Negative Regulation of Adipogenesis by Kaempferol, a Component of Rhizoma Polygonati falcatum in 3T3-L1 Cells

Rhizoma Polygonati falcatum (RPF) has been used as a traditional herbal medicine in Asia, because of its anti-hyperglycemic, anti-triglycemic, and anti-tumor activity. In this study, we determined the anti-adipogenic potential of RPF extract and its component kaempferol in 3T3-L1 adipocytes, and the underlying molecular mechanism(s) using microarray analysis. Adipocyte differentiation of 3T3-L1 cells was significantly impaired by RPF extract and kaempferol as monitored by Oil Red O staining and quantitative measurement of lipid accumulation. Additionally, the mRNA expression of adipogenesis genes decreased on treatment with kaempferol. The role of kaempferol at the genome-wide level was further assessed by a microarray approach. Our analysis indicated that kaempferol decreased the expression of adipogenic transcription factors (Pparγ, Cebpβ, Srebp1, Rxrβ, Lxrβ, Rorα) and genes involved in triglyceride biosynthesis (Gpd1, Agpat2, Dgat2), while increasing lipolysis-related genes, such as Tnfα, Lsr, and Cel. Finally, co-transfection assays using luciferase reporter gene and reverse transcription-polymerase chain reaction (RT-PCR) analysis using peroxisome proliferator-activated receptor-γ (PPARγ) target genes indicated that kaempferol significantly repressed rosiglitazone-induced PPARγ transcriptional activity. Overall, our data suggests that kaempferol, a major component of RPF, may be beneficial in obesity, by reducing adipogenesis and balancing lipid homeostasis partly through the down-regulation of PPARγ.