Isolation and Identification of Signature Flavonoid Compounds in Coreopsis tinctoria Nutt.

In this study, the solvent extraction and purification of flavonoids from three cultivars (coded as 1, 2 and 3) of Coreopsis tinctoria Nutt. were optimized based on the content of total flavonoids and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity. The flavonoids were analyzed and identified by high performance liquid chromatography (HPLC), mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. The results showed that methanol was found to be the best solvent for the extraction of flavonoids. The yield of flavonoids extracted from the first cultivar was the highest, and the total flavonoid content and DPPH radical scavenging capacity of the extract were 65.01 mg/g and 73.59%, respectively. Top 10 most abundant flavonoids were tentatively by HPLC-MS. Eight monomeric compounds were purified from the extract by macroporous resin chromatography, vacuum column chromatography, atmospheric column chromatography and gel permeation chromatography, and these compounds were identified as luteolin, 7,8,3’,4’-tetrahydroxyflavanone, taxifolin, okanin, quercetin, quercetagetin, flavanomarein and marein by MS and NMR spectroscopy. Okanin was determined as the signature flavonoid compound in C. tinctoria Nutt. by HPLC and DPPH radical scavenging activity.