The degradation of proanthocyanidins: dynamic mechanisms to digital solutions

Proanthocyanidins (PAs), a class of polyphenolic polymers widely distributed in plants, exhibit diverse biological activities with promising applications. However, the bioavailability and biological activity of PAs are strongly dependent on their degree of polymerization (DP). Polymeric proanthocyanidins (PPAs) with high DP show low bioavailability due to inability to penetrate biological membranes, limiting their practical utilization. Thus, the degradation of PPAs into oligomeric proanthocyanidins (OPAs) or bioactive small molecular compounds has become a research focus to enhance their value. This review systematically summarizes the structural characteristics of PAs and comprehensively compares the mechanisms, advantages, and limitations of degradation technologies, including chemical, physical, and biological methods. Among these, biodegradation, driven by enzymes, is promising for its environmental friendliness, mild conditions, and high specificity. Enzymes synergistically degrade PAs via oxidative cleavage, ester hydrolysis, and specific bond scission. Notably, digital technologies like computational chemistry and artificial intelligence aid in predicting pathways, optimizing conditions, and designing systems, bridging microscale mechanisms and macroscale patterns. Despite significant progress, challenges remain: PA structural complexity, lack of standardized analytics, and scaling issues. Future research should focus on multi-omics to explore enzymatic mechanisms, construct high-efficiency microbial consortia, and integrate digital solutions for precise degradation control.