Amphotericin B-incorporated polymeric micelles composed of poly(d,l-lactide-co-glycolide)/dextran graft copolymer.

In this study, we prepared amphotericin B (AmpB)-encapsulated polymeric micelle of poly(d,l-lactide-co-glycolide) (PLGA) grafted-dextran (DexLG) copolymer and characterized its physicochemical properties in vitro. The average particle size of AmpB-encpasulated DexLG polymeric micelles was around 30-150nm while particle size of empty polymeric micelles was below 100nm according to the copolymer composition. The morphology of AmpB-encapsulated polymeric micelle of DexLG copolymer was spherical shapes at transmission electron microscopy (TEM) observation. At 1H NMR study, specific peaks of AmpB and DexLG copolymer was obtained at DMSO but specific peaks characterized to AmpB and PLGA was disappeared at D2O environment. These results indicated that AmpB was encapsulated into the micellar core of polymeric micelle. XRD results also support these results, indicating that specific crystal peaks of AmpB and broad peaks of DexLG copolymer were obtained but specific peaks of AmpB was disappeared at polymeric micelles while physical mixture of AmpB/empty polymeric micelles showed both specific peaks. Drug release rate was decreased according to the increase of drug contents and increase of PLGA component of DexLG copolymer. At the minimal inhibition concentration (MIC) study using Candida albicans, AmpB-encapsulated polymeric micelle showed almost similar effectives on the growth inhibition of microorganisms. These showed that AmpB-encapsulated polymeric micelle of DexLG copolymer can be considered to potential antifungal agent carriers.

Cytotoxicity of amphotericin B-incorporated polymeric micelles composed of poly(DL-lactide-co-glycolide)/dextran graft copolymer.

In this study, we prepared amphotericin B (AmpB)-encapsulated polymeric micelle of poly(DL-lactideco-glycolide) (PLGA) grafted-dextran (DexLG) copolymer for the cytotoxicity test. The average particle size of AmpB-encapsulated DexLG polymeric micelles was around 30 approximately 70 nm and their morphology showed spherical shapes. Since aggregation states of AmpB are related to intrinsic cytotoxicity, prevention of AmpB aggregation in aqueous solution will provide low cytotoxicity and increased antimicrobial activity for the infectious disease. At UV/VIS spectrum measurement, polymeric micelle prepared from methanol/water mixture (method B) showed a monomeric state of AmpB while polymeric micelle prepared from DMSO (method A) showed an aggregated state. During the hemolysis activity test, polymeric micelle from method B showed reduced hemolysis activity compared to AmpB itself and polymeric micelle from method A. These results indicated that AmpB-incorporated polymeric micelle prepared from methanol/water mixture has low cytotoxicity and favorable antimicrobial activity.

Antitumor effect of adriamycin-encapsulated nanoparticles of poly(DL-lactide-co-glycolide)-grafted dextran.

In this study, we prepared adriamycin (ADR)-encapsulated core-shell type nanoparticles of a poly(DL-lactide-co-glycolide) (PLGA) grafted-dextran (DexLG) copolymer and evaluated its antitumor activity in vitro and in vivo. The particle size of ADR-encapsulated DexLG nanoparticles was around 50-200 nm and the morphology was spherical shapes at transmission electron microscopy (TEM) observation. Since reconstitution of lyophilized nanoparticles is essential to practical use in vivo, ADR-encapsulated DexLG nanoparticles were lyophilized and reconstituted them into deionized water. Although reconstitution process caused increase of particle size, drug release behavior of nanoparticles was not significantly changed before and after reconstitution process. The ADR-encapsulated DexLG nanoparticles were less cytotoxic than free ADR plus empty nanoparticles at in vitro, while empty DexLG nanoparticles did not significantly affect cell viability. Even if free ADR plus empty nanoparticles are most effective to inhibit tumor growth at tumor-induced animal model using CT-26 cells, ADR-encapsulated DexLG nanoparticles showed increased survivability of mice. These results indicated that ADR-encapsulated DexLG nanoparticles are promising vehicles for antitumor drug delivery.

Antifungal mechanism of an antimicrobial peptide, HP (2--20), derived from N-terminus of Helicobacter pylori ribosomal protein L1 against Candida albicans.

The antifungal activity and mechanism of HP (2-20), a peptide derived from the N-terminus sequence of Helicobacter pylori Ribosomal Protein L1 were investigated. HP (2--20) displayed a strong antifungal activity against various fungi, and the antifungal activity was inhibited by Ca(2+) and Mg(2+) ions. In order to investigate the antifungal mechanism(s) of HP (2-20), fluorescence activated flow cytometry was performed. As determined by propidium iodide staining, Candida albicans treated with HP (2-20) showed a higher fluorescence intensity than untreated cells and was similar to melittin-treated cells. The effect on fungal cell membranes was examined by investigating the change in membrane dynamics of C. albicans using 1,6-diphenyl-1,3,5-hexatriene as a membrane probe and by testing the membrane disrupting activity using liposome (PC/PS; 3:1, w/w) and by treating protoplasts of C. albicans with the peptide. The action of peptide against fungal cell membrane was further examined by the potassium-release test, and HP (2-20) was able to increase the amount of K(+) released from the cells. The result suggests that HP (2-20) may exert its antifungal activity by disrupting the structure of cell membrane via pore formation or directly interacts with the lipid bilayers in a salt-dependent manner.