Enhancement of antioxidant properties of Gongolaria barbata (Phaeophyceae) by optimization of combined light intensity and salinity stress

ABSTRACT

The present study aimed to optimize the light intensity coupled with different salinity regimes for enhanced growth and antioxidant properties of the brown seaweed Gongolaria barbata. Five experimental trials (T₁–T₅) were suggested using response surface methodology, where growth rate and antioxidant properties of G. barbata were evaluated in each run at the end of the experiment. The model for growth rate showed differences not statistically significant among all studied groups. However, concentration of methanol extract needed to scavenge 50% of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals (IC₅₀), total phenolics, total flavonoids, total carotenoids, chlorophyll a and chlorophyll c showed significant differences among the five studied groups. Total phenolic and flavonoid contents were primarily affected by light, showing the highest values of 2.08 mg gallic acid equivalent g⁻¹ and 2.41 mg rutin g⁻¹ at 50 µmol photon m⁻² s⁻¹. However, salinity stress showed a more pronounced impact on pigments. DPPH scavenging activity was influenced by the concentration of other compounds, which showed a significant increase by 34% in group T₄. The present study recommended light intensity of 53.86 µmol photons m⁻² s⁻¹ at 24.02‰ salinity as the optimum conditions to achieve the maximum antioxidant activity along with phenolic and flavonoid contents (desirability = 0.82), without significant impact on the growth.

KEYWORDS:

• Aquaculture
• Marine natural products
• Seaweeds
• Secondary metabolites

ACKNOWLEDGEMENTS

The authors are thankful to Prof. Dr. Nermin BERİK, Faculty of Marine Sciences and Technology, Çanakkale, Turkey, for providing the necessary help for carrying out this study.

AUTHOR CONTRIBUTIONS

İA, ECÇ and GT contributed to the conception and design of experiments. İA and OS performed the experiments. İA and ECÇ carried out data analysis. İA, ECÇ and AA did the writing. AA carried out the review and editing. İA has the responsibility for the integrity of the work and the correspondence.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.