Supercritical CO2 extraction of oleoresin from marigold (Tagetes erecta L.) flowers and determination of its antioxidant components with online HPLC-ABTS•+ assay

BACKGROUND: Marigold is a traditional medicine herb which shows good pharmacological activity in many aspects. It is very important to obtain and investigate the specific bioactive compounds from marigold. The objective of the study was to extract the oleoresin from marigold with supercritical CO2 (SC-CO2) at different pressures and temperatures, detect the fatty acid composition by gas chromatography-mass spectrometry and investigate the antioxidative components in the extracts by combined online high-performance liquid chromatography-2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid (HPLC-ABTS(center dot+)) post-column assay and HPLC-tandem mass spectrometry. RESULTS: For the pressure range (20-40 MPa) and temperature range (30-70 degrees C), 30 MPa/70 degrees C gave the highest yield of oleoresin (58.9 g kg(-1)). The dominant fatty acids of marigold flower oleoresin were linoleic acid (>26.41%), palmitic acid (>24.22%) and oleinic acid (>20.12%). Significant effects of the extraction pressure and temperature on the antioxidant activity were observed (P < 0.05). Lutein esters, alpha-tocopherol, beta-tocopherol, gamma-tocopherol and delta-tocopherol were the dominant antioxidant compounds in the extracts. CONCLUSION: The study has shown that the yield and total antioxidant activity of the marigold extracts were affected by the pressure and temperature of SC-CO2, and that online HPLC technique could be used as an efficient and rapid method for separation and identification of bioactive compounds from a complex mixture. (C) 2011 Society of Chemical Industry