title: (1) H NMR-Guided Isolation of Formyl-Phloroglucinol Meroterpenoids from the Leaves of Eucalyptus robusta.
abstract: Nine formyl-phloroglucinolmeroterpenoids (FPMs), namely, eucalrobusones A-I (1-9), were isolated from the leaves of Eucalyptus robusta by tracking the phenolic hydroxyl (1) H NMR peaks. The Snatzke helicity rules for the Cotton effects of twisted benzene rings were applied to elucidate the absolute configurations of the FPMs. These findings, along with NMR spectroscopy, the circular dichroism (CD) exciton chirality method, and CD calculations, allowed complete structures for the FPMs to be assigned. Eucalrobusones A-F (1-6) are novel adducts formed between a formyl-derived carbon atom on the phloroglucinol ring and monoterpene and sesquiterpene components. Eucalrobusones G-I (7-9) are the first examples of FPMs with cubebane part structures connected by an unusual 1-oxaspiro[5.5]undecane subunit. Among these isolates, eucalrobusone C (3) showed significant cytotoxicity against HepG2, MCF-7, and U2OS cancer cell lines, with IC50 values less than 10 μm. Compound 3 significantly blocks cell proliferation in MCF-7 cells and induces MCF-7 cell death through apoptosis.
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing, 210009, P. R. China.
authors.forename: Zhi-Chun
authors.initials: ZC
authors.lastname: Shang
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing, 210009, P. R. China. cpu_lykong@126.com.
authors.forename: Ming-Hua
authors.initials: MH
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing, 210009, P. R. China.
authors.forename: Kai-Li
authors.initials: KL
authors.lastname: Jian
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing, 210009, P. R. China.
authors.forename: Xiao-Bing
authors.initials: XB
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing, 210009, P. R. China. skeepjack@163.com.
authors.forename: Ling-Yi
authors.initials: LY
authors.lastname: Kong
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002942:Circular Dichroism; D005052:Eucalyptus / Q000737:chemistry*; D006801:Humans; D061986:MCF-7 Cells; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010696:Phloroglucinol / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry*; D012717:Sesquiterpenes / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D013729:Terpenes / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D012717:Sesquiterpenes; D013729:Terpenes; D010696:Phloroglucinol
keywords: NMR spectroscopy; circular dichroism; cytotoxicity; structure elucidation; terpenoids