Aliskiren (ALS) is a direct renin inhibitor with low bioavailability and high drug cost. The goal of this study was to increase the bioavailability of ALS through nanoformulation. The optimized formulation was then evaluated in spontaneously hypertensive rats (SHRs). We developed an ALS poly(lactic-co-glycolic) acid nanoparticle (ALS-NP) through the emulsion–diffusion–evaporation method with various solvents, stabilizer concentrations, and centrifugation speeds. SHRs were orally dosed with 30 mg/kg ALS or dose equivalent ALS-NP. Several parameters were assayed in plasma and/or urine at baseline and 24 h post-dose, while pharmacokinetic analysis included serial sampling. The optimum formulation was found with ethyl acetate, a 1.00% w/v didodecyldimethylammonium bromide concentration, and a 10,000 r/min (15,554 g) centrifugation speed. A 168% relative bioavailability was observed as a result of ALS-NP administration along with significant, as determined by Student’s t-test, increases in the maximum ALS plasma concentration (p = 0.0189) and the area under the plasma concentration–time curve from 0 to infinity (p = 0.0095). Conversely, a reduction was found in oral volume of distribution (p = 0.0009) and oral clearance (p = 0.0298). Blood urea nitrogen increased significantly after dosing in both groups (p < 0.0001 and p < 0.0001); however, no statistical difference was found between endpoint levels (p > 0.05) following one-way analysis of variance (ANOVA). Kidney injury molecule-1 increased following ALS dosing (p = 0.0486), while ALS-NP showed a decrease (p = 0.027) which was also significantly decreased compared to ALS-Final (p = 0.0008) when examined using two-way ANOVA. Urinary potassium excretion decreased significantly, as shown by two-way ANOVA, only in the ALS group (p = 0.0274) which was also significantly reduced compared to ALS-NP-Final (p = 0.016). Using the current formulation and at the dosage tested, ALS-NP showed a more favorable pharmacokinetic profile and positive kidney changes compared to ALS in regard to select outcomes. Thus, NP formulation may further improve ALS renoprotection in addition to increasing bioavailabilty.

Purpose: Athough an effective direct renin inhibitor, aliskiren (ALS) presents with a low bioavailability coupled with high drug cost. As nanoformulation may increase drug bioavailability, our laboratory developed an ALS-loaded poly(lactic-co-glycolic) acid nanoparticle (ALS-NP) formulation. As such, the influence of nanoformulation on drug pharmacokinetic parameters were examined in this study. Methods: Following a single oral dose of ALS (n=7; 30 mg/kg) or ALS-NP (n=7; ALS dose equivalent), rats underwent pharmacokinetic sampling (0, 0.5, 1, 2, 4, 6, 8, 12, and 24 hrs post-dose). Plasma samples were assayed using LCMS-IT-TOF (coefficient of variation of <5%). Pharmacokinetic parameters (half-life, t1/2; maximum plasma concentration, Cmax; time to reach Cmax, tmax; the area under the plasma concentration time curve from 0 to infinity, AUC0-∞; apparent volume of distribution, V/F; and oral clearance, CLoral) were calculated using WinNonlin and evaluated using Student’s t-test with statistical significance set at p<0.05. All values shown as mean±SD. Results: While t1/2 (p=0.0517) and tmax (p=0.0961) were not significantly altered, Cmax in the ALS-NP group (448.53±49.07 mg/L) was elevated compared to control (288.60±148.07 mg/L; p=0.0189). ALS-NP also presented with a 168% relative bioavailability compared to ALS with respective AUC0-∞values of2592.82±600.51 and 1538.40±678.17 hr.mg/L (p=0.0095). The V/F of ALS-NP (128.56±43.67 L/kg) was significantly reduced (p=0.0009) compared to ALS (540.33±245.57 L/kg). A significant reduction (p=0.0298) was also detected in CLoral (ALS-NP, 12.26±3.59 L/hr/kg vs. ALS, 23.44±11.45 L/hr/kg) Conclusion: This study indicates that ALS-NP can be used to improve bioavailability of the drug.

