Retention of Eucalyptol, a Natural Volatile Insecticide, in Delivery Systems Based on Hydroxypropyl‐β‐Cyclodextrin and Liposomes
Résumé
Eucalyptol(Euc)is a natural monoterpene with insecticide effects. Being highly volatile and sensitive to ambient conditions, its encapsulation would enlarge its application.Euc-loaded conventional liposomes(CL), cyclodextrin/drug inclusion complex and drug-in-cyclodextrin-in-liposomes (DCL) were prepared to protect Euc from degradation, reduce its evaporation and provide its controlled release.The liposomal suspension was freeze-dried using hydroxypropyl-ß-cyclodextrin (HP-ß-CD) as cryoprotectant.The liposomes were characterized before and after freeze-drying.The effect of Euc on the fluidity of liposomal membrane wasalso examined. A release study of Euc from delivery systems, in powder and reconstituted forms, was performed by multiple head extraction at 60ºC after 6 months of storage at 4ºC.CL and DCL suspensions were homogeneous, showed nanometric vesicles size,spherical shapeand negative surface charge before and after freeze-drying. Moreover, HP-ß-CD did not affect the fluidity of liposomes. CL formulations presented a weak encapsulation for Euc. The loading capacity of eucalyptol in DCL was 38 times higher than that in CL formulation.In addition, freeze-dried DCL and HP-ß-CD/Euc inclusion complex showed ahigher retention of eucalyptol than CL delivery system.Both carrier systems HP-ß-CD/Euc and Euc-loaded DCL decreased Euc evaporationand improved its retention
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