ABSTRACT
<p><b>OBJECTIVE</b>The leaves of Chromolaena odorata, a highly invasive shrub found growing wild worldwide, are traditionally used for wound healing. Due to its high flavonoid contents, we aimed to find a new application for this plant. Preliminary tests using its ethanolic leaf extract showed that it could suppress the accumulation of lipids in adipocytes. We therefore studied the anti-adipogenic effect of several C. odorata leaf extracts and the relationship between molecular structure and bio-activity of its isolated flavonoid constituents using 3T3-L1 preadipocytes/adipocytes as a model.</p><p><b>METHODS</b>Three leaf extracts and thirteen flavonoids isolated from C. odorata were tested for their effect on lipid accumulation in 3T3-L1 adipocytes using AdipoRed reagent, with quercetin as the positive control. The effects of active flavonoids on the adipocytes were confirmed by oil red O staining and visualized under a light microscope.</p><p><b>RESULTS</b>n-Hexane and ethyl acetate extracts of C. odorata leaves displayed anti-adipogenic activity. The latter extract was the more potent one, especially at 40 µg/mL. Four flavonoids, pectolinarigenin, kaempferide, 4,2'-dihydroxy-4',5',6'-trimethoxychalcone and dillenetin, exhibited significant, concentration-dependent inhibitory effects on lipid accumulation in 3T3-L1 adipocytes. The most potent flavonoid obtained in this study was 4,2'-dihydroxy-4',5',6'-trimethoxychalcone, which caused 75% and 90% inhibition of cellular lipid accumulation at 30 and 50 µmol/L, respectively. Both kaempferide and 4,2'-dihydroxy-4',5',6'-trimethoxychalcone were major constituents in the ethyl acetate extract of this plant.</p><p><b>CONCLUSION</b>C. odorata leaves contained several flavonoids with anti-adipogenic effects against lipid accumulation in 3T3-L1 adipocytes. The plant, normally considered a useless weed, may actually provide an abundant source of biologically active flavonoids.</p>