Aliskiren is the first representative of a new class of drugs, the low molecular weight renin inhibitors, orally active and clinically used in a new effective treatment for hypertension. In the present study, the methods were developed and validaded for assessment of aliskiren in pharmaceutical products. Aliskiren samples were also submitted to the physicochemical tests, meeting the specifications. The analysis by reversed-phase liquid chromatography were performed using Waters XBridge (150 mm x 4.6 mm i. d.), maintained at 25 °C. The mobile phase was consisted of acetonitrile/ water (95:5, v/v)/ 25 mM phosphoric acid pH 3.0 (40:60, v/v), run at flow rate of 1 mL/min and using UV detection at 229 nm. The chromatographic separation was obtained within 3.68 minutes. The spectrophotometric method was also developed and validaded, and the aliskiren can be quantified at 279 nm, using water as diluent. The procedures were validated evaluating parameters such as the specificity, linearity, precision, accuracy, limits of detection and quantitation, and robustness, giving results within the acceptable range. The proposed methods were applied for the analysis of pharmaceutical products, showing significant correlation (P > 0.05) of the results. The dissolution test was developed using 900 mL of 0.1 M of chloridric acid 37 ± 0.5 °C as dissolution medium, apparatus paddle at a stirring rate of 50 rpm and quantitation by spectrophotometric method. Therefore, the procedures can be applied to improve the quality control of pharmaceutical products and to assure the safety and therapeutic efficacy of the drug. / O alisquireno é o primeiro representante de uma nova classe de inibidores da renina, de baixo peso molecular e ativo por via oral, sendo utilizado clinicamente em um novo e eficaz tratamento para a hipertensão arterial (HA). No presente trabalho, foram desenvolvidos e validados métodos para avaliação de alisquireno em produtos farmacêuticos. Submeteram-se os produtos aos testes físico-químicos, mostrando que cumprem as especificações. As análises por cromatografia líquida em fase reversa foram realizadas utilizando coluna Waters XBridge (150 mm x 4,6 mm d. i.), mantida à 25 ºC. A fase móvel foi composta de acetonitrila/ água (95:5, v/v)/ ácido fosfórico 25 mM pH 3,0 (40:60, v/v), eluída na vazão de 1 mL/min e detecção no ultravioleta a 229 nm. A separação cromatográfica foi obtida no tempo de 3,68 minutos. Paralelamente, desenvolveu-se e validou-se método por espectrofotometria no ultravioleta (UV) em 279 nm, utilizando água como diluente. Os procedimentos foram validados, avaliando-se os parâmetros de especificidade, linearidade, precisão, exatidão, robustez e limite de detecção e quantificação, cujos resultados cumpriram os requisitos preconizados. Os métodos propostos foram aplicados na análise de produtos farmacêuticos, demonstrando correlação significativa dos resultados (P > 0,05). Desenvolveu-se método de dissolução do fármaco, utilizando como meio 900 mL de ácido clorídrico 0,1 M mantido a 37 ± 0,5 °C, aparato pá, rotação de 50 rpm e quantificação por espectrofotometria no UV. Desse modo, estabeleceram-se procedimentos que podem ser aplicados para aprimorar o controle da qualidade de medicamentos, bem como contribuir para garantir a segurança e eficácia no uso terapêutico.