Inhibitory role of silk cocoon extract against elastase, hyaluronidase and UV radiation-induced matrix metalloproteinase expression in human dermal fibroblasts and keratinocytes.

Topical delivery of potent antioxidants maintain the redox balance of the skin, which leads to the downregulation of matrix metalloproteinase (MMP) expression and prevents UV radiation-induced photoaging. In this study, we aimed at investigating the inhibitory role of silk cocoon extract (SCE) isolated from the Antheraea assamensis (AA), Bombyx mori (BM), and Philosamia ricini (PR) silk varieties against UV radiation-induced MMP expression. Incubation of elastase and hyaluronidase with Antheraea assamensis silk cocoon extract (AASCE) caused 50% inhibition of activity. The assessment of total collagen content using the Sirius red assay showed that AASCE (10 μg mL-1) and Philosamia ricini silk cocoon extract (PRSCE at 100 μg mL-1 concentration) post-treatment significantly enhanced the total collagen content in UVA1 and UVB irradiated HDF cells, whereas BM silk cocoon extract (BMSCE at 100 μg mL-1 concentration) post-treatment significantly enhanced the total collagen content in UVA1-irradiated HDF cells. Gene expression studies revealed AASCE and PRSCE post-treatment downregulated the expression of interleukin (IL)-6, MMP-1 and upregulated procollagen genes in UV irradiated HDF cells. Gelatin zymography studies with AASCE post-treatment downregulated the release of MMP-2 and MMP-9 by HaCaT cells. The overall results validate AASCE efficiently shielding UV radiation-induced collagen and elastin degradation by downregulation of MMP expression, substantiating its further use as a potent antioxidant complement in skin care formulations.