Complete Assignment of the 1H and 13C NMR Spectra of Carthamin Potassium Salt Isolated from Carthamus tinctorius L.

Carthamin potassium salt isolated from Carthamus tinctorius L. was purified by an improved traditional Japanese method, without using column chromatography. The ¹H and ¹³C nuclear magnetic resonance (NMR) signals of the pure product were fully assigned using one- and two-dimensional NMR spectroscopy, while the high purity of the potassium salt and deprotonation at the 3′ position of carthamin were confirmed by atomic adsorption spectroscopy and nano-electrospray ionization mass spectrometry.