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objectives of this study were: to determine the presence of prorenin and the receptor of (pro)renin [(P)RR] in cumulus cells (CC) and oocytes; evaluate the role of prorenin in the resumption of oocyte meiosis, ovulation and on levels of plasma progesterone (P4). The mRNA expression of prorenin and (P) RR was evaluated in oocytes and cumulus cells of the bovine species. The mRNA of prorenin and (P)RR was detected in CC, in oocytes only mRNA expression of (P)RR was found. The role of prorenin in the resumption of meiosis was determined from 3 experiments using a co-culture of cumulus-oocyte complex (COC) and follicular halves. In the first experiment, three different concentrations of prorenin (10-10, 10-9, and 10-8M) were tested, which stimulated the resumption of meiosis similar to the positive control and angiotensin II (Ang II). In experiment 2, the co-culture was supplemented with prorenin (10-10M) and aliskiren (direct inhibitor of renin, 10-3M, 10-5M and 10-7M). The aliskiren blocked the resumption of meiosis-induced by prorenin in all concentrations tested. The aliskiren (10-5M and 10-7M) was also evaluated in isolation in a culture system of COCs without follicular halves and the rate of oocytes that resumed meiosis was not different of the positive control. The third experiment was conducted to evaluate the stimulation of meiosis resumption by prorenin independent of Ang II using the combination of prorenin (10-10M) and saralasin [nonspecific Ang II receptor antagonist - Sar (10-5M)], which obtained a rate of oocytes at metaphase I (MI) similar to the positive control and treatments of AngII and prorenin. The prorenin also resumed the oocyte meiosis in a culture system of COCs suplemmented with forskolin, wicth blocks the meiosis by intracellular cAMP accumulation. To evaluate the regulation of (P)RR mRNA in the theca and granulosa cells by LH, cows who achieved follicular diameter ≥12mm after synchronization were submitted to the ovariectomy 0, 3, 6, 12 and 24 hours after GnRH analogue treatment. There was a higher mRNA expression of (P)RR in the theca cells at hour 6; and at hour 3 in the granulosa cells. The effect of (P)RR in ovulation and plasma P4 during luteinization was observed cows that were synchronized and induced by GnRH analogue (IM) associated for intrafollicular aliskiren (10-5M) or PBS (0hour/0day) and the ovulation was evaluated at 24, 48 and 72 hours by ultrasound, wicth was not different of the control (PBS). The leves of plasma P4 was analysed at day 6 and 8 after GnRH and intrafollicular treatment only in the cows that ovulated. The intrafollicular (P)RR blocks decreased plasma P4 at day 6. It was concluded that the prorenin / (P)RR participates in the peri-ovulatory period: in the resumption of oocyte meiosis independently of AngII, in the ovulation by LH stimulation to (P)RR mRNA and in the P4 synthesis during luteinization. / Os objetivos deste estudo foram: determinar a presença de prorenina e receptor de (pro)renina [(P)RR] nas células do cumulus (CC) e em oócitos; avaliar o papel da prorenina na retomada da meiose oocitária; na ovulação e sobre os níveis de progesterona plasmática (P4). A expressão do RNAm de prorenina e (P)RR foi avaliada em oócitos e CC da espécie bovina. O RNAm de prorenina e (P)RR foi detectado nas células do cumulus; nos oócitos ocorreu apenas expressão de RNAm de (P)RR. O papel da prorenina na retomada da meiose foi determinado a partir de 3 experimentos utilizando um sistema de co-cultivo de complexo-cumulus oócito (COC) e metades foliculares. No primeiro experimento, foram testadas três concentrações de prorenina (10-10; 10-9; e 10-8M), as quais estimularam a retomada da meiose semelhante ao controle positivo e angiotensina II (Ang II). No experimento 2, o co-cultivo foi suplementado com prorenina (10-10M) e alisquireno (inibidor direto de renina; 10-3M, 10-5M e 10-7M). O alisquireno bloqueou a retomada da meiose induzida pela prorenina em todas concentrações testadas. O alisquireno (10-5M e 10-7M) também foi avaliado isoladamente em sistema de cultivo de COC sem metades foliculares e a taxa de oócitos que retomaram a meiose não diferiu do controle positivo. O experimento 3 foi realizado para avaliar o estímulo da retomada da meiose pela prorenina independente da Ang II utilizando a associação de prorenina (10-10M) e saralasina [antagonista do receptor da Ang II - Sar (10-5M)], a qual obteve taxa de oócitos em