http://www.mdpi.com/journal/ijms/special_issues/structure_property_activity/ Dear Colleagues, Polyphenols (flavonoids, phenolic acids etc.) are abundant phytochemicals in human diet, and evidence for their role in the prevention of various diseases such as cardiovascular and neurodegenerative diseases and cancer is emerging. Mechanisms involved in the health-promoting activities of these compounds are far from clear. The goal of this special issue is to present novel results about structure-activity relationships (SAR) and quantitative structure-activity (property) relationships (QSAR/QSPR) of polyphenols, which may help in resolving the mode of actions of these food phenolics. They may also help in the design of new and efficient polyphenols, which could be used as potential therapeutic agents. With best regards, Prof. Dr. Nenad Trinajstic Guest Editor Submission All papers should be submitted to ijms@mdpi.org. To be published continuously until the deadline and papers will be listed together at the special issue website. Submitted papers should not have been published previously, nor be under consideration for publication elsewhere. All papers are refereed through a peer-review process. A guide for authors is available on the Instructions for Authors page. The International Journal of Molecular Sciences is an international peer-reviewed monthly journal published by Molecular Diversity Preservation International. Open Access publication fees are 800 CHF per paper. English correction fees and/or formatting fees (250 CHF) will be added in certain cases (1050 CHF per paper for those papers that require extensive additional formatting and/or English corrections). Leading Papers and Reviews Amic, D.; Davidovic-Amic, D.; Beslo, D.; Rastija, V; Lucic, B.; Trinajstic, N. SAR and QSAR of the Antioxidant Activity of Flavonoids. Curr. Med. Chem. 2007, 14, 827-845. Reis, M.; Lobato, B.; Lameira, J.; Santos, A.S.; Alves, C.N. A theoretical study of phenolic compounds with antioxidant properties. Eur. J. Med. Chem. 2007, 42, 440-446. Khlebnikov, A.I.; Schepetkin, I.A.; Domina, N.G.; Kirpotina, L.N.; Quinn, M.T. Improved quantitative structure–activity relationship models to predict antioxidant activity of flavonoids in chemical, enzymatic, and cellular systems. Bioorg. Med. Chem. 2007, 15, 1749-1770. Cabrera, M.; Simoens, M.; Falchi, G.; Lavaggi, M.L.; Piro, O.E.; Castellano, E.E.; Vidal, A.; Azqueta, A.; Monge, A.; de Cerain, A.L.; Sagrera, G.; Seoane, G.; Cerecetto H.; Gonzalez, M. Synthetic chalcones, flavanones, and flavones as antitumoral agents: Biological evaluation and structure-activity relationships. Bioorg. Med. Chem. 2007, 15, 3356-3367. Cai, Y.Z.; Sun, M.; Xing, J.; Luo, Q.; Corke H. Structure-radical scavenging activity relationships of phenolic compounds from traditional Chinese medicinal plants. Life Sci. 2006, 78, 2872-2888. Raad, I.; Terreux, R.; Richomme, P.; Matera, E.L.; Dumontet, C.; Raynaud, J.; Guilet, D. Structure–activity relationship of natural and synthetic coumarins inhibiting the multidrug transporter P-glycoprotein. Bioorg. Med. Chem. 2006, 14, 6979-6987. Brand, W.; Schutte, M.E.; Williamson, G.; van Zanden, J.J.; Cnubben, N. H.P.; Groten, J.P.; van Bladeren P.J.; Rietjens I.M.C.M. Flavonoid-mediated inhibition of intestinal ABC transporters may affect the oral bioavailability of drugs, food-borne toxic compounds and bioactive ingredients. Biomed. Pharmacother. 2006, 60, 508-519. Lameira, J.; Medeiros, I.G.; Reis, M.; Santos, A.S.; Alves, C.N. Structure-activity relationships study of flavone compounds with anti-HIV-1 integrase activity: A density functional theory study. Bioorg. Med Chem. 2006, 14, 7105-7112. Prabhakar, Y.S.; Gupta, M.K.; Roy, N.; Venkateswarlu, Y. A high dimensional QSAR study on the aldose reductase inhibitory activity of some flavones: Topological descriptors in modeling the activity. J. Chem Inf. Model. 