Enhanced Dissolution of Ursodeoxycholic Acid from the Solid Dispersion

Solid dispersions of a very slightly water-solubte drug, ursodeoxycholic acid (UDCA), were prepared using urea, mannitol, and PEG 6000 as a carrier, and the solubility of UDCA was determined in water-ethanol (1:1) mixed solvent as a function of UDCA-carrier ratio. The solubility of UDCA was slightly improved when urea or PEG 6000 was used as a carrier. The powder x-ray diffraction measurements revealed that UDCA did not exist in the crystalline state in the solid dispersions. Differential scanning calorimetry (DSC) studies showed that UDCA was able to dissolve in the melt of urea, mannitol, and PEG 6000. The effect of carriers of solid dispersions on the UDCA dissolution rate was examined. The dissolution rate of UDCA was markedly increased from the solid dispersions of urea, PEG 6000, and mannitol, respectively.     

EFFECT OF ZEOLITE CRYSTALLITE SIZE ON Pt/KL CATALYSTS USED FOR THE AROMATIZATION OF n-OCTANE

The effects of varying zeolite crystallite size in n-octane aromatization over Pt/KL have been studied on a series of catalysts. Various KL zeolites were synthesized via microwave-hydrothermal treatment, which allows for good control of crystallite morphology. Zeolites with different crystallite sizes were prepared by varying aging time (17-24 h), amount of barium (0-445 ppm), and seeding (0-8 wt%). The results showed that higher aging time resulted in smaller zeolite crystallite size, whereas the addition of barium resulted in larger crystallite size. Moreover, the addition of seeding reduced the crystallite size from 1.47 to 0.94 μm. Pt supported on different zeolite catalysts (Pt/KL) was prepared by vapor phase impregnation (VPI). The fresh catalysts were characterized by DRIFTS of adsorbed CO and volumetric hydrogen chemisorption. The results indicated that Pt clusters are well dispersed inside the zeolite channel in all the catalysts prepared. The aromatization of n-octane was tested on the different catalysts at 500°C and atmospheric pressure. It was found that the catalytic activity of all catalysts dropped rapidly after about 200 min on stream due to coke plugging inside the pore of the KL zeolite. It was also observed that less ethylbenzene (EB) and o-xylene (OX) were obtained as the conversion increased because both EB and OX are converted to smaller molecules such as benzene, toluene, etc., by secondary hydrogenolysis. Furthermore, the EB/OX ratio increases with zeolite crystallite size due to an enhanced preferential conversion of the larger OX molecules compared to the narrower EB as their path through the pores is restricted.     

Comparison of antioxidant capacities and cytotoxicities of certain fruit peels

This work was undertaken to explore the potential of fruit waste materials as sources of powerful natural antioxidants. The peels of eight kinds of fruits commonly consumed and grown in Thailand were used. The ethanolic fruit peel extracts were subjected to the scavenging tests of DPPH and ABTS radicals. Results from both assays were in good agreement that the top three markedly high free radical-scavenging power was from the peel extracts of Punica granatum (pomegranate), Nephelium lappaceum (rambutan), and Garcinia mangostana (mangosteen). The IC₅₀ values to quench the DPPH free radicals of these three extracts were 0.003, 0.006, and 0.023 mg/ml and the trolox equivalent antioxidant capacity (TEAC) values from ABTS assay were 4.066, 3.074, and 3.001 mM/mg, respectively. The extract of mangosteen peel showed moderate toxicity to Caco-2 cells and high toxicity to peripheral blood mononuclear cells (PBMC) with the IC₅₀ values of 32.0 and 4.9 μg/ml, respectively. Pomegranate peel extract stimulated Caco-2 cell and PBMC proliferation with the ED₅₀ of 4.7 and 44.4 μg/ml, respectively. Peel extract of rambutan exhibited extremely high value of IC₅₀ (>100 μg/ml) against both cell types indicating non-toxic activity to the cells. It was concluded that the peel of rambutan may be considered potentially useful as a source of natural antioxidants for food or drug product because of its high antioxidant activity and non-toxic property to normal cells.     

