Peptide dendrimer-conjugates of ketoprofen: Synthesis and ex vivo and in vivo evaluations of passive diffusion, sonophoresis and iontophoresis for skin delivery.

The aim of this study was to evaluate skin delivery of ketoprofen when covalently tethered to mildly cationic (2+ or 4+) peptide dendrimers prepared wholly by solid phase peptide synthesis. The amino acids glycine, arginine and lysine formed the dendrimer with ketoprofen tethered either to the lysine side-arm (Nε) or periphery of dendrimeric branches. Passive diffusion, sonophoresis- and iontophoresis-assisted permeation of each peptide dendrimer-drug conjugate (D1-D4) was studied across mouse skin, both in vitro and in vivo. In addition, skin toxicity of dendrimeric conjugates when trialed with iontophoresis or sonophoresis was also evaluated. All dendrimeric conjugates improved aqueous solubility at least 5-fold, compared to ketoprofen alone, while also exhibiting appreciable lipophilicity. In vitro passive diffusion studies revealed that ketoprofen in its native form was delivered to a greater extent, compared with a dendrimer-conjugated form at the end of 24h (Q24h (µg/cm2): ketoprofen (68.06±3.62)>D2 (49.62±2.92)>D4 (19.20±0.89)>D1 (6.45±0.40)>D3 (2.21±0.19). However, sonophoresis substantially increased the skin permeation of ketoprofen-dendrimer conjugates in 30min (Q30min (µg/cm2): D4 (122.19±7.14)>D2 (66.74±3.86)>D1 (52.10±3.22)>D3 (41.66±3.22)) although ketoprofen alone again proved superior (Q30min: 167.99±9.11µg/cm2). Next, application of iontophoresis was trialed and shown to considerably increase permeation of dendrimeric ketoprofen in 6h (Q6h (µg/cm2): D2 (711.49±39.14)>D4 (341.23±16.43)>D3 (89.50±4.99)>D1 (50.91±2.98), with a Q6h value of 96.60±5.12µg/cm2 for ketoprofen alone). In vivo studies indicated that therapeutically relevant concentrations of ketoprofen could be delivered transdermally when iontophoresis was paired with D2 (985.49±43.25ng/mL). Further, histopathological analysis showed that the dendrimeric approach was a safe mode as ketoprofen alone. The present study successfully demonstrates that peptide dendrimer conjugates of ketoprofen, when combined with non-invasive modalities, such as iontophoresis can enhance skin permeation with clinically relevant concentrations achieved transdermally.

Molecular Determinants of the Cellular Entry of Asymmetric Peptide Dendrimers and Role of Caveolae.

Caveolae are flask-shaped plasma membrane subdomains abundant in most cell types that participate in endocytosis. Caveola formation and functions require membrane proteins of the caveolin family, and cytoplasmic proteins of the cavin family. Cationic peptide dendrimers are non-vesicular chemical carriers that can transport pharmacological agents or genetic material across the plasma membrane. We prepared a panel of cationic dendrimers and investigated whether they require caveolae to enter into cells. Cell-based studies were performed using wild type or caveola-deficient i.e. caveolin-1 or PTRF gene-disrupted cells. There was a statistically significant difference in entry of cationic dendrimers between wild type and caveola-deficient cells. We further unveiled differences between dendrimers with varying charge density and head groups. Our results show, using a molecular approach, that (i) expression of caveola-forming proteins promotes cellular entry of cationic dendrimers and (ii) dendrimer structure can be modified to promote endocytosis in caveola-forming cells.

Express in Vitro Plasmid Transfection Achieved with 16+ Asymmetric Peptide Dendrimers.

