Role of IL-6 and STAT3 signaling in dihydropyridine-induced gingival overgrowth fibroblasts.

OBJECTIVES: This study analyzed the role of the interleukin (IL)-6/signal transducer and activator of transcription 3 (STAT3) pathway in dihydropyridine-induced gingival overgrowth (DIGO) fibroblasts. MATERIALS AND METHODS: Tissue samples were obtained through surgical dissection from five DIGO patients and five healthy individuals. Cell cultures were conditioned with nifedipine (Nif) (0.34 µM) and stimulated with IL-1ß (10 ng/ml) to clarify whether IL-6 upregulates extracellular matrix overproduction or has an impact on the cell proliferation rate of DIGO fibroblasts. STAT3 was knocked down using short hairpin (sh)RNA to determine its role in collagen (Col) type I alpha 1 (Colα1(I)) synthesis. RESULTS: Results showed that phosphorylated (p)STAT3 nuclear translocation was activated by a simulated autocrine concentration (50 ng/ml) of IL-6, and application of an anti-IL-6 antibody significantly decreased the pSTAT3/STAT3 ratio in DIGO fibroblasts. STAT3 knockdown significantly decreased STAT3 and Colα1(I) expressions in DIGO cells. DIGO tissues presented stronger proliferating cell nuclear antigen (PCNA) expression than did healthy individuals under the effect of IL-1ß/Nif treatment. CONCLUSIONS: Gingival inflammation (e.g., IL-1ß) and taking dihydropyridine (e.g., Nif) may additively stimulate Col overproduction through the IL-6-STAT3-Colα1(I) cascade in DIGO cells. IL-6-STAT3 signaling may be considered a target for the control of DIGO.

Cilnidipine loaded poly (ε-caprolactone) nanoparticles for enhanced oral delivery: optimization using DoE, physical characterization, pharmacokinetic, and pharmacodynamic evaluation.

Cilnidipine (CND), an anti-hypertensive drug, possesses low oral bioavailability due to its poor aqueous solubility, low dissolution rate, and high gut wall metabolism. In the present study, an attempt has been made to prepare CND loaded polycaprolactone based nanoparticles (CND-PCL-NPs) by nanoprecipitation method applying the concepts of Design of Experiments. Critical factors affecting particle size and loading efficiency (LE%) were assessed by a hybrid design approach, comprising of Mini Run Resolution IV design followed by Box-Behnken design. Particle size, PDI, zeta potential and LE% of optimized formulations of CND-PCL-NPs were 220.3 ± 2.6 nm, 0.25 ± 0.1, -19.5 ± 0.9 mV, and 46.4 ± 1.8%, respectively. No significant changes were observed in the physical stability of nanoparticles when stored at 25 °C/60% RH over a period of 3 months. Oral pharmacokinetic studies revealed that Fabs of CND-PCL-NPs (0.55) were significantly higher than the CND suspension (0.26). Pharmacodynamic studies have revealed that the mean percent reduction in systolic blood pressure (% ΔSBP) was significantly higher in the case of CND-PCL-NPs (42%) as compared to CND suspension (24%). Optimized CND-PCL-NPs offer great potential in providing higher and sustained antihypertensive effect compared to conventional formulations of CND.

Therapeutic potential of proteasome inhibitors for dihydropyridine-induced gingival overgrowth.

OBJECTIVES: NF-κB plays a crucial role in collagen overproduction in dihydropyridine-induced gingival overgrowth (DIGO) fibroblasts. We aim to investigate the role of the kappa B (IκB) kinase (IKK)-NF-κB pathway and downstream collagen type I (Col I) synthesis in DIGO cells and to demonstrate the therapeutic strategy of interference of this pathway with proteasome inhibitors. METHODS: Gingival fibroblasts from DIGO (n = 5) and healthy (n = 5) patients were selected and stimulated with IL-1ß, nifedipine, or both. All experiments were run in triplicate and independently for each primary cell sample. RESULTS: The results demonstrated that both drugs additively mediated NF-κB activity by activating IKKα/ß phosphorylation. They also triggered nuclear translocation of NF-κB, Rela, and p50 (*p < .05) and increased Col I production in both healthy and DIGO cells. The addition of proteasome inhibitors, including bortezomib and MG132, promoted the accumulation of phosphorylated p-IκBα, prevented the subsequent cytosol-to-nuclear translocation of p50 and Rela (*p < .05), and abbreviated the biosynthesis of Col I in DIGO cells. CONCLUSIONS: We suggested that IKK-IκBα activation is mediated by proinflammatory cytokines and CCBs in DIGO cells and triggers downstream NF-κB-Col I synthesis. Proteasome inhibitors may strategically interfere with the IKK-IκBα-NF-κB-Col I pathway and inhibit the etiopathogenesis of DIGO.

