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[Preventive effect and mechanism of ultrafine powder of Dendrobium candidum on photoaging model mice].

Chinese herbal medicine ultrafine powder has become a research hotspot for the addition of cosmetic raw materials. Dendrobium candidum is a traditional Chinese herbal medicine. Its extract and stem extract are already cosmetic raw materials and its water extract has the effect of preventing photoaging,but D. candidum ultrafine powder has not been accepted as a raw material for cosmetics,and no relevant research on photoaging prevention has been reported. In this experiment,the ultra-fine powder and fine powder of D. candidum to prevent photoaging were observed and compared,and its mechanism of action was discussed to provide a basis for the prevention of skin photoaging products. Seventy-two female ICR mice were randomly divided into normal group,model group,solvent group,titanium dioxide(Ti O2) group,isooctyl salicylate(2-ES) group,D. candidum ultrafine powder 1(DP1),ultrafine powder 2(DP2) and fine powder(DP3) groups. The photoaging model was established by ultraviolet irradiation for 8 weeks,and the model was intervened while modeling. The skin wrinkle grade,elastic parameters,skin microcirculation blood flow,skin structure and pathological changes(skin thickness,skin collagen fiber,elastic fiber) were observed,the skin transforming growth factor-β1(TGF-β1),Smad3 levels were determined,and the type Ⅰ and type Ⅲ collagen,matrix metalloproteinase-1(MMP-1),activated protein-1(AP-1),VEGF expression were detected. The results showed that ultrafine powder(DP1,DP2) significantly reduced the wrinkle level and skin blood flow of the model mice(P<0. 05,P<0. 01); DP1,DP2 and DP3 could significantly reduce the thickness of the epidermis(P<0. 001),improve collagen fiber,elastic fiber hyperplasia,and distortion and decrease VEGF expression,and DP1 is better than DP2 and DP3; each group could up-regulate type Ⅰ collagen,down-regulate type Ⅲ collagen,AP-1,MMP-1 protein expression,and DP1 improvement optimal. However,it has no obvious effect on TGF-β1 and Smad3. The ultrafine powder and fine powder of D. candidum have certain preventive effect on photoaging,and the effect of ultrafine powder is better than that of fine powder. Ultrafine powder may down-regulate the expression of type Ⅲ collagen,AP-1 and MMP-1 by up-regulating type Ⅰ collagen. Inhibition of collagen degradation plays a role in preventing photoaging.