Paracaseolide A, first α-alkylbutenolide dimer with an unusual tetraquinane oxa-cage bislactone skeleton from Chinese mangrove Sonneratia paracaseolaris.

A novel α-alkylbutenolide dimer, paracaseolide A (2), characterized by an unusual tetraquinane oxa-cage bislactone skeleton bearing two linear alkyl chains, was isolated from the mangrove plant Sonneratia paracaseolaris. The structure of 2 was elucidated by extensive spectroscopic analysis. A plausible retrosynthetic pathway for paracaseolide A (2) was proposed. Compound 2 exhibited significant inhibitory activity against dual specificity phosphatase CDC25B, a key enzyme for cell cycle progression, with an IC(50) value of 6.44 μM.