metáfase I (MI) semelhante ao controle positivo e aos tratamentos AngII e prorenina. A prorenina também retomou a meiose oocitária em cultivo de COCs suplementado com forskolin, que bloqueia a meiose pelo acumulo de AMPc intracelular.Para avaliar a possível influência do pico de LH na expressão do RNAm de (P)RR nas células da teca e granulosa, vacas que apresentaram folículo ≥12mm de diâmetro após a sincronização farmacológica do ciclo estral foram ovariectomizadas 0, 3, 6, 12 e 24 horas após aplicação do análogo do GnRH. Houve maior expressão de RNAm de (P)RR nas células da teca na hora 6; e na hora 3 nas células da granulosa. O papel do (P)RR na ovulação e sobre a P4 plasmática durante a luteinização foi verificado em vacas sincronizadas farmacológicamente, induzidas pelo análogo de GnRH (IM) associado ao alisquireno (10-5M) ou PBS intrafolicular (hora 0/ dia 0) e foram avaliadas por ultrason 24, 48 e 72 horas quanto a ovulação, a qual não diferiu do controle (PBS). Os níveis de P4 plasmática foram analisados nos dias 6 e 8 após GnRH e tratamento intrafolicular apenas nas vacas que ovularam, nas quais o bloqueio de (P)RR reduziu P4 no dia 6. Concluiu-se que a prorenina/(P)RR participa do periodo peri-ovulatório: na retomada da meiose oocitária de forma independente da AngII, na ovulação pelo estímulo de LH sobre RNAm do (P)RR e na síntese de P4 durante a luteinização.

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As associações entre obesidade, doença hepática gordurosa não alcoólica (NAFLD) e diabetes mellitus tipo 2 (DM2) são bem estabelecidas, e o sistema renina-angiotensina (SRA) pode proporcionar uma ligação entre eles. O bloqueio do SRA em diferentes níveis pode estar relacionado a respostas na resistência à insulina, remodelagem do pâncreas e do fígado em um modelo de obesidade induzida por dieta. Camundongos C57BL/6 foram alimentados com uma dieta hiperlipídica (HF) durante oito semanas e depois tratados com alisquireno (50 mg/kg/dia), enalapril (30 mg/kg/dia) ou losartana (10 mg/kg/dia) por um período adicional de seis semanas. As drogas foram incorporadas na dieta. Avaliou-se a massa corporal (MC), pressão arterial, consumo e gasto energético (GE), metabolismo da glicose e lipídico, histopatologia pancreática e hepática, análise hormonal, imunohistoquímica, perfil gênico e/ou proteico do SRA no pâncreas, gliconeogênese hepática, sinalização da insulina, oxidação e acúmulo lipídico. Todos os inibidores do SRA reduziram significativamente o aumento da pressão arterial nos camundongos alimentados com dieta HF. O tratamento com enalapril, mas não alisquireno ou losartana, reduziu o ganho de MC e a ingestão alimentar; aumentou o GE; amenizou a intolerância à glicose e resistência à insulina; melhorou a massa de células alfa e beta; impediu a redução da adiponectina plasmática e restaurou a sensibilidade à leptina. Além disso, o tratamento com enalapril melhorou a expressão proteica nas ilhotas pancreáticas de Pdx1, GLUT2, ECA2 e do receptor Mas. O tratamento com losartana apresentou uma elevação na expressão proteica de AT2R no pâncreas. No fígado, a administração de enalapril atenuou a esteatose hepática, o acúmulo de triglicerídeos e preveniu o aumento dos níveis de PEPCK, G6Pase e do GLUT2. Do mesmo modo, o enalapril melhorou a transdução dos sinais da insulina através da via IRS-1/Akt, bem como reduziu os níveis de expressão gênica e/ou proteica de PPAR-gama, SREBP-1c e FAS. Esses resultados sugerem que a inibição da ECA com enalapril atenuou muitos efeitos deletérios provocados pelo consumo da dieta HF, incluindo: normalização da morfologia e função das ilhotas pancreáticas, proteção contra a resistência à insulina e acúmulo de lipídios no fígado. Estes efeitos protetores do enalapril podem ser atribuídos, principalmente, à redução no ganho de MC e ingestão alimentar, aumento do GE, ativação do eixo ECA2/Ang(1-7)/receptor Mas e dos