Interactions of the dipeptide paralysin β-Ala-Tyr and the aminoacid Glu with phospholipid bilayers

AbstractExisting evidence points out that the biological activity of β-Ala-Tyr may in part related to its interactions with the cell membranes. For comparative reasons the effects of Glu were also examined using identical techniques and conditions. In order to examine their thermal and dynamic effects on membrane bilayers a combination of DSC, Raman and solid state NMR spectroscopy on DPPC/water model membranes were applied and the results were compared. DSC data showed that Glu perturbs to a greater degree the model membrane compared to β-Ala-Tyr. Thus, alteration of the phase transition temperature and half width of the peaks, abolishment of the pretransition and influence on the enthalpy of the phase transition were more pronounced in the Glu loaded bilayers. Raman spectroscopy showed that incorporation of Glu in DPPC/water bilayers increased the order in the bilayers in contrast to the effect of the dipeptide. Several structural and dynamical properties of the DPPC multilamellar bilayers with and without the dipeptide or Glu were compared using high resolution C-13 MAS (Magic Angle Spinning) spectra and spectral simulations of inhomogeneously broadened, stationary P-31 NMR lineshapes measured under CP (Cross-polarization) conditions. These methods revealed that the aminoacid Glu binds in the close realm of the phosphate in the hydrophilic headgroup of DPPC while β-Ala-Tyr is located more deeply inside the hydrophobic zone of the bilayer. The P-31 NMR simulations indicated restricted fast rotary motion of the phospholipids about their long axes in the organized bilayer structure. Finally, by the applied methodologies it is concluded that the two molecules under study exert dissimilar thermal and dynamic effects on lipid bilayers, the Glu improving significantly the packing of the lipids in contrast to the smaller and opposite effect of the dipeptide

Thermal, dynamic and structural properties of drug AT1 antagonist olmesartan in lipid bilayers

It is proposed that AT1 antagonists (ARBs) exert their biological action by inserting into the lipid membrane and then diffuse to the active site of AT1 receptor. Thus, lipid bilayers are expected to be actively involved and play a critical role in drug action. For this reason, the thermal, dynamic and structural effects of olmesartan alone and together with cholesterol were studied using differential scanning calorimetry (DSC), 13C magicangle spinning (MAS) nuclear magnetic resonance (NMR), cross-polarization (CP) MAS NMR, and Raman spectroscopy as well as small- and wide angle X-ray scattering (SAXS and WAXS) on dipalmitoylphosphatidylcholine (DPPC) multilamellar vesicles. 13C CP/MAS spectra provided direct evidence for the incorporation of olmesartan and cholesterol in lipid bilayers. Raman and X-ray data revealed how both molecules modify the bilayer's properties. Olmesartan locates itself at the head-group region and upper segment of the lipid bilayers as 13C CP/MAS spectra show that its presence causes significant chemical shift changes mainly in the A ring of the steroidal part of cholesterol. The influence of olmesartan on DPPC/cholesterol bilayers is less pronounced. Although, olmesartan and cholesterol are residing at the same region of the lipid bilayers, due to their different sizes, display distinct impacts on the bilayer's properties. Cholesterol broadens significantly the main transition, abolishes the pre-transition, and decreases the membrane fluidity above the main transition. Olmesartan is the only so far studied ARB that increases the gauche:trans ratio in the liquid crystalline phase. These significant differences of olmesartan may in part explain its distinct pharmacological profile

Physicochemical study of the interaction of bioactive molecules with lipid membranes

