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1. http://Generational-theory.com/forum/user-234894.html says:

   08/03/2025 at 10:03 am

   Introduction

   Types of Steroids

   Effects and Side Effects

   History and Usage

   # Contents

   ## Steroid
   Steroids are a class of organic compounds characterized by a specific type of chemical structure.
   They are primarily found in animals, plants, fungi, and some bacteria,
   where they play diverse roles in biological processes.
   Steroids have three interconnected rings, with functional groups such as hydroxyl or ketone groups attached to the molecule.

   Their structure is crucial for their activity, enabling
   them to act as hormones, vitamins, or other bioactive compounds.

   ## Page version status
   This page is based on content from Wikipedia and other reliable sources.
   It has been reviewed and updated by experts in the field.
   For more detailed information, please refer to the original
   source materials.

   ## Nomenclature
   The nomenclature of steroids refers to the systematic naming of these compounds.
   Steroids are named based on their structural features or biological
   functions. For example, “cholesterol” refers to a specific steroid
   molecule produced in the liver and used in animal cell membranes.
   Other examples include “sex hormones,” such as estrogen and testosterone, which are steroidal
   molecules involved in reproduction and endocrine regulation.

   ## Rings and functional groups
   Steroids have a unique structure with three interconnected rings.

   The core of the steroid framework consists of two cyclohexane rings fused together, forming a bicyclic system.

   Functional groups, such as hydroxyl (-OH) or ketone (C=O) groups, are
   attached to this framework and play a critical role in determining the biological activity of the molecule.
   These functional groups can influence steroid behavior,
   such as their affinity for specific receptors or their solubility in different environments.

   ## Naming convention
   The naming convention for steroids follows specific rules that help
   differentiate between the various types of steroidal molecules.
   The name often includes a prefix derived from the class
   of compounds (e.g., “sterol” for cholesterol, “keto” for ketone-containing sterols).
   Additional suffixes may indicate modifications or functional groups present on the molecule.
   This system ensures clarity and precision in communication within scientific communities.

   ## Species distribution
   Steroids are distributed across a wide range of species. Their
   presence is not limited to one type of organism, as they can be found in both eukaryotes and prokaryotes.
   For example:
   – **Eukaryotic organisms**: Steroids are abundant in animals, plants, fungi, and
   single-celled eukaryotes like protozoa.
   – **Prokaryotic organisms**: Sterols, a type of steroid, are found in bacterial cell
   membranes and play a role in maintaining membrane integrity.

   ## Eukaryotic
   In eukaryotic organisms, steroids serve various biological
   functions. For instance:
   – Animals produce a wide variety of steroids, including sex hormones
   (e.g., estrogen, testosterone) that regulate reproduction and metabolism.

   – Plants synthesize sterols as part of their cell membranes, contributing to the strength and structure
   of these cellular structures.
   – Fungi also produce sterols, such as ergosterol, which
   is essential for the integrity of fungal cell membranes.

   ## Prokaryotic
   In prokaryotic organisms, sterols are a key component of bacterial cell membranes.
   These sterols help maintain membrane fluidity and flexibility, ensuring that the cell can function under various environmental conditions.

   While sterols are common in bacteria and archaea,
   they are not typically found in other types of prokaryotes, such as viruses.

   ## Fungal
   Fungi produce a variety of sterols, including ergosterol,
   which is a fundamental component of fungal cell membranes.
   Ergosterol’s structure differs slightly from cholesterol, the primary sterol in animals, but it serves similar
   functions in maintaining membrane integrity and facilitating the transport
   of ions and nutrients across the membrane.

   ## Plant
   In plants, sterols are essential for the structural
   integrity of cellular membranes. Unlike animals, plants do not synthesize
   cholesterol but instead produce a related molecule called phytosterol.
   Phytosterols share some structural similarities with animal sterols but have unique features that
   make them suited to plant biology. These compounds
   contribute to membrane stability and help regulate growth and
   development in plants.

   ## Animal
   Animals are perhaps the most complex users of steroids, producing a
   vast array of these molecules for various purposes. For example:

   – **Sex hormones**: Steroids such as testosterone (male) and estrogen (female) play critical roles in reproduction and sexual differentiation.
   – **Adrenal steroids**: The adrenal glands produce corticosteroids,
   which are involved in stress response and immune function.
   – **Vitamin D**: A steroid molecule derived from cholesterol that is essential for bone health and calcium
   absorption.
   – **Other sterols**: Cholesterol itself is a vital
   component of animal cell membranes and precursor to various hormones and other bioactive compounds.

   ## Types
   Steroids can be categorized based on their function or structure:
   – **By function**: Sex steroids (e.g., estrogen,
   testosterone), adrenal steroids (e.g., cortisol),
   vitamin D derivatives, and sterols like cholesterol.

   – **By structure**: Intact ring systems, cleaved rings, contracted rings, or
   expanded rings.