Beads fabricated from alginate,hyaluronic acid,and gelatin using ionic crosslinking and layer-by-layer coating techniques for controlled release of gentamicin

The alginate/hyaluronic acid (AL/HA) blended beads at different ratios (AL70HA30, AL50HA50, and AL30HA70) were formed by ionic crosslinking technique. The layer-by-layer coating of the beads with two opposite charged molecules, positive-charged type A gelatin (GA), and negative-charged AL, using alternate soaking technique was introduced to stabilize the beads. The AL70HA30, AL50HA50 beads showed high stability because of high ionic crosslinked AL component. Two-layer coating resulted in an appropriate layer that maximized the stability of the AL/HA beads. The higher ratio of HA resulted in the higher water absorption ability but degradation rate was accelerated. An antibiotic gentamicin was loaded into the beads with the entrapment efficiency of 69–89%. The beads containing 30% and 50% HA and coated with two layers showed a sustained release of gentamicin while the release behavior was governed by the diffusion and degradation of the beads. The gentamicin released from all beads also potentially inhibited the growth of Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative) bacteria up to at least 48 h. These beads with antibacterial activity can be further explored for the application as bone void filling material for treatment of infection in bone diseases such as osteoarthritis or rheumatoid. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46893.     

Carboxymethyl mungbean starch as a new pharmaceutical gelling agent for topical preparation

An application of carboxymethyl mungbean starch (CMMS) as a gelling agent in the topical pharmaceutical preparation was investigated. CMMS was prepared using specific conditions that yielded a high-viscosity product. Polymer gels and gel bases were prepared at 1-10% (wt/wt), and physicochemical studies were carried out in comparison with four standard gelling agents: carbopol 940 (CP), hydroxypropylmethyl cellulose (HPMC), methyl cellulose (MC), and sodium carboxymethyl cellulose (SCMC). Piroxicam was used as a model drug to study the drug release profile of the gel formulations. The tackless, greaseless, and transparent CMMS gels exhibited pseudoplastic behavior with thixotropy at concentrations less than 5% (wt/wt). At a concentration of 5% (wt/wt) and higher, the semisolid gels showed plastic flow characteristics. Viscosity and X-ray diffraction results indicated a good compatibility between CMMS and the acidic piroxicam. No precipitation of piroxicam or phase separation was observed during a stability test. The release rate of piroxicam from 3% (wt/wt) CMMS gel was 1,003.79 +/- 105.08 microg/cm(2), which was comparable with 947.66 +/- 133.70 microg/cm(2) obtained from a 0.5% (wt/wt) carbopol formulation. The release profiles of both formulations were consistent and remained unchanged after 2 months' storage. Viscosity played an important role in controlling the release rate of low concentration CMMS formulations by regulating the drug diffusion. At a concentration of 5% (wt/wt) CMMS and higher, the release rates of piroxicam were not significantly different. A plausible explanation based on the nature of the gelling agent was proposed. Stability and drug release profiles of CMMS and commercial gelling agents were compared. The results supported the potential use of CMMS as a new, effective gelling agent for topical gel preparation.     

Comparative study on acid-induced gelation of myosin from Atlantic cod (Gardus morhua) and burbot (Lota lota)

Physicochemical and rheological properties of myosin from Atlantic cod and burbot during acid-induced gelation at room temperature (22–23 °C) by d-gluconic acid-δ-lactone (GDL) were monitored. Turbidity and particle size of both myosins increased and salt soluble content decreased when pH decreased, suggesting the formation of protein aggregates caused by acidification. The formation of disulphide bonds in myosin gelation was induced by acid. Ca²⁺-ATPase activity of myosin decreased (p < 0.05), while surface hydrophobicity increased during acidification (p < 0.05). Furthermore, the decreases in maximum transition temperature (T_max) and the denaturation enthalpies (ΔH) were found in both myosins. During acidification, the increases in storage modulus (G′) and loss modulus (G″) of myosin were observed (p < 0.05), revealing the formation of elastic gel matrix. Thus, gelation of myosin from Atlantic cod and burbot could take place under acidic pH via denaturation and aggregation. However, myosin from Atlantic cod was generally more favourable to gelation than was burbot myosin.     

