Polyprenylated Benzophenones and Tocotrienol Derivatives from the Edible Fruits of Garcinia oblongifolia Champ. ex Benth. and Their Cytotoxicity Activity

The fruits of Garcinia oblongifolia Champ. ex Benth. were famous as an edible fruit in tropical regions of China. Because of its unique taste and great nutritional value, the ripe fresh fruits of G. oblongifolia could be eaten directly or used as raw materials for natural beverages and food supplements. In this work, six new polyprenylated benzophenones (1–6) and one new dimeric tocotrienol derivative (7), together with 18 known ones (8–25), were isolated from the fruits of G. oblongifolia. Compounds 1–4 were peculiar polycyclic polyprenylated acylphloroglucinols (PPAPs) featuring the rare carbon skeleton of a bicyclo[3.4.1]decane-1,3-diketone. Moreover, all isolates (1–25) were evaluated for their cytotoxicity activities against nasopharyngeal carcinoma (NPC) cell lines (CNE1 and CNE2). Among these isolates, compound 6 exhibited the strongest cytotoxicity activity on CNE1 and CNE2 cells with the IC50 values of 7.8 ± 0.2 and 9.1 ± 0.3 μM, respectively. Further mechanistic investigation demonstrated that 6 could induce mitophagy to promote Caspase-9/GSDME-mediated pyroptosis through triggering ROS in NPC cells.