The Protection Effects Of Glycyrrhizic Acid On Photo-damaged Human Skin Induced By Nano-zinc Oxide

Glycyrrhizic acid is one of the main whitening active ingredients of licorice(Glycyrrhiza). Studies have suggested that glycyrrhizic acid has shown anti-inflammatory,anti-oxidant, melanin inhibition, free radicals scavenging, antiviral and anticanceractivities. Glycyrrhizic acid solution, which is quite photo stable and thermal stable, isused for the treatment of inflammation of the skin caused by intense sunlight. If it wasadded to skin care production or sunscreen cosmetic, its effectiveness could be ensured insome extent.Vitamin C is a accepted water-soluble antioxidant, with good anti-oxidation, anti-freeradicals, to inhibit tyrosinase activity, to deoxidate the skin pigment melanin andto promote collagen growth properties. It is also a common ingredient in skin whiteningproducts. However, its water-solution is very unstable, which is easily oxidized in hotenvironments or light conditions. Thus limited the application of vitamin C in skin careproduction or sunscreen cosmetics.This study, the human keratinocyte cells (HaCaT cells) was used as a skin cell modelto determine whether glycyrrhizic acid could protect human skin cells againstphoto-damage caused by nano-zinc oxide nanoparticles under UVB/UVA irradiation, andthe presence of nitrite. First, the stability of glycyrrhizic acid PBS-solution wasdetermined by HPLC. Then, the cell viabilities under different conditions were assayed byMTT method. Finally, protein tyrosine nitration in HaCaT cells was detected byimmunofluorescence experiments and Western blotting.The results showed that glycyrrhizic acid PBS-solution was nice photo-stability andthermal stability; glycyrrhizic acid can do dependently protect human skin cells againstphoto-damage induced by nitrite、nano ZnO-50and UV irradiation system. However,when nano ZnO-50was replaced by nano ZnO-90, the protection was lost. These resultssuggested that glycyrrhizic acid had protective effects human skin cells photo-damageinduced by nitrite, nano ZnO-50and UV system.