Abstract
Obesity is an abnormal medical condition caused by accumulation of body fat that presents negative health impacts. Adipocyte hyperplasia, also known as adipogenesis, is one of the major manifestations of obesity. In the present study, we isolated six phenanthrene derivatives (compounds 1–6) from the ethyl acetate fraction of Spiranthes sinensis and investigated their anti-adipogenic activity. We found that among the six phenanthrene derivatives, compound 6 (sinensol-C) exhibited strong inhibitory activity against intracellular lipid accumulation in 3T3-L1 adipocytes, with an IC50 value of 12.67 μM. Sinensol-C remarkably suppressed the accumulation of lipid droplets and adipogenesis, via down-regulation of adipogenic transcription factors, including peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), sterol regulatory element binding protein-1 (SREBP-1c), fatty acid synthase (FAS), and fatty acid binding protein 4 (FABP4), during adipocyte differentiation in 3T3-L1 cells. In addition, treatment with sinensol-C significantly increased the adenosine monophosphate-activated protein kinase (AMPK) activity in 3T3-L1 cells. Taken together, these data strongly suggest that sinensol-C regulates adiogenesis via down-regulation of adipogenic transcription factors and up-regulation of AMPK. Furthermore, this is the first study that demonstrates that sinensol-C has the capacity to modulate adipogenesis.
Highlights
After adipogenesis, the 3T3-L1 cells were stained with oil red O (ORO) solution to determine the accumulation of lipid droplets
Our results clearly indicated that sinensol-C inhibits the genes and proteins of adipogenic transcription factors (PPARγ, CCAAT/enhancer binding protein α (C/EBPα), and SREBP-1c), and promotes expression of adiponectin
We found that sinensol-C significantly attenuated lipid accumulation and adipocyte differentiation of 3T3-L1 cells in a dose-dependent manner
Summary
Spiranthes sinensis, commonly known as the Chinese spiranthes, belongs to the familyOrchidaceae and is widely distributed in Eastern Asia, including China, Japan, and Taiwan [1,2].In traditional Chinese medicine, S. sinensis has been used to treat various human diseases such as sexual dysfunction, hemoptysis, epistaxis, headache, chronic dysentery, and meningitis [3].Molecules 2020, 25, 4204; doi:10.3390/molecules25184204 www.mdpi.com/journal/moleculesIn addition, modern scientific investigations have indicated that S. sinensis possesses various pharmacological activities, including being anti-HBV, anti-inflammatory, anti-oxidant, anti-bacterial, and anti-cancer [4,5,6,7,8]. In traditional Chinese medicine, S. sinensis has been used to treat various human diseases such as sexual dysfunction, hemoptysis, epistaxis, headache, chronic dysentery, and meningitis [3]. Medicinal plants to prevent obesity have been widely investigated [9]. Many reports have indicated that bioactive compounds isolated and identified from plants are potentially useful to prevent or treat obesity [10,11,12]. Isolation of anti-adipogenic compounds from medicinal plants can provide therapeutic and preventive strategies for the development of new applications. S. sinensis contains various types of bioactive compounds, such as phenanthrenes, flavonoids, coumarins, and steroids [13,14,15,16]. There is insufficient evidence to show the anti-adipogenesis effect of
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