Evaluation of Turmeric Nanoparticles as Anti-Gout Agent: Modernization of a Traditional Drug

Background and objectives: Turmeric has assisted in the control of inflammation and pain for decades and has been used in combination with other nutraceuticals to treat acute and chronic osteoarthritis pain. Recently, the effect of turmeric, turmeric extract, or curcuminoids on musculoskeletal pain, either by themselves or in conjunction with other substances, has been reported. The aim of this study was to develop and characterize turmeric nanoparticles (T-NPs) for various parameters, both in vitro and in vivo. Materials and Methods: The T-NPs were successfully synthesized and characterized using particle size analysis, solubility improvement, SEM, EDX, X-ray diffraction, and in vivo antigout activity in mice model. Results: The T-NPs were of about 46 nm in size with a positive zeta potential +29.55 ± 3.44 and low polydispersity index (PDI) (0.264). Furthermore, the diseased mice, with induced gout via monosodium urate crystals, were treated with 5, 10, and 20 ppm T-NPs, administered orally, and the anti-gout potential was observed through measurement of joint diameter and changes in biochemical parameters, including lipid profile, renal function test, and liver function tests which significantly reduced the levels of these biochemical parameters. Conclusions: Uric acid levels were significantly reduced after the treatment with T-NPs. indicating that T-NPs show superior potential against gout management. Thus, T-NPs can be developed as an efficient antigout agent with minimum toxicities.

Synthesis of uranyl(II), vanadyl(II) and zirconyl urate complexes, spectral, thermal and biological studies

Three urate chelations were obtained when uric acid was reacted with UO2(CH3COO)2H2O, VOSO4·XH2O and ZrOCl2·XH2O salts with neutralized with 0.1 M NaOH aqueous media. The 1:2 metal-to-ligand complexes [(UO2)2(C5H2N4O3)2](H2O), [(ZrO)2(H2O)2(C5H2N4O3)2] and [VO((C5H3N4O3)2] were characterized by elemental analyses, molar conductivity, (infrared, Raman and UV-vis) spectra, effective magnetic moment in Bohr magnetons, and thermal analysis (TG/DTG). The urate ligand coordinates as mononegative bidentate donor towards the mononuclear central vanadium atom and coordinated as binegative tetradentate mode towards the binuclear dioxouranium and zirconyl centers. The antibacterial activity of the metal complexes were tested against some kind of bacteria and fungi strains and compared with uric acid. The ligand, ZrO(II) and UO2(II) complex showed a week potential degradation on calf thymus DNA, whereas VO(II) complex slightly degraded the DNA.

Method for the synthesis of uric acid derivatives

A general procedure to obtain tetra-substituted uric acid by stepwise N-alkylation is described. 2,6-Dichloropurine (1) was condensed with 1-propanol by Mitsunobu reaction to give 9-propyl congener (2). Treatment of 2 with ammonia gave adenine derivative (4a), which was converted to the 8-oxoadenine (5b) in 3 steps. Methylation of 5b proceeded site-specifically to give 6-amino-2-chloro-7,8-dihydro-7-methyl-9-propylpurin-8-one (6) as a sole product. Compound 6 was successively treated with NaNO2 and iodomethane to give 2-chloro-1,6,7,8-tetrahydro-1,7-dimethyl-9-propylpurin-6,8-dione (9) accompanied by the O6-methyl product (8) in 75% and 6.9%, respectively. After nucleophilic substitution of 9 with NaOAc, the product (11) was reacted with iodomethane to give the uric acid (12) and the 2-methoxy product (13) in 46% and 15.5%, respectively. However, the reaction of 11 with the benzylating agents gave only O-benzyl products (14a,b).