Lacidipine Amorphous Solid Dispersion Based on Hot Melt Extrusion: Good Miscibility, Enhanced Dissolution, and Favorable Stability.

The present study aimed to increase the in vitro dissolution rate of lacidipine, a poorly water-soluble drug, by formulating amorphous solid dispersions (ASDs) using hot-melt extrusion (HME). Differential scanning calorimetry, powder X-ray diffraction, polarized light microscopy, and Fourier transform infrared were used to characterize the optimal formulations and evaluate the physical stability for the stress test. Film-casting method and hot-stage microscopy were applied to study the miscibility of lacidipine and the drug carriers. In vitro dissolution tests were conducted as the final evaluation index. The optimal formulations were successfully obtained with Soluplus and PVP VA64 at a drug/carrier ratio of 1:10 (w/w), Fourier transform infrared studies revealed the hydrogen bonding between drug and polymers, and in vitro dissolution rates of the optimal formulations were extremely enhanced compared to bulk lacidipine and physical mixtures, similar with that of the commercial tablet. The ASD formulated with Soluplus showed better physical stability than that with PVP VA64. A strong hydrogen bonding and good drug-polymer miscibility were essential to hinder the recrystallization of lacidipine ASDs. In conclusion, the lacidipine ASD formulated with Soluplus showed a significant increase in in vitro dissolution rate and favorable physical stability in the stress test.

Evaluation of the chiral recognition properties and the column performances of three chiral stationary phases based on cellulose for the enantioseparation of six dihydropyridines by high-performance liquid chromatography.

Separations of six dihydropyridine enantiomers on three commercially available cellulose-based chiral stationary phases (Chiralcel OD-RH, Chiralpak IB, and Chiralpak IC) were evaluated with high-performance liquid chromatography (HPLC). The best enantioseparation of the six chiral drugs was obtained with a Chiralpak IC (250 × 4.6 mm i.d., 5 µm) column. Then the influence of the mobile phase including an alcohol-modifying agent and alkaline additive on the enantioseparation were investigated and optimized. The optimal mobile phase conditions and maximum resolution for every analyte were as follows respectively: n-hexane/isopropanol (85:15, v/v) for nimodipine (R = 5.80) and cinildilpine (R = 5.65); n-hexane/isopropanol (92:8, v/v) for nicardipine (R = 1.76) and nisoldipine (R = 1.92); and n-hexane/isopropanol/ethanol (97:2:1, v/v/v) for felodipine (R = 1.84) and lercanidipine (R = 1.47). Relative separation mechanisms are discussed based on the separation results, and indicate that the achiral parts in the analytes' structure showed an important influence on the separation of the chiral column.

Enhancement of solubility and oral bioavailability of manidipine by formation of ternary solid dispersion with d-α-tocopherol polyethylene glycol 1000 succinate and copovidone.

