ARTICLE Responses of the phenolic compounds of Zea mays under heavy metal stress Dursun Kısa 1 . Mahfuz Elmastas ¸ 2 . Lokman O ¨ ztu ¨rk 1 . O ¨ mer Kayır 3 Received: 20 July 2016 / Accepted: 4 October 2016 / Published online: 12 October 2016 Ó The Korean Society for Applied Biological Chemistry 2016 Abstract Heavy metal toxicity is one of the major abiotic stresses caused by physiological and biochemical changes. Plants have evolved various phytochemical defense mechanisms to cope with this abiotic stress conditions. Phenolic compounds are one of the stress responses and have multiple roles in respect to adaptation of plants to the environment. In the present study, we aimed to evaluate the differential accumulation of various phenolics with HPLC in the leaves of corn exposed to increasing heavy metal doses in the plant growth medium. The application of Cd, Cu, and Pb increased the total phenolics in all treatments compared to control groups. Chlorogenic acid and rutin were the main phenolic compounds in respect to quanti- fying. However, the contents of caffeic acid, ferulic acid, and vanillic acid were comparatively lower than chloro- genic acid and rutin in all samples. The content of chlorogenic acid significantly increased and rutin slightly increased in the treatment of the heavy metals. The levels of caffeic acid and ferulic acid significantly decreased in all exposures of heavy metals compared to control groups. The content of vanillic acid changed according to heavy metal types and doses in the leaves of corn, and the low doses of Pb and Cd increased the level of vanillic acid. We show that there is a positive correlation with the total phenolic content and chlorogenic acid when the corn is exposed to Pb. Moreover, there are negative correlations between total phenolic compound and caffeic acid, ferulic acid in the application of Cu and Cd. Keywords Caffeic acid Á Chlorogenic acid Á Ferulic acid Á Heavy metal Á Phenolic compound Á Rutin Á Vanillic acid Introduction Heavy metals are one of the main abiotic stress factors, and they have caused some physiological and biochemical changes in the plants. The excess of heavy metals affects the various parameters of plant metabolism such as pho- tosynthesis, mineral distribution, and antioxidant defense system (Nazar et al. 2012). The contamination of soil with heavy metals increases as a result of agricultural activities such as uses of fertilizers, herbicides, and pesticides prac- tices (Demirezen and Aksoy 2005). Environmental condi- tions have changed the plant growth and development, and plants have acquired adaptation mechanisms to survive their life (Lequeux et al. 2010). Heavy metals such as Cd and Pb are unnecessary, and others such as Cu, Fe, and Zn are required for plant life cycles. However, the high level of Cu shows a toxic effect and caused retention of plant development. They are considered as very significant contaminant and affect the electron transport system (ETS), chloroplast, thylakoid membrane, plastoquinone, and car- otenoids (Sharma and Dubey 2005). The primary response of plants exposed to heavy metals is the formation of reactive oxygen species (ROS), and it Electronic supplementary material The online version of this article (doi:10.1007/s13765-016-0229-9) contains supplementary material, which is available to authorized users. & Dursun Kısa drsn57@hotmail.com 1 Department of Biology, Faculty of Science and Arts, Gaziosmanpasa University, 60250 Tokat, Turkey 2 Department of Chemistry, Faculty of Science and Arts, Gaziosmanpasa University, 60250 Tokat, Turkey 3 Department of Chemistry, Graduate School of Natural and Applied Science, Gaziosmanpasa University, 60250 Tokat, Turkey 123 Appl Biol Chem (2016) 59(6):813–820 Online ISSN 2468-0842 DOI 10.1007/s13765-016-0229-9 Print ISSN 2468-0834