In the past, lipid bilayers were only thought as static entities and served mainly as barriers for the toxic substances. Today, it is well recognized that they are dynamic structures that play an important role in determining drug action. A new scientific field named lipidomics cavers this aspect. Based on this concept, we sought to examine the role of lipid bilayers for the amphiphilic molecules vinblastine and vincristine which are proposed to act on the membrane lipid bilayer. It has also been proposed that each membrane perturbing drug has its own fingerprint and this may determine its pharmacological effects. For this reason, we found it very interesting to study the membrane interactions of vinblastine and vincristine and made an effort to correlate their fingerprint and pharmacological action. To achieve this aim we investigated the interactions caused by the insertion of Vinca alkaloids vinblastine and vincristine in lipid bilayers of dipalmitoylphospatidylocholine (DPPC), by using the physicochemical techniques of Differential Scanning Calorimetry (DSC) and Raman Spectroscopy. In addition, we studied the effect of this two pharmaceutical molecules with the presence of cholesterol.The thorough analysis of the obtained results point out that: a) the insertion of Vinca alkaloids in lipid bilayers causes partial interdigitation of aliphatic chains, a phenomenon which influences the biological activity of these molecules; b) the incorporation of this pair of molecules results in the creation of various and distinct domains attributed to their different developed interactions; c) after their localization in membrane bilayers they exhibit similarities and differences in terms of synergistic effect with the bioactive molecule of cholesterol.Η παρούσα εργασία αφορά τη φυσικοχημική μελέτη των αναπτυσσόμενων αλληλεπιδράσεων μεταξύ βιοδραστικών μορίων με τις λιπιδικές μεμβράνες. Πιο συγκεκριμένα, αφορά τη διευρεύνηση των αλληλεπιδράσεων που προκαλεί η εισδοχή των αλκαλοειδών της βίγκας (Vinca Alkaloids) βιμπλαστίνης (Vinblastine) και βιγκριστίνης (Vincristine) στις λιπιδικές διπλοστιβάδες της διπαλμιτικής φωσφατιδυλοχολίνης (DPPC), μέσω των φυσικοχημικών τεχνικών Διαφορικής Θερμιδομετρίας Σαρώσεως και φασματοσκοπίας Raman. Επίσης, μελετήθηκε η δράση των φαρμακευτικών αυτών μορίων, παρουσία χοληστερόλης.Από τη μια, η Διαφορική Θερμιδομετρία Σάρωσης (DSC), χρησιμοποιήθηκε για την ανάλυση των θερμικών αλλαγών που προκαλεί η εισδοχή των δύο φαρμακευτικών μορίων στις λιπιδικές διπλοστιβάδες. Τα αποτελέσματά της ανέδειξαν ομοιότητες αλλά και διακριτές διαφορές στον τρόπο με τον οποίο αλληλεπιδρούν με αυτές, γεγονός που οφείλεται στο διαφορετικό αποτύπωμά τους στις λιπιδικές διπλοστιβάδες, παρόλο που πρόκειται για δυο παρεμφερή μόρια της ίδιας οικογένειας ενώσεων.Από την άλλη, η φασματοσκοπία Raman, χρησιμοποιήθηκε για την ανάλυση των δομικών αλλαγών που επιφέρει η ενσωμάτωση των αλκαλοειδών της βίγκας στις λιπιδικές διπλοστιβάδες. Τα αποτελέσματά της, ανέδειξαν ομοιότητες αλλά και διαφορές στον τρόπο αλληλεπίδρασής τους με αυτές, γεγονός που επηρεάζει το φαρμακευτικό προφίλ και τη δράση των δύο μελετούμενων μορίων.Η συστηματική μελέτη και ανάλυση των παραπάνω αποτελεσμάτων, οδήγησε α) στη διαπίστωση της αλληλοεισχώρησης (interdigitation) των αλειφατικών αλυσίδων των λιπιδικών διπλοστιβάδων, ενός σημαντικού φαινομένου που παίζει ρόλο στη βιολογική δραστικότητα των μορίων, β) στην επεξήγηση των αλληλεπιδράσεων που αναπτύσσονται μεταξύ των βιοδραστικών μορίων και των λιπιδικών διπλοστιβάδων μέσω της δημιουργίας διαφορετικών τμημάτων (domains) των λιπιδικών διπλοστιβάδων και γ) στη διαφορετική δράση τους παρουσία χοληστερόλης

Hydroponic Cultivation of Vine Leaves with Reduced Carbon Footprint in a Mediterranean Greenhouse

Vine leaves are considered a delicacy food however they are only produced as a byproduct for a short harvest period due to grape cultivation practices and numerous chemical applications. In this work, vine plants were cultivated hydroponically in a greenhouse, to extend the cultivation period and along with high plant density, maximize fresh leaves yield. Four different substrates were tested—Perlite, Perlite-Attapulgite, Perlite-Zeolite, 1.7Perlite-higher density planting—with soil treatment as a control, and the experimental cultivation lasted a total of about seven months in the year 2021. Quantitative and qualitative characteristics such as leaves number and weight, color of leaves, nitrates, photosynthetic parameters, total phenols, and plant nutrient concentrations were assessed, while the product’s environmental impact was calculated. The 1.7Perlite treatment produced a 1.6–2.0 times higher number of leaves per hectare than the other hydroponic treatments and 8.7 times higher than the soil treatment, while no statistically significant differences were found regarding qualitative characteristics. Consequently, the 1.7P treatment resulted in a 1.4 to 7.6 times lower product carbon footprint compared to the other treatments. In future research, substrates water and nutrient retention will be further studied along with year-round production in a heated greenhouse with full climate control so that plants are kept evergreen

Hydroponic Cultivation of Vine Leaves with Reduced Carbon Footprint in a Mediterranean Greenhouse

Vine leaves are considered a delicacy food however they are only produced as a byproduct for a short harvest period due to grape cultivation practices and numerous chemical applications. In this work, vine plants were cultivated hydroponically in a greenhouse, to extend the cultivation period and along with high plant density, maximize fresh leaves yield. Four different substrates were tested—Perlite, Perlite-Attapulgite, Perlite-Zeolite, 1.7Perlite-higher density planting—with soil treatment as a control, and the experimental cultivation lasted a total of about seven months in the year 2021. Quantitative and qualitative characteristics such as leaves number and weight, color of leaves, nitrates, photosynthetic parameters, total phenols, and plant nutrient concentrations were assessed, while the product’s environmental impact was calculated. The 1.7Perlite treatment produced a 1.6–2.0 times higher number of leaves per hectare than the other hydroponic treatments and 8.7 times higher than the soil treatment, while no statistically significant differences were found regarding qualitative characteristics. Consequently, the 1.7P treatment resulted in a 1.4 to 7.6 times lower product carbon footprint compared to the other treatments. In future research, substrates water and nutrient retention will be further studied along with year-round production in a heated greenhouse with full climate control so that plants are kept evergreen