Tissue response and biodegradation of composite scaffolds prepared from Thai silk fibroin,gelatin and hydroxyapatite

This work aimed to investigate tissue responses and biodegradation, both in vitro and in vivo, of four types of Bombyx mori Thai silk fibroin based-scaffolds. Thai silk fibroin (SF), conjugated gelatin/Thai silk fibroin (CGSF), hydroxyapatite/Thai silk fibroin (SF4), and hydroxyapatite/conjugated gelatin/Thai silk fibroin (CGSF4) scaffolds were fabricated using salt-porogen leaching, dehydrothermal/chemical crosslinking and an alternate soaking technique for mineralization. In vitro biodegradation in collagenase showed that CGSF scaffolds had the slowest biodegradability, due to the double crosslinking by dehydrothermal and chemical treatments. The hydroxyapatite deposited from alternate soaking separated from the surface of the protein scaffolds when immersed in collagenase. From in vivo biodegradation studies, all scaffolds could still be observed after 12 weeks of implantation in subcutaneous tissue of Wistar rats and also following ISO10993-6: Biological evaluation of medical devices. At 2 and 4 weeks of implantation the four types of Thai silk fibroin based-scaffolds were classified as “non-irritant” to “slight-irritant”, compared to Gelfoam^® (control samples). These natural Thai silk fibroin-based scaffolds may provide suitable biomaterials for clinical applications.     

Modification of human cancellous bone using Thai silk fibroin and gelatin for enhanced osteoconductive potential

The modification of human cancellous bone (hBONE) with silk fibroin/gelatin (SF/G) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)/N-hydroxysuccini-mide (NHS) crosslinking was established. The SF/G solutions at a weight ratio of 50/50 and the solution concentrations of 1, 2, and 4 wt % were studied. SF/G sub-matrix was formed on the surface and inside pore structure of hBONE. All hBONE scaffolds modified with SF/G showed smaller pore sizes, less porosity, and slightly lower compressive modulus than unmodified hBONE. SF/G sub-matrix was gradually biodegraded in collagenase solution along 4 days. The hBONE scaffolds modified with SF/G, particularly at 2 and 4 wt % solution concentrations, promoted attachment, proliferation, and osteogenic differentiation of bone marrow-derived mesenchymal stem cells (MSC), comparing to the original hBONE. The highest cell number, ALP activity and calcium production were observed for MSC cultured on the hBONE scaffolds modified with 4 wt % SF/G. The mineralization was also remarkably induced in the cases of modified hBONE scaffolds as observed from the deposited calcium phosphate by EDS. The modification of hBONE with SF/G was, therefore, the promising method to enhance the osteoconductive potential of human bone graft for bone tissue engineering.     

Enhanced Sulfur Tolerance of Bimetallic PtPd/Al2O3 Catalysts for Hydrogenation of Tetralin by Addition of Fluorine

A series of mono- and bi-metallic Pt-Pd/Al₂O₃ samples with and without F were studied as aromatic hydrogenation catalysts. The effects of changing the order of impregnation of the Pt precursor and F as well as varying the calcination temperature (300–500 °C) were investigated. Temperature programmed reduction (TPR) results demonstrate the presence of a higher fraction of dispersed metal precursor species left on the surface from the impregnation (PtO _x Cl _y ) on the Pt/Al₂O₃ sample calcined at high temperature. The impregnation of F before the Pt precursor significantly decreases the interaction between the metal and the support. However, this decrease is not observed when F is impregnated after the metal precursor. For the bimetallic Pt-Pd catalysts, the sample prepared adding F before the metal show a higher degree of Pt-Pd interaction than either the parent Pt-Pd/Al₂O₃ catalyst or the one prepared with F added later. TPD of ammonia result show the increase in strong acid sites when F is present. Activity tests for tetralin hydrogenation in the presence of 350 ppm dibenzothiophene indicate a better sulfur tolerance for all F-promoted catalysts, especially Pt-Pd.     

The Possible Positive Mechanisms of Pirenoxine in Cataract Formation

Cataract is the leading cause of blindness worldwide. A diverse range of medication has been invented to prevent or treat cataract. Pirenoxine (PRX), a drug with strong antioxidant properties, has been used topically to treat cataract, and there is much evidence to demonstrate the beneficial effects of PRX on lens opacity from in vitro and in vivo models. In clinical use, PRX has been prescribed worldwide by ophthalmologists for over six decades; however, there is still controversy with regard to its efficacy, and thus PRX remains an off-label use for cataract treatment. This comprehensive review summarizes and discusses evidence pertinent to the mechanisms of PRX and its efficacy mainly on cataract models. The issues that have been deemed uncertain over the six-decade use of PRX are examined. The information summarized in this review should provide insights into contriving novel approaches for the treatment of cataract.