Effect Of Baicalin-loaded In Microemulsion And Microemulsion-based Gel On Acute Gouty Arthritis And Preliminary Safety Evaluation

Baicalin(BA)is a flavonoid compound extracted from the root of Scutellaria baicalensis Georgi and has a variety of pharmacological effects such as anti-inflammatory,antioxidant,anticancer,liver protection,antibacterial,antiviral,anticonvulsant and neuroprotective effects.Microemulsion is a thermodynamically stable system formed by oil phase,water phase,surfactant and cosurfactant in a specific proportion.They are new drug carriers and can increase the solubility of poorly soluble drugs.Microemulsion-based gel(MEG)is to add appropriate gel matrix to microemulsion,which can increase the adhesion of microemulsion and prolong the action time of drug.Acute gouty arthritis(AGA)is an inflammatory disease caused by hyperuricemia,which results in deposition of urate crystals on joints and surrounding tissues and causes red swelling,heat pain and other symptoms.Our group prepared Baical-loaded in microemulsion-based gels(B-MEG)and Baical-loaded in microemulsion(B-ME)in the early stage.In this paper,the effects and mechanisms of B-MEG and B-ME against gouty arthritis using in vivo and in vitro methods,and guinea pig skin irritation experiments were also performed.1 In vivo experiments:(1)The experiment of the effect of B-MEG on acute gouty arthritis was carried out in mice.An acute gouty arthritis model was prepared by subcutaneous injection of 2%sodium urate solution into the skin of the hind paw of the mouse.Kunming mice were randomly divided into normal group,model group,B-MEG high-dose group(containing 1%baicalin),low-dose group(containing 0.25%baicalin)and positive control drug Futalin group,10 mice in each group.The drug was administered once every day for consecutive 7 days,and the model was established 1 hour after the last administration.The results showed that compared with the normal group,the skin of the model group was significantly swollen,and the pathological examination of the skin showed more inflammatory cell infiltration.The serum SOD decreased,MDA and H2O2 levels increased significantly,indicating successful modeling.Compared with the model group,the Futalin group significantly reduced the swelling rate of the hind foot in the mice at 1h,2h,4h,6h,10h and 24h after model establishment(P<0.01),and the B-MEG high dose group and the low dose group was significantly reduced the swelling rate of the hind foot in the mice(P<0.05 or P<0.01)at 6h,10h and 24h after model establishment,and there was no obvious dose-effect relationship.The Futalin group,B-MEG high dose group and low dose group extremely significantly decreased the MDA and H2O2 levels in sera(P<0.01);Futalin group,B-MEG high dose group and low dose group significantly reduced the inflammatory response in pathological examination.(2)The effect of B-MEG on mouse ear swelling was observed.Compared with the model group,the Futalin group,the B-MEG high-dose group and the low-dose group all significantly inhibited xylene-induced ear swelling in mice(P<0.01),and the inhibition rates were 83.9%,64.7%and 74.3%,respectively.(3)Effect of B-MEG on acetic acid-induced writhing in mice was carried out.Compared with the model group,Futalin group and the low and high dose of B-MEG groups significantly inhibited the number of writhing in mice induced by acetic acid(P<0.01),and the inhibition rates were 61.8%,33.1%and 47.5%,respectively.(4)irritation test results of B-MEG on guinea pig skin showed that in the single-dose and multiple-dose skin irritation test,except for the skin roughness at the damaged part of the affected part,there was no erythema,no edema,no pigmentation,no bleeding point and no skin faintness.The stimulation intensity scores were all 0 at each time point.There was no significant difference between the B-MEG group and the blank microemulsion gel group.The diet and activities of the animals in each group were normal during the experiment.2 In vitro experiments,the effect of B-ME on the proliferation and inflammation of sodium citrate-stimulated HaCaT cells was observed.The effects of different concentrations of sodium urate on the proliferation of HaCaT cells were observed.The model of cell inflammation was induced by 2mg/mL sodium urate.The experiment was divided into normal group,model group,blank microemulsion group,baicalin groups and B-ME groups at different concentration of 5,10,20?g/mL baicalin.Results showed that baicalin protects inflammatory cells in a dose-dependent manner,but B-ME has no obvious protective effect.In summary,B-MEG has significant anti-inflammatory,analgesic and anti-gouty arthritis effect,its mechanism is related to its antioxidant effect,and skin irritation is small.However,it reduces the body weight of mice,and its safety needs further study.