Myrcaulones A–C, Unusual Rearranged Triketone–Terpene Adducts from Myrciaria cauliflora

作者：Ming Chen, Wen‐Jing Wang, Ni-Ping Li, Hu-Hu Zeng, Hong Guo, Ren‐Wang Jiang, Lei Wang, Wen‐Cai Ye · 发表于：Journal of Natural Products · 年份：2020 · DOI：10.1021/acs.jnatprod.0c00283 · 被引用次数：12 · 研究领域：Plant biochemistry and biosynthesis、Natural product bioactivities and synthesis、Traditional and Medicinal Uses of Annonaceae

Three rearranged triketone–terpene adducts, myrcaulones A–C ( 1 – 3 ), were isolated from the leaves of Myrciaria cauliflora . Myrcaulones A ( 1 ) and B ( 2 ) feature a new carbon skeleton with an unprecedented spiro[bicyclo[3.1.1]heptane-2,2′-cyclopenta[ b ]pyran] core. Myrcaulone C ( 3 ) possesses an unusual cyclobuta[6,7]cyclonona[1,2- b ]cyclopenta[ e ]pyran backbone. Their structures with absolute configurations were elucidated by NMR spectroscopy, X-ray diffraction, and electronic circular dichroism calculations. A plausible biogenetic pathway for myrcaulones A–C involving the rearrangement of a triketone unit is also proposed. In addition, myrcaulones A ( 1 ) and B ( 2 ) exhibited inhibitory effects against tumor necrosis factor-α and nitric oxide generation induced by lipopolysaccharide in RAW 264.7 macrophages.