Complementarity of DFT Calculations, NMR Anisotropy, and ECD for the Configurational Analysis of Brevipolides K–O from Hyptis brevipes

Brevipolides K–O (1–5), five new cytotoxic 6-(6′-cinnamoyloxy-2′,5′-epoxy-1′-hydroxyheptyl)-5,6-dihydro-2H-pyran-2-ones (IC50 values against six cancer cell lines, 1.7–10 μM), were purified by recycling HPLC from Hyptis brevipes. The structures, containing a distinctive tetrahydrofuran ring, were es...

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Bibliographic Details
Published inJournal of natural products (Washington, D.C.) Vol. 80; no. 1; pp. 181 - 189
Main Authors Suárez-Ortiz, G. Alejandra, Cerda-García-Rojas, Carlos M., Fragoso-Serrano, Mabel, Pereda-Miranda, Rogelio
Format Journal Article
LanguageEnglish
Published WASHINGTON American Chemical Society and American Society of Pharmacognosy 27.01.2017
Amer Chemical Soc
Subjects
Anisotropy
Cell Line
Chemistry, Medicinal
Humans
Hyptis - chemistry
Inhibitory Concentration 50
Life Sciences & Biomedicine
Magnetic Resonance Spectroscopy
Molecular Structure
Pharmacology & Pharmacy
Plant Sciences
Pyrones - chemistry
Pyrones - isolation & purification
Pyrones - pharmacology
Quantum Theory
Science & Technology
Stereoisomerism
GEOMETRIES
X-RAY CRYSTALLOGRAPHY
ABSOLUTE-CONFIGURATION
5,6-DIHYDRO-ALPHA-PYRONES
SPICIGEROLIDE
ASSIGNMENT
CONFORMATIONAL-ANALYSIS
CYTOTOXICITY
MOLECULAR-FORCE FIELD
COUPLING-CONSTANTS
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Summary:Brevipolides K–O (1–5), five new cytotoxic 6-(6′-cinnamoyloxy-2′,5′-epoxy-1′-hydroxyheptyl)-5,6-dihydro-2H-pyran-2-ones (IC50 values against six cancer cell lines, 1.7–10 μM), were purified by recycling HPLC from Hyptis brevipes. The structures, containing a distinctive tetrahydrofuran ring, were established by comprehensive quantum mechanical calculations and experimental spectroscopic analysis of their NMR and ECD data. Detailed analysis of the experimental NMR 1H–1H vicinal coupling constants in comparison with the corresponding DFT-calculated values at the B3LYP/DGDZVP level confirmed the absolute configuration of 3 and revealed its conformational preferences, which were further strengthened by NOESY correlations. NMR anisotropy experiments by the application of Mosher’s ester methodology and chemical correlations were also used to conclude that this novel brevipolide series (1–5) share the same absolute configuration corresponding to C-6­(R), C-1′(S), C-2′(R), C-5′(S), and C-6′(S).
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ISSN:0163-3864
1520-6025
DOI:10.1021/acs.jnatprod.6b00953