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1 H NMR‐Guided Isolation of Formyl‐Phloroglucinol Meroterpenoids from the Leaves of Eucalyptus robusta
Author(s) -
Shang ZhiChun,
Yang MingHua,
Jian KaiLi,
Wang XiaoBing,
Kong LingYi
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201601732
Subject(s) - undecane , chemistry , chirality (physics) , phloroglucinol , stereochemistry , circular dichroism , nuclear magnetic resonance spectroscopy , phycocyanobilin , organic chemistry , biology , cyanobacteria , chiral symmetry breaking , physics , quantum mechanics , phycocyanin , bacteria , nambu–jona lasinio model , genetics , quark
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 IC 50 values less than 10 μ m . Compound 3 significantly blocks cell proliferation in MCF‐7 cells and induces MCF‐7 cell death through apoptosis.