Response surface optimization of enzymatic hydrolysis and ROS scavenging activity of silk sericin hydrolysates

Abstract

Context Sericin, a protein found in wastewater from the silk industry, was shown to contain a variety of biological activities, including antioxidant. The enzymatic conditions have been continuously modified to improve antioxidant effect and scavenging capacity against various free radicals of silk sericin protein. Objective Variables in enzymatic reactions, including pH, temperature and enzyme/substrate ratio were analysed to discover the optimum conditions for antioxidant activity of sericin hydrolysates. Materials and methods Hydrolysis reaction catalysed by Alcalase ® was optimized through response surface methodology (RSM) in order to generate sericin hydrolysates possessing potency for % inhibition on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, ferric-reducing power and peroxyl scavenging capacity. Flow cytometry was performed to evaluate cellular ROS level in human HaCaT keratinocytes and melanin-generating MNT1 cells pre-treated either with 20 mg/mL RSM-optimized sericin hydrolysates or 5 mM N -acetyl cysteine (NAC) for 60 min prior exposure with 1 mM hydrogen peroxide (H 2 O 2 ). Results Among these three variables, response surface plots demonstrate the major role of temperature on scavenging capacity of sericin hydrolysates. Sericin hydrolysates prepared by using Alcalase ® at RSM-optimized condition (enzyme/substrate ratio: 1.5, pH: 7.5, temperature: 70 °C) possessed % inhibition against H 2 O 2 at 99.11 ± 0.54% and 73.25 ± 8.32% in HaCaT and MNT1 cells, respectively, while pre-treatment with NAC indicated the % inhibition only at 30.26 ± 7.62% in HaCaT and 51.05 ± 7.14% in MNT1 cells. Discussion and conclusions The acquired RSM information would be of benefit for further developing antioxidant peptide from diverse resources, especially the recycling of waste products from silk industry.

Melatonin/Sericin Wound Healing Patches: Implications for Melanoma Therapy

“…Thus, for wound healing patches it was essential to include them as proof of the regeneration processes of the skin. Finally, numerous reports have shown that both melatonin and sericin but also resveratrol and turmeric exhibit high antioxidant potential [262][263][264][265]. The elevating secretion of pro-inflammatory cytokines, increased cell proliferation and oxidation processes can damage cell membrane integrity and lead to DNA fragmentation [7,27].…”

Optimizing the Conditions of Pretreatment and Enzymatic Hydrolysis of Sugarcane Bagasse for Bioethanol Production

“…Hemicelluloses and celluloses are degraded to sugar monomers by enzymatic hydrolysis. The enzymolysis effects are related to enzyme dosage, time, and solid-to-liquid ratio. , …”