Cocrystal of Apigenin with Higher Solubility, Enhanced Oral Bioavailability, and Anti-inflammatory Effect

Apigenin (4′,5,7-trihydroxyflavone, APG) is a bioflavonoid found in some herbs, vegetables, and fruits. APG can reduce inflammation, which is associated with many chronic aging diseases. However, the solubility and bioavailability of APG is quite low; thus, its utility in the body is questionable. Herein, a new cocrystal (APG-BPY) assembled by APG and BPY (4,4′-bipyridine) has been successfully prepared. A single-crystal structure of this cocrystal was illustrated, and comprehensive characterizations were performed in detail. In aqueous buffer, experiments with the dissolution profile of APG-BPY showed that the maximum concentration of APG is approximately ∼40 times higher than that of APG raw material. This result yielded an optimized pharmacokinetics performance, as demonstrated by the improved relative bioavailability of F_rel = 3.9. Furthermore, the anti-inflammatory response in vivo was evaluated by pharmacodynamic experiments; the percentage inhibition of inflammation was 56% for APG-BPY, in comparison with 26% of pure APG. The enhanced efficacy and low toxicity results indicate the development of a pharmaceutically acceptable form of APG that may be potentially clinically available.