Carbohydrate-Derived Polytriazole Nanoparticles Enhance the Anti-Inflammatory Activity of Cilostazol

Abstract

Poly(amide-triazole) and poly(ester-triazole) synthesized from d-galactose as a renewable resource were applied for the synthesis of nanoparticles (NPs) by the emulsification/solvent evaporation method. The NPs were characterized as stable, spherical particles, and none of their components, including the stabilizer poly(vinyl alcohol), were cytotoxic for normal rat kidney cells. These NPs proved to be useful for the efficient encapsulation of cilostazol (CLZ), an antiplatelet and vasodilator drug currently used for the treatment of intermittent claudication, which is associated with undesired side-effects. In this context, the nanoencapsulation of CLZ was expected to improve its therapeutic administration. The carbohydrate-derived polymeric NPs were designed taking into account that the triazole rings of the polymer backbone could have attractive interactions with the tetrazole ring of CLZ. The activity of the nanoencapsulated CLZ was measured using a matrix metalloproteinase model in a lipopolysaccharide-induced inflammation system. Interestingly, the encapsulated drug exhibited enhanced anti-inflammatory activity in comparison with the free drug. The results are very promising since the stable, noncytotoxic NP systems efficiently reduced the inflammation response at low CLZ doses. In summary, the NPs were obtained through an innovative methodology that combines a carbohydrate-derived synthetic polymer, designed to interact with the drug, ease of preparation, adequate biological performance, and environmentally friendly production.

Scheme 1. Chemical Structures of Monomers, PET, PAT, and Cilostazol (CLZ)

Figure 1

Top: Intensity vs particle diameter distribution plot of NPs: (a) PET-P-v and PET-P-CLZ and (b) PAT-P-v and PAT-P-CLZ. Bottom: Volume vs particle diameter distribution plot of NPs: (c) PET-P-v and PET-P-CLZ and (d) PAT-P-v and PAT-P-CLZ.

Figure 2

SEM images of NPs: (a) PET-P-v, (b) PET-P-CLZ, (c) PAT-P-v, and (d) PAT-P-CLZ.

Figure 3

Aromatic and NH region of ¹H NMR spectra (500 MHz, DMSO-d₆) of (a) PAT-P-CLZ, (b) PAT-P-v, (c) CLZ, (d) PET-P-CLZ, and (e) PET-P-v.

Figure 4

FTIR-ATR spectra of (a) CLZ, (b) PET, (c) PET-P-v NPs, (d) PET-P-CLZ NPs, (e) physical mixture PET + P + CLZ, (f) PVA, (g) CLZ, (h) PAT, (i) PAT-P-v NPs, (j) PAT-P-CLZ NPs, (k) physical mixture PAT + P + CLZ, and (l) PVA.

Figure 5

Cumulative release of CLZ vs time.

Figure 6

In vitro CLZ activity. MMP-9 gelatinase activity was determined by zymography in supernatants of NRK cells after 24 h of the indicated treatments (a) at 100 μM CLZ or (b) in a dose–response experiment at 70, 50, and 25 μM CLZ in the presence of LPS stimulus or in nonstimulated cells (NS). **p < 0.01 vs NS; #p < 0.05; ##p < 0.01; ###p < 0.001 vs LPS.