This manuscript is focused on the influences of Cu(II) and Fe(III) metals on the cells and exudate phenolic profiles of the green microalgae Dunaliella tertiolecta. Few reports have focused on the identification and quantification of polyphenols in microalgae, and only our previously reported study has focused on the implications of polyphenols in microalgae growing under metal stress (Limnol. Oceanogr. 58(1), 2013, 144–152; doi:10.4319/lo.2013.58.1.0144). This is the second in vitro study to determine the involvement of polyphenols in the microalgae cellular response under high level of Cu(II) and Fe(III) in natural seawater.
Significant differences in the phenolic profiles were found depending on the metal added to the seawater. These different phenolic compounds excreted is the response of the microalga against the metal stress conditions. The great increase in phenolic compounds exuded by the cells at the highest copper concentration may reflect the involvement of these compounds in protection in conditions of copper toxicity. Cells exposed to copper excreted a larger amount of polyphenols as a protective mechanism to alleviate the toxicity of the copper in the solution: these phenolic compounds are implicated countering metal toxicity at the membrane surface and slowing down the toxicity of metals in the extra-cellular media.
Determining how polyphenol concentrations change in response to high metal levels demonstrates the role of polyphenols in microalgae and might be useful to help explain the dynamics of this important class of compounds in seawater (Mar. Chem. 2014, 158: 10-16; doi:10.1016/j.marchem.2013.11.001). The phytomedicinal potential of Dunaliella tertiolecta is underlined by the antioxidant activity of extracts and high contents of gentisic acid, (+) catechin and other phenolic compounds. These microalgae may be exploited for the production of health foods and as an antioxidant carrier in the food and pharmaceutical industries.
About the author
Milagros Rico was born in Tenerife (Canary Islands, Spain). She studied chemistry at the University of La Laguna and received her Ph.D. from the University of La Laguna for her work on the synthesis of microalgal trans-fused polyether toxins under the guidance of Dr. Julio Delgado Martín in 1994. She subsequently undertook postdoctoral studies at the Georg-August-Universität Göttingen, Germany until December 1996 (Contract-Nº ERBCHBI-CT94-1465) and she worked as a Marie Curie Training and Mobility Postdoctoral Fellow at Konstanz University (Germany, contract-Nº ERB FMBI-CT-961370). Since October 1997, she has held an academic position, currently Assoc. Professor, at the University of Las Palmas de Gran Canaria. Since March 2012 until April 2015 she was Vice-Dean for Quality Assurance in the Faculty of Marine Sciences. Currently, she is responsible for the quality assurance and enhancement at the University of Las Palmas de Gran Canaria. Her primary research focus is the identification and quantification of biologically active natural products, and designing methodology to assist in this endeavour. The research group also enjoys dabbling in medicinal and organic chemistry, studying the variability of the profiles of organic compounds biologically active in several plan species (marine and terrestrial) and in microalgae growing under metal stress.
About the author
Prof. Dr. J. Magdalena Santana-Casiano was born in Gran Canaria, Spain. She received her degree in Marine Science in 1988 and her Ph.D in Chemical Oceanography in 1991 from the University of Las Palmas de Gran Canaria, obtaining the extraordinary Prize for Doctoral Thesis. In 1990 she began to teach at the ULPGC, in the Faculty of Marine Sciences. Since July 2010 she is Vice-Dean of postgraduate studies. In May 2011 she obtained the position of full professor in Chemical Oceanography. Her research training has been complemented with various stays in the Rosenstiel School of Marine and Atmospheric Science, at the University of Miami. Her research focuses on the two lines that the QUIMA-ULPGC group has developed, one corresponding to the study of the carbon dioxide system in the oceans, and the second responsible for the study of the physical and chemical processes of trace metals in the marine environment, in particular iron. She has published more than sixty research papers and has participated in several national and European projects. She is currently the lead investigator of the project EACFe of the Spanish Government. Since 2009, she maintains a partnership with the Shirshov Institute of Oceanology (SIO), Russian Academy of Science, for the study of the hydrographic CLIVAR A5930N (A1E) section and from 2011 with the Spanish Institute of Oceanography, IEO-COC, for the oceanographic study of the seawater properties around the underwater volcano off the island of El Hierro.
