Vitamin B2 Catabolism: Nature's Route from Riboflavin to Acetoacetate and Pyruvate
Sreyashi Sinha1, Xiaohong Jian1, Sanjoy Adak1
1Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States.
ACS Central Science
|December 31, 2025
Summary
Researchers reconstituted the riboflavin catabolic pathway enzymes in vitro. This study elucidates riboflavin breakdown, impacting nutrition and quorum sensing research.
Area of Science:
- Biochemistry
- Metabolic pathways
Background:
- Riboflavin (vitamin B2) metabolism is crucial for various biological processes.
- The complete catabolic pathway of riboflavin remained largely uncharacterized.
- Understanding riboflavin breakdown is essential for nutritional and microbial ecology studies.
Purpose of the Study:
- To clone and reconstitute the enzymes involved in the riboflavin catabolic pathway.
- To elucidate the sequential steps and key enzymes in riboflavin degradation.
- To investigate the metabolic fate of riboflavin and its derivatives.
Main Methods:
- Enzyme cloning and expression.
- In vitro reconstitution of the multi-step catabolic pathway.
- Biochemical assays to characterize enzyme activities and reaction intermediates.
Main Results:
- Successfully reconstituted the entire riboflavin catabolic pathway in vitro.
- Identified key enzymes including P450, thiamin-dependent decarboxylase, xanthine oxidase, Rieske dioxygenase, and catechol dioxygenase.
- Demonstrated the conversion of riboflavin to lumichrome, followed by degradation of the isoalloxazine ring and subsequent breakdown to pyruvate and acetoacetate.
Conclusions:
- The elucidation of the riboflavin catabolic pathway fills a significant gap in understanding vitamin B2 metabolism.
- This pathway yields substrates for the citric acid cycle, linking riboflavin breakdown to central energy metabolism.
- The findings provide a foundation for assessing riboflavin catabolism's role in nutrition and lumichrome's function as a quorum sensor mimic.
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