Founctional Research Of A New Peptide Which Promotes The Skin Acute Photodamage

Objective:When the skin is exposed to ultraviolet radiation,it can induce a variety of harmful effects,such as photoaging,the production of skin erythema,the production of melanin,and eventually may lead to various skin cancers such as basal cell carcinoma,squamous cell carcinoma and malignant melanoma.The use of sunscreen and various antioxidants can help skin relieve the pressure of resisting acute photodamage.At present,the most widely used antioxidants are those of low molecular weight,such as vitamin C.However,long-term excessive use of such antioxidants with low activity and poor stability can cause some side effects,exemplified by diarrhea and gastrointestinal diseases.Therefore,the discovery and development of new types of antioxidants are of great urgency.This project aims to study the structure and function of a novel antioxidant peptide OM-GL15.Methods:We captured a green odorous frog(Odorrana margaretae)in the wild.After cDNA synthesis,illumina MiSeq sequencing and processing of data,a peptide was identified from the skin.Subsequently,free radical scavenging and Fe3+reduction experiments were carried out on the high purity samples.The acute photodamage animal models were established to detect the the ability of the samples to resist acute photodamage,and then a series of tests such as western blot assay,biochemical indicators in vivo were performed to explore the mechanism of samples in anti-photodamage.ELISA,HE and TUNEL staining were used to observe and analyze the effect of the samples on the apoptosis pathway in the acute photodamage.Results:1.The peptide,OM-GL15,identified of amphibian Odorrana margaretae is composed of 15 amino acids and the sequence is ’GLLSGHYGRASPVAC’;2.Compared with the negative control,OM-GL15 showed scavenging activities against ABTS+or DPPH and Fe3+reduction ability;3.In the acute photodamage animal models,compared with the UVB control,erythema in the OM-GL15(1 μM)groups were significantly reduced,both skin elasticity and moisture decreased in the group;4.At the same time,H&E staining of the mouse skin tissue showed that the epidermal layer changed in each group.The integrity of the epidermis in the OM-GL15(1 μM)group was close to that found in the normal group,and almost no cells under the epidermis were sunburnt;5.In TUNEL staining,compared with the normal group,many deeply stained apoptotic cells were detected in the epidermis of the UVB group.However,the apoptotic cells almost disappeared in the OM-GL15(1 μM)group and were significantly decreased in the OM-GL15(100 nM)and Vc groups.6.Compared with the normal group,the level of 8-OHdG in the UVB group increased significantly,while application of OM-GL15(100 nM,1 μM)down-regulated the 8-OHdG level in mouse skins;7.After UVB irradiation,OM-GL15 inhibited the expression of p53,caspase-3,caspase-9,and Bax,but increased the level of Bcl-2.Thus,OM-GL15 inhibited apoptosis of keratinocytes through the mitochondrial pathway.Conclusions:1.A novel peptide,OM-GL15,with a mature sequence of’GLLSGHYGRASPVAC’,was identified from the skin of amphibian Odorrana margaretae;2.OM-GL15 showed scavenging activities against ABTS+or DPPH and Fe3+reduction ability;3.Compared with UVB group,OM-GL15(1 μM)group significantly reduced skin elasticity and moisture,reduced interstitial edema and erythema,inhibited the production of apoptotic cells,and reduced the production of LPO and its by-product MDA;4.OM-GL15 impeded the expression of the p53 protein by inhibiting the DNA damage of epidermal cells,and further inhibited the mitochondrial apoptosis pathway mediated by caspase-9 and caspase-3 and down regulated the expression of Bax and up-regulated the expression of Bcl-2;5.Therefore,OM-GL15 has potential application value in protecting skin from UVB radiation damage,as well as in the development of anti-UVB skin photodamage drugs.