In Vitro susceptibilities of wild and drug resistant Leishmania donovani amastigotes to piperolactam A loaded hydroxypropyl-β-cyclodextrin nanoparticles.

Abstract 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 piperolactam A (PL), isolated after bioactivity guided fractionation from root extracts of Piper betle was accentuated in detail. Activity potentiation was achieved via cyclodextrin complexation. Crude hydro-ethanolic extract (PB) and three fractions obtained from PB and fabricated PL-hydroxypropyl-β-cyclodextrin (HPBCD) nanoparticles were evaluated for antileishmanial activity. Tests were performed against L . donovani wild-type, sodium stibogluconate, paromomycin and field isolated (GE1) resistant strains in axenic amastigote and amastigote in macrophage models. PL-HPBCD complex was characterized and FITC loaded HPBCD nanoparticles were assessed for macrophage internalization in confocal microscopic studies. Isolated and purified PL from most potent, alkaloid rich ethyl acetate fraction of PB showed high level of antileishmanial activities in wild-type (IC 50  = 36 μM), sodium stibogluconate resistant (IC 50  = 103 μM), paromomycin resistant (IC 50  = 91 μM) and field isolated resistant (IC 50  = 72 μM) strains together with cytotoxicity (CC 50  = 900 μM) in mouse peritoneal macrophage cells. Inclusion of PL in HPBCD nanoparticles resulted in 10-fold and 4–10-fold increase in selectivity indexes (CC 50 /IC 50 ) for wild-type and drug resistant strains, respectively. Drug-carrier interactions were clearly visualized in FT-IR studies. Complete incorporation of PL in HPBCD cavity was ascertained in DSC and XRD analyses. 180 nm size stable nanospheres showed macrophage internalization within 1 h of incubation. Piperolactam A (PL), a representative of the inchoate skeleton of aristolactam chassis might be the source of safe and affordable antileishmanial agents for the cure of deadly Leishmania infections.