   ## Rings and functional groups
   The number and arrangement of rings in the steroid framework influence its biological activity.

   For example:
   – **Intact ring system**: Steroids with all three rings intact often retain their basic structural features,
   allowing them to interact with specific receptors and perform
   normal cellular functions.
   – **Cleaved rings**: Modified steroids where one or more rings have been broken or altered can result
   in compounds with different properties. These derivatives may be more effective at targeting specific cellular pathways or receptors.

   – **Contracted rings**: Steroids with one ring contracted into a smaller, often five-membered
   structure are common in certain hormones and signaling molecules.

   – **Expanded rings**: Some steroid derivatives have additional carbons added to the ring
   system, altering their shape and function.

   ## Biological significance
   Steroids are biologically significant compounds with
   diverse roles in organisms. They serve as signaling molecules, hormone precursors, and
   structural components of cell membranes. For example:
   – **Signaling**: Steroids can act as hormones, transmitting signals within and
   between cells to regulate gene expression and cellular activity.

   – **Vitamin D**: A steroid derivative that is essential
   for bone health and calcium absorption.
   – **Cholesterol**: A major component of animal cell membranes,
   which also serves as a precursor for sex hormones and other steroidal molecules.

   ## Biosynthesis and metabolism
   The biosynthesis of steroids involves complex
   biochemical pathways that convert simple precursors into highly
   structured molecules. The two primary pathways for steroid synthesis are the Mevalonate pathway (also known as the cholesterol
   biosynthesis pathway) and the alternative pathways, such as the reverse transport of sterols in cells.

   ### Mevalonate pathway
   The Mevalonate pathway is a series of enzymatic reactions that convert
   acetyl-CoA into mevalonic acid, which serves as a precursor for the synthesis of cholesterol and other steroids.
   This pathway is active in most animals and plays a critical role in maintaining cellular health and homeostasis.

   ### Steroidogenesis
   Steroidogenesis refers to the process by which sterols are synthesized and modified into
   biologically active molecules. For example, cholesterol
   can be converted into vitamin D in sunlight, or transformed into sex hormones like estrogen and testosterone.

   This process is tightly regulated by the body to ensure that steroid levels remain within a healthy range.

   ### Alternative pathways
   In addition to the Mevalonate pathway, alternative pathways
   for steroid biosynthesis exist, particularly in certain tissues and organisms.
   These pathways may involve different precursors or unique enzymatic modifications, allowing for the production of specialized sterols tailored to specific biological needs.

   ### Catabolism and excretion
   Once steroids have fulfilled their biological function,
   they are broken down by enzymes known as steroid
   sulfatases and sulfotransferases. This process, known as catabolism,
   converts the steroids into inactive metabolites that can be safely excreted from the body.
   The excretion of sterols is a critical step in maintaining homeostasis and preventing the buildup of
   potentially harmful levels of these molecules.

   ## Isolation, structure determination, and methods of
   analysis
   The isolation and structural determination of steroids are essential for understanding their
   biological roles and developing new therapies. Techniques such as chromatography, mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy are
   commonly used to isolate and analyze steroidal compounds.

   These methods allow researchers to identify unknown steroids or study the structure
   of known molecules in detail.

   ## Chemical synthesis
   The chemical synthesis of steroids involves the use of organic chemistry techniques to
   construct these molecules from simpler precursors. While natural
   methods dominate in biological contexts, synthetic approaches have
   been developed for the purposes of research and drug development.
   Synthesis can be challenging due to the complexity of the steroid
   framework, but advanced methodologies have made it possible to create sterols
   with specific structural modifications.

   ### Precursors
   The synthesis of steroids begins with precursors such as mevalonic acid
   or isopentenyl pyrophosphate (IPP), which are derived from acetyl-CoA.
   These compounds undergo a series of enzymatic reactions
   to produce the steroid nucleus, the core structure of all sterols.

   ### Semisynthesis
   Semisynthesis involves the chemical manipulation of naturally occurring steroids or their
   derivatives to create new molecules with desired properties.
   This approach is particularly useful for modifying existing sterols to enhance their biological
   activity or improve their pharmacokinetics.

   ### Total synthesis
   Total synthesis refers to the de novo construction of steroids from non-steroidal precursors, without relying on natural sources.
   This method is often used in drug discovery to create
   molecules with therapeutic potential. The challenge lies in replicating the complex structure and biological activity of naturally
   occurring sterols.

   ## Research awards
   Over the years, significant research has been conducted into the chemistry, biology, and applications of steroids.

   Notable scientists in this field have received awards for their contributions to understanding steroid metabolism,
   biosynthesis, and function. These achievements have led to advancements in fields
   such as medicine, nutrition, and pharmacology.

   ## See also
   – **Lipid metabolism**
   – **Endocrinology**
   – **Biochemistry**

   ## References
   This article is based on publicly available information and does not constitute
   medical advice. Always consult a healthcare professional for medical concerns or before starting any
   new treatment regimen.

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