CONTEXT: Low bioavailability of oral manidipine (MDP) is due to its low water solubility. OBJECTIVE: The objective of this study was to increase the solubility and bioavailability of MDP by fabricating ternary solid dispersion (tSD) with d-α-tocopherol polyethyleneglycol-1000-succinate and copovidone. METHODS: In this study, solid ternary phase diagram was applied in order to check the homogeneity of tSD prepared by melting and solidifying with dry ice. The physicochemical properties of different formulations were determined by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and hot stage microscopy. Their solubility, dissolution, stability and bioavailability were also investigated. RESULTS AND DISCUSSION: The results demonstrated that tSD obtained from ternary phase diagram divided into homogeneous and non-homogeneous regions. In the homogenous region, the transparent characteristics of tSD was observed and considered as a glass solution, which have a higher MDP solubility than that in non-homogenous region. The hot stage microscopy, DSC and PXRD confirmed that solid dispersion was formed in which MDP was molecularly dispersed in the carriers, especially in the homogenous region of phase diagram. FTIR analysis demonstrated strong hydrogen bonding between amine groups of MDP and carbonyl groups of copovidone, which supported a higher solubility and dissolution of tSD. The pharmacokinetic study in Wistar rats showed that the tSD had the greatest effect on oral bioavailability. Immediate hypotensive effect of tSD was also observed in vivo. CONCLUSIONS: The improvement of stability, dissolution and oral bioavailability of MDP could be achieved by using tSD technique.

Improved stability of solid dispersions of manidipine with polyethylene glycol 4000/copovidone blends: application of ternary phase diagram.

CONTEXT: Manidipine (MDP) is generally used clinically as an antihypertensive agent; however, the bioavailability of orally administered MDP is limited due to their very low water solubility. OBJECTIVE: The objectives of this research were, therefore, to increase the solubility of MDP by the formation of ternary solid dispersions (tSD) with polyethylene glycol 4000 (PEG4000) and copovidone and to improve their stability. METHODS: Solid ternary phase diagram was constructed to find homogeneous solid dispersion region after melting and solidifying at low temperature with different quenching substances. The pulverized powder of solid dispersions was then determined, for their physicochemical properties, by differential scanning calorimetry, powder X-ray diffractometry, Fourier transform infrared (FTIR) spectroscopy and hot stage microscopy. The solubility and dissolution of MDP from the tSD were investigated. The physical stability of tSD was also determined under accelerated condition at 40 °C/75% relative humidity (RH) for 6 months. RESULTS AND DISCUSSION: The results showed that MDP was molecularly dispersed in PEG4000 and copovidone when the tSD was created from homogeneous region of solid ternary phase diagram. FTIR results confirmed that strong hydrogen bonding was presented between MDP and copovidone, leading to a significant increase in the solubility and dissolution of MDP. After storage at accelerated condition (40 °C/75%RH) for 6 months, the tSD still showed a good appearance and high solubility. CONCLUSION: The results of this study suggest that tSD prepared by melting has promising potential for oral administration and may be an efficacious approach for improving the therapeutic potential of MDP.

Bioactivity In Vitro of Quercetin Glycoside Obtained in Beauveria bassiana Culture and Its Interaction with Liposome Membranes.

Quercetin (Q) was used as substrate for regioselective glycosylation at the C-7 position catalyzed by Beauveria bassiana AM278 strain. As a result the glycoside quercetin 7-O-ß-d-(4″-O-methyl)glucopyranoside (Q 7-MeGlu) was formed. The goal of the studies was to determine the anti-oxidative (liposome membrane protection against free radicals IC50Q 7-MeGlu = 5.47 and IC50Q = 4.49 µM) and anti-inflammatory (COX-1 and COX-2 enzymes activity inhibition) properties of Q 7-MeGlu as compared to Q. Every attempt was made to clarify the antioxidant activity of these molecules, which are able to interact with egg phosphatidylcholine liposomes, using a fluorometric method (by applying the probes MC540, TMA-DPH and DPH). The results indicated that Q 7-MeGlu and Q are responsible for increasing the packing order, mainly in the hydrophilic but also in hydrophobic regions of the membrane (Q > Q 7-MeGlu). These observations, confirmed by a ¹H-NMR method, are key to understanding their antioxidant activity which is probably caused by the stabilizing effect on the lipid membranes. The results showed that Q 7-MeGlu and Q have ability to quench the human serum albumin (HSA) intrinsic fluorescence through a static quenching mechanism. The results of thermodynamic parameters indicated that the process of formation complexes between studied molecules and HSA was spontaneous and caused through Van der Waals interactions and hydrogen bonding.

