Premium
Prenylated Flavanones from Monotes engleri : On‐line Structure Elucidation by LC/UV/NMR
Author(s) -
Garo Eliane,
Wolfender JeanLuc,
Hostettmann Kurt,
Hiller Wolf,
Antus SÁNdor,
Mavi Steven
Publication year - 1998
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19980810325
Subject(s) - chemistry , flavanone , stereochemistry , candida albicans , prenylation , two dimensional nuclear magnetic resonance spectroscopy , natural product , flavonoid , organic chemistry , enzyme , biology , genetics , antioxidant
The CH 2 Cl 2 extract of Monotes engleri Gilg. (Dipterocarpaceae) showed antifungal activity against the yeast Candida albicans in our bioautographic TLC assays. After a first fractionation of the crude extract, the bioactivity was located in one of the fractions. To perform an efficient targeted isolation of the active compounds, LC/UV/MS and LC/UV/NMR analyses of the crude extract and the active fraction were performed. LC/UV/, LC/MS, and LC/NMR data (1D and 2D) allowed the identification of 1 as ( 2S)‐2,3‐dihydro‐5,7‐dihydroxy–{3‐hydroxy‐4‐[(3‐methylbut‐2‐enyl) oxy]phenyl}‐4 H‐ 1‐benzopyran‐4‐one , a new prenylated flavanone, named monoteson A. Subsequent isolation of 1 has permitted the determination of its absolute configuration on the basis of CD measurements. Theree other prenylated flavanoes 2–4 were isolated from the same extract. Compound 3 was identified as 2‐ (3, 5‐dihydroxyphenyl) ‐2,3‐dihydro‐5, 7‐dihydroxy‐6, 8‐bis (3‐methylbut‐2‐enyl)‐4 H‐ 1‐benzopyran‐4‐one , another new natural product, named monotesone B. The structures of 2 and 4 were established as selinone and lonchocarpol A, respectively. The antifungal activity against Candida albicans was determined for all compounds.