Protective Effect Of Topically Applied Polypeptide From Chlamys Farreri Against Ultraviolet Radiation-induced Chronic Skin Photoaging In Guinea Pig

AIM Chronic ultraviolet-irradiated guinea pig model was established, in order to investigate the photoprotective effect in guinea pig of topical polypeptide from Chlamys farreri (PCF) against chronic skin damage induced by ultraviolet A (UVA) and ultraviolet B (UVB) radiation. MATHODS Polypeptide from Chlamys farreri (PCF, M=800-1000) is a novel marine polypeptide which was isolated by our topic group using enzymetically engineering technique. Chronic ultraviolet-irradiated guinea pig model was established. A total of 48 guinea pigs were randomly divided into four different groups as follows: control group; model group (UVR only); 5 % PCF group (5 % PCF + UVR); 20 % PCF (20 % PCF + UVR). Guinea pigs were irradiated 3 times weekly with 2.701 J-cm-2 UVA radiation and 6.4 m J-cm-2 UVB radiation per exposure for the first seven weeks. In the following seven weeks, guinea pigs were irradiated 5 times weekly with 5.402 J-cm-2 UVA radiation and 17m J-cm-2 UVB radiation per exposure. The total UVA and UVB dose were 245.791 J-cm-2 and 729.4m J-cm-2 separately. The UVB dose chosen was reported to be approximately 50 % for the minimal erythemic dose (MDE) for this animal. Visible changes in the skin including wrinkling, sagging and erythema were observed every other week. Transversal wrinkling in the dorsal skin were counted. Malondialdehyde (MDA) in the dorsal skin was determined using TBA methods.Antioxidant enzymes including superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) were determined using biochemical methods. The amounts of hydroxyproline and other amino acids in guinea pig skin were determined by automatic amino acid analyzer. RESULTS Wrinkling, sagging and erythema were appeared in the dorsal skin of guinea pig induced by UV irradiation. The difference among the model group and control group was significant (P < 0.05, P <0.01). PCF (5 % and 20%) was found to greatly protect the dorsal skin of guinea pig against wrinkling, sagging and erythema induced by UV irradiation in a concentration-dependent manner. The effect of PCF was enhanced with its concentration within the range of 5% and 20%. PCF was able to reduce the MDA formation caused by UV irradiation in the dorsal skin, meanwhile increased the activities of SOD and GSH-px. The differences among the PCF groups and UV model group were significant (P < 0.05, P<0.01). Long-term UV radiation could dramatically reduce the amounts of hydroxyproline, aspartic acid, threonine, glycine, phenylalanine and lysine in guinea pig skin (P < 0.05 compared with control), meanwhile, pretreatment with 5 % and 20 % PCF prior to UV radiation could increase the amounts of these amino acids in guinea pig skin (P < 0.05 compared with UV model). CONCLUSION Chronic ultraviolet-irradiated guinea pig model was established successfully, the total UVA and UVB dose were 245.791 J cm-2 and 729.4m J-cm"2 separately. PCF was used as one kind of antioxidants, which attenuated lipid peroxidation, reduced the MDA formation, increased activities of antioxidant enzymes SOD and GSH-px. The chronic topical application of PCF could protect skin from photoaging.