The aim of the present study was to evaluate the effects of dietary supplementation with dried orange pulp on antioxidant capacity of egg yolk and the possible side effects on performance and egg quality of laying hens. A total of 189 animals, reared in 21 replicate enriched cages with 9 hens each, were randomly allocated into 3 treatment groups: control group (C) that was offered a basal diet without orange pulp addition, group (OP) that was offered a diet supplemented with dried orange pulp (Citrus sinensis) at 9% and group EN that was offered the basal diet further supplemented with 0.767 g hesperidin and 0.002 g naringin per kg of feed (levels of hesperidin and naringin that are contained in dried orange pulp of OP group). The diets were offered for 30 days and were isocaloric and isonitrogenous. Oxidative stability of egg, expressed as ng malondialdehyde (MDA) per g of yolk, performance and egg quality parameters were determined throughout the 30 d experimental period. Oxidative stability of fresh and stored eggs for 30 and 90 d was improved when hens were fed a diet supplemented with OP in comparison with controls (P < 0.05). Ten days of dietary supplementation with OP were enough for apparent beneficial effects on yolk oxidative stability and consequently egg shelf life. However, feed intake and laying rate were decreased whereas feed conversion ratio (FCR) was increased in group of hens supplemented with OP in comparison with both controls and hens fed with hesperidin and naringin (P < 0.05). The reduced values of feed intake may be attributed to the low palatability of OP and not only negatively affected performance but also resulted in deterioration of egg quality parameters. Hens fed with OP produced slightly lighter eggs with a lower eggshell percentage, thickness and strength and a less orange yolk color in comparison with controls (P < 0.05). The negative effects of dietary supplementation with OP on egg production and quality may be alleviated by a gradual increase of OP levels in hens' diet that could offer an adaptation to OP incorporation in the diet.

The renin–angiotensin–aldosterone system (RAAS) plays a key role in the regulation of blood pressure. Renin is the rate limiting enzyme of the RAAS and aliskiren is a highly potent and selective inhibitor of the human renin. Renin is known to be active both in the circulating blood stream as well as locally, when bound to the (pro)-renin receptor ((P)RR). In this study we have investigated a possible mechanism of action of aliskiren, in which its accumulation in the plasma membrane is considered as an essential step for effective inhibition. Aliskiren's interactions with model membranes (cholesterol rich and poor) have been investigated by applying different complementary techniques: differential scanning calorimetry (DSC), Raman spectroscopy, magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and small- and wide-angle X-ray scattering (SAXS and WAXS). In addition, in silico molecular dynamics (MD) calculations were applied for further confirmation of the experimental data. Aliskiren's thermal effects on the pre- and main transition of dipalmitoyl-phosphatidylcholine (DPPC) membranes as well as its topographical position in the bilayer show striking similarities to those of angiotensin II type 1 receptor (AT1R) antagonists. Moreover, at higher cholesterol concentrations aliskiren gets expelled from the membrane just as it has been recently demonstrated for the angiotensin receptor blocker (ARB) losartan. Thus, we propose that both the AT1R and the (P)RR-bound renin active sites can be efficiently blocked by membrane-bound ARBs and aliskiren when cholesterol rich membrane rafts/caveolae are formed in the vicinity of the receptors.

We extend to you a warm and sunny Aloha in celebration of the 23 rd American Peptide Symposium and the 6 th International Symposium.The meeting theme, Peptides Across the Pacific, embraced the spirit of the scientific and social program.Peptides Across the Pacific encompassed the important role that peptide science currently plays in so many disciplines and explored the potential impact peptides can make in scientific fields that have yet to realize the utility of these wonderful molecules.The scientific program for 2013

