Study On Carvacrol/Glycoside Microemulsion System And Its Inhibitory Effect On Malassezia

Dandruff is a skin condition that plagues up to half of the world’s population and is associated with the excessive proliferation of Malassezia.Traditional medications for the treatment of Malassezia have the disadvantages of poor adherence,unpredictable clinical efficacy,and the emergence of drug resistance and side effects.These drawbacks have prompted people to look for natural and mild plant ingredients as alternatives.As the main component of natural plant essential oils,carvacrol has been widely studied because of its excellent antibacterial and anti-inflammatory effects.However,carvacrol is unstable and water-insoluble,which limits its practical application in cosmetics,food,and biopesticides.Microemulsification technology has great potential to solve the problem of solubilization of hydrophobic antimicrobial substances,but the components that make up microemulsions such as surfactants may affect the preparation and application of microemulsions.Among them,alkyl polyglucoside(APG)as a natural nonionic surfactant,non-toxic,non-irritating,broad-spectrum antibacterial,completely biodegradable,obtained from renewable raw materials(vegetable oil,sugar,starch)has attracted attention.At present,the basic research on the application of carvacrol microemulsion system using APG as a surfactant and used in anti-dandruff products has rarely been reported.In order to improve the hydrophilicity and antibacterial effect of carvacrol,this thesis used APG-0810 and Tween-80 as surfactants to construct a U-type carvacrol/glycoside microemulsion system,and the effects of each component on the bacteriostatic effect of carvacrol/glycoside microemulsion system were studied using Malassezia furfur as the test strain,and the product stability,bactericidal effect and antiseptic properties of scalp essence and scalp scrub were further studied using carvacrol composite microemulsion as the carrier,providing technical support and theoretical support for the research and development of new natural antibacterial emulsions and the development of plant anti-dandruff products.The main results are as follows:(1)The phase behavior of carvacrol microemulsion was studied by pseudo-ternary phase diagram.Results showed that when Tween-80 alone as surfactant could form carvacrol U-type microemulsion,and when Tween-80 and APG-0810 compound as surfactant with 1:1 could improve the solubilization ability of APG-0810.The addition of 1,3-BG or DPG as cosurfactants,respectively,can increase the area of the monophasic region of carvacrol composite microemulsion system.The single-phase region area increases with the increase of short-chain alcohols.When 1,3-BG is used as a cosurfactant and APG is compounded with Tween-80 as surfactant,the infinite dilution line of carvacrol microemulsion can be effectively increased.(2)Carvacrol/1,3-BG/Tween-80 and carvacrol/1,3-BG/Tween-80:APG-0810(1:1)microemulsion systems were characterized,and their particle sizes were between 10-20 nm,with good uniformity,and good high and low temperature,centrifugation and storage stability.The conductivity experiment showed that with the increase of water content,the structure of carvacrol composite microemulsion system changed from W/O type to bicontinuous type and finally changed to O/W type,which proved it was a U-type microemulsion system.(3)Using Malassezia furfur as the test strain,the effects of surfactant type and oleic alcohol ratio on the antibacterial activity of carvacrol microemulsion system were studied by in vitro antibacterial experiments,and the effect of exposure time on the bactericidal effect of carvacrol microemulsion system was evaluated.The results showed that carvacrol/1,3-BG/APG-0810 and carvacrol/1,3-BG/APG-0810:Tween-80(1:1)microemulsion system had better antibacterial effect against Malassezia furfur than carvacrol/1,3-BG/Tween-80 microemulsion system,and the components of carvacrol composite microemulsion formed by combining surfactants with APG-8010 and Tween-80 had better synergistic effects between the components of carvacrol composite microemulsion.The bacteriostatic effect of carvacrol composite microemulsion system is proportional to the content of essential oils,inversely proportional to the content of surfactants and cosurfactants activity.When the mass ratio of carvacrol/1,3-BG(2:1)to the compound surfactant is 1:9(hereinafter referred to as AT3)and the mass ratio of carvacrol/1,3-BG(3:1)to the compound surfactant is 1:9(hereinafter referred to as AT4),the microemulsion system has the best bacteriostatic effect,and the growth of Malassezia can almost completely inhibit when the carvacrol concentration is 0.08%.When the content of carvacrol and cosurfactant is the same,the lower the surfactant content,the better the bacteriostatic effect.When the total content of surfactant and cosurfactant activity is the same,the lower the surfactant content,the better the bacteriostatic effect.(4)The sterilization test showed that the sterilization rate of carvacrol composite microemulsion system increased with the increase of contact time and essential oil concentration.When the concentration of carvacrol in AT3 and AT4 systems is 0.5%and 1%,the sterilization rate can reach more than 99% within 24 hour.(5)The carvacrol composite microemulsion system was prepared into scalp essence and scalp scrub to test its stability,sterilization and antiseptic effects in the product.The results showed that the washing products containing carvacrol composite microemulsion system were stable and had good bactericidal performance and antiseptic effect under the formulation of lower application concentration and natural mild surfactant Tween-80 and cosurfactant 1,3-BG.