níveis de adiponectina, o que promove uma melhora na ação hepática da insulina e leptina, normalização da gliconeogênese, amenizando a NAFLD. / The associations between obesity, NAFLD (non-alcoholic fatty liver disease) and diabetes are well established, and the reninangiotensin system (RAS) may provide a link among them. . The blocking of the RAS at different levels may be related to responses on insulin resistance, remodeling of the pancreas and liver in a model of diet-induced obesity. Mice (C57BL/6) were fed on a high-fat (HF) diet for 8 weeks and then treated with aliskiren (50 mg/kg/day), enalapril (30 mg/kg/day) or losartan (10 mg/kg/day) for an additional 6 weeks. The drugs were incorporated into the diet. We assessed body mass (BM), blood pressure, energy intake and expenditure (EE), glucose and lipid metabolism, pancreatic and hepatic histopathology, hormonal analysis, immunohistochemistry, the expression profile of genes and/or proteins affecting pancreas RAS, hepatic gluconeogenesis, insulin signaling and lipid oxidation and accumulation. All RAS inhibitors significantly attenuated the increased blood pressure in mice fed a HF diet. Treatment with enalapril, but not aliskiren or losartan, significantly attenuated BM gain, increased EE, enhanced the glucose intolerance and insulin resistance; improved the alpha and beta cell mass; prevented the reduction of plasma adiponectin and restored leptin sensibility. Furthermore, enalapril treatment improved the protein expression of the pancreatic islet Pdx1, GLUT2, ACE2 and Mas receptors. Losartan treatment showed the greatest AT2R expression in the pancreas. In the liver, the enalapril administration improved hepatic steatosis, triglycerides and prevented the increase hepatic protein levels of PEPCK, G6Pase and GLUT2. Additionally, enalapril improved the deleterious effects on the HF diet by upregulating the signal transduction through the IRS-1/Akt pathway, as well as downregulatin the protein levels and mRNA expression of PPAR-gamma, SREBP-1c and FAS. Our findings indicate that ACE inhibition with enalapril attenuated several of the deleterious effects of the HF diet. In summary, enalapril appears to be responsible for the normalization of islet morphology and function, a protective role against hepatic insulin resistance and lipid accumulation in the liver. These protective effects of enalapril were attributed, primarily, to the reduction in body mass gain and food intake, increasing EE, the enhancement of the ACE2/Ang (1-7)/Mas receptor axis and adiponectin levels, enhancing hepatic insulin action, leptin and gluconeogenesis, and attenuating NAFLD.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As associações entre obesidade, doença hepática gordurosa não alcoólica (NAFLD) e diabetes mellitus tipo 2 (DM2) são bem estabelecidas, e o sistema renina-angiotensina (SRA) pode proporcionar uma ligação entre eles. O bloqueio do SRA em diferentes níveis pode estar relacionado a respostas na resistência à insulina, remodelagem do pâncreas e do fígado em um modelo de obesidade induzida por dieta. Camundongos C57BL/6 foram alimentados com uma dieta hiperlipídica (HF) durante oito semanas e depois tratados com alisquireno (50 mg/kg/dia), enalapril (30 mg/kg/dia) ou losartana (10 mg/kg/dia) por um período adicional de seis semanas. As drogas foram incorporadas na dieta. Avaliou-se a massa corporal (MC), pressão arterial, consumo e gasto energético (GE), metabolismo da glicose e lipídico, histopatologia pancreática e hepática, análise hormonal, imunohistoquímica, perfil gênico e/ou proteico do SRA no pâncreas, gliconeogênese hepática, sinalização da insulina, oxidação e acúmulo lipídico. Todos os inibidores do SRA reduziram significativamente o aumento da pressão arterial nos camundongos alimentados com dieta HF. O tratamento com enalapril, mas não alisquireno ou losartana, reduziu o ganho de MC e