Methylated homoisoflavonoids liriopeins A-D as apoptosis inducers and macrophage-activating anticancer agents: Synthesis and biological evaluation.

Homoisoflavonoids, a unique subclass of flavonoids with an additional C3 carbon, exhibit diverse pharmacological activities. Herein, we report the first total synthesis and stereochemical elucidation of liriopeins A-D, naturally occurring homoisoflavonoids bearing methyl substituents on their A ring. Using regioselective aromatic halogenation and late-stage Suzuki-Miyaura methylation, we achieved straightforward access to the four compounds and resolved their enantiomers by chiral-phase HPLC. The absolute configuration of the natural liriopeins was unambiguously determined to be the (R)-form, representing the first structural confirmation of these natural products. In contrast, the synthetic (S)-enantiomer of liriopein C exhibited the markedly stronger cytotoxicity against non-small-cell lung cancer cells, with sub-micromolar IC values. Mechanistic studies revealed the induction of apoptosis, as confirmed by Annexin V/7-AAD staining and poly (ADP-ribose) polymerase cleavage. In addition to its direct cytotoxicity, liriopein C treatment enhanced macrophage-mediated tumor cell clearance in vivo, significantly increasing the uptake of cancer cells by F4/80CD11b peritoneal macrophages. These findings demonstrate that liriopeins possess dual antitumor and immunomodulatory activity, highlighting their potential as natural product-inspired leads for cancer immunochemotherapy.