Physicochemical characterization of Pelophylax ridibundus egg jelly and determination of its biological activity on melanoma cancer

In this thesis, the jelly structure, excreted for feeding, growing, and protecting the embryos of the selected test organism Pelophylax ridibundus (P. ridibundus), an amphibian species belonging to Ranidae family, was characterized in detail for the first time and gained to the literature. Physicochemical analysis (FT-IR, TGA, XRD, SEM-EDX, and elemental analysis) of the egg jelly structure of P. ridibundus, selected due to being cosmopolitan and ease of culture, demonstrated that the structure consists entirely of carbohydrate and protein. Through HPLC analysis, it was found that the egg jelly, identified to have 96 µg/mL carbohydrate, includes glucose, mannose, and xylose in its profile. 2,4 µg/µL protein was detected in the structure by LC-MS/MS analysis, and the protein profile was determined according to the Uniprot/Swissprote database data. Sialic acid-binding lectin, one of the identified 12 proteins, draws attention because of its ability to inhibit tumor growth via the way of the macrophage system against tumor cells. It was hypothesized for the first time in this study that the egg jelly, protecting the embryo of Amphibia in polluted aquatic conditions and acting the role of a strong barrier by contributing to its growth and improvement, may have positive effects on the skin, as inspired particularly by the protective functions of UV lights on the embryo in these challenging nature conditions. It was predicted within the framework of the current research study that the egg jelly of Amphibia could have a strong biological activity as a biomaterial discussed in the research on melanoma, the most aggressive skin cancer with a high metastatic index. Through cell studies carried out with MTT analysis and xCELLigence device enabling synchronous measurement, it was identified that while 5 mg/mL selective dose of egg jelly of P. ridibundus shows an anticancer effect (viability < %30) on melanoma cancer cells (A375), it does not show cytotoxicity (viability > %70) towards healthy human skin cells. It was clearly demonstrated for the first time in this thesis study that amphibian egg jelly, a natural miracle, exerts efficient bioactivity on melanoma cells and can be a potential treatment.