2006, 46, 86-92. Sadeghipour, M.; Terreux, R.; Phipps J. Flavonoids and tyrosine nitration: structure–activity relationship correlation with enthalpy of formation. Toxic. in Vitro 2005, 19, 155-165. van Zanden, J.J.; Wortelboer, H.M.; Bijlsma, S.; Punt, A.; Usta, M.; van Bladeren, P.J.; Rietjens, I.M.C.M.; Cnubben, N.H.P. Quantitative structure activity relationship studies on the flavonoid mediated inhibition of multidrug resistance proteins 1 and 2. Biochem. Pharmacol.2005, 69, 699-708. Zhang, H.Y. Structure-Activity Relationships and Rational Design Strategies for Radical-Scavenging Antioxidants. Curr. Comp.-Aided Drug Des. 2005, 1, 257-273. Zhang, S.; Yang, X.; Coburn, R.A.; Morris, M.E. Structure activity relationships and quantitative structure activity relationships for the flavonoid-mediated inhibition of breast cancer resistance protein. Biochem.Pharmacol. 2005, 70, 627-639. Fernández, M.; Caballero, J.; Helguera, A.M.; Castro, E.A.; González, M.P. Quantitative structure–activity relationship to predict differential inhibition of aldose reductase by flavonoid compounds. Bioorg. Med.Chem. 2005, 13, 3269-3277. Mukherjee, S.; Mukherjee, A.; Saha, A. QSAR modeling on binding affinity of diverse estrogenic flavonoids: electronic, topological and spatial functions in quantitative approximation. J. Mol. Struct. (Theochem) 2005, 715, 85-90. Rasulev, B.F.; Abdullaev, N.D.; Syrov, V.N.; Leszczynski, J.A Quantitative Structure-Activity Relationship (QSAR) Study of the Antioxidant Activity of Flavonoids. QSAR Comb. Sci. 2005, 24, 1056-1065. Nemeikaite-Ceniene, A.; Imbrasaite, A.; Sergediene, E.; Cenas, N. Quantitative structure-activity relationships in prooxidant cytotoxicity of polyphenols: Role of potential of phenoxyl radical/phenol redox couple. Arch. Biochem. Biophys. 2005, 441, 182-190. Rackova, L.; Firakova, S.; Kostalova, D.; Steferk, M.; Sturdik, E.; Majekova, M. Oxidation of liposomal membrane suppressed by flavonoids: Quantitative structure-activity relationship. Bioorg. Med Chem. 2005, 13, 6477-6484. Fylaktakidou K.C.; Hadjipavlou-Litina D.J.; Litinas K.E.; Nicolaides D.N. Natural and synthetic coumarin derivatives with anti-inflammatory/antioxidant activities Current Pharmaceutical Design. 2004, 10, 3813-3833. Amic, D.; Davidovic-Amic, D.; Beslo, D.; Trinajstic, N. Structure-Radical Scavenging Activity Relationships of Flavonoids. Croat. Chem. Acta 2003, 76, 55-61. Sadik, C.D.; Sies, H.; Schewe, T. Inhibition of 15-lipoxygenases by flavonoids: structure-activity relations and mode of action. Biochem. Pharmacol. 2003, 65, 773-781. Van Hoorn, D.E.C.; Nijveldt, R.J.; Van Leeuwen, P.A.M.; Hofman, Z.; M'Rabet, L.; De Bont, D.BA.; Norren, K.V. Accurate prediction of xanthine oxidase inhibition based on the structure of flavonoids. Eur. J. Pharm. 2002, 451, 111-118 Kim, D.O.; Lee, C.Y. Comprehensive Study on Vitamin C Equivalent Antioxidant Capacity (VCEAC) of Various Polyphenolics in Scavenging a Free Radical and its Structural Relationship. Crit. Rev. Food Sci. Nutr. 2004, 44, 253-273. http://www.mdpi.com/1422-0067/10/3/1081/ DNA damage by reactive species is associated with susceptibility to chronic human degenerative disorders. Anthocyanins are naturally occurring antioxidants, that may prevent or reverse such damage. There is considerable interest in anthocyanic food plants as good dietary sources, with the potential for reducing susceptibility to chronic disease. While structure-activity relationships have provided guidelines on molecular structure in relation to free hydroxyl- radical scavenging, this may not cover the situation in food plants where the anthocyanins are part of a complex mixture, and may be part of complex structures, including anthocyanic vacuolar inclusions (AVIs). Additionally, new analytical methods have revealed new structures in previously-studied materials. We have compared the antioxidant activities of extracts from six anthocyanin-rich edible plants (red cabbage, red lettuce, blueberries, pansies, purple sweetpotato skin, purple sweetpotato flesh and Maori potato flesh) using three chemical assays (DPPH, TRAP and ORAC), and the in vitro Comet assay. Extracts from the flowering plant, lisianthus, were used for comparison. The