Potential usage of rays' mucus extracts in biomedical applications

In this study, the potential use of various extracts obtained from ray epidermal mucus in biomedical fields has been examined and evaluated based on scientific principles. Four stingray species Dasyatis marmorata, D. pastinaca, Gymnura altavela, and Raja miraletus were preferred because of high abundance through commercial trawl and tramel nets operations in Iskenderun Bay and their intensive secretion of mucus when caught. The thesis study consists of four parts. In the first part of the thesis, the total protein content by the Bradford analysis, volatile compounds by GC/MS analysis in epidermal mucus samples of D. marmorata, D. pastinaca, G. altavela and R. miraletus, and vitamin E (α-tocopherol) concentration by HPLC analysis in R. miraletus mucus were determined. The total protein concentration in D. marmorata, D. pastinaca, G. altavela and R. miraletus epidermal mucus was found to be 4.61, 4.87, 4.89 and 3.94 mg/ml, respectively. The major compounds obtained from the GC/MS analysis were determined 2-Isopropyl-5-methyl-1-heptanol (10.04%), 2-tert-Butyl-4-isopropyl-5-methylphenol (7.95%), Dokosan (7.98%) and Dodecanoic acid (% 15.76) for D. marmorata epidermal mucus; Cyclooctasiloxane (11.22%), Cyclononacyloxane (14.49%), 1H-Purin-6-amine, [(2-fluorophenyl) methyl] (13.4%), Cyclodeazyloxane (12.10%), Lucenin-2 (11.37%) and Octasiloxane (10.57%) for D. pastinaca epidermal mucus; 1-Nonene (8.13%), 2-Isopropyl-5-methyl-1-heptanol (12.24%), 2-Hydroxy-3-phenyl-2H-1-benzopyran (11.83%), Eicosan (14.25%) and Dodecanoic acid (21.37%) for G. altavela epidermal mucus; Tetracoxamethyl (36.08%), Cyclodeazyloxane (31.56%) and Octasiloxane (32.36%) for R. miraletus epidermal mucus. As a result of the HPLC analysis, the vitamin E concentration in R. miraletus mucus was detected as 13.78 µg/ml. In the second part of the thesis, the antibacterial activity of D. marmorata, D. pastinaca, G. altavela and R. miraletus epidermal mucus samples against gram negative bacteria strains (Escherichia coli and Klebsiella pneumoniae) and gram positive bacteria strains (Bacillus subtilis and Enterococcus faecalis) were revealed by the disc diffusion and spectrophotometric broth microdilution methods. The strongest antibacterial activity for the disc diffusion method was determined in the acidic mucus extract of G. altavela (GaAC) with an inhibition zone diameter of 2.90 mm against B. subtilis. For the spectrophotometric broth microdilution method, the strongest antibacterial activity was determined in the acidic mucus extract of D. marmorata (DmAC) with a MIC value of 8.99 µl against K. pneumoniae.In the third part of the thesis, the antifungal activity of D. marmorata, D. pastinaca, G. altavela and R. miraletus epidermal mucus samples against fungal strains (Candida albicans and Candida parapsilosis) were also determined by the disc diffusion and spectrophotometric broth microdilution methods. The strongest antifungal activity for the disc diffusion method was also detected in the acidic mucus extract of G. altavela (GaAC) with an inhibition zone diameter of 2.40 mm against C. parapsilosis. For the spectrophotometric broth microdilution method, the strongest antifungal activity was also found in the acidic mucus extract of G. altavela (GaAC) with a MIC value of 9.40 µl against C. albicans. In the fourth part of the thesis, anticarcinogenic activities of the epidermal mucus of G. altavela were investigated on the lung carcinoma cell line (A549) by cell viability test (MTT analysis). However, no anticarcinogenic activity was detected on the A549 cell line. The results have shown that bioactive substances in extracts obtained from ray epidermal mucus can be commercialized as a marine-derived natural product in potential areas in the biomedical sectors when the bioactive substances in the extracts are characterized and developed by more detailed analyzes and supported by prototype applications in related fields. This study was supported by TÜBİTAK 2211-C Domestic Priority Areas Doctorate Scholarship Program.