Valsartan is a marketed drug with high affinity to the type 1 angiotensin (AT1) receptor. It has been reported that AT1 antagonists may reach the receptor site by diffusion through the plasma membrane. For this reason we have applied a combination of differential scanning calorimetry (DSC), Raman spectroscopy and small and wide angle X-ray scattering (SAXS and WAXS) to investigate the interactions of valsartan with the model membrane of dipalmitoyl-phosphatidylcholine (DPPC). Hence, the thermal, dynamic and structural effects in bulk as well as local dynamic properties in the bilayers were studied with different valsartan concentrations ranging from 0 to 20 mol%. The DSC experimental results showed that valsartan causes a lowering and broadening of the phase transition. A splitting of the main transition is observed at high drug concentrations. In addition, valsartan causes an increase in enthalpy change of the main transition, which can be related to the induction of interdigitation of the lipid bilayers in the gel phase. Raman spectroscopy revealed distinct interactions between valsartan with the lipid interface localizing it in the polar head group region and in the upper part of the hydrophobic core. This localization of the drug molecule in the lipid bilayers supports the interdigitation view. SAXS measurements confirm a monotonous bilayer thinning in the fluid phase, associated with a steady increase of the root mean square fluctuation of the bilayers as the valsartan concentration is increased. At high drug concentrations these fluctuations are mainly governed by the electrostatic repulsion of neighboring membranes. Finally, valsartans' complex thermal and structural effects on DPPC bilayers are illustrated and discussed on a molecular level.

This work presents a thorough investigation of the interaction of the novel synthetic pyrrolidinone analog MMK3 with the model membrane system of dipalmitoylphosphatidylcholine (DPPC) and the receptor active site. MMK3 has been designed to exert antihypertensive activity by functioning as an antagonist of the angiotensin II receptor of subtype 1 (AT(1)). Its low energy conformers were characterized by 2D rotating-frame Overhauser effect spectroscopy (ROESY) in combination with molecular dynamics (MD) simulations. Docking study of MMK3 shows that it fits to the AT(1) receptor as SARTANs, however, its biological activity appears to be lower. Thus, differential scanning calorimetry (DSC), Raman spectroscopy and small angle X-ray scattering (SAXS) experiments on the interaction of MMK3 with DPPC bilayers were carried out and results demonstrate that the drug is well incorporated into the membrane leaflets and furthermore causes partial bilayer interdigitation, although less effective than SARTANs. Thus, it appears that the nature of the bilayer matrix and the stereoelectronic active site requirements of the receptor are responsible for the low bioactivity of MMK3.

Several steroidal esters of alkylating agents have been synthesized and tested in vitro and in vivo in various experimental cancer types. 3β-Hydroxy-17α-aza-D-homo-5-androsten-7,17-dione-N,N-bis(2-chloroethyl) aminophenylacetate (I) is a highly active compound. DSC scans show differences between the alkylating agent alone and in conjugation with the steroidal part in the broadening and lowering of the phase transition of DPPC bilayers. These differences may in part explain the better pharmacokinetic profile and lower toxicity of conjugated congener I versus the alkylating agent alone.

Platinum(II) and palladium(II) complexes with 2-acetyl pyridine and pyridine-2-carbaldehyde N(4)-ethyl-thiosemicarbazones, HAc4Et and HFo4Et respectively were synthesized and found to exhibit a cytotoxic potency in a very low micromolar range and to be able to overcome the cisplatin resistance of A2780/Cp8 cells. The biologically active complexes Pd(Fo4Et)2 (1), Pd(Ac4Et)2 (2), Pt(Fo4Et)2 (3) and Pt(Ac4Et)2 (4) were tested for their perturbation in model membrane bilayers. The aim was to investigate if there is a possible relation between their mechanism of action in membranes with their biological activity. Indeed, it was found that complexes of deprotonated HAc4Et, (2) and (4), are more perturbing than complexes of deprotonated HFo4Et, (1) and (3).

Biological membranes play an essential role in the drug action. They constitute the first barrier for drugs to exert their biological action. AT1 antagonists are amphiphilic molecules and are hypothesized to act on AT1 receptor through incorporation (first step) and lateral diffusion through membrane bilayers (second step). Various biophysical methods along with Molecular Modelling were applied in order to explore the plausible two step proposed mechanism of action for this class of antihypertensive drugs.

The synthesis of unnatural amino acids is an area of research that has attracted special attention in recent years. Unnatural amino acids play an important role in the design and synthesis of peptide mimetics, enzyme inhibitors and bioactive compounds. Aldehydes obtained from a–amino acids constitute a class of chiral synthons useful in the synthesis of optically active bioactive compounds and, in particular, in the synthesis of unnatural amino acids. Here, we present an efficient route for the synthesis of enantiopure unnatural a–amino acids and 2–amino alcohols starting from serine. Boc–L–Ser(Bn)–OH ( 1 ) was reduced to alcohol by the mixed anhydride–NaBH 4 method and oxidized to aldehyde by treatment with NaOCl/Ac-NH–TEMPO. Wittig–type olefination reaction of the key intermediate aldehyde 2 with various ylides produced unsaturated derivatives 3 . Hydrogenation, followed by oxidation with NaOCl in the presence of AcNH–TEMPO and tetrabutylammoni-um hydrogensulphate, as a phase transfer catalyst, gave unnatural amino acids 4 .

