The Anthocyanin Extracted From Purple-Fleshed Sweet Potato Exhibited Anti-Photoaging Effects On UVB-Irradiated BALB/c-nu Mouse Skin

Purple sweet potato is widely planted in China and has broad prospects for development.It is generally considered as a kind of typical homology of medicine and food because of its high nutritional value.Many studies have demonstrated that purple sweet potato has various active ingredients.Anthocyanin is one of the main active ingredients.The present study was aimed to study the antioxidant activity,constituents and stability of anthocyanins extracted from Yuzixiang No.10 purple sweet potato?PSP-AE?.In addition,we explored the anti-photoaging effect and possible mechanism of PSP-AE on UVB-induced BALB/c-nu mice skin.The aim of this study was to provide the theoretical basis and reference for newly-developed anti-photoaging products and drugs.The main results were as follows:?1?The PSP-AE was extracted by ultrasound-assisted extraction and the optimal extraction process was as follows:extraction temperature at 58?,material liquid ratio of 1:35,extraction time for 6 min,extraction concentration of 80%and power of 105W.Under the above conditions,the content of PSP-AE was the highest,which was2.398±0.022 mg/g·DW.In addition,the antioxidant activity of PSP-AE was stronger than ascorbic acid.?2?After purification of the anthocyanins extracted from purple sweet potato?PSP-AE?by AB-8 macroporous resin,the PSP-AE compositions were identified preliminarily.The results showed the maximum absorption wavelength of PAP-AE was 528 nm,and the molecular structure contained benzene ring,glycoside,hydroxyl,methoxyl and oxygen heterocycle.Six different compounds were found using UPLC-QTOF-MS,and they were cyanidin 3-p-hydroxybenzoylsophoroside-5-gluscoside,peonidin 3-p-hydroxybenzoylsophoroside-5-gluscoside,cyanidin 3-caffeoylsophoroaide-5-glucoside,cyanidin3-feruloylsophoroaide-5-glucoside,peonidin 3-caffeoylsophoroaide-5-glucoside,peonidin 3-feruloylsophoroaide-5-glucoside,respectively.?3?The effects of different factors on the stability of PSP-AE were evaluated by the color change and preservation rate as evaluation indexes.The results showed that PSP-AE had a better light and heat stability,but the color and preservation rate was evidently decreased under long-term light and high temperature conditions.Therefore,PSP-AE should be preserved in the dark or low temperature environments?4??.Under the acidic conditions especially pH of 3,the PSP-AE was more stable.Different metal ions had different effects on the stability of PSP-AE.Al³⁺and Fe³⁺could change the color and had unfavorable effects on PSP-AE,while Na⁺,K⁺,Mg²⁺and Ca²⁺were not obversed adverse effects on the color and preservation rate of PSP-AE.In addition,PSP-AE was sensitive to reductant Na₂SO₃ and oxidant H₂O₂ and should be avoided to use or remain.?4?The photoaging model of BALB/c-nu mice induced by UVB-irradiation was established to study the anti-photoaging effect of PSP-AE on mice skin.The results showed that PSP-AE could alleviate UVB-induced the skin damage,suppress epidermal hyperplasia and improve the content of skin moisture and hydroxyproline.Additionally,PSP-AE effectively increased the activities of antioxidant enzymes?SOD,CAT and GSH-Px?and total antioxidant capacity?T-AOC?in serum and skin tissue,while inhibited the levels of MDA and pro-inflammatory cytokines?TNF-?and IL-6?.Collectively,these results demonstrated that PSP-AE had effect of anti-photoaging activity.?5?The possible mechanism of PSP-AE against UVB-induced skin photoaging was explored.The results showed that PSP-AE decreased the ROS generation and remarkably inhibited the expressions of phosphorylated JNK,ERK and p38 proteins of MAPK family.Likewise,UVB-induced the nuclear translocation of NF-?B were diminished by pretreatment of PSP-AE,as well as the expression of AP-1 and MMP-1was significantly inhibited.Collectively,these data suggested that PSP-AE had the potential to attenuate the UVB-irradiated skin oxidative stress and inflammatory response via modulating MAPK and NF-?B signaling pathways.