Structure and origin of bile acids: an overview

Area of Science:

• Biochemistry
• Organic Chemistry
• Comparative Biology

Background:

• Bile acids are crucial steroid acids synthesized in the liver.
• Naturally occurring bile acids exhibit diverse structures with varying hydroxyl group positions and stereochemistry.
• Understanding bile acid structure is key to their physiological roles.

Purpose of the Study:

• To provide a comprehensive overview of the structure and origin of naturally occurring bile acids.
• To describe the common structural features of bile acids, including stereochemistry and ring conformations.
• To highlight unusual bile acid structures identified in various species, particularly reptiles and amphibians.

Main Methods:

• Literature review and structural analysis of naturally occurring bile acids.
• Comparative analysis of bile acid structures across different species.
• Identification and characterization of novel bile acid structures from biological sources.

Main Results:

• Most bile acids belong to the 5beta-series with specific hydroxyl group orientations (alpha-oriented at C3, C6, C7, C12, C23).
• The archetypal bile acid, 5beta-cholanic acid, serves as a precursor for other C24 bile acids.
• Naturally occurring C27 bile acids, including hydroxy derivatives of coprostanic acid, have been identified in reptiles.

Conclusions:

• Bile acid structures are conserved but exhibit significant diversity, especially in non-mammalian species.
• The study provides a foundation for understanding bile acid evolution and function.
• Further research into unusual bile acids may reveal novel biological activities.