HPLC-UV guided isolation of anti-inflammatory polyacetylene glucosides from Carthamus tinctorius L.

HPLC-UV guided fractionation led to the isolation of nineteen previously undescribed polyacetylene glucosides (1-19) from the florets of Carthamus tinctorius L. Their structures, including the absolute configurations, were established by analysis of UV, IR, HRESIMS, 1D and 2D NMR data, together with enzymatic hydrolysis and ECD calculations. Compounds 1 and 2 were polyacetylene glucosides bearing an unusual furan ring. Compounds 3-6 were rare polyacetylene glucosides with an α-l-arabinofuranosyl moiety, while compound 3 comprised a 1-O-α-l-arabinofuranosyl-(1 → 3)-β-d-glucopyranosyl disaccharide unit. Compounds 2, 4, 5, 8, 11-13, 16, and 18 showed inhibition of nitric oxide secretion in lipopolysaccharide-stimulated RAW264.7 cells with IC50 values ranging from 5.0 to 40.0 μM.