a ingestão alimentar; aumentou o GE; amenizou a intolerância à glicose e resistência à insulina; melhorou a massa de células alfa e beta; impediu a redução da adiponectina plasmática e restaurou a sensibilidade à leptina. Além disso, o tratamento com enalapril melhorou a expressão proteica nas ilhotas pancreáticas de Pdx1, GLUT2, ECA2 e do receptor Mas. O tratamento com losartana apresentou uma elevação na expressão proteica de AT2R no pâncreas. No fígado, a administração de enalapril atenuou a esteatose hepática, o acúmulo de triglicerídeos e preveniu o aumento dos níveis de PEPCK, G6Pase e do GLUT2. Do mesmo modo, o enalapril melhorou a transdução dos sinais da insulina através da via IRS-1/Akt, bem como reduziu os níveis de expressão gênica e/ou proteica de PPAR-gama, SREBP-1c e FAS. Esses resultados sugerem que a inibição da ECA com enalapril atenuou muitos efeitos deletérios provocados pelo consumo da dieta HF, incluindo: normalização da morfologia e função das ilhotas pancreáticas, proteção contra a resistência à insulina e acúmulo de lipídios no fígado. Estes efeitos protetores do enalapril podem ser atribuídos, principalmente, à redução no ganho de MC e ingestão alimentar, aumento do GE, ativação do eixo ECA2/Ang(1-7)/receptor Mas e dos níveis de adiponectina, o que promove uma melhora na ação hepática da insulina e leptina, normalização da gliconeogênese, amenizando a NAFLD. / The associations between obesity, NAFLD (non-alcoholic fatty liver disease) and diabetes are well established, and the reninangiotensin system (RAS) may provide a link among them. . The blocking of the RAS at different levels may be related to responses on insulin resistance, remodeling of the pancreas and liver in a model of diet-induced obesity. Mice (C57BL/6) were fed on a high-fat (HF) diet for 8 weeks and then treated with aliskiren (50 mg/kg/day), enalapril (30 mg/kg/day) or losartan (10 mg/kg/day) for an additional 6 weeks. The drugs were incorporated into the diet. We assessed body mass (BM), blood pressure, energy intake and expenditure (EE), glucose and lipid metabolism, pancreatic and hepatic histopathology, hormonal analysis, immunohistochemistry, the expression profile of genes and/or proteins affecting pancreas RAS, hepatic gluconeogenesis, insulin signaling and lipid oxidation and accumulation. All RAS inhibitors significantly attenuated the increased blood pressure in mice fed a HF diet. Treatment with enalapril, but not aliskiren or losartan, significantly attenuated BM gain, increased EE, enhanced the glucose intolerance and insulin resistance; improved the alpha and beta cell mass; prevented the reduction of plasma adiponectin and restored leptin sensibility. Furthermore, enalapril treatment improved the protein expression of the pancreatic islet Pdx1, GLUT2, ACE2 and Mas receptors. Losartan treatment showed the greatest AT2R expression in the pancreas. In the liver, the enalapril administration improved hepatic steatosis, triglycerides and prevented the increase hepatic protein levels of PEPCK, G6Pase and GLUT2. Additionally, enalapril improved the deleterious effects on the HF diet by upregulating the signal transduction through the IRS-1/Akt pathway, as well as downregulatin the protein levels and mRNA expression of PPAR-gamma, SREBP-1c and FAS. Our findings indicate that ACE inhibition with enalapril attenuated several of the deleterious effects of the HF diet. In summary, enalapril appears to be responsible for the normalization of islet morphology and function, a protective role against hepatic insulin resistance and lipid accumulation in the liver. These protective effects of enalapril were attributed, primarily, to the reduction in body mass gain and food intake, increasing EE, the enhancement of the ACE2/Ang (1-7)/Mas receptor axis and adiponectin levels, enhancing hepatic insulin action, leptin and gluconeogenesis, and attenuating NAFLD.