About the author
Prof. Dr. Melchor González-Dávila was born in Tenerife. He studied chemistry at the University of La Laguna, graduated in 1984 and received his doctorate in 1987. He began teaching in 1984 at the University of Las Palmas de Gran Canaria, in the Faculty of Marine Sciences. His research training has been completed with research in the University of Hamburg and the Rosenstiel School of Marine and Atmospheric Science of the University of Miami. In May 2010, he became full professor at the ULPGC in the area of Chemical-Physic. He is the director of the QUIMA-ULPGC research group. His research focuses on the two lines that the QUIMA-ULPGC group develops, one, responsible for the study of the carbon dioxide system in the oceans and the second the study of physical and chemical processes of trace metals in the marine environment. He has more than 70 research papers published in high impact factor journals including works in the journals Science and Nature, and has participated in several national and European projects. He is responsible for measurements of the carbon dioxide system in the ESTOC station, ICOS-ESFRI project member and leader of the WP1 of the European project CARBOCHANGE 2011-2015. Since February, 2012, he is the Dean of the Faculty of Marine Sciences.
About the author
Aridane G. Gonzalez is mostly focusing on elucidating the biogeochemical cycles of metals and the development of new biomonitors to measure and control the metal contamination in atmospheric and aquatic environments. Both lines are directly linked because the description of physico-chemical properties of biosorbents notably improves our knowledge about the chemistry of heavy and trace metals in the environment. The physico-chemistry of metals is of great significance for characterizing a good bioindicator. He started working on metal chemistry upon finishing his degree (2004), doing volunteer scientific work during the last year with a studentship from the Spanish government. During his PhD (national grant FPI), I studied the oxidation of Fe(II) in the presence of organic exudates and copper in natural seawater. These organic exudates where collected from the marine diatom Phaeodactylum tricornutum and the marine green-alga Dunaliella tertiolecta. Since 2011, his postdoctoral experience has been developed in Spain (Canary Islands) for 1 year (2011-2012) and France: Toulouse (2012-2014) and Brest (2015-2016). The most solid feature of his research lines is the unification of the physico-chemistry of metals (as a marine chemist) in natural waters with the biogeochemistry on biosurfaces (as a biogeochemist). Both of them enable me to integrate specific techniques that are not common in Spain (stable isotopic fractionation by MC-ICP-MS and X-ray Absorption Spectroscopy, XAS from ESRF (Synchrotron) in France) and are not extensively used in Europe. But he realized that the only way to understand the natural systems is by covering the highest possible number of concepts in experimental science to be able to reproduce the environment.
About the author
Aroa López was born in Gran Canaria (Canary Islands, Spain). She studied Marine Sciences at the University of Las Palmas de Gran Canaria in 2004, and received her Ph. D. under the guidance of Assoc. Prof. Milagros Rico in 2016 for her work on the identification and quantification of phenolic compounds in several microalgae, macroalgae and terrestrial plant species. Currently, she teaches mathematics at a high school.
Environ Sci Pollut Res Int. 2015;22(19):14820-8.
López A1, Rico M2, Santana-Casiano JM1, González AG1, González-Dávila M1.
[expand title=”Show Affiliations”]
- Departamento de Química, Facultad de Ciencias del Mar, Universidad de Las Palmas de Gran Canaria, Campus de Tafira, 35017, Las Palmas de Gran Canaria, Canary Islands, Spain.
- Departamento de Química, Facultad de Ciencias del Mar, Universidad de Las Palmas de Gran Canaria, Campus de Tafira, 35017, Las Palmas de Gran Canaria, Canary Islands, Spain. [email protected]
The present study investigates the phenolic profile of exudates and extracts of the green algae Dunaliella tertiolecta, harvested in natural seawater in the absence (control) and in the presence of Cu(II) (315 and 790 nmol L(-1)) and Fe(III) (900 nmol L(-1)) in order to identify and quantify the phenolic compounds produced under metallic stress conditions. The presence of metal ions modifies the growth of cells and changes cell metabolism by producing phenolic compounds adapted to the solution. The use of reversed-phase high-performance liquid chromatography (RP-HPLC) permitted the identification of 14 phenolic constituents. The concentration and type of polyphenols detected in cell extracts and in solution are directly related with the metal and its concentration during growth cultures, achieving 1.4 times higher levels of polyphenols under 790 nmol Cu(II) L(-1) with respect to the control experiments. Microalga excretes polyphenols to be adapted to the environmental conditions. Gentisic acid, (+) catechin and (-) epicatechin, the most prominent phenolic compounds detected in the algae extracts, showed high antioxidant activity in inhibiting 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. This potent activity may be related to its presence in cells and exudates in high concentrations.
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