Sericin from Bombyx mori cocoons. Part I: Extraction and physicochemical-biological characterization for biopharmaceutical applications

•Crude sericin extracts of Bombyx mori silk cocoons were produced via two approaches.•Sericin exhibited antioxidant and antimicrobial activities.•The crude sericin extracts had obvious radical scavenging effects with DPPH assay.•No cytotoxic, genotoxic and mutagenic effects whatsoever were found.•Sericin might be a valuable addition for food and biopharmaceutical applications.

In the present research effort, production of crude sericin extracts from Bombyx mori silk cocoons was attempted using two different approaches. Sericin was extracted from cocoons by high-temperature autoclaving followed either by lyophilization or freezing-thawing precipitation, to obtain a crude sericin powder. The physico-chemical and biological characteristics of the crude sericin extracts were evaluated in detail, via FTIR, XRD, XRF, XRT, UV-vis scanning, TGA and DSC, protein quantification, antimicrobial activity, free radical scavenging activity, cytotoxic activity, potential for inducing chromosomal aberrations via Allium cepa assays, and genotoxicity via Comet™ analyses. The molecular weight distribution of the crude sericin extracts was also investigated, via sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the results duly compared to standard sericin. The results gathered clearly suggest that the crude sericin extracts had both obvious radical scavenging effects with the 2.2-diphenyl-1-picryl-hydrazil (DPPH) assay, and antibacterial activity, further suggesting that this protein might be a valuable addition for either food and biopharmaceutical applications.

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