Leontopodic acid—a novel highly substituted glucaric acid derivative from Edelweiss (Leontopodium alpinum Cass.) and its antioxidative and DNA protecting properties Stefan Schwaiger, a Rinaldo Cervellati, b Christoph Seger, a Ernst P. Ellmerer, c Nancy About, d Isabelle Renimel, d Ce ´line Godenir, d Patrice Andre ´, d Frank Gafner e and Hermann Stuppner a, * a Institut fu ¨r Pharmazie, Abteilung Pharmakognosie, Leopold-Franzens-Universita ¨t Innsbruck, Innrain 52, A-6020 Innsbruck, Austria b Dipartimento di Chimica “G. Ciamican”, Universita ´ di Bologna, Via Selmi 2, I-40126 Bologna, Italy c Institut fu ¨r Organische Chemie, Leopold-Franzens-Universita ¨t Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria d Laboratoires Actifs, Biologie et Cosme ´tique, LVMH R&D, F-45800 Saint Jean de Braye, France e AlpaflorLtd./Pentapharm, Engelgasse 109, CH-4002 Basel, Switzerland Received 8 November 2004; revised 23 February 2005; accepted 2 March 2005 Available online 30 March 2005 Abstract—Leontopodic acid—a novel full substituted hexaric acid derivative, was isolated from the aerial parts of Edelweiss (Leontopodium alpinum Cass.) as one of the major compounds. The complex structure of leontopodic acid-2-[(3S)-3-hydroxybutanoate]- 3,4,5-tris-[(2E)-3-(3,4-dihydroxyphenyl)-2-propenoate]-D-glucaric acid—was elucidated by mass spectrometry, 1D- and 2D NMR spectroscopy and HPLC monitored transesterification. Leontopodic acid exhibited pronounced antioxidative effects in the Briggs-Rauscher (BR) model [(r.a.c.) m 3.4G0.5] and the trolox equivalent antioxidant capacity (TEAC) method (TEAC value of 1.53G0.11). The antioxidative properties of this compound were confirmed by the 3D method, an in vitro assay evaluating DNA protection against oxidative damage (IC 50 : 1.89 mM). q 2005 Elsevier Ltd. All rights reserved. 1. Introduction Free radicals and reactive oxygen species (ROS) are produced by most cells. They play a crucial role in cellular metabolism and mediate critical biochemical reactions and physiologic effects, for example, eicosanoid synthesis, phagocyte activity, cytochrome P-450 and peroxidase function, pyruvate and coenzyme A metabolism, carboxyl- ation of glutamic acid by vitamin K-dependent enzymes, and the reduction of ribonucleosides. Maintenance of the normal redox balance of a cell, ensuring a transitory ROS generation, is controlled by compounds that are antioxidants (e.g., the antioxidant vitamins) or by enzymes, both constitutive and inducible. If the antioxidant defense systems fail ROS are produced in excess and oxidative stress-an imbalance between oxidants and antioxidants in favor of the former, and potentially leading to damage—can arise. 1 As a result, ROS can damage cells by interactions with critical macromolecules, including DNA, proteins, and lipids, which leads to toxicity. They are believed to be involved in the etiology of a wide array of human disorders. For example, reactive oxygen species have been linked to coronary heart disease, atherosclerosis, cancer, diabetes, cataract, arthritis, toxic liver injury, adverse drug reactions, immune hypersensitivity, inflammation, reperfusion injury, neurological disease, and aging. 2 Plant constituents, widely 0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.tet.2005.03.002 Tetrahedron 61 (2005) 4621–4630 Figure 1. Structure of leontopodic acid. Keywords: Leontopodium alpinum; Asteraceae; Glucaric acid; Caffeic acid; Briggs-Rauscher reaction; TEAC; 3D; Leontopodic acid. * Corresponding author. Tel.: C43 512 507 5300; fax: C43 512 507 29 39; e-mail: hermann.stuppner@uibk.ac.at