The protein collagen is the most predominant and important protein of the skin and therefore its physicochemical and thermal properties are important to be known. DSC has been applied in order to study the thermal changes caused by using different concentrations of the gentamycin antibiotic in fibrous membranes FM, named AMATCOL at different scanning rates. The thermal effect consisting of several peaks of the fibrous collageneous membrane alone or with different percentages of drug is simplified to a broad peak after 24h equilibration time. The 35–70°C endothermic effect attributed to the collapse of the tripple-helical domain of collagen due to the dehydration is affected by the presence of gentamycin. The endothermic peaks due to vaporization of bound water at the temperatures of 90–120°C are also affected by the presence of gentamycin. This region consists of two peaks at low percentage of gentamycin and at higher percentages the peak near 120°C decreases in intensity and finally disappears. The re-absorption of the water is more significant in the preparations containing gentamycin after 24h equilibration time indicating that antibiotic makes a more stable complex with collagen molecules aiding this process. A minimum of re-absorption occurs when the concentration of gentamycin is 2% w/w in accordance with pore size and nitrogen gas permeability measurements. The collagen denaturation occurs at higher temperature when gentamycin is incorporated in fibrous membranes FM. This is an evidence that gentamycin stabilizes the cross-linkings between structural units (covalent, hydrophobic links) due to its interactions with collagen and water. Data resulted from differential scanning calorimetry (DSC) have been corroborated with those resulted from the porosity analysis. Specific morphology of fibrous collageneous membranes FM structure, containing macro-, micro-, and nano-pores resulted from freeze drying, acts on the gas and water vapor permeability, as well as water absorption. These characteristics are important in trans-dermal carriage of gentamycin contained in FM membranes.

Three series of ring-substituted ether phospholipids were synthesized carrying N,N,N-trimethylammonium, N-methylpiperidino, or N-methylmorpholino headgroups. The first series is substituted by 2-cyclohexyloxyethyl or 2-(4-alkylidenecyclohexyloxy)ethyl groups, the second series by cyclohexylidenealkyl or adamantylidenealkyl moieties, and the third series by 2-aryloxyethyl or 6-aryloxyhexyl groups in the alkyl portion of the molecule. The antileishmanial activity of the new compounds was evaluated in vitro against the promastigote forms of L. donovani and L. infantum using an MTT (3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide)-based microassay as a marker of cell viability. Analogues 12, 15, 24, 30, 32, 41, 43, and 45 were more potent than the control compound miltefosine (hexadecylphosphocholine) against both L. donovani and L. infantum while, derivatives 13 and 42 were equipotent to miltefosine. Analogues 16, 17, 19, 20 were more potent than miltefosine against L. infantum and compounds 27, 31, 44 were more active than miltefosine against L. donovani. Differential scanning calorimetry (DSC) was used to probe the role of individual ether phospholipids on the physicochemical properties of model membranes. The DSC scans showed that the active compounds have a more profound effect on the thermotropic properties of model membrane bilayers than the less active ones.

Physicochemical methods were used to study the thermal and dynamic changes caused by losartan in the membrane bilayers. In addition, molecular modeling was implemented to explore its topography both in membranes and AT1 receptor. Its incorporation resulted in the modification of thermal profile of dipalmitoyl phosphatidylcholine (DPPC) bilayers in a concentration dependent way up to 20mol% as it is depicted from the combination of differential scanning calorimetry (DSC) and MAS data. In particular, the presence of losartan caused lowering of the phase transition temperature and abolishment of the pretransition. T1 experiments revealed the location of the drug into the membrane bilayers. The use of a combination of biophysical methods along with docking experiments brought out a possible two-step mechanism which involves incorporation of losartan at the interface of membrane bilayers and diffusion in the upper parts of AT1 receptor helices IV–VII.