Antioxidant potential of seaweeds occurring at Karachi coast of Pakistan


  • Amna Tariq
  • Jehan Ara
  • Viqar Sultana
  • Syed Ehteshamul-Haque
  • Mohammad Athar


The oxidative damage caused by reactive oxygen species (ROS) caused damage to bio-molecules leading to various diseases such as cancer, coronary heart diseases, renal failure, diabetes, ageing etc. There is an increasing interest in natural antioxidants because of the safety and toxicity problems of synthetic antioxidant. In this study, antioxidant activity of aqueous and ethanol extracts of 15 different seaweeds and total phenolic contents were evaluated. DPPH (2, 2-Diphenyl-1 -picrylhydrazyl) assay was used to determine free radical scavenging activity. The aqueous extracts showed more promising antioxidant activity as compare to ethanol extracts. Antioxidant activity of most of the seaweed reached at maximum after 180 to 220 minutes and then declined suddenly or gradually. Antioxidant activity of some seaweed was more or less equal to alpha- tocopherol used as standard antioxidant. After 180 minutes, the highest antioxidant activity was found in Caulerpa taxifolia (64.63%), Stokeyia indica (63.67%), Ulva fasciata (63.28%), Dictyota dichotoma var. velutricata (62.74%) as compared to 62.24% of alpha-tocopherol. All the test seaweeds were found to contain polyphenols at various concentrations. However, presence of polyphenol in some seaweeds did not show any correlation with antioxidant activity.