Development and evaluation of a cedrol-loaded nanostructured lipid carrier system for in vitro and in vivo susceptibilities of wild and drug resistant Leishmania donovani amastigotes.

Leishmaniasis is an epidemic in various countries, and the parasite Leishmania donovani is developing resistance against available drugs. In the present study the antileishmanial action of cedrol was evaluated in vitro and in vivo. Activity potentiation was achieved via nanostructured lipid carrier (NLC) complexation of cedrol. Cedrol-loaded NLC was prepared through the hot-melting emulsification-ultrasonication method. The cedrol- NLC prepared did not require the use of any organic solvents. The characterization of NLC-C1 and NLC-C2 revealed that particle size was 46.62nm and 54.73nm for 3.85%, and 7.48% drug loading, respectively and negative charge of -19.2mV and -23.7mV. The cedrol-loaded NLC were found to be spherical with a smooth surface. Drug-carrier interactions were clearly visualized in FT-IR studies. Incorporation of cedrol in NLC was ascertained in DSC and XRD analysis. Antileishmanial activities of free cedrol and cedrol-NLC were performed against L. donovani wild-type, sodium stibogluconate, paromomycin and field isolated resistant strains in axenic amastigotes and amastigotes in macrophage model. Coumarin-6 loaded NLC nanoparticles were assessed for macrophage internalization in confocal microscopic studies. Cedrol showed significant antileishmanial activity in wild-type (IC50 =1.5μM), sodium stibogluconate resistant (IC50 =2μM), paromomycin resistant (IC50 =1.8μM) and field isolated resistant (IC50 =1.35μM) strains in macrophage together with cytotoxicity (CC50 =74μM) in mouse peritoneal macrophage cells. Incorporation of cedrol in NLC-C2 resulted in 2.1-fold and 2-fold increase in selectivity indexes (CC50 /IC50 ) for wild-type and drug resistant strains, respectively. In addition, in vivo studies revealed that bioactivity of NLC-C2 were 2.3 to 3.8-fold increased in wild-type and 3 to 4.9-fold increased in drug resistant strains when compared with free cedrol; administered orally in mouse leishmaniasis model. Overall, NLC-C2 showed superior antileishmanial activity to free cedrol and miltefosine in oral dose. These findings support the use of NLCs for oral delivery of poorly water-soluble antileishmanial drugs in treatment of leishmaniasis.

CHEMICAL COMPOUNDS: Cedrol (PubChem CID: 65575); Compritol® 888 ATO (PubChem CID: 62726); Triolein (PubChem CID: 5497163); Pluronic F68 (PubChem CID: 24751); Soya lecithin (PubChem CID: 57369748); Sodium deoxycholate (PubChem CID: 23668196); Miltefosine (PubChem CID: 3599); Paromomycin (PubChem CID: 165580); Amphotericin B (PubChem CID: 5280965); Sodium stibogluconate (PubChem CID: 16683012).