Melipatulinones A-C, Three Lignan-Phloroglucinol Hybrids from Melicope patulinervia

(±)-Melipatulinones A-C (1-3), three unique enantiomeric pairs of lignan-phloroglucinol hybrids along with the biogenetically related compound melipatulignan A (4), were isolated from the leaves of Melicope patulinervia. Melipatulinones A (1) and B (2) share a novel spiro[hydrobenzofuran-2,3'-furan] 5/5/6 tricyclic ring system, while melipatulinone C (3) features an unprecedented spiro[cyclopenta[b]hydrofuran-2,3'-furan] 5/5/5 tricyclic framework. Their structures were determined by spectroscopic methods, electronic circular dichroism (ECD) calculations, and X-ray diffraction. Compounds 1-3 exhibited a pancreatic lipase inhibitory effect.