title: Inhibition of cyclooxygenase-2 and inducible nitric oxide synthase by silymarin in proliferating mesenchymal stem cells: comparison with glutathione modifiers.
abstract: Silymarin, a mixture of flavonolignans, is extracted from milk thistle (Silybum marianum) and has a strong antioxidant activity and exhibits anticarcinogenic, anti-inflammatory, and cytoprotective effects. In this study we attempted to determine whether silymarin and the glutathione modifiers, buthionine sulfoxamine (BSO) and N-acetylcysteine (NAC), are involved in regulation of cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) in proliferating mesenchymal stem cells (MSCs). Cellular glutathione was manipulated during a 14-day culture using BSO, NAC and silymarin. At intervals of 2, 7 and 14 days, cells were collected and COX-2 and iNOS levels were measured. In parallel, generation of cellular H(2)O(2) and glutathione were measured. Supplementation of the culture media with BSO caused a dose-dependent decrease in MSC proliferation, whereas NAC or silymarin elevated the proliferation (p < 0.05). Treatment of MSC with NAC or silymarin caused a significant decrease in COX-2 levels. However, COX-2 levels in cells treated with high levels of NAC (1.0 mM) were significantly lower than those in MSCs treated with high levels of silymarin (100 μM). BSO (1.0 and 5.0 μM) caused a significant increase in COX-2 on days 2, 7 and 14. BSO caused a significant increase in iNOS, whereas NAC or silymarin decreased cellular iNOS. Overall result show that glutathione, iNOS and COX-2 in proliferating MSCs are affected by silymarin treatment. It appears that glutathione is the main target of silymarin, and in consequence iNOS and COX-2 are affected in response to silymarin treatment.
authors.affiliation: Department of Biochemistry, Faculty of Medical Sciences, Tarbiat Modares University, POB 14115-111, Tehran, Islamic Republic of Iran.
authors.forename: Hamidreza
authors.initials: H
authors.lastname: Ahmadi-Ashtiani
authors.forename: Abdolamir
authors.initials: A
authors.lastname: Allameh
authors.forename: Hosein
authors.initials: H
authors.lastname: Rastegar
authors.forename: Masoud
authors.initials: M
authors.lastname: Soleimani
authors.forename: Elham
authors.initials: E
authors.lastname: Barkhordari
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology*; D019328:Buthionine Sulfoximine / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000187:drug effects* / Q000201:enzymology; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012838:Silymarin / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D004791:Enzyme Inhibitors; D012838:Silymarin; D019328:Buthionine Sulfoximine; D006861:Hydrogen Peroxide; C496319:NOS2 protein, human; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D005978:Glutathione; D000111:Acetylcysteine