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Comparison of Anti‐obesity Effects of Onion Peels by Different Extraction Methods Using 3T3‐L1 and Primary Brown Adipocytes In Vitro
Author(s) -
Lee Sang Gil,
Kang Hye Won
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.691.37
Subject(s) - adipogenesis , lipogenesis , carnitine palmitoyltransferase i , white adipose tissue , chemistry , fatty acid synthase , adipose tissue , carnitine , beta oxidation , peroxisome proliferator activated receptor gamma , peroxisome , brown adipose tissue , fatty acid , biochemistry , medicine , gene
Obesity, indicated by excess body fat accumulation, is a serious health problem. Various functional foods have been attracted for improving obese condition. Onion peel, a by‐product of onion has shown possible benefits in obesity studies. Since onion peel is not the edible part of onion, it is important to select a relevant extraction method to obtain beneficial compounds from onion peel for a targeted purpose. Different extracting process causes the distinct selectivity of functional compounds which may have different biological effects. Here, we utilized two onion peel extracts obtained through 60% ethanol extraction (OPE) and boiling water extraction (OPW). The purpose of this study was to compare anti‐obesity effect of OPE and OPW in white and brown adipocytes which are related to energy storage and utilization, respectively. Briefly, 3T3‐L1, fibroblasts that mimic white preadipocytes and primary brown preadipocytes isolated from interscapular brown adipose tissue of 4 week‐old male C57BL/6 mice were cultured and differentiated into mature adipocytes. Various concentrations of OPE and OPW were treated to the cells during differentiation and then gene expression was measured using real‐time PCR. In 3T3‐L1 cells, OPE decreased the expression of proliferator‐activated receptor γ (PPARγ), fatty acid synthase, and acetyl‐CoA carboxylase genes which are involved in adipogenesis and lipogenesis respectively whereas OPW did not. Interestingly, both OPE and OPW significantly increased the expression of carnitine palmitoyltransferase 1 α and PPARγ coactivator 1 α (PGC1α) genes which are related to the regulation of fatty acid oxidation. In brown adipocytes, PPARγ was significantly decreased by both OPE and OPW treatment. Only OPE significantly increased uncoupling protein 1 (UCP1) gene which is associated with a non‐shivering thermogenesis, increasing energy expenditure by utilizing fatty acids. However UCP1 gene was not altered by OPW treatment. This was not correlated with the expression of PGC1α gene and other downstream genes of PGC1α. Collectively, onion peel extracts exhibited anti‐obesity effects in both white and brown adipocytes. However, the effects and mechanisms were affected by the different extraction methods. Support or Funding Information Supported by USDA