Asymmetric cationic amino acid-based dendrimers are highly branched chemically derived gene vectors developed to transport cargo such as plasmid DNA across the plasma membrane. We have previously demonstrated their propensity to enter cells that form caveolae, driven by positive charge density and promoted by arginine head groups. Caveolae are plasma membrane subdomains serving a number of cellular functions including endocytosis. Their formation requires membrane proteins (caveolins) and cytoplasmic proteins (cavins), so that gene disruption of either caveolin-1 or cavin-1 (also known as PTRF, i.e., polymerase I and transcript release factor) results in caveola deficiency. Here we evaluated the ability of a 16+ charged asymmetric arginine dendrimer to transfect plasmid DNA into cultured cells. We unveiled efficient transfection efficiencies (≥30%) 24-48 h after exposing the cells to dendrimer/pDNA complexes for only 5 min. Using wild type (WT) and caveolin-1 or PTRF gene-disrupted, i.e., caveola-deficient mouse embryo fibroblasts, we further show that caveolae promote pDNA transfection by 16+ charged asymmetric arginine dendrimers.

Are caveolae a cellular entry route for non-viral therapeutic delivery systems?

The development of novel therapies increasingly relies on sophisticated delivery systems that allow the drug or gene expression-modifying agent of interest entry into cells. These systems can promote cellular targeting and/or entry, and they vary in size, charge, and functional group chemistry. Their optimization requires an in depth knowledge of the cellular routes of entry in normal and pathological states. Caveolae are plasma membrane invaginations that have the potential to undergo endocytosis. We critically review the literature exploring whether drug or nucleic acid delivery systems exploit and/or promote cellular entry via caveolae. A vast majority of studies employ pharmacological tools, co-localization experiments and very few make use of molecular tools. We provide clarification on how results of such studies should be interpreted and make suggestions for future studies.

Bioprecursor prodrugs: molecular modification of the active principle.

A large number of therapeutic medications have undesirable properties that may generate pharmacological, pharmaceutical, or pharmacokinetic barriers in clinical drug applications. Metabolism of drugs by Phase-I & Phase-II metabolic pathways for possibility of active metabolites, which could in turn useful for rational designing of bioprecursor prodrugs of the active principle of interest. This review summarizes various approaches & development of drugs, namely bioprecursor prodrugs and active metabolites related to bioprecursor prodrugs.

Pharmacology and chemistry of diabetes mellitus and antidiabetic drugs: a critical review.

Diabetes mellitus, an epidemic metabolic disorders characterized by high blood glucose level associated with various macrovascular and microvascular complications, is one of the main causes of human suffering across the globe. Researchers around the world mainly focused on insulin, insulin analogues, oral hypoglycemic agents and various other complementary and alternate medicines to control the blood glucose levels in diabetes. The present review summarizes the disorders associated with elevation of blood glucose level, biochemical & endocrinological aspects and the current strategies to control. The emphasis has been laid in particular on the new potential biological targets and the possible treatment as well as the current ongoing research status on new generation hypoglycemic agents.

Oseltamivir: a first line defense against swine flu.

Oseltamivir (has known by its brand name 'Tamiflu') is a prodrug, requiring ester hydrolysis for conversion to the active form, Oseltamivir carboxylate. Oseltamivir was the first orally active neuraminidase inhibitor commercially developed by US based Gilead Sciences and is currently marketed by F. Hoffmann-La Roche (Roche). Oseltamivir is an antiviral drug which works by blocking the function of the viral neuraminidase protein. US FDA approved Oseltamivir for prophylaxis of uncomplicated influenza A and B. Currently, Oseltamivir is the only first line defense drug available for the treatment of Swine Flu. Orally Oseltamivir is well tolerated and effective in treatment of influenza in adolescents and adults, including the elderly and patients with chronic cardiac and/or respiratory disease. Many of the pharmaceutical companies targeted Oseltamivir as a block buster molecule. In present review, we have tried to cover chemistry, mode of binding, total synthesis, current patent status, adverse effect and clinical status of Oseltamivir giving emphasis on medicinal chemistry aspect.

Rheumatoid arthritis: a new challenge in coming era.

Rheumatoid arthritis (RA) is mainly an auto-immune disease characterized by inflammation in joints. 1 in 50 people develop RA at some stage and at any age. This review summarizes the etiology, pathophysiology, risk factor, and treatment related to RA. The emphasis has been laid in particular on the new potential biological targets and the possible treatment as well as the current ongoing research status on RA.