Synthesis And In Vitro Drug Release Properties Of HA-CCM Polymeric Prodrug

Curcumin is a low molecular weight natural polyphenolic compound, Recently, numerous articles were released discussing the health beneficial effects of curcumin such as antioxidant, anti-inflammatory,anti-cancer and many others ?curcumin are low water solubility, rapid hydrolytic degradation and poor bioavailability,which limits its potential applications in food and pharmaceutical industries?hyaluronic acid(HA), a naturally occurring polysaccharide composed of N-acetyl-D-glucosamine and D-glucuronic acid, hydrophilic, biodegradable, natural polymers polysaccharide. has a strong affinity with cell-specific surface markers such as CD44 and RHAMM. Chemical modification and conjugation of HA have been achieved by utilizing reactive functional groups in HA such as carboxylic groups and hydroxyl groups. for improve the solubility, stability and bioavailability of curcumin in aqueous medium., we designed and prepared pH-activatable Curcumin(CCM) prodrug micellar nanoparticles by conjugating CCM onto water soluble hyaluronic acid(HA) block polymer via an acid-labile ester bond to HA block. HA–CCM conjugate was characterized using dynamic light scattering(DLS) and transmission electron microscopy(TEM), FT-IR and NMR. the main contents and conclusions of this study are as follows:(1) In this study, hydrophobic drug curcumin was covalently conjugated to the C-6 carboxylate functionality of hydrophilic hyaluronic acid via an ester linkage to produce HA-Ccm conjugate. The covalent conjugation was confirmed by FTIR, 1H NMR. It was confirmed by the structure characterization that Curcumin was successfully grafted onto hyaluronic acid backbone. Different drug content prodrug were synthesized by controlling the charge ratio of reaction raw materials. The content of Curcumin in prodrug cungugates measured by ultraviolet and visible spectrophotometer spectrophotometry was 0.9423%, 1.1854%, 1.5273%, 1.7704%, and1.7895%(wt.%,respectively). Compared with the water solubility of pure curcumin, the conjugated form of curcumin is 16.25-fold more soluble, showed satisfactory water-solubility, and the solubility relate to the drug content of Curcumin.(2) The amphiphilic polymer prodrug can self-assembled in aqueous solution into mono-disperse core-shell micellar nanoparticles, the critical micelle concentration(CMC) of HA–CCM conjugate was 0.1175mg/mL characterized by fluorescent probe spectroscopy using pyrene as a hydrophobic fluorescence probe. The size distribution of HA–CCM conjugate in solution was measured by dynamic light scattering(DLS) with an average diameter of around 205 nm. TEM images show round shaped HA–CCM conjugate micelle with an average diameter of around 150 nm. The sizes obtained from DLS measurement was higher from what is observed from TEM was expected in the sense that in solution the micelles would be in an expanded form due to the high hydrophilicity of the HA moieties. With the increases of the drug content of HA-CCM conjugate, the nanoparticle size, zeta potential were decrease gradually. The stability of curcumin prodrug nanoparticles in pH7.4 phosphate buffer media has been studied, the size increased from 186 nm to 212 nm for HA-CCM3 nanoparticles in in successive 14 days.However, the increase is still acceptable since for the sizes were aroud 200 nm. in which size nanoparticle capacity for a good blood circulation.(3) The in vitro drug release behaviors of different HA-CCM prodrug polymeric micelle nanoparticles were studied in different simulation environment, such as pH 7.4phosphate buffer solution(PBS), pH5.0 and pH6.0 acetate buffer. The in vitro release studies indicate that drug release from HA-CCM prodrug nanoparticles was highly pH-dependant, within 18 h CCM content released from HA-CCM4 less than 18%, while the accumulative release rate was highly than 52% at pH 6.0, and the CCM accumulative release rate extremely high more than 83% when in pH5.0 acetate buffer.In additon, with the decrease of drug content of HA-CCM nanoparticles, the accumulative release rate showed a decrease trend, whie the total accumulative release rate is near close.Therefore, the above reseach indicat that the covalently conjugated HA-CCM prodrug increased the water solubility of Curcumin, and improved the stability of Curcumin. The ester linkage in the covalently conjugated make the prodrug a pH-sensitive, which favored produrg sabilization in blood circulation until produrg was aggregated at tumor tissue by the Permeation and Retention effect(EPR effect). Also, the amphiphilic self-assembled micellar nanoparticles could be a promissing nanocarrier for deliver another hydrophobic anti-cancer durg, achieve a combination therapy.