Novel preparation of bilirubin-encapsulated pluronic F-127 nanoparticles as a potential biomaterial for wound healing.

Cutaneous wounds deteriorate the health of patients and liable for high economic loss. Previous studies showed promising wound healing potentials of bilirubin, however, this macromolecule constrained with poor water solubility and skin penetration. In this study, Pluronic F-127, a non-ionic copolymer surfactant, was used for the encapsulation of the wound healing agent the bilirubin. With this strategy, spherical shaped bilirubin nanoparticles of ∼100-150 nm with zeta potential ranging from -13.43 ± 0.56 to -17.53 ± 0.43 mV were obtained. Topical applications of bilirubin nanoparticle (0.3%) on cutaneous wounds of rats showed promising wound healing in comparison with other topical treatments. This topical nano-formulation also modulates the cytokine and growth factor responses in the treated group. On day 7 of healing, bilirubin nanoparticles treatment significantly reduced TNF-α and increased IL-10 levels with increased VEGF and TGF-ß1 expressions. Simultaneously, prominent pro-healing activities could be observed histopathologically. These include increased blood vessels, reduced inflammatory cells, more myofibroblasts, increased deposition of collagen fibres, and early re-epithelialization. The changes were prominent in bilirubin nanoparticles (0.3%) treated group indicating better granulation tissue, quality of healing and wound maturity. In conclusion, the proposed new encapsulated bilirubin nanoparticles strategy significantly improved wound healing by modulation of cytokines and growth factors response in comparison with native bulk bilirubin. These observations support its potential as a novel biomaterial for wound healing in the future.

Improved antioxidant, antimicrobial and anticancer activity of naringenin on conjugation with pectin.

The purpose of the present study was to improve the aqueous solubility of naringenin by conjugating with water-soluble polysaccharide carrier, pectin. The pectin-naringenin conjugate was synthesized employing dicyclohexylcarbodiimide and dimethylaminopyridine. The conjugation was confirmed by various physicochemical characterizations. The results of differential scanning calorimetry, X-ray diffraction and morphological analyses revealed semi-crystalline nature of the conjugate. The chromatographic analysis showed 37.069 µg naringenin/mg of conjugate. The conjugate was determined to have molecular weight of 6.22 × 104 kDa by static light scattering. In silico molecular mechanistic simulations performed for pectin and naringenin revealed the energetic and geometrical stability within the polysaccharide-polyphenol conjugate. The critical aggregation concentration was in the range of 44.67-56.23 µg/mL as determined by dynamic light scattering and fluorescence spectroscopy. On in vitro release, 99.4% (pH 1.2) and 57.62% (pH 7.4) of naringenin were found to be released over a period of 30 h and 48 h, respectively. Further, the release of naringenin followed Higuchi's square-root kinetics with diffusion as the possible release mechanism. A comparative evaluation for antioxidant activity revealed a significantly higher radical scavenging activity of conjugate over the naringenin. Further, the conjugate exhibited significantly higher antimicrobial action against Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa while a comparable antimicrobial activity was observed against Escherichia coli and Bacillus subtilis. The cytotoxicity studies of the synthesized conjugate showed anti-cancer activity against NIH: OVCAR-5 cells. In conclusion, the pectin-naringenin conjugate presented hydrocolloidal properties with improved therapeutic efficacy and delivery over the native polyphenol.

Epstein-Barr virus glycoprotein gB and gHgL can mediate fusion and entry in trans, and heat can act as a partial surrogate for gHgL and trigger a conformational change in gB.

UNLABELLED: Epstein-Barr virus (EBV) fusion with an epithelial cell requires virus glycoproteins gHgL and gB and is triggered by an interaction between gHgL and integrin αvß5, αvß6, or αvß8. Fusion with a B cell requires gHgL, gp42, and gB and is triggered by an interaction between gp42 and human leukocyte antigen class II. We report here that, like alpha- and betaherpesviruses, EBV, a gammaherpesvirus, can mediate cell fusion if gB and gHgL are expressed in trans. Entry of a gH-null virus into an epithelial cell is possible if the epithelial cell expresses gHgL, and entry of the same virus, which phenotypically lacks gHgL and gp42, into a B cell expressing gHgL is possible in the presence of a soluble integrin. Heat is capable of inducing the fusion of cells expressing only gB, and the proteolytic digestion pattern of gB in virions changes in the same way following the exposure of virus to heat or to soluble integrins. It is suggested that the Gibbs free energy released as a result of the high-affinity interaction of gHgL with an integrin contributes to the activation energy required to cause the refolding of gB from a prefusion to a postfusion conformation. IMPORTANCE: The core fusion machinery of herpesviruses consists of glycoproteins gB and gHgL. We demonstrate that as in alpha- and betaherpesvirus, gB and gHgL of the gammaherpesvirus EBV can mediate fusion and entry when expressed in trans in opposing membranes, implicating interactions between the ectodomains of the proteins in the activation of fusion. We further show that heat and exposure to a soluble integrin, both of which activate fusion, result in the same changes in the proteolytic digestion pattern of gB, possibly representing the refolding of gB from its prefusion to its postfusion conformation.

