Characterization of an extract of the jellyfish Cassiopea andromeda, Forsskål, 1775 (Scyphozoa, Cnidaria) and study of its antioxidant activity, cytotoxicity, and ability to modulate Gap Junction Intercellular Communications in cancer cells

The blooms of Mediterranean jellyfish are becoming increasingly frequent causing damage to ecosystems and to human productive activities, on the other hand they can represent abundant bio-resources easily accessible to the inhabitants of coastal communities. The studies presented here aim to the biochemical characterization of the biomass of the invasive zooxanthellatae jellyfish Cassiopea andromeda, Forsskål, 1775 (Cnidaria, Rhizostomeae) collected in the port area of Palermo (Sicily, Italy), and on the possible biological activities of some partially purified extracts. The first part of the thesis includes the composition analysis and a preliminary biochemical characterization of the jellyfish Cassiopea andromeda. Aqueous (PBS) and hydroalcoholic (80% ethanol) soluble components were obtained from the whole jellyfish and from both oral arms and umbrella. The insoluble components were hydrolysed by sequential enzymatic digestion with pepsin and collagenase. Both aqueous and hydroalcoholic extracts containing soluble compounds, as well as the hydrolysed peptides were biochemically characterized for their proteins and phenols contents, and for their antioxidant activity. A notable yield as well as a considerable antioxidant activity was detected in almost all assessed samples mainly in the extracts containing soluble compounds. The PBS extracts from oral arms samples have a higher yield in organic matter and are richer in proteins and phenols as compared to the hydroalcoholic extracts, whereas the hydroalcoholic extracts, showed a stronger antioxidant activity than aqueous soluble compounds. The second part of the thesis deepens the study of the hydroalcoholic extracts, which show the greatest antioxidant activity and have been further fractionated, biochemically characterized and their biological activity has been evaluated on different human and murine cancer cell systems. When the hydroalcoholic extract was fractionated, the resulting hydrophilic fractions obtained from both umbrellas and oral arms samples, resulted to be rich in proteins and phenols, with a strong antioxidant activity in oral arms fractions. The potential cytotoxic activity of four jellyfish fractions of the hydroalcoholic extract were assayed on human breast cancer cells (MCF-7 and MB-MDA-231 cells lines) and on two rat liver epithelial cells, WB-ras and WB-neo cells lines. In order to elucidate the action mechanism of the cytotoxicity against cancer cells, the ability of the four jellyfish extract fractions to modulate the function of the Gap Junction mediated Intercellular Communication (GJIC) was also assessed on both rat liver epithelial cell lines, WB-ras and WB-neo cell lines. When administrated on Human cancer cells, the lipophilic and hydrophilic fractions resulted to strongly reduce the cell viability of both MCF-7 and MB-MDA-231 cells lines, with a stronger effect of the hydrophilic fractions than the lipophilic ones. As expected, the cytotoxic effect was more evident in MCF-7 cells than in the resistant MB-MDA-231 cells, however a notable cytotoxic effect was also exerted on the resistant MB-MDA-231 cell line. The cytotoxic effect on cancer cells was also confirmed by assessment of the two fractions on rat liver cell lines, the ras-transformed epithelial cells (WB-ras) and the normal epithelial cells (WB-neo) where the lipophilic fractions resulted to be more cytotoxic than the hydrophilic ones, thus proving the presence of possible lipophilic bioactive compounds in jellyfish tissues or in their endosymbiotic zooxanthellae. The same fractions have also demonstrated the ability to improve GJIC in the non-communicating tumorigenic WB-ras cells and had no effect on GJIC in the well-communicating WB-neo cells. In conclusion, all the results suggest that the invasive zooxanthellatae Cassiopea andromeda jellyfish, like other Mediterranean blooming jellyfish, represent a valuable biomass and a sustainable source of compounds with biological activity for current and future applications. However, other studies and research will lead to a better understanding of the biology and the potential use of the upside-down Cassiopea andromeda jellyfish.