Experimental determination and computational interpretation of biophysical properties of lipid bilayers enriched by cholesteryl hemisuccinate.

Cholesteryl hemisuccinate (CHS) is one of the cholesterol-mimicking detergents not observed in nature. It is, however, widely used in protein crystallography, in biochemical studies of proteins, and in pharmacology. Here, we performed an extensive experimental and theoretical study on the behavior of CHS in lipid membranes rich in unsaturated phospholipids. We found that the deprotonated form of CHS (that is the predominant form under physiological conditions) does not mimic cholesterol very well. The protonated form of CHS does better in this regard, but also its ability to mimic the physical effects of cholesterol on lipid membranes is limited. Overall, although ordering and condensing effects characteristic to cholesterol are present in systems containing any form of CHS, their strength is appreciably weaker compared to cholesterol. Based on the considerable amount of experimental and atomistic simulation data, we conclude that these differences originate from the fact that the ester group of CHS does not anchor it in an optimal position at the water-membrane interface. The implications of these findings for considerations of protein-cholesterol interactions are briefly discussed.

Application of PEG-400 as a green biodegradable polymeric medium for the catalyst-free synthesis of spiro-dihydropyridines and their use as acetyl and butyrylcholinesterase inhibitors.

A simple, efficient and green approach for the synthesis of spiro-dihydropyridines derivatives by one-pot multi-component reaction of isatin or acenaphthoquinone derivatives (1 equiv) with malononitrile (1 equiv) and N,N'-substituted-2-nitroethene-1,1-diamines (1 equiv) in PEG-400 under catalyst-free conditions is described. This method provides several advantages such as environmental friendliness, short reaction time, and simple workup procedure for the synthesis of biologically important compounds. The ability of synthesized compounds in inhibition of acetyl and butyrylcholinesterase were investigated both in vitro and in silico. All compounds showed moderate to high level activity against both acetyl and butyrylcholinesterase. There was a good correlation between in vitro and in silico studies.

Management of periodontal disease in patients using calcium channel blockers - gingival overgrowth, prescribed medications, treatment responses and added treatment costs.

OBJECTIVES: Gingival overgrowth (GO) is an adverse drug reaction in patients using calcium channel blockers (CCBs). Little is known about the effects of CCBs on the management of periodontal diseases. The aim of this study was to assess how the use of CCBs affects the long-term supportive treatment and outcomes in patients undergoing periodontal therapy. METHODS: All patients using CCBs during the initial treatment and/or the supportive periodontal therapy (SPT) were selected from a periodontal practice. Patients were scored using a Gingival Overgrowth Index (GOI). The effects of CCB types and dosages were assessed in terms of the frequency and the severity of GO, treatment responses, substitutions and extra treatment costs. Mean values, Standard Deviation (SD) and range were calculated. The Mann-Whitney test was used to assess statistically significant differences (p < 0.05) for GO between patients with good and poor oral hygiene, differences between before and after terminating or replacing the CCBs, possible differences between drug dosages (Dihydropyridine 5 mg and 10 mg) and differences between three drug combinations (CCB and inhibitors of the renin-angiotensin system (IRAS), CCB and non-IRAS, CCB and statins). RESULTS: One hundred and twenty-four patients (58 females, 66 males, 4.6% of the patient population) were using CCBs. 103 patients were assessed. Average age was 66.53 years (SD. 9.89, range 42-88) and the observation time was 11.30 years (SD 8.06, range 1-27). Eighty-nine patients had GO, 75 of these required treatment for GO. Terminating or replacing with alternatives to CCBs resulted in significant decreases in GO (p = 0.00016, p = 0.00068) respectively. No differences were found between good and poor oral hygiene (p = 0.074), drug dosages or the various drug combinations. Surgical treatment was more effective than non-surgical treatment in controlling the GO. Long-term tooth loss was 0.11 teeth per patient per year. Forty-two patients needed re-treatments for GO, resulting in an extra life cost per patient of €13471 (discounted €4177). CONCLUSION: The majority of patients (86.4%) using CCBs experienced GO. 47.2% of these experienced recurrence(s) of GO during the SPT and needed re-treatments with resulting added costs. The long-term tooth loss was considerably higher for patients using CCBs than for other patients groups from the same practice setting.

