Antioxidant and antimicrobial activity of Echinometra mathaei and Holothuria leucospilota

The aim of this study was to investigate the antibacterial activity of sea cucumber Holothuria leucospilota and sea urchin Echinometra mathaei extracts on Gram-positive and Gram-negative bacteria, the antioxidant activity and inhibitory power of DPPH. Samples of sea cucumber and sea urchin were collected from around Qeshm Island. Antimicrobial activity of sea urchin was performed by examining the diameter of the growth inhibition zone and in sea cucumber by tube dilution method. Concentrations of 40, 80, 120, 160 and 200mg/mL were used to evaluate the antioxidant activity. The results showed that the antioxidant activity of the extracts of both animals increased with increasing the concentration of the extract (P<0.05) and at the concentration of 200mg/mL reached to 320±5.57 and 420±6.95mg of ascorbic acid/g of extract in sea urchin and sea cucumber, respectively. In all studied concentrations, the antioxidant activity of sea cucumber was higher than sea urchin (P<0.05). In both animals, the concentration of 200 mg/mL of peptide extract with 20.21±5.15 and 56.11±3.76mg of ascorbic acid/g, had the highest free radical scavenging power and in both species, DPPH inhibition activity was lower compared to ascorbic acid (P<0.05). Peptide extracts of all three parts of the gonads, skin and spines of the studied animals were able to inhibit Staphylococcus aureus. Concentrations of 1000 and 1500μg/mL of peptide extract of sea urchin gonad were able to inhibit all bacteria but no significant difference was observed between these two concentrations (P>0.05). The results of the present study showed that sea urchin and sea cucumber can be rich sources of antibacterial and antioxidant compounds. The results of the present study showed that sea urchin was able to show antibacterial effect on gram-negative bacteria.