Anti-adipogenic activity of Carduus crispus and its constituent apigenin in 3T3-L1 adipocytes by downregulating PPARγ and C/EBPα

Carduus crispus, native to Europe and Asia, is a traditional herbal medicine used for treating inflammatory disorders in Korea. Obesity is characterized by a state of chronic inflammation with increased inflammatory markers along with the expression and release of inflammation-related adipokines. Most anti-obesity drugs have been developed based on this concept. Our research for anti-obesity agents derived from C. crispus utilized the 3T3-L1 cell line. The methanol extract was initially screened and exhibited significant inhibition of adipogenesis in 3T3-L1 adipocytes. Among five liquid-liquid partition fractions, the ethyl acetate (EA) fraction showed the most potent suppressive effect compared with hexane, chloroform, n-butanol, and water. The EA fraction was considered for further study because of the presence of abundant polyphenols, including flavonoids. To isolate the active components from the EA fraction, elution-extrusion countercurrent chromatography was used. Among the seven fractions from the EA layer, fraction 6 inhibited lipid accumulation as well as CCAAT/enhancer-binding protein alpha and peroxisome proliferator-activated receptor gamma protein expression levels. The active component apigenin (fraction 6) was confirmed using high-performance liquid chromatography, electrospray ionization mass spectrometry, and one-dimensional nuclear magnetic resonance spectroscopy. The present data suggest that apigenin is one of the main bioactive compounds from C. crispus for inhibiting adipogenesis in 3T3-L1 adipocytes via the activation of AMP-activated protein kinase.