title: Cytotoxic and anti-inflammatory effects of onion peel extract on lipopolysaccharide stimulated human colon carcinoma cells.
abstract: The present study investigated the cytotoxic activity of ethanol extract of onion peel (OPE) in HT-29 human colon carcinoma cells. High-performance liquid chromatography (HPLC) analysis was performed to determine the amounts of phenolic acids and flavonoids in OPE. In addition, the influence of OPE on antioxidant- and inflammation-associated gene expression was also determined in a model of lipopolysaccharide (LPS)-stimulated HT-29 cells. HPLC analysis showed that OPE contained well-known antioxidant compounds, including p-coumaric acid, vanillic acid, epicatechin, and morin. After incubation with OPE, HT-29 cells showed either a loss of normal nuclear architecture or detachability from each other. The cytotoxic effects of OPE on HT-29 cells were confirmed by MTT and LDH release assays. LPS-induced oxidative conditions effectively downregulated TNF-α mRNA expression in OPE pretreated HT-29 cells compared with cells only stimulated with LPS. In addition, the expression of heme oxygenase-1 (HO-1) and glutathione S-transferase (GSTs) detoxification genes (i.e., GSTM1, GSTT1, and GSTP1) was upregulated after treatment with LPS at sublethal concentrations. However, the LPS-induced mRNA expression of HO-1 and GSTs was significantly attenuated by treatment with OPE. Therefore, onion peel extract is a promising component of future nutraceuticals and value-added products.
authors.affiliation: Department of Food and Nutrition, Kyungnam University, Changwon 631-701, Republic of Korea.
authors.forename: Jungmi
authors.initials: J
authors.lastname: Kim
authors.forename: Ji-Sang
authors.initials: JS
authors.lastname: Kim
authors.forename: Eunju
authors.initials: E
authors.lastname: Park
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D000975:Antioxidants / Q000032:analysis / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003373:Coumaric Acids / Q000032:analysis; D005419:Flavonoids / Q000032:analysis; D005786:Gene Expression Regulation / Q000187:drug effects; D005982:Glutathione Transferase / Q000235:genetics; D019073:HT29 Cells / Q000187:drug effects; D051547:Heme Oxygenase-1 / Q000235:genetics; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D019697:Onions; D010936:Plant Extracts / Q000032:analysis / Q000494:pharmacology*; D011422:Propionates; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics; D047309:Flavones
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000975:Antioxidants; D003373:Coumaric Acids; D005419:Flavonoids; D005982:Glutathione Transferase; D051547:Heme Oxygenase-1; D007770:L-Lactate Dehydrogenase; D008070:Lipopolysaccharides; D010936:Plant Extracts; D011422:Propionates; D014409:Tumor Necrosis Factor-alpha; C008548:morin; D047309:Flavones; C496541:HMOX1 protein, human; C413545:glutathione S-transferase T1; C495469:p-coumaric acid
keywords: Cell proliferation; Human colon carcinoma cells; Lipopolysaccharide; Onion peel