Anti-inflammatory properties of a- and c-tocopherol

Natural vitamin E consists of four different tocopherol and four different tocotrienol homologues (a,b, c, d) that all have antioxidant activity. However, recent data indicate that the different vitamin E homologues also have biological activity unrelated to their antioxidant activity. In this review, we discuss the anti-inflammatory properties of the two major forms of vitamin E, a-tocopherol (aT) and c-tocopherol (cT), and discuss the potential molecular mechanisms involved in these effects. While both tocopherols exhibit anti-inflammatory activity in vitro and in vivo, supplementation with mixed (cT-enriched) tocopherols seems to be more potent than supplementation with aT alone. This may explain the mostly negative out0098-2997/$ see front matter 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.mam.2007.01.003 Abbreviations: aT, a-tocopherol; bT, b-tocopherol; CEHC, carboxyethyl hydroxychroman; Con A, concanavalin A; COX, cyclooxygenase; CRP, C-reactive protein; CVD, cardiovascular disease; DTH, delayed type hypersensitivity; dT, d-tocopherol; cT, c-tocopherol; H2O2, hydrogen peroxide; ICAM-1, intercellular adhesion molecule 1; IL-1b, interleukin 1b; IL-2, interleukin 2; IL-4, interleukin 4; IL-5, interleukin 5; IL6, interleukin 6; IFN-c, interferon c; LOX, lipoxygenase; LPS, lipopolysaccharide; LTB4, leukotriene B4; NFjB, nuclear factor jB; NO, nitric oxide; NOS, nitric oxide synthase; O 2 , superoxide; PGE2, prostaglandin E2; PHA, phytohemagglutinin; PKC, protein kinase C; PMA, phorbol 12-myristate 13-acetate; PP2A, protein phosphatase 2A; PPAR, peroxisome proliferator-activated receptor; SOD, superoxide dismutase; TNF-a, tumor necrosis factor a; VCAM-1, vascular cell adhesion molecule 1. * Corresponding author. Tel.: +41 31 632 8707; fax: +41 31 632 3550. E-mail addresses: [email protected] (E. Reiter), [email protected] (Q. Jiang), stephan.christen@ ifik.unibe.ch (S. Christen). E. Reiter et al. / Molecular Aspects of Medicine 28 (2007) 668–691 669 comes of the recent large-scale interventional chronic disease prevention trials with aT only and thus warrants further investigation. 2007 Elsevier Ltd. All rights reserved.