In-vitro antioxidant and in-vivo photoprotective effect of three lyophilized extracts of Sedum telephium L. leaves

Sedum telephium L. is a medicinal plant used in antiquity to cure many type s of inflammatory skin diseases. The leaves (without the external cuticle), are used to promote healing and reduce skin inflammation and pain, and con tain various components. We found two major components: flavonol glycosides and polysaccharides, with molecular weight between 13 000 and 13 500 Da. W e evaluated the in-vitro antioxidant and in-vivo skin photoprotective effec ts of three lyophilized extracts obtained from the juice of S. telephium L. leaves: a total lyophilized juice, a lyophilized flavonolic fraction, and a lyophilized polysaccharidic fraction. Two in-vitro models were used: the bleaching of the stable 2,2-diphenyl-1-picrylhydrazyl (DPPH.) radical, and the protective effect against UV-induced peroxidation on phosphatidylcholin e multilamellar vesicles, as model membranes. The antioxidant/radical scave nging activity of each lyophilized extract was also assessed in-vivo by det ermining their ability to reduce UVB-induced skin erythema (monitored by re flectance spectrophotometry) in healthy human volunteers. The findings of the in-vitro experiments clearly demonstrated that, unlike the lyophilized polysaccharidic fraction, the lyophilized flavonolic fracti on and total lyophilized juice possess strong antioxidant/free radical scav enging properties, which are likely due to phenolic compounds. Consistent w ith these findings, gel formulations of both the total lyophilized juice an d, to a greater degree, the lyophilized flavonolic fraction appeared to pos sess a strong protective effect against UV-induced skin erythema in-vivo, w hereas the lyophilized polysaccharidic fraction was completely ineffective. The in-vitro and in-vivo results suggest that, both the total lyophilized j uice and, in particular, the lyophilized flavonolic fraction, but not the l yophilized polysaccharidic fraction of S. telephium L. leaves, have photopr otective effects against UVB-induced skin damage.