PCSK9/LDLR System and Rheumatoid Arthritis-Related Atherosclerosis

Background/Aims: Rheumatoid arthritis (RA) is associated with the emergence of cardiovascular disease, while chronic inflammation is considered a common denominator for their parallel progression. The Proprotein convertase subtilisin/kexin type 9 (PCSK9)/LDL-Receptor (LDLR) system is of high importance during atherogenesis, via regulating the clearance of LDL from the circulation; nevertheless the role of this molecular mechanism during RA-related atheromatosis is not known.</p> Methods: Herein, high-resolution ultrasound measurements for arterial hypertrophy, atheromatosis and arterial stiffness as well as comprehensive biochemical profiling were performed in 85 RA patients. The circulating levels of PCSK9 and LDLR were measured and their potential associations as well as of the PCSK9/LDLR ratio with patients' characteristics and the degree of atherosclerosis were investigated.</p> Results: Increased LDLR levels and decreased PCSK9/LDLR ratio were found in RA patients with at least 2 atheromatic plaques as compared to the ones without any plaques. In addition the levels of both PCSK9 and LDLR were positively correlated with the presence of atheromatic plaques as an age- and gender- adjusted multivariate analysis revealed.</p> Conclusions: Our data imply that the PCSK9/LDLR system plays a significant role during RA-related atherosclerosis and may therefore be used as a screening tool for disease progression in the future.</p&gt

Does Sodium Intake Induce Systemic Inflammatory Response? A Systematic Review and Meta-Analysis of Randomized Studies in Humans

Experimental studies suggest that sodium induced inflammation might be another missing link leading to atherosclerosis. To test the hypothesis that high daily sodium intake induces systemic inflammatory response in humans, we performed a systematic review according to PRISMA guidelines of randomized controlled trials (RCTs) that examined the effect of high versus low sodium dose (HSD vs. LSD), as defined per study, on plasma circulating inflammatory biomarkers. Eight RCTs that examined CRP, TNF-a and IL-6 were found. Meta-analysis testing the change of each biomarker in HSD versus LSD was possible for CRP (n = 5 studies), TNF-a (n = 4 studies) and IL-6 (n = 4 studies). The pooled difference (95% confidence intervals) per biomarker was for: CRP values of 0.1(−0.3, 0.4) mg/L; TNF-a −0.7(−5.0, 3.6) pg/mL; IL-6 −1.1(−3.3 to 1.1) pg/mL. Importantly, there was inconsistency between RCTs regarding major population characteristics and the applied methodology, including a very wide range of LSD (460 to 6740 mg/day) and HSD (2800 to 7452 mg/day). Although our results suggest that the different levels of daily sodium intake are not associated with significant changes in the level of systemic inflammation in humans, this outcome may result from methodological issues. Based on these identified methodological issues we propose that future RCTs should focus on young healthy participants to avoid confounding effects of comorbidities, should have three instead of two arms (very low, “normal” and high) of daily sodium intake with more than 100 participants per arm, whereas an intervention duration of 14 days is adequate

Development of a CP 31P NMR Broadline Simulation Methodology for Studying the Interactions of Antihypertensive AT1 Antagonist Losartan with Phospholipid Bilayers

A cross-polarization (CP) 31P NMR broadline simulation methodology was developed for studying the effects of drugs in phospholipids bilayers. Based on seven-parameter fittings, this methodology provided information concerning the conformational changes and dynamics effects of losartan in the polar region of the dipalmitoylphosphatidylcholine bilayers. The test molecule for this study was losartan, an antihypertensive drug known to exert its effect on AT1 transmembrane receptors. The results were complemented and compared with those of differential scanning calorimetry, solid-state 13C NMR spectroscopy, Raman spectroscopy, and electron spin resonance. More specifically, these physical chemical methodologies indicated that the amphipathic losartan molecule interacts with the hydrophilic-head zone of the lipid bilayers. The CP 31P NMR broadline simulations showed that the lipid molecules in the bilayers containing losartan displayed greater collective tilt compared to the tilt displayed by the load-free bilayers, indicating improved packing. The Raman results displayed a decrease in the trans/gauche ratio and increased intermolecular interactions of the acyl chains in the liquid crystalline phase. Additional evidence, suggesting that losartan possibly anchors in the realm of the headgroup, was derived from upfield shift of the average chemical shift σiso of the 31P signal in the presence of losartan and from shift of the observed peak at 715 cm−1 attributed to C-N stretching in the Raman spectra