Micelle-enhanced spectrofluorimetric method for determination of lacidipine in tablet form; application to content uniformity testing.

A highly sensitive, simple and rapid spectrofluorimetric method was developed for the determination of lacidipine (LCP) in tablets. The proposed method is based on the investigation of the fluorescence spectral behavior of LCP in both sodium dodecyl sulphate (SDS) and the tween-80 micellar system. In aqueous solutions of acetate buffer (pH 4.5), the fluorescence intensities of LCP were greatly enhanced (ca. 2.4 and 4.3 folds) in the presence of either SDS or tween-80, respectively. The fluorescence intensity was measured at 444 nm after excitation at 277 nm using either SDS or tween-80 as a surfactant. The fluorescence-concentration plots were rectilinear over the ranges of 50.0-500.0 ng/ml and 5.0-200.0 ng/ml with lower detection limits of 5.11 and 2.06 ng/ml and lower quantification limits of 17 and 6.87 ng/ml using SDS and tween-80, respectively. The method was successfully applied to the analysis of LCP in commercial tablets and the results were in good agreement with those obtained with the comparison method. Furthermore, content uniformity testing of pharmaceutical tablets was also conducted.

Development and Characterization of Solid Self-emulsifying Drug Delivery System of Cilnidipine.

The present investigations highlight the development of solid self-emulsifying drug delivery system (solid-SEDDS) for improved oral delivery of the poorly water-soluble drug; cilnidipine. Liquid SEDDS of the drug were formulated using Capryol 90 as the oil phase, Tween 80 as the surfactant, and Transcutol HP as the co-surfactant after screening various vehicles. The prepared systems were characterized for self-emulsification time, robustness to dilution, % transmittance, globule size, drug release, and thermodynamic stability. Ternary phase diagrams were plotted to identify the area of microemulsification. The optimized liquid SEDDS was transformed into a free-flowing powder using Neusilin US2 as the adsorbent. Solid self-emulsifying powder retained the self-emulsifying property of the liquid SEDDS. Differential scanning calorimetric, X-ray powder diffraction studies revealed the possibility of transformation of the crystalline form of the drug to the amorphous form in the SEDDS prepared with the carrier. The morphology of solid-SEDDS from scanning electron microscopy studies demonstrated the presence of spherical, granular particles indicating good flowing ability. Dissolution studies revealed enhanced dissolution of the drug from the solid system compared with the pure drug and its marketed formulation. Similarly, the in vitro absorption profile of the drug from the formulated SEDDS was significantly higher compared with pure drug. Thus it can be concluded that solid-SEDDS, amenable for development of solid dosage form, can be successfully developed using Neusilin US2 with the potential of enhancing the solubility, dissolution rate, and bioavailability of the drug.

Gastroretentive pulsatile release tablets of lercanidipine HCl: development, statistical optimization, and in vitro and in vivo evaluation.

The present study was aimed at the development of gastroretentive floating pulsatile release tablets (FPRTs) of lercanidipine HCl to enhance the bioavailability and treat early morning surge in blood pressure. Immediate release core tablets containing lercanidipine HCl were prepared and optimized core tablets were compression-coated using buoyant layer containing polyethylene oxide (PEO) WSR coagulant, sodium bicarbonate, and directly compressible lactose. FPRTs were evaluated for various in vitro physicochemical parameters, drug-excipient compatibility, buoyancy, swelling, and release studies. The optimized FPRTs were tested in vivo in New Zealand white rabbits for buoyancy and pharmacokinetics. DoE optimization of data revealed FPRTs containing PEO (20% w/w) with coat weight 480 mg were promising systems exhibiting good floating behavior and lag time in drug release. Abdominal X-ray imaging of rabbits after oral administration of the tablets, confirmed the floating behavior and lag time. A quadratic model was suggested for release at 7th and 12th h and a linear model was suggested for release lag time. The FPRT formulation improved pharmacokinetic parameters compared to immediate release tablet formulation in terms of extent of absorption in rabbits. As the formulation showed delay in drug release both in vitro and in vivo, nighttime administration could be beneficial to reduce the cardiovascular complications due to early morning surge in blood pressure.