extracts showed differential effects in the chemical assays, suggesting that closely related structures have different affinities to scavenge different reactive species. Integration of anthocyanins to an AVI led to more sustained radical scavenging activity as compared with the free anthocyanin. All but the red lettuce extract could reduce endogenous DNA damage in HT-29 colon cancer cells. However, while extracts from purple sweetpotato skin and flesh, Maori potato and pansies, protected cells against subsequent challenge by hydrogen peroxide at 0oC, red cabbage extracts were pro-oxidant, while other extracts had no effect. When the peroxide challenge was at 37oC, all of the extracts appeared pro-oxidant. Maori potato extract, consistently the weakest antioxidant in all the chemical assays, was more effective in the Comet assays. These results highlight the dangers of generalising to potential health benefits, based solely on identification of high anthocyanic content in plants, results of a single antioxidant assay and traditional approaches to structure activity relationships. Subsequent studies might usefully consider complex mixtures and a battery of assays. http://www.mdpi.com/1422-0067/10/3/1081/ Wed, 11 Mar 2009 00:00:00 CET International Journal of Molecular Sciences 2009-03-11 10 3 Article 1081 1103 1422-0067 Dietary Protection Against Free Radicals: A Case for Multiple Testing to Establish Structure-activity Relationships for Antioxidant Potential of Anthocyanic Plant Species 2009-03-11 doi: 10.3390/ijms10031081 Martin Philpott Chiara Cheng Lim Lynnette R. Ferguson http://www.mdpi.com/1422-0067/9/6/951/ The most potent catechin in green tea is (-)-epigallocatechin-3-gallate [(-)- EGCG], which, however, is unstable under physiological conditions. To discover more stable and more potent polyphenol proteasome inhibitors, we synthesized several novel fluoro-substituted (-)-EGCG analogs, named F-EGCG analogs, as well as their prodrug forms with all of -OH groups protected by acetate. We report that the prodrug form of one F-EGCG analog exhibited greater potency than the previously reported peracetate of (-)- EGCG to inhibit proteasomal activity, suppress cell proliferation, and induce apoptosis in human leukemia Jurkat T cells, demonstrating the potential of these compounds to be developed into novel anti-cancer and cancer-preventive agents. http://www.mdpi.com/1422-0067/9/6/951/ Mon, 02 Jun 2008 00:00:00 CEST International Journal of Molecular Sciences 2008-06-02 9 6 Article 951 961 1422-0067 Prodrugs of Fluoro-Substituted Benzoates of EGC as Tumor Cellular Proteasome Inhibitors and Apoptosis Inducers 2008-06-02 doi: 10.3390/ijms9060951 Zhiyong Yu Xu Long Qin Yan Yan Gu Di Chen Qiuzhi Cindy Cui Tao Jiang Sheng Biao Wan Q. Ping Dou http://www.mdpi.com/1422-0067/9/3/235/ A series of 7-hydroxy, 8-hydroxy and 7,8-dihydroxy synthetic chromone derivatives was evaluated for their DPPH free radical scavenging activities. A training set of 30 synthetic chromone derivatives was subject to three-dimensional quantitative structure-activity relationship (3D-QSAR) studies using molecular field analysis (MFA). The substitutional requirements for favorable antioxidant activity were investigated and a predictive model that could be used for the design of novel antioxidants was derived. Regression analysis was carried out using genetic partial least squares (G/PLS) method. A highly predictive and statistically significant model was generated. The predictive ability of the developed model was assessed using a test set of 5 compounds (r2pred = 0.924). The analyzed MFA model demonstrated a good fit, having r2 value of 0.868 and crossvalidated coefficient r2cv value of 0.771. http://www.mdpi.com/1422-0067/9/3/235/ Fri, 29 Feb 2008 00:00:00 CET International Journal of Molecular Sciences 2008-02-29 9 3 Article 235 246 1422-0067 3D-QSAR Investigation of Synthetic Antioxidant Chromone Derivatives by Molecular Field Analysis 2008-02-29 doi: 10.3390/ijms9030235 Weerasak Samee Patcharawee Nunthanavanit Jiraporn Ungwitayatorn