Η υπέρταση είναι ένας από τους σημαντικότερους παράγοντες που αυξάνει τα καρδιαγγειακά επεισόδια τα οποία ευθύνονται περίπου για το ήμισυ των θανατηφόρων επεισοδίων στους ενήλικους. To σύστημα ρενίνης-αγγειοτασίνης-αλδοστερόνης (ΣΡΑΑ) διαδραματίζει καθοριστικό ρόλο στην παθοφυσιολογία των καρδιαγγειακών νόσων. Η αναστολή του ΣΡΑΑ σε παθολογικές καταστάσεις μπορεί να πραγματοποιηθεί με αναστολή του ενζύμου της ρενίνης ή παρεμπόδιση της σύνδεσης της ΑΙΙ με τους υποδοχείς ΑΤ1. Έχει διατυπωθεί η υπόθεση ότι τα αμφοτερικά μόρια για να αλληλεπιδράσουν με τον υποδοχέα θα πρέπει πρώτα να εισδύσουν σε κατάλληλη τοπογραφική θέση στις βιολογικές μεμβράνες και μετά με διάχυση να προσεγγίσουν το ενεργό κέντρο όπου όταν προσδεθούν με μία σειρά αντιδράσεων θα εξασκήσουν τη βιολογική τους δράση. Για την κατανόηση του ρόλου των μεμβρανών στο σύστημα ΣΡΑΑ μελετήθηκαν οι αλληλεπιδράσεις της αλισκιρένης (αναστολέας ρενίνης) και ολμεσαρτάνης (ανταγωνιστής αγγειοτασίνης ΙΙ) σε μοντέλα διπλοστιβάδων διπαλμιτικής φωσφατιδυλοχολίνης με ή χωρίς χοληστερόλη. Οι μελέτες διεξήχθησαν κάνοντας χρήση Πυρηνικού Μαγνητικού Συντονισμού (υγρής και στερεής κατάστασης), Διαφορικής Θερμιδομετρίας Σάρωσης, Φασματοσκοπίας Raman και Περίθλασης Ακτίνων-Χ. Σύγκριση των πειραματικών αποτελεσμάτων με άλλες σαρτάνες που μελετήθηκαν κάνοντας χρήση τις ίδιες τεχνικές απόδειξαν ότι όλα τα φάρμακα του ΣΡΑΑ εντοπίζονται στην ενδιάμεση φάση όπου εξασκούν διαφορετικές υδρόφιλες και λιπόφιλες αλληλεπιδράσεις. Επομένως το κάθε φάρμακο αποτυπώνει τη δική του σφραγίδα μέσα στις λιπιδικές διπλοστιβάδες. Αυτή η μοναδικότητα στις αλληλεπιδράσεις κάθε φαρμάκου με τις λιπιδικές διπλοστιβάδες ίσως να σχετίζεται και με τη μοναδικότητα του στο φαρμακευτικό του προφίλ. Ένα άλλο ενδιαφέρον αποτέλεσμα που προέκυψε από τις μελέτες είναι ότι η ολμεσαρτάνη σε μεθανολικό διάλυμα τόσο σε χαμηλή θερμοκρασία όσο και σε θερμοκρασία δωματίου δεν είναι σταθερή και μετατρέπεται στο αιθερικό της παράγωγο το οποίο ταυτοποιήθηκε φασματοσκοπικά. Στις ίδιες συνθήκες δεν παρατηρήθηκε εστεροποίηση. / Hypertension is one of the major risk factors responsible for the increase of half of the cardiovascular episodes in the adults. The system of Renin-Angiotensin-Aldosterone (RAAS) plays a determinative role in the pathophysiology of cardiovascular diseases. In a pathological state the aim is to block the generation of Angiotensin II through inhibition of rennin or angiotensin converting enzymes or its action on AT1 receptor. It has been hypothesized that amphiphilic molecules in order to exert their action on the receptor site, they have first to enter into the lipidic core of the lipid bilayers and then diffuse towards the active site. Thus, if this mechanism is applied, the lipidic part of the membrane bilayers appears to play an important role in the membrane action. To comprehend on the membrane:drug interactions we have studied the effects of olmesartan and aliskiren using dipalmitoylphosphatidylcholine bilayers with or without cholesterol. Various physical chemical methodologies such as liquid and solid state NMR , x-ray diffraction, Raman spectroscopy and Differential Scanning Calorimetry have been applied. The comparative results with other SARTANs showed that all drugs of the RAAS system act on the polar group and upper part of the alkyl chain, but exert different interactions. Thus, each drug is characterized by its own fingerprint in terms of its interactions and this may explain its unique pharmacological profile. Another, intriguing result derived from this thesis dissertation is the observation that olmesartan in methanolic solution is converted to its ether analogue. This isolated product was unambiguously structurally elucidated using a combination of LC-MS and 2D NMR spectroscopy.