PCL/PHBV microparticles as innovative carriers for oral controlled release of manidipine dihydrochloride.

Microparticles of poly(ε-caprolactone) (PCL) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) containing manidipine dihydrochloride (MAN) were successfully prepared by the simple emulsion/solvent evaporation method. All formulations showed loading efficiency rates greater than 80% and average particle size less than 8 µm. Formulations had spherical shape with smooth and porous surface for PCL and PHBV, respectively. According to Fourier-transform infrared spectroscopy, initial components were not chemically modified during microencapsulation. X-ray diffraction patterns and differential scanning calorimetry demonstrated that this process led to drug amorphization. In vitro dissolution studies showed that all microparticles prolonged MAN release, mainly which one obtained using PCL that contained 5% of drug loaded (PCL-M5). Animal studies demonstrated that formulation PCL-M5 was able to keep the variation of mean arterial pressure after phenylephrine administration up to 24 hours. These data confirmed the sustained antihypertensive effect of the investigated microparticles. Results provided an experimental basis for using formulation PCL-M5 as a feasible carrier for oral controlled release of MAN intended for treating high blood pressure.

Influence of different polymers on crystallization tendency and dissolution behavior of cilnidipine in solid dispersions.

CONTEXT: Cilnidipine (CN) is a novel dihydropyridine calcium antagonist that is practically insoluble in aqueous media and exhibits a low oral bioavailability or limited clinical efficacy. OBJECTIVE: This study investigated the effects of three commercial and chemically diverse polymers - PVP, PVP/VA and Soluplus - on crystallization tendency and in vitro dissolution profiles of CN in order to determine an optimum carrier for composing the preferred solid dispersion (SD) of CN. METHODS: All these co-evaporated systems were characterized up to 3 months by thermoanalytical (DSC), crystallographic (POM, PXRD), microscopic (SEM) and spectroscopic (FTIR) techniques. RESULTS: The results showed that the polymers could be sorted by their effects of inhibiting CN crystallization in the ascending order: Soluplus, PVP/VA, PVP. The sequence was in accordance with that of the strength of drug-polymer hydrogen bonds revealed by FTIR spectra. It could be ascribed to relative hydrogen-bonding acceptor strengths of N-vinylpyrrolidone moiety in the polymer molecules. On the other hand, all the SDs showed enhanced dissolution profiles compared to pure CN alone. On their effects of enhancing CN dissolution, the polymers could be sorted in the descending order: Soluplus, PVP, PVP/VA. CONCLUSIONS: It implied that the dissolution behavior of CN could bear a close relationship to both hydration capacity and hydrogen-bonding interaction tendency of moieties of the polymers. It might suggest an optimal formulation for CN comprising both PVP and Soluplus.

Fabrication, optimization, and evaluation of lyophilized lacidipine-loaded fatty-based nanovesicles as orally fast disintegrating sponge delivery system.

Lacidipine (LCD) is a potent antihypertensive agent. Fatty-based nanovesicles (FNVs) were designed to improve LCD low solubility and bioavailability. LCD-FNVs were formulated according to different proportions of cetyl alcohol, cremophor®RH40, and oleic acid adopting Box-Behnken Design. The optimized LCD-FNVs, composed of cetyl alcohol 48.4 mg, cremophor®RH40 120 mg, and oleic acid 40 mg, showed minimum vesicle size (124.8 nm), maximum entrapment efficiency % (91.04 %) and zeta potential (-36.3 mV). The optimized FNVs were then used to formulate the lyophilized orally fast-disintegrating sponge (LY-OFDS). The LY-OFDS had a very short disintegration time (58 sec), remarkably high % drug release (100 % after 15 mins), and increased the drug transbuccal permeation by over 9.5-fold compared to the drug suspension. In-vivo evaluation of antihypertensive activity in rats showed that the LY-OFDS reduced blood pressure immediately after 5 min and reached normal blood pressure 4.5-fold faster than the marketed oral tablets. In the In-vivo pharmacokinetic study in rabbits, the LY-OFDS showed 4.7-fold higher bioavailability compared with the marketed oral tablet. In conclusion, the LY-OFDS loaded with LCD-FNVs is a safe, and non-invasive approach that can deliver LCD effectively to the blood circulation via the buccal mucosa giving superior immediate capabilities of lowering high blood pressure and increasing the drug bioavailability.

