Pickering emulsion stabilized by cashew gum- poly-l-lactide copolymer nanoparticles: Synthesis, characterization and amphotericin B encapsulation.

In this work, we provide proof-of-concept of formation, physical characteristics and potential use as a drug delivery formulation of Pickering emulsions (PE) obtained by a novel method that combines nanoprecipitation with subsequent spontaneous emulsification process. To this end, pre-formed ultra-small (d.∼10 nm) nanoprecipitated nanoparticles of hydrophobic derivatives of cashew tree gum grafted with polylactide (CGPLAP), were conceived to stabilize Pickering emulsions obtained by spontaneous emulsification. These were also loaded with Amphotericin B (AmB), a drug of low oral bioavailability used in the therapy of neglected diseases such as leishmaniasis. The graft reaction was performed in two CG/PLA molar ratio conditions (1:1 and 1:10). Emulsions were prepared by adding the organic phase (Miglyol 812®) in the aqueous phase (nanoprecipitated CGPLAP), resulting the immediate emulsion formation. The isolation by centrifugation does not destabilize or separate the nanoparticles from oil droplets of the PE emulsion. Emulsions with CGPLAP 1:1 presented unimodal distributions at different CGPLA concentration, lower values in size and PDI and the best stability over time. The AmB was incorporated in the emulsions with a process efficiency of 21-47%, as determined by UV-vis. AmB in CGPLAP emulsions is in less aggregated state than observed in commercial AmB formulation.

Chemically sulfated galactomannan from Dimorphandra gardneriana seed: characterization and toxicity evaluation.

Dimorphandra gardneriana galactomannan (DG) was sulfated in pyridine:formamide using chlorosulfonic acid as the sulfation agent. The degree of substitution was 0.32, determined from the sulfur percentage. Confirmation of sulfation was obtained by FTIR spectroscopy through the presence of an asymmetrical SO stretching vibration at 1,259 cm(-1). NMR data showed that the sulfation occurred on primary hydroxyl groups. NMR and GPC data indicate degradation during reaction with elimination of galactose. At the maximum tested concentration of 1,000 µg/mL, unmodified DG polysaccharide did not show a statistically significant cytotoxicity in Vero cells by the MTT method. Therefore, the CC50>1,000 µg/mL obtained for the sulfated polysaccharides from D. gardneriana in Vero cells point to its lower cytotoxicity than the sulfated galactomannan from Mimosa scabrella.