Effect of Phlorethol from the Brown Alga Costaria costata (Turn.) Saund. (Order Laminariales) on Gametes and Embryogenesis of the Sea Urchin Strongylocentrotus intermedius (A. Agassiz, 1864)

The effect of a fraction of phlorethol (CcPh), one of the polyphenolic compounds isolated from the brown alga Costaria costata (Turn.) Saund (Laminariales), on gametes and embryogenesis of the sea urchin Strongylocentrotus intermedius (A. Agassiz, 1864) was studied. Using a model of developing sea urchin embryos, it was shown that phlorethol at concentrations ≤700 µg/mL did not exert cytotoxic effect on early developmental stages (from zygote to 16-celled stage blastomere). The embryotoxic effect of phlorethol, causing death of 50% of embryos, was expressed in a concentration (I) range of 50 < I ≤ 100 µg/mL only after 24 h of incubation, in the blastula stage. When exposed to concentrations of ≥100 µg/mL, embryos that survived to the blastula stage did not develop further and died after 36 h of incubation. Under the effect of phlorethol, the fertilizing capacity of sea urchin spermatozoa and oocytes reduced. The concentration of phlorethol inhibiting fertilization by 50% (IC₅₀) when acting on sperm was 1.28±0.38 µg/mL and when acting on oocytes was 3.83±0.82 µg/mL. Thus, phlorethol reduces the fertilizing capacity of sea urchin gametes at concentrations much lower than embryotoxic concentrations and can potentially find practical application as part of new contraceptive drugs for mammals and humans.