Conjugation of steroids with PAMAM nanoparticles

Complexes of Indomethacin with 4-Carbomethoxy-pyrrolidone PAMAM Dendrimers Show Improved Anti-inflammatory Properties and Temperature-Dependent Binding and Release Profile

COX-2 inhibitors such as nonsteroidal anti-inflammatory drugs (NSAIDs) are the most common treatment for chronic inflammatory diseases like arthritis and atherosclerosis. However, they are associated with severe side effects such as cardiovascular events or stomach bleeding, due to coinhibition of other enzymes (COX1) and off-target accumulation. PAMAM dendrimers can solubilize lipophilic drugs and increase their circulation time; furthermore, PAMAM dendrimers seem to have some accumulation in inflammatory sides. Three different generations of 4-carbomethoxypyrrolidone (Pyr) surface-modified PAMAM dendrimers were complexed with the NSAID drug indomethacin, and their in-solution thermodynamic profiles were studied by means of NMR experiments. The binding stoichiometry was found dependent on solvent system and dendrimer generation. Larger dendrimers (G3-Pyr) were found to bind indomethacin through entropy driven binding mode, while G1-Pyr and G2-Pyr expressed an enthalpy driven complex formation, which means that the binding constants have a generational temperature dependency. G1/2-Pyr showed reduced binding with increasing temperature, which could be important for drug release at inflammatory sites, which have, in general, elevated temperatures. In vitro studies elucidated that the indomethacin drug remained its activity when delivered as a dendrimer-indomethacin complex. A slight reduction in toxicity profile was noticed for G2/G3-Pyr-indomethacin dendrimers. Both free indomethacin and dendrimer-indomethacin complex inhibited a variety of pro-inflammatory cytokines in LPS treated cells. However, only the indo-dendrimer complexes showed a significant reduction of IL-1β in LPS-treated THP-1 cells, which was not present in the control with free indomethacin.

Fabrication and characterization of chitosan conjugated eurycomanone nanoparticles: In vivo evaluation of the biodistribution and toxicity in fish

Chitosan nanoparticles (CNPs) have been proven considerable delivery agents due to their remarkable physicochemical properties. Present study reports the fabrication of CNPs by ionic gelation process and their characterization by different approaches. The constructed nanoparticles were successfully conjugated with eurycomanone with significant entrapment efficiency. Particle size of chitosan and chitosan conjugated eurycomanone nanoparticles were 126.2nm and 130nm respectively. Scanning electron microscopy showed that the particles were spherical in shape and well dispersed. Cross-linking between CNPs and eurycomanone (CENPs) were confirmed by Fourier-transform infrared (FTIR) spectroscopy. Fluorescent nanoparticles were prepared by using Rhodamine-6G dye, characterised by SEM and confirmed for conjugation by FTIR. Biodistribution of CENPs showed the presence of fluorescent nanoparticles in liver, kidney, testes and brain of C. magur. The toxicity of CENPs was evaluated by comparing the histological sections of catfish testes collected from treated and control group. No signs of toxicity were seen in testes after the delivery of CENPs. Molecular docking study revealed high spontaneous binding ability of chitosan with eurycomanone and aromatase enzyme. The study reports that CNPs can act as a stabilizing agent for eurycomanone formulation and could be a promising approach to increase the reproductive performance of the fishes.

Al cation induces aggregation of serum proteins

Al cation is known to induce protein fibrillation and causes several neurodegenerative disorders. We report the spectroscopic, thermodynamic analysis and AFM imaging for the Al cation binding process with human serum albumin (HSA), bovine serum albumin (BSA) and milk beta-lactoglobulin (b-LG) in aqueous solution at physiological pH. Hydrophobicity played a major role in Al-protein interactions with more hydrophobic b-LG forming stronger Al-protein complexes. Thermodynamic parameters ΔS, ΔH and ΔG showed Al-protein bindings occur via hydrophobic and H-bonding contacts for b-LG, while van der Waals and H-bonding interactions prevail in HSA and BSA adducts. AFM clearly indicated that aluminum cations are able to force BSA and b-LG into larger or more robust aggregates than HSA, with HSA 4±0.2 (SE, n=801) proteins per aggregate, for BSA 17±2 (SE, n=148), and for b-LG 12±3 (SE, n=151). Thioflavin T test showed no major protein fibrillation in the presence of Al cation. Al complexation induced major alterations of protein conformations with the order of perturbations b-LG>BSA>HSA.

Review on the delivery of steroids by carrier proteins

Due to the poor solubility of steroids in aqueous solution, delivery of these biomaterials is of major biomedical importance. We have reviewed the conjugation of testosterone and it aliphatic dimer and aromatic dimer with several carrier proteins, human serum albumin (HSA), bovine serum albumin (BSA) and milk beta-lactoglobulin (b-LG) in aqueous solution at physiological pH. The results of multiple spectroscopic methods, transmission electron microscopy (TEM) and molecular modeling were compared here. Steroid-protein bindings are via hydrophilic and H-bonding contacts. HSA forms more stable conjugate than BSA and b-LG. The stability of steroid-protein conjugates is testosterone>dimer-aromatic>dimer-aliphatic. Encapsulation of steroids by protein is shown by TEM images. Modeling showed the presence of H-bonding, which stabilized testosterone-protein complexes with the free binding energy of -12.95 for HSA and -11.55 for BSA and -8.92kcal/mol for b-LG conjugates. Steroid conjugation induced major perturbations of serum protein conformations. Serum proteins can transport steroids to the target molecules.