Investigating The Mechanism Of Enhancement Effect Of Consituents Of Ledum Palustre L.Palustre On Drug Skin Permeation

Objective:In this study,enhancement ability and safty of contituents of EO was invesitigated.Moreover,enhancement mechanisms of the constituents of EO were revealed from the aspect of drug,transdermal permeation enhancers(TPEs)and skin,which provided important pharmaceutical excipients for transdermal drug delivery system.Method:Firstly,the main constituents of EO was screened to obtain TPEs with strong enhancement ability.The composition of EO was determined by GC-MS,and constituents with high content were selected as study object.By using donepezil(DNP)and diclofenac(DCF)as model drugs,enhancement ability of constituents and EO were evaluated by in vitro skin permeation test.Safety of constituents and EO were investigated by in vivo skin erythema analysis.Secondly,the mechanism of enhancement mechanism of TPEs was explored from two aspects:on one hand,confocal laser scanning microscopy(CLSM),attenuated total reflection-fourier transform infrared spectroscopy(ATR-FTIR)and molecular docking were used to investigate the mechanism of how TPEs disrupted intercellular lipid;on the other hand,skin retention amount test,partition coefficient and molecular modeling were used to investigate the effect of TPEs on drug partition into the skin.Results:The main constituens of EO were sabinene(SA),terpineol(TE),p-Cymene(CY),Cuminaldehyde(CU).By the results of in vitro transdermal test,CU showed strong enhancement ability for skin permeation of DNP,while SA showed strong enhancement ability for DCF.Their enhancement ratio(ER)were 7.40 and 2.77,respectively.Safety of CU was much better than that of EO,while safety of SA was similar to that of EO.The enhancement mechanism of CU was investigated further.By the results of ATR-FTIR,both CU and DNP disrupted intercellular lipid.Both CU and DNP interacted with the head of CER by hydrogen bond.Their hydrogen bond energy were-3.476 kcal/mol and-2.079 kcal/mol,respectively,which indicated that interaction between CU and CER was stronger than that between DNP and CER.Therefore,CU destroyed the interaction between DNP and CER,which was favorable to drug diffusion in skin and promote drug absorption through skin.Besides,drug skin retention amount,partition coefficient showed great correlation with ER,which suggested that CU had an effect on drug partition into skin.By the results of molecular modeling,DNP(?DNP = 21.92 MPa1/2)was different with DPPC(?DPPC = 18.20 MPa1/2)in solubility parameter,which indicated their compatibility was bad.Solubility parameter of CU-DPPC became similar to that of DNP because of addition of CU.Therefore,CU facilitated drug partion into skin to promote drug absorption through skin.Conclusion:In this study,CU showed strong enhancement ability and high safety by the results of in vitro transdermal test and in vivo skin erythema analysis.It increased drug skin permeation by two aspects:on one hand,CU destroyed the interaction between DNP and intercellular lipid and increased the mobility of intercellular lipid;on the other hand,CU changed solubility parameter of skin by interacting with intercellular lipid,which facilitated DNP partition into skin.Both of two aspects above promoted drug abosorption though skin.