Flavonoids kaempferide and 4,2′-dihydroxy-4′,5′,6′-trimethoxychalcone inhibit mitotic clonal expansion and induce apoptosis during the early phase of adipogenesis in 3T3-L1 cells

Objective: Kaempferide and 4,20-dihydroxy-40,50,60-trimethoxychalcone (DTMC) are two major flavonoids found in Chromolaena odorata Linn. leaf extract. The aim of this study was to elucidate the mechanism by which these two flavonoids exerted their effect on adipogenesis. The inhibitory effect of kaempferide and DTMC on adipocyte differentiation and their mechanisms involving mitotic clonal expansion (MCE) and apoptosis during the early stage of adipogenesis were investigated. Methods: Confluent 3T3-L1 preadipocytes were induced to differentiate and exposed to the flavonoids during various phases of differentiation. Intracellular lipid accumulation, cell density and expression of the transcription factors peroxisome proliferator-activated receptor gamma and CCAAT/enhancer-binding proteins alpha were assessed using AdipoRed, Oil red O and Western blot assays. Effects of both flavonoids on cell proliferation and apoptosis were also determined by carboxyfluorescein diacetate succinimidyl ester and annexin V-fluorescein isothiocyanate/propidium iodide-staining assays, respectively. Results: Kaempferide and DTMC showed significant, concentration-dependent anti-adipogenic activity and effect on cell density in the early phase of adipogenesis. The expression of the transcription factors seemed to be reduced when the treatment was prolonged or in the early phase of adipogenesis. These flavonoids interrupted MCE via inhibition of preadipocyte proliferation and induction of apoptosis. DTMC was nearly three times more potent than kaempferide in inducing apoptosis. Conclusion: Kaempferide and DTMC exerted their anti-adipogenic activity through inhibition of MCE, either by suppressing cell proliferation or by inducing apoptosis during the early phase of differentiation. (C) 2019 Shanghai Changhai Hospital. Published by Elsevier B.V. All rights reserved.