Amphibian-derived Antioxidant Peptide OS-LL11 Protects Against Skin Damage Caused By UVB Radiation In Mice

Objectives:Exploring the protective effects of specific antioxidant peptides in the skin secretions of the Odorrana schmackeri on ultraviolet radiation could help develop new drugs or cosmetics and provide evidence for understanding the molecular basis of amphibian adaptation.Methods:The dorsal skin of mice was irradiated with ultraviolet radiation lamp.The radiation dose was 150 mJ/cm2 every day for the first week,and the radiation dose was 300 mJ/cm2 every other day for the second and third week.After each radiation,the sample(OS-LL11 dissolved in ddH2O)was smeared on the dorsal skin of mice.After the end of the experiment,the dorsal skin tissue of mice was taken for pathological section staining to observe the changes of epidermis and dermis.The possible mechanism research mainly includes the detection of the antioxidant activity,anti-inflammatory activity and anti-apoptotic effect of the samples.The detection of antioxidant activity mainly included free radical scavenging ability(ABTS,DPPH)in vitro and the expression of antioxidant related enzymes(SOD,GSH,NO,H2O2,LPO,MDA,CAT,LDH),reactive oxygen species(ROS)and antioxidant related proteins(Keap1,HO-1,GCLM,NQO1)at animal and cell levels.The anti-inflammatory activity mainly included the detection of inflammatory cytokines and immunoregulatory factors(IL-1α,IL-1β,IL-6,TNF-α).The detection of anti-apoptotic effect mainly included the detection of apoptotic cells(TUNEL)and apoptosis-related factors(8-OHdG,Bax,Bcl-2).Results:(1)This study have obtained a new bioactive peptide from Odorrana Schmackerii,named OS-LL11,whose precursor peptide consists of 61 amino acids and whose mature peptide sequence from the N-terminal to the C-terminal is’LLPPWLCPRNK’.(2)The experimental results of the apparent effects of the samples on the experimental animals showed that:OS-LL11 had significantly improved in the aspects of erythra,desquamation and scab;OS-LL11 showed significant improvement in the thickening of the epidermis and dermis of the dorsal skin of the mice after using sample treatment.(3)The results of the possible mechanism research as follows:OS-LL11 had the ability to directly scavenging ABTS free radicals;OS-LL11 could enhance the activities of antioxidant enzymes and increase the levels of related biochemical indexes,OS-LL11 can inhibit the release of ROS,reduce the level of oxidative stress related biochemical indicators and boost antioxidant related protein expression;The results showed that the levels of inflammatory cytokines and immunoregulatory factors(IL-1α,IL-1β,IL-6,TNF-α)were significantly decreased after OS-LL11 treatment;TUNEL staining results showed that OS-LL11 down-regulated the number of apoptotic bodies,and inhibited the occurrence of apoptosis in the epidermis,down-regulate the level of 8-OHdG,increase the level of Bcl-2 and decrease the level of Bax,and protect cells from apoptosis caused by oxidative stress,thus showing anti-apoptosis ability,Conclusions:(1)Here,reports one natural peptide OS-LL11,which were first identified from the skin secretions of Odorrana schmackeri,the peptide mature amino acid sequence is‘LLPPWLCPRNK’。(2)It can significantly improve the UVB radiation-induced dorsal skin photodamage in mice,it also reduces epidermal and dermal thickening caused by UVB radiation.(3)OS-LL11 showed the ability to directly scavenging ABTS free radicals.At the same time,it also showed a antioxidant capacity.In addition,OS-LL11 showed anti-inflammatory activity.Finally,OS-LL11 showed anti-apoptotic effects.