Binding of peptides corresponding to the carboxy-terminal region of human-ß-defensins-1-3 with model membranes investigated by isothermal titration calorimetry.

Human-ß-defensins HBD-1-3 are important components of the innate immune system. Synthetic peptides Phd-1-3 with a single disulphide bond, spanning the cationic C-terminal region of HBD-1-3, have antimicrobial activity. The interaction of Phd-1-3 with model membranes was investigated using isothermal titration calorimetry (ITC) and steady-state fluorescence polarization to understand the biophysical basis for the mechanism of antimicrobial action. Calorimetric titration of POPE:POPG (7:3) vesicles with peptides at 25°C and 37°C showed complex profiles with two distinct regions of heat changes. The data indicate binding of Phd-1-3 at 37°C to both negative and zwitterionic lipid vesicles is exothermic with low enthalpy values (ΔH~-1.3 to -2.8kcal/mol) as compared to amphipathic helical antibacterial peptides. The adsorption of peptides to negatively charged lipid membranes is modulated by electrostatic interactions that are described by surface partition equilibrium model using Gouy-Chapman theory. However, this model could not explain the isotherms of peptide binding to zwitterionic lipid vesicles. Fluorescence polarization of TMA-DPH (1-[4-(trimethylammonio) phenyl]-6-phenyl-1,3,5-hexatriene) and DPH (1,6-diphenyl-1,3,5-hexatriene) located in the head group and acyl chain region respectively, indicates that the peptides interact with interfacial region of negatively charged membranes. Based on the results obtained, we conclude that adsorption of cationic peptides Phd-1-3 on lipid surface do not result in conformational change or pore formation. It is proposed that interaction of Phd-1-3 with the negatively charged lipid head group causes membrane destabilization, which in turn affects the efficient functioning of cytoplasmic membrane proteins in bacteria, resulting in cell death.

Bilayer properties of giant magnetic liposomes formed by cationic pyridine amphiphile and probed by active deformation under magnetic forces.

We synthesize giant magnetic liposomes by a reverse-phase evaporation method (REV) using a new self-assembling Cationic Pyridine Amphiphile (CPA) derived from 1,4-dihydropyridine as liposome-forming agent and a magnetic ferrofluid based on γ-Fe(2)O(3) nanoparticles. Having in view the potential interest of CPA in targeted transport by magnetic forces, the mechanical elastic properties of such bilayers are here directly investigated in vesicles loaded with magnetic nanoparticles. Bending elastic modulus K(b) ∼ 0.2 to 5k(B)T and pre-stress τ ∼ 3.2 to 12.10(-6) erg/cm(2) are deduced from the under-field deformations of the giant magnetic liposomes. The obtained K(b) values are discussed in terms of A. Wurgers's theory.

PEG-mediated one-pot multicomponent reactions for the efficient synthesis of functionalized dihydropyridines and their functional group dependent DNA cleavage activity.

Polyethylene glycol (PEG) has been found to be an inexpensive, non-toxic and useful medium for the one pot synthesis of highly functionalized dihydropyridines using multicomponent reactions (MCRs) at room temperature under catalyst free conditions. The notable features of this protocol are: mild reaction condition, applicability to wide range of substrates, reusability of the PEG and good yields. The interaction of the synthesized compounds with pUC19 plasmid DNA was also analyzed. Some of the synthesized compounds showed interesting functional group dependent nuclease activity for plasmid DNA cleavage under physiological conditions.