Cyclopia intermedia (Honeybush) Induces Uncoupling Protein 1 and Peroxisome Proliferator-Activated Receptor Alpha Expression in Obese Diabetic Female db/db Mice.

Previously, we reported that a crude polyphenol-enriched fraction of Cyclopia intermedia (CPEF), a plant consumed as the herbal tea, commonly known as honeybush, reduced lipid content in 3T3-L1 adipocytes and inhibited body weight gain in obese, diabetic female leptin receptor-deficient (db/db) mice. In the current study, the mechanisms underlying decreased body weight gain in db/db mice were further elucidated using western blot analysis and in silico approaches. CPEF induced uncoupling protein 1 (UCP1, 3.4-fold, p < 0.05) and peroxisome proliferator-activated receptor alpha (PPARα, 2.6-fold, p < 0.05) expression in brown adipose tissue. In the liver, CPEF induced PPARα expression (2.2-fold, p < 0.05), which was accompanied by a 31.9% decrease in fat droplets in Hematoxylin and Eosin (H&E)-stained liver sections (p < 0.001). Molecular docking analysis revealed that the CPEF compounds, hesperidin and neoponcirin, had the highest binding affinities for UCP1 and PPARα, respectively. This was validated with stabilising intermolecular interactions within the active sites of UCP1 and PPARα when complexed with these compounds. This study suggests that CPEF may exert its anti-obesity effects by promoting thermogenesis and fatty acid oxidation via inducing UCP1 and PPARα expression, and that hesperidin and neoponcirin may be responsible for these effects. Findings from this study could pave the way for designing target-specific anti-obesity therapeutics from C. intermedia.

Comparing the effects of tumor necrosis factor alpha, lipopolysaccharide and palmitic acid on lipid metabolism and inflammation in murine 3T3-L1 adipocytes.

AIMS: This study aimed to develop a model of dysregulated lipid metabolism and inflammation by treating 3T3-L1 adipocytes with tumor necrosis factor alpha (TNFα), lipopolysaccharide (LPS), and palmitic acid (PA) individually or in combination to assess their effects and mechanism of action. MAIN METHODS: Differentiated 3T3-L1 adipocytes were treated with TNFα (10 ng/mL), LPS (100 ng/mL), and PA (0.75 mM) individually or in combination for 24 h. Lipolysis, lipid content, inflammation, and the expression of lipid metabolism and inflammation genes were assessed by glycerol release quantification, Oil Red O staining, enzyme-linked immunosorbent assays, and quantitative reverse transcription-polymerase chain reaction, respectively. KEY FINDINGS: Exposure of 3T3-L1 adipocytes to TNFα stimulated lipolysis, reduced lipid accumulation, decreased adiponectin (ADIPOQ) secretion, and increased secretion of pro-inflammatory adipokines, monocyte chemoattractant protein 1 (MCP-1), interleukin 6 (IL-6), and interleukin 1 beta (IL-1ß). These changes were accompanied by decreased expression of lipid metabolism genes, increased expression of pro-inflammatory genes (MCP-1 and IL-6), and decreased expression of the anti-inflammatory gene, ADIPOQ. Exposure to LPS and PA, alone or in combination did not affect these parameters, while co-treatment with TNFα, LPS, and PA enhanced lipolysis and decreased ADIPOQ secretion compared to TNFα treatment. SIGNIFICANCE: Dysregulation of lipid metabolism and inflammation in 3T3-L1 adipocytes is attributed to TNFα rather than LPS and PA. We propose that exposing 3T3-L1 adipocytes to TNFα presents a suitable in vitro model of adipocyte dysfunction that closely resembles the complexity of obesity in vivo.