NMR study of some anthraquinones from rhubarb

Abstract

The 1H and 13C NMR spectra of the anthraquinones physcion, emodin, chrysophanol, aloe‐emodin and rhein were assigned. The previously preferred assignments for C‐2 and C‐4 in physcion were reversed. The NOE technique was used for the assignment of the 1H signals and SEFT and/or heteronuclear decoupling for 13C resonances.

Bioassay-guided isolation of anti-algal constituents from Inula helenium and Limonium myrianthum

“…Final structure confirmation was accomplished by comparing 1 H and 13 C NMR data with that reported in the literature. [6][7][8][9] Chrysophanol (1,8-dihydroxyanthraquinone) was the most active of the four compounds isolated from fractions B and C from the L. myrianthum extract with a LCIC of 10 µg/mL towards O. perornata and at least 10X more toxicity when compared with the LCIC results (>100 µg/mL) of S. capricornutum.…”

“…Compounds 1 and 4 were converted to their respective mono-epoxide isomers 5α-epoxyalantolactone (2) and 4(15)α-epoxyisoalantolactone (5) using previously described methods. 9,16 Similarly, compound 1 was oxidized to its respective diol, 11,13-dihydroxyalantolactone (3), using previously described methods and procedures. 9 Identification of all compounds was performed by comparison of spectral data with that reported in the literature.…”

“…9,16 Similarly, compound 1 was oxidized to its respective diol, 11,13-dihydroxyalantolactone (3), using previously described methods and procedures. 9 Identification of all compounds was performed by comparison of spectral data with that reported in the literature. 9,16 Isolation and identification of Limonium myrianthum compounds.…”

“…9 Identification of all compounds was performed by comparison of spectral data with that reported in the literature. 9,16 Isolation and identification of Limonium myrianthum compounds. A portion of the L. myrianthum CH 2 Cl 2 roots extract (3.010 g) was adsorbed to silica gel and applied to a silica gel chromatography column (40-63 µm, 40 x 150 mm, 60 Å).…”

Bioactive anthraquinone dimers from the leafhopper pathogenic fungus Torrubiella sp. BCC 28517

“…A mycelial extract of this strain exhibited cytotoxicity to oral cavity cancer cells (KB) and small-cell lung cancer cells (NCI-H187) with respective IC 50 values of 1.66 and 0.79 mg ml À1 . We report here the isolation, structure elucidation and biological activities of two new anthraquinone dimers, torrubiellins A (1) and B (2), together with the known anthraquinones, chrysophanol (3), 7,8 aloe-emodin (4) 7 and emodin (5) (Figure 1). 7,9 RESULTS AND DISCUSSION Torrubiellin A (1) was obtained as a dark-brown solid, and the molecular formula was established as C 30 H 20 O 8 , from the protonated quasi-molecular ion peak in the HRESIMS.…”