Complex topology formed between drugs/beta-cyclodextrins/liposomes/cells, using nuclear magnetic resonance - NMR techniques

Orientador: Anita Jocelyne MarsaioliTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuimicaResumo: A encapsulação de drogas, em particular anestésicos locais (ALs), em sistemas carreadores como lipossomas (EPC) ou ciclodextrinas (b-CD) é uma metodologia desenvolvida para diminuição da toxicidade sistêmica, aumento da analgesia e maior absorção do que os correspondentes ativos livres. O estudo das interações dos complexos (ALs/b-CD, AL/EPC e ALs/ b-CD/EPC) foi realizado utilizando técnicas de RMN de H (ROESY 1D, DOSY e STD). Através destas, observou-se que o ALs proparacaína (PPC) interage com a b-CD e que na presença de vesículas de lipossomas (MLV, 400nm e 100nm) as moléculas de PPC deixam a b-CD para formar um novo complexo (PPC/EPC). Entretanto, espectros de RMN-STD revelaram sinais de b-CD quando lipossomas foram saturados em -0,5 ppm, que é consistente com a existência de um complexo ternário PPC/b-CD/EPC. Em um segundo momento do trabalho, foi avaliado a topologia de complexos formados entre o ALs prilocaína (PLC), b-CD e vesículas de lipossomas de EPC variando o pH (10,0, 7,0 e 5,5). Os experimentos de STD mostraram que a liberação da PLC da b-CD para o lipossoma e formação do complexo PLC/EPC foi maior a pH 10,0 do que a pH 5,5. Espectros de DOSY forneceram constantes de associações maiores em pH 10,0, indicando maior interação da PLC/EPC e preferência da PLC pela fase aquosa em pH 5,5. A técnica de RMN-STD também foi aplicada pioneiramente para o estudo do Quorum Sensing usando (S)-N-(3-oxo-octanoyl)-HSL e cepas de A. tumefaciens NTL4(pZLR4). Vesículas de lipossomas foram usadas como modelo de membrana para o estudo do mecanismo de Quorum Sensing. Concluiu-se então que a difusão da HSL através da parte lipídica da membrana celular é um importante evento para o sucesso da comunicação bacteriana.Abstract: Encapsulation of local anesthetics (Als) in drug delivery systems as liposomes (EPC) or cyclodextrins (b-CD) is a known methodology to decrease toxicity, increase anesthetic effect duration and absorption than the free drug. Thus evaluation of the stability of supramolecular complexes is important and here several complexes (ALs/b-CD, AL/EPC e ALs/ b-CD/EPC) were evaluated using H NMR techniques (ROESY 1D, DOSY e STD). We observed that proparacaine (PPC) interacts with b-CD and in the presence of liposomes (MLV, 400 or 100 nm) that PPC molecules migrate from the b-CD to the liposome producing new binary complexes (PPC/EPC). Additionally, STD H NMR revealed b-CD signals upon liposome saturation at -0.5 ppm which was consistent with the existence of a ternary complex PPC/b-CD/EPC. We have also evaluated the topologies of PLC/b-CD/EPC complexes at different pHs (10.0, 7.0, 5.5). The STD¿NMR experiments revealed that more PLC is released to liposome from the PLC/b-CD complex at pH 10.0 than at pH 5.5. