Biotransformation of Steroids and Alkaloids

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Questions and Answers

Which of the following organisms are known to transform steroid molecules?

Escherichia coli

Saccharomyces cerevisiae

Rhizopus nigricans (correct)

Bacillus subtilis

What stage of growth can steroids be added to cultures for transformation?

Only during the exponential phase

Either during simultaneous inoculation or stationary stage (correct)

Only during the lag phase

Only during the decline phase

Which of the following bacteria is NOT mentioned as capable of steroid transformation?

Corynebacterium simplex

Streptomyces spp.

Mycobacterium spp.

Streptococcus spp. (correct)

What recent method has been employed in the transformations of steroids?

Immobilized cells Signup and view all the answers

Which of the following statements about fungal spores and steroids is true?

Fungal spores may sometimes be inoculated when steroids are added. Signup and view all the answers

What is one of the early microbial transformations of steroids documented in the content?

Transformation of dehydroepiandrosterone to testosterone Signup and view all the answers

Why is microbial transformation preferred over traditional chemical synthesis for steroid production?

Microbial transformations are simpler and require fewer steps. Signup and view all the answers

What is a significant challenge in the traditional chemical synthesis of cortisone?

The lengthy process requiring 32 chemical steps. Signup and view all the answers

Which organism was used to convert cortisol to prednisolone?

Corynebacterium simplex Signup and view all the answers

How do microbial transformations differ from traditional fermentations like penicillin synthesis?

Microbial transformations bring about relatively minor structural changes. Signup and view all the answers

What was the initial method for producing cortisone before microbial transformation became more common?

Chemical synthesis beginning with deoxycholic acid. Signup and view all the answers

Which of the following is NOT a type of chemical functionalization mentioned in the content?

Enzymatic hydrolysis Signup and view all the answers

What does the microbial transformation of steroids help in the generation of?

New drugs and intermediaries. Signup and view all the answers

What is the base skeleton of steroids characterized by?

A tetracyclic ring system Signup and view all the answers

Which of the following compounds is NOT categorized as a sterol?

Testosterone Signup and view all the answers

What role do hydroxyl groups play in the physiological activity of steroids?

They influence the biological activity based on their position. Signup and view all the answers

Which type of transformations can microorganisms perform on steroids?

Hydroxylation and halogenation Signup and view all the answers

What is the significance of C-11β in steroids related to its biological activity?

It plays a crucial role in anti-inflammatory activity. Signup and view all the answers

What is the purpose of adding non-ionic surface-acting agents like Tween 80 in the medium?

To bind to the steroids and improve availability Signup and view all the answers

Which steroid transformation method is highlighted for its effectiveness?

Microbiological transformations Signup and view all the answers

What important drug discovery began with the hydroxylation of progesterone?

Corticosteroids Signup and view all the answers

Why are mineral salts media used in steroid fermentation processes?

They are simple and cost-effective Signup and view all the answers

Which nitrogen source is commonly used in the media for steroid transformations?

Soybean meal Signup and view all the answers

What defines the hydroxylated steroids, known as sterols?

They contain a hydroxyl group usually at position C3. Signup and view all the answers

What characterizes the steroids derived from androstane, pregnane, and estrane?

They have significant hormonal activity. Signup and view all the answers

What form of microorganisms primarily contributes to steroid transformations?

Fungi and bacteria Signup and view all the answers

In the context of steroid transformations, which statement regarding solvent toxicity is true?

The steroid is often added in small amounts to minimize toxic effects Signup and view all the answers

How does the level of steroid added during transformation vary?

It depends on the transforming ability of the organisms Signup and view all the answers

Which transformation is NOT typically associated with steroid transformations by microorganisms?

Condensation Signup and view all the answers

Study Notes

Overview of Steroids

Steroids are organic compounds derived from alcohols, characterized by a tetracyclic ring system with 17 carbon atoms.
The base skeletons are known as cyclopentanoperhydrophenanthrenes, including structures like gonane and estrane.
Hydroxylated steroids, or sterols, have an OH group typically substituted at position C3 and include crucial compounds such as cholesterol, bile acids, sex hormones, and corticosteroids.

Biological Functions

Steroids perform critical roles in biological systems:
- Hormonal activity from androstane, pregnane, and estrane derivatives.
- Bile acids aid in fat digestion and absorption.
- Cardiotonic aglycones are utilized in heart disease treatment.
Sterols maintain cell membrane integrity and serve as precursors for bile acids and steroid hormones.

Structure and Activity Correlation

Physiological activity is influenced by:
- Structure and orientation of functional groups within the tetracyclic structure.
- Specific positions, such as:
  - C-11β – essential for anti-inflammatory effects.
  - C-17β – defines androgenic properties.
  - Aromatization of ring A – confers estrogenic effects.
  - Corticosteroids feature a 3-keto-4-ene group and a pregnane side chain at C-17.

Microbiological Transformations

The introduction of hydroxyl groups through biohydroxylation is a key step in synthesizing physiologically active steroids.
Microbiological transformations are effective for steroid bioconversion, often achieving what is challenging with conventional methods.
Notable historical developments:
- In 1950, cortisol and progesterone transformations using Rhizopus species marked a significant advance in steroid synthesis.

Historical Context in Steroid Manufacture

The first microbial steroid transformation occurred in 1937, producing testosterone from dehydroepiandrosterone via Corynebacterium sp.
The curative effects of cortisone on rheumatoid arthritis highlighted the need for efficient steroid manufacturing methods.
Traditional methods were lengthy, such as producing cortisone through a laborious 32-step process from deoxycholic acid.

Types of Microbial Transformations

Common transformation reactions include:
- Hydroxylation, dehydrogenation, reduction, side chain degradation, lactone formation, aromatization, isomerization, and hydrolysis.
Both steroid hormones and non-hormonal steroids like bile acids and alkaloids have been transformed.

Fermentation Conditions

Transformation media generally consist of mineral salts and carbon sources (glucose, dextrin, glycerol).
Non-water-soluble steroids require a water-miscible lipid solvent like acetone or ethanol to allow microbial action.
Non-ionic surfactants such as Tween 80 are added to reduce surface tension and enhance steroid availability.

Microorganisms Involved

Various fungi and bacteria are utilized for steroid transformations, including:
- Fungi: Rhizopus nigricans, Curvularia lunata, Fusarium spp.
- Bacteria: Mycobacterium spp., Corynebacterium simplex, Streptomyces spp.
Transformations can be initiated at different growth stages of the microorganisms, and can involve resting or stationary cultures.

Techniques and Innovations

The introduction of immobilized cells represents a modern advancement in steroid transformations.
Specific techniques allow for targeted modifications to the steroid skeleton, facilitating the creation of new drug intermediates.

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Description

Explore the complex biotransformation processes of steroids and alkaloids. This quiz delves into the chemical structure, functions, and significance of these organic compounds in various biological systems. Test your knowledge on their hydroxylation and distribution in nature.