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Chemical characterization and bioactivities of sericin extracted from silkworm cocoons from two regions of Portugal

Publication . Reis, Sara Filipa Gomes; Vaz, Josiana A.

Along the years, sericin has been undervalued and discarded as waste from the textile silk industry. However, recent studies have shown that sericin has great potential for biomedical applications. The potential for medicinal applications depends on its physicochemical properties and molecular heterogeneity. In addition, the characteristics of sericin are influenced by its extraction method, its origin and the variety of cocoon. This work aimed to characterize the biochemical and bioactivities of sericin from Bragança and Castelo Branco. Sericin was extracted using the autoclave method, and its physicochemical properties were then characterized by analyzing its amino acid content by HPLC. In addition, its potential for antioxidant by TBARS and CAA assays, anti- inflammatory by NO inhibition, antimicrobial by microdilution method, anti-proliferative by SBR assay, and anticoagulant activities by APTT method was evaluated. In its pure state, sericin did not have a high content of free amino acids, with tyrosine being identified as the most abundant. On the other hand, when hydrolyzed sericin showed a higher content of amino acids and serine was the most abundant. In terms of bioactivities, the sericin tested did not show antioxidant or anti-inflammatory potential in the tests carried out. Despite this, it showed anti-proliferative activity in contact with human tumor cell lines and in non-tumor cell lines at a minimum concentration of 0.52 and 0.32 mg /mL, respectively. As far as antimicrobial activity is concerned, sericin proved capable of inhibiting the growth of the bacteria and fungi tested at concentrations between 5 and 10 mg/mL. Finally, sericin was also shown to be able to prolong the coagulation time in adult mice plasma, presenting anticoagulant potential. The sericin from Bragança and Castelo Branco, collected in 2019, did not differ greatly, differences in amino acid composition were identified. In addition, the sericin collected in Bragança in 2021 and 2022, S3 and S4, respectively, showed differences compared to the other samples and showed the best antiproliferative, antibacterial and anticoagulant potential. Additionally, there are also differences between extracted and commercial samples.

2023Master thesis

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