Préalablement, une synthèse de l’aliskiren, un inhibiteur de la rénine développé pour le traitement de l’hypertension, a été réalisée auprès du groupe Hanessian. Durant cette synthèse, une réaction clé de cyclisation par métathèse, menant à la formation de lactone à neuf membres, a été réalisée. Durant cette réaction, nous avons observé une différence de réactivité entre les diastéréomères, menant à la formation de monolactones et de dilactones, générant ainsi de l’intérêt pour l’étude des facteurs en cause. Le présent mémoire rapporte et détaille les résultats de cette analyse quant à la formation de monomères versus celle de dimères par cyclisation à l’aide de catalyseurs de Grubbs et l’impact de différentes conditions réactionnelles et la diastéréochimie relative sur la réaction. Un intérêt pour la formation de liens benzyliques nous a incité à approfondir notre compréhension d’une méthodologie de substitution nucléophile diastéréosélective catalysée par des acides. Le rationnel mit de l’avant par les groupes Bach et Olah a procuré une compréhension du mécanisme réactionnel sur lequel nous avons basé nos observations subséquentes. Nous avons porté notre attention sur l’alkylation d’arènes, de phénols et de sulfonamides. Diverses régiosélectivités et diastéréosélectivités ont pu être observées en présence de substrats dérivés de la synthèse de l’aliskiren, de nitroalcools ainsi que de azidoalcools en utilisant plusieurs acides de Lewis et de Brønsted. / Previously, a synthesis of aliskiren, a renin inhibitor developed for the treatment of hypertension, was developed in the Hanessian group. As part of that synthesis, they used a ring-closing metathesis which led to the formation of a nine-membered lactone, a key intermediate of the synthesis. During the reaction, we observed a difference in reactivity between the various diastereoisomers leading to the formation of mono- and dilactones, inciting us to study the various factors involved. The present master’s thesis reports and details the results of the study of monomers versus dimers formation by cyclization using Grubbs’s catalysts and the effect of various reaction conditions and relative configuration on the reaction. An interest for the formation of benzylic bonds drove us to deepen our comprehension of a methodology of diastereselective nucleophilic substitution catalysed by acids. The rational brought forth by the Bach and Olah groups served as a basis for our understanding of the mechanism involved upon which we based our following observations. We focused our attention on the alkylation of arenes, phenols and sulfonamides. Various regioselectivities and diastereoselectivities were observed on substrates derived from the aliskiren’s synthesis, nitroaocohols and azidoalcohols while using various Lewis and Brønsted acids.