Nanoemulsions as vehicles for transdermal delivery of aceclofenac

The aim of the present study was to investigate the potential of a nanoemulsion formulation for transdermal delivery of aceclofenac. Various oil-in-water nanoemulsions were prepared by the spontaneous emulsification method. The nanoemulsion area was identified by constructing pseudoternary phase diagrams. The prepared nanoemulsions were subjected to different thermodynamic stability tests. The nanoemulsion formulations that passed thermodynamic stability tests were characterized for viscosity, droplet size, transmission electron microscopy, and refractive index. Transdermal permeation of aceclofenac through rat abdominal skin was determined by Franz diffusion cell. The in vitro skin permeation profile of optimized formulations was compared with that of aceclofenac conventional gel and nanoemulsion gel. A significant increase in permeability parameters such as steady-state flux (J(ss)), permeability coefficient (K(p)), and enhancement ratio (E(r)) was observed in optimized nanoemulsion formulation F1, which consisted of 2% wt/wt of aceclofenac, 10% wt/wt of Labrafil, 5% wt/wt of Triacetin, 35.33% wt/wt of Tween 80, 17.66% wt/wt of Transcutol P, and 32% wt/wt of distilled water. The anti-inflammatory effects of formulation F1 showed a significant increase (P < .05) in percent inhibition value after 24 hours when compared with aceclofenac conventional gel and nanoemulsion gel on carrageenan-induced paw edema in rats. These results suggested that nanoemulsions are potential vehicles for improved transdermal delivery of aceclofenac.     

Formulation and development of floating capsules of celecoxib: In vitro and in vivo evaluation

The objective of the present study was to develop a hydrodynamically balanced system for celecoxib as single-unit floating capsules. Various grades of low-density polymers were used for formulation of these capsules. The capsules were prepared by physical blending of celecoxib and the polymer in varying ratios. The formulation was optimized on the basis of in vitro buoyancy and in vitro release in citrate phosphate buffer pH 3.0 (with 1% sodium lauryl sulfate). Capsules prepared with polyethylene oxide 60K and Eudragit RL100 gave the best in vitro percentage release and were used as the optimized formulation. By fitting the data into zero-order, first-order, and Higuchi models, we concluded that the release followed zero-order kinetics, as the correlation coefficient (R value) was higher for zero-order release. For gamma scintigraphy studies, celecoxib was radiolabeled with technetium-99m by the stannous reduction method. To achieve the maximum labeling efficiency the process was optimized by studying the reaction at various pH conditions and stannous concentration levels. The radiolabeled complex was added to the optimized capsule, and dissolution studies were performed to ensure that there was no leaching of radioactivity from the capsules. Gamma imaging was performed in rabbits to assess the buoyancy of the optimized formulation. The optimized formulation remained buoyant during 5 hours of gamma scintigraphic studies in rabbits.     

Molecular genetic analysis reveals that a nonribosomal peptide synthetase-like (NRPS-like) gene in Aspergillus nidulans is responsible for microperfuranone biosynthesis

Genome sequencing of Aspergillus species including Aspergillus nidulans has revealed that there are far more secondary metabolite biosynthetic gene clusters than secondary metabolites isolated from these organisms. This implies that these organisms can produce additional secondary metabolites, which have not yet been elucidated. The A. nidulans genome contains 12 nonribosomal peptide synthetase (NRPS), one hybrid polyketide synthase/NRPS, and 14 NRPS-like genes. The only NRPS-like gene in A. nidulans with a known product is tdiA, which is involved in terrequinone A biosynthesis. To attempt to identify the products of these NRPS-like genes, we replaced the native promoters of the NRPS-like genes with the inducible alcohol dehydrogenase (alcA) promoter. Our results demonstrated that induction of the single NRPS-like gene AN3396.4 led to the enhanced production of microperfuranone. Furthermore, heterologous expression of AN3396.4 in Aspergillus niger confirmed that only one NRPS-like gene, AN3396.4, is necessary for the production of microperfuranone.     

The membrane anchors of the heme chaperone CcmE and the periplasmic thioredoxin CcmG are functionally important

The cytochrome c maturation system of Escherichia coli contains two monotopic membrane proteins with periplasmic, functional domains, the heme chaperone CcmE and the thioredoxin CcmG. We show in a domain swap experiment that the membrane anchors of these proteins can be exchanged without drastic loss of function in cytochrome c maturation. By contrast, the soluble periplasmic forms produced with a cleavable OmpA signal sequence have low biological activity. Both the chimerical CcmE (CcmG'-'E) and the soluble periplasmic CcmE produce low levels of holo-CcmE and thus are impaired in their heme receiving capacity. Also, both forms of CcmE can be co-precipitated with CcmC, thus restricting the site of interaction of CcmE with CcmC to the C-terminal periplasmic domain. However, the low level of holo-CcmE formed in the chimera is transferred efficiently to cytochrome c, indicating that heme delivery from CcmE does not involve the membrane anchor.     

A comparative study on lipid peroxidation, activities of antioxidant enzymes and viability of cattle and buffalo bull spermatozoa during storage at refrigeration temperature

A comparative study was conducted to monitor the activities of some antioxidant enzymes, lipid peroxidation and viability of cattle and buffalo bull spermatozoa during storage of semen at refrigeration temperature over a period of 72 h. Semen samples, collected from six cross bred cattle bulls (group I) and six Murrah buffalo bulls (group II), were diluted in egg-yolk-citrate and the spermatozoa were separated from seminal plasma by centrifugation at 4 degrees C in a refrigerated centrifuge. The malondialdehyde (MDA) production in group I increased from 1.17+/-0.29 at 0 h to 7.50+/-0.52 nmol/10(8)spermatozoa after 72 h of storage while in group II it increased from 1.99+/-0.26 to 8.70+/-0.10 nmol/10(8)spermatozoa in the same period. However, buffalo bull spermatozoa had a significantly higher (p<0.05) lipid peroxidation at 0 h as well as at 12, 24 and 48 h (p<0.01) periods. The activities of antioxidant enzymes viz. SOD, GPx and G6PD in both the groups showed a similar pattern of change i.e. the activities declined successively in spermatozoa and increased in the seminal plasma. However, the activities of these three enzymes remained significantly higher in the cattle bull spermatozoa than that in buffalo bull spermatozoa. Amount of MDA produced in spermatozoa of both the groups was negatively correlated while SOD, GPx and G6PD activities in spermatozoa were positively correlated to the motility and viability of spermatozoa. Sperm motility as well as viability was significantly less (p<0.05) in group II than that in group I. SOD, GPx and G6PD activities in spermatozoa of both the groups were negatively correlated to lipid peroxidation of spermatozoa cell membrane. The results showed that the less activities of antioxidant enzymes in buffalo bull spermatozoa was due to higher lipid peroxidation that indicated that they were more prone to oxidative stress as compared to cattle bull spermatozoa when stored at refrigeration temperature.