Morphological, molecular identification and evaluation of antioxidant activity of seahorses from the Moroccan coasts

Abstract

Seahorses, part of the small marine teleost fish family Syngnathidae, are increasingly under threat due to habitat degradation and overfishing. Notably used in traditional Chinese medicine, these fish have demonstrated significant pharmacological and cosmetic properties. In Morocco, however, seahorses are minimally exploited. This study aims to explore the biodiversity of Moroccan seahorses, focusing on identifying species from the Atlantic and Mediterranean coasts both morphologically and molecularly, and evaluating their antioxidant activity. The research involved collecting 62 dried seahorses from local fishermen. These specimens were subjected to detailed morphological and molecular identification through the DNA barcoding method, concentrating on the mitochondrial marker Cytochrome Oxidase I (COI) gene. Following DNA extraction and amplification, the sequences were analyzed for species identification and phylogenetic relationships. Additionally, the antioxidant activities of the seahorses were quantified using assays such as ABTS, reducing power, phosphomolybdenum, and β-carotene-linoleic acid. The combined morphological and molecular analyses consistently identified all specimens as Hippocampus hippocampus, and phylogenetic trees suggested a close relation with European and Turkish counterparts. Furthermore, the antioxidant assays revealed significant activity, with the ABTS assay showing an IC50 of 14.571 mg/mL ± 0.334, and the β-carotene-linoleic acid assay showing an IC50 of 1.273 mg/mL ± 0.166. The reducing power and phosphomolybdenum assays recorded EC50 values of 1.868 mg/mL ± 0.033 and 1.156 mg/mL ± 0.112, respectively. These results confirm the high antioxidant potential of Moroccan seahorses, suggesting their therapeutic value and necessitating measures for their biodiversity preservation at a national level.

Keywords: Antioxidant activity; COI; DNA barcoding; Morphological identification; Seahorse.

Fig. 1

Sampling sites of Hippocampus of the two Moroccan coasts. S1: Quaà Asserasse; S2: Stehat; S3: Chmaala; S4: El Jebeha; S5: El Jadida; S6: Agadir; S7: Dakhla.

Fig. 2

Illustrative Example of Seahorses Harvested from the Moroccan Coastline.

Fig. 3

NJ tree of seahorses inferred from COI sequences with 1000 bootstrap replicates.

Fig. 4

Antioxidant activity of seahorse. A: ABTS; B: β-Carotene blanching inhibition; C: reducing power; D: total antioxidant capacity. All the data were expressed in mean ± standard deviation (SD) for three independent experiments.