DSPC Liposomes Improve Transport of L-cysteine and Reduce Metabolic Activity

Aims: In this work, we developed and characterized liposomal formulations that encapsulate L-cysteine to study their further application in drug delivery and amino acid supplementation. The lipids used were 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC).

Methodology: Encapsulation efficiency and amino acid release were determined. For biophysical characterization of the three formulations, the size, surface charge and surface packing were also studied. Cell viability was analyzed with MTT reagent after treatments with formulations ir order to study efficiency of these systems in induce changes in metabolism.

Results: Results showed that L-cysteine interacts at the polar head level and that this interaction stabilizes the surface charge and prevents aggregation. We also determined the influence on cell metabolism in all formulations. The presence of L-cysteine in the DSPC formulation induced deeper changes in metabolism, evidencing that this formulation provides better transport of this amino acid.

Conclusion: Liposomes developed herein are well suited for the application in the delivery of L-cysteine. Particularly, they can encapsulate nearly all the L-cysteine and can retain it for 6 hours. Also, L-cysteine stabilized liposomes, preventing their aggregation. L-cysteine encapsulated in the DSPC formulation induced deeper changes in cell metabolism, causing a decrease in metabolic activity; this was probably due to a higher entry, thus a better liposome-mediated transport. Considering that the smaller the particle, the better the circulation, we believe that the stabilization of the vesicle by L-cysteine may allow these transporters to have higher circulation times. Based on the above, we conclude that the DSPC formulation is the best suited for further application in L-cysteine delivery.