Uric acid synthesis by rat liver supernatants from purine bases, nucleosides and nucleotides. Effect of allopurinol

The synthesis of uric acid from purine bases, nucleosides and nucleotides has been measured in reaction mixtures containing rat liver supernatant and each one of the following compounds at 1 mM concentration (except xanthine, 0.5 mM and guanosine and guanine, 0.1 mM). The rates of the reaction, expressed as nanomoles of uric acid synthesized g-1 of wet liver min-1 were: ATP, 10; ADP, 37; AMP, 62; adenosine, 108; adenine 6; adenylosuccinate, 9; IMP 32; inosine, 112; hypoxanthine, 50; GTP, 19; GDP, 19; GMP, 27; guanosine, 34; guanine, 72; XMP, 10; xanthosine, 24; xanthine, 144. These figures divided by 55 correspond to nanomoles of uric acid synthesized min-1 per mg-1 of protein. The rate of synthesis of uric acid obtained with each one of those compounds at 0.1 and 0.05 mM concentrations was also determined. ATP (1 mM) strongly inhibited uric acid synthesis from 0.05 mM AMP (91 per cent) and from 0.05 mM ADP (88 per cent), but not from adenosine. CTP or UTP (1 mM) also inhibited (by more than 90 per cent) the synthesis of uric acid from 0.05 mM AMP. Xanthine oxidase was inhibited by concentrations of hypoxanthine higher than 0.012 mM. The results favour the view that the level of uric acid in plasma may be an index of the energetic state of the organism. Allopurinol, besides inhibiting uric acid synthesis, reduced the rate of degradation of AMP. The ability of crude extracts to catabolize purine nucleotides to uric acid is an important factor to be considered when some enzymes related to purine nucleotide metabolism, particularly CTP synthase, are measured in crude liver extracts.

Tophus-derived monosodium urate monohydrate crystals are biologically much more active than synthetic counterpart

Monosodium urate monohydrate (MSUM) crystals derived from a tophus surgically removed from patients suffering from gout and MSUM prepared from a supersaturated solution of sodium urate were studied and compared with respect to their ability to: (1) stimulate chemiluminescence (CL) production by human polymorphonuclear (PMN) cells, (2) induce hemolysis of the human red blood cells and (3) induce inflammation when injected in the rat paw and knee joint. Human MSUM crystals were considerably more active in stimulating CL production by PMN cells and in inducing synovial inflammation. Both serum and papain pretreatment of human MSUM crystals caused inhibition of their enhancing effect on CL production by PMN cells. Papain pretreatment only reduced their phlogogenic activity. Uncoated and, to a much lesser extent, serum-coated human MSUM crystals induced secretion by mononuclear cells (MNC) of the factor(s) that considerably enhanced CL production by PMN cells. Both tophus-derived and synthetic crystals appeared to be weak hemolytic agents. Serum pretreatment of synthetic MSUM crystals reduced their hemolytic activity. These results suggest that surface coating, destroyed by papain treatment, was probably responsible for cell activation induced by human MSUM crystals.

Chemiluminescent determination of adenosine, inosine, and hypoxanthine/xanthine

A fully automatic method for analysis of adenosine, inosine, and hypoxanthine/xanthine which combines the specificity of enzymatic catalysis and sensitivity of chemiluminescence is presented. The hydrogen peroxide formed by sequential catabolism of purines to uric acid is detected by the oxidation of luminol in the presence of peroxidase. The method takes advantage of the fact that light output in the H2O2/luminol system is transient. By adopting a two-step procedure this feature enables selective determination of adenosine, inosine, and hypoxanthine/xanthine. In step 1 any purines lower in the catabolic sequence than the analyte under study are converted to uric acid. Light emission is allowed to decay to baseline levels. During step 2 the analyte is selectively degraded. The H2O2 formed leads to a new light emission which is proportional to the square of analyte concentration. The method can be performed with commercially available reagents and enzymes and requires minimal processing of biological samples. Excellent agreement has been obtained with HPLC analysis. Sensitivity is in the range of 5-10 nmol/liter in as little as 0.1 ml. More than 200 samples per day can be analyzed by a single operator.

Morphological characteristics of monosodium urate: a transmission electron microscopic study of intact natural and synthetic crystals

Transmission electron microscopic studies of synthetic and natural monosodium urate crystals dried on formvar coated grids showed identical internal structures in all crystals. At higher magnification the crystals' surface showed angular or wavy irregularities, and more rarely some crystals appeared to have other tiny crystals on the surface. Protein-like surface coating was not observed except in crystals from one asymptomatic patient in whom synovial fluid was loaded with monosodium urate crystals, but no inflammatory cells were present. Heated synthetic monosodium urate crystals retained the ultrastructural characteristics in their interior but they lost their needle or rod-like shape. Transmission electron microscopic study of monosodium urate crystals dried on formvar coated grids provides a quick method of investigating crystal ultrastructure.