions in cells and body fluids. Maintaining this ionic balance is critical, as any disruption can lead to serious health issues.

Both types of adrenocortical hormones share a common structural feature: they contain a hydroxyl (–OH) group at carbon 11. A helpful mnemonic to remember this is "Adriana hydrates 11 times," which emphasizes the importance of hydration and mineral balance associated with these hormones.

In summary, understanding the functions and structures of glucocorticoids and mineralocorticoids is essential for grasping how adrenocortical hormones influence overall health and physiological processes.

Steroids Example 3

Steroid hormones are a class of hormones derived from cholesterol, characterized by their four-ring structure. Understanding the structural differences among these hormones is crucial for identifying their functions and classifications. For instance, testosterone, a key androgen, contains a methyl group at carbon 10, which is numbered as carbon 19 in its structure. This detail is essential for distinguishing it from other steroid hormones.

Adrenocortical hormones, which include glucocorticoids and mineralocorticoids, do not universally possess a hydroxyl (–OH) group at carbon 10; instead, they typically have a methyl group at this position. The presence of a hydroxyl group is more characteristic of carbon 11 in these hormones. This distinction is vital for understanding their biochemical properties and interactions.

Estrogens, such as estrone, lack the methyl group at carbon 10 due to the presence of an aromatic ring in their structure. The aromaticity of this ring leads to a configuration where carbon 10 cannot accommodate a methyl group without exceeding its bonding capacity. This structural feature is significant in differentiating estrogens from other steroid hormones.

In contrast, progesterone, classified as a progestin, does not have an aromatic ring in its structure, which sets it apart from estrogens like estrone. Recognizing these structural differences is essential for understanding the diverse roles that steroid hormones play in physiological processes.

In summary, the correct statement regarding steroid hormones is that the methyl group at carbon 10 is absent in estrogens due to the aromatic ring, making this the only accurate option among the statements provided.

Classify dexamethasone into one of the steroid hormone classes.

• A. Androgen
• B. Estrogen
• C. Progestin
• D. Adrenocortical hormone

Answer: (D)

Oxymetholone is used to treat anemia and to promote weight gain and muscle growth. Based on this information, classify oxymetholone into one of the three classes of sex hormones.

• A. Androgens
• B. Estrogens
• C. Progestins

Answer: (A)

Here’s what students ask on this topic:

What is the basic structure of steroids?

Steroids are non-hydrolyzable lipids characterized by a tetracyclic structure, consisting of three cyclohexane rings and one cyclopentane ring. This structure is based on the Androstane skeleton. The rings are labeled A, B, C, and D, and are numbered in alphabetical order. The two methyl groups are located at carbons 10 and 13, and are numbered 18 and 19, respectively. This tetracyclic structure is crucial for the biological functions of steroids, including their role as hormones.

What are the differences between cis and trans ring junctions in steroids?

In steroids, ring junctions can be either cis or trans. Trans ring junctions are more stable and rigid compared to cis junctions. In trans junctions, the substituents on the ring junctions are on opposite sides, making the structure more planar. In contrast, cis junctions have substituents on the same side, leading to a less stable and more flexible structure. Most natural steroids have trans ring junctions, contributing to their rigidity and stability.

What are the main types of steroid hormones and their functions?

Steroid hormones are broadly classified into two categories: sex hormones and adrenocortical hormones. Sex hormones include androgens (e.g., testosterone) and estrogens (e.g., estradiol), which regulate sexual characteristics and reproductive functions. Adrenocortical hormones include glucocorticoids (e.g., cortisol), which regulate glucose metabolism and reduce inflammation, and mineralocorticoids (e.g., aldosterone), which manage electrolyte balance. These hormones play crucial roles in various physiological processes.

How do you draw the structure of testosterone?

To draw the structure of testosterone, start with the basic steroid skeleton, which includes three cyclohexane rings and one cyclopentane ring. Number the carbons from 1 to 17. Add a carbonyl group at carbon 3, a double bond between carbons 4 and 5, and a beta hydroxyl group at carbon 17. Ensure the two methyl groups at carbons 10 and 13 are in the beta (up) position. This will give you the complete structure of testosterone.

What is the role of adrenocortical hormones?

Adrenocortical hormones are a category of steroid hormones produced by the adrenal glands. They are divided into glucocorticoids and mineralocorticoids. Glucocorticoids, such as cortisol, regulate glucose metabolism and reduce inflammation. Mineralocorticoids, such as aldosterone, manage the balance of sodium and potassium ions in cells and body fluids. These hormones are essential for maintaining homeostasis and responding to stress.