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.
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.Go To Environ Sci Pollut Res Int