Dimeric Furanones with a Unique Polycyclic Spiro Skeleton from Hawk Tea

Six novel furanone derivatives, hawktealide A–F (1–6), featuring a novel 5/6/5 tricyclic system containing with a spiro-ring, were isolated from hawk tea. The structures of these compounds were confirmed using high-resolution electrospray ionization mass spectrometry (HR-ESIMS), nuclear magnetic resonance (NMR), electronic circular dichroism (ECD), and single-crystal X-ray diffraction data. Compounds 1–3 showed concentration-dependent cytotoxicity against AsPC-1 and HCT-116 cells. Compound 1 was notably more potent against AsPC-1 cells than against HCT-116 or L02 cells. Further experiments revealed that compound 1 induced autophagy, inhibited migration, and caused cell cycle arrest in AsPC-1 cells.