Synthesis of gum kondagogu-g-poly(N-vinyl-2-pyrrolidone) and its evaluation as a mucoadhesive polymer.

The purpose of the present study was to synthesize gum kondagogu-g-poly(N-vinyl-2-pyrrolidone) and to evaluate its mucoadhesive properties. UV-assisted graft co-polymerization of N-vinyl-2-pyrrolidone on gum kondagogu was carried out employing three-factor, three-level central composite experimental designs. It was observed that the concentrations of N-vinyl pyrrolidone and ammonium persulphate exerted a significant antagonistic and synergistic influence on grafting efficiency respectively. The graft co-polymer was characterized by FT-IR, DSC and SEM study. Mucoadhesive properties of the graft-copolymer were evaluated by formulating buccal discs employing metronidazole as the model drug. On comparative evaluation buccal discs formulated using gum kondagogu-g-poly(N-vinyl pyrrolidone) showed higher ex vivo bioadhesion time than the discs formulated using gum kondagogu. In vitro release study showed an almost similar release profile of metronidazole from the buccal discs of gum kondagogu and gum kondagogu-g-poly(N-vinyl-2-pyrrolidone). Thus, grafting of N-vinyl-2-pyrrolidone on gum kondagogu enhances its mucoadhesion without significantly affecting the release behaviour.

Stability studies on aqueous and oily ophthalmic solutions of diclofenac.

Various aqueous and oily diclofenac ophthalmic formulations were subjected to accelerated and long term stability studies. Degradation of diclofenac was found to follow first-order kinetics. Among the aqueous formulations containing preservative, formulation with PMA, PMN, SA, MP/PP and SMS showed diclofenac content above 90% after 6 months of accelerated and 12 months of room temperature storage. Diclofenac 0.1%, w/v aqueous formulation (pH 7.4), with 5-10% overages, containing SMS, MP/PP or PMN look promising taking both stability and corneal permeability in view. However, for use in cataract surgery formulation without preservative appears ideal. Oily ophthalmic formulations except those in olive and mustard oil, had more than 90% drug content after 6 months of accelerated and 12 months of room temperature storage. Diclofenac (0.2%, w/v) ophthalmic solution in sesame oil with 3% overage and containing benzyl alcohol (0.5%, v/v) as preservative, appears ideal, taking both stability and corneal permeability in view.

In vitro corneal permeation of diclofenac from oil drops.

In vitro transcorneal permeation of diclofenac from oil drops was studied using freshly excised goat cornea. The maximum apparent corneal permeability coefficient (Papp) was obtained with 0.2% (w/v) diclofenac drops in sesame oil followed by safflower oil, while formulation in castor oil provided minimal Papp. The addition of benzyl alcohol, a preservative, in oil drops, increased the Papp value of diclofenac. Partition experiments indicated increased partitioning of diclofenac in the aqueous phase in the presence of benzyl alcohol, and the same could be responsible for the benzyl alcohol-induced increase in Papp. The solubility of diclofenac was higher in castor, arachis, and sunflower oil. But drug permeation from 0.5-1.0% (w/v) diclofenac drops in castor oil or 0.5% (w/v) drops in arachis /sunflower oil was less than that observed with 0.2% (w/v) drops in sesame oil. Thus diclofenac 0.2% (w/v) drops in sesame oil containing 0.5% (v/v) benzyl alcohol provides maximum Papp. The formulation increased corneal hydration indicating corneal damage. Since corneal hydration is less than 83% the damage appears to be reversible. The saturation solubility of diclofenac in sesame oil at 4 degrees C is 0.33% (w/v). Hence diclofenac 0.2% (w/v) solution in sesame oil will not precipitate at 4 degrees C and therefore the chances of crystallization of diclofenac from the formulation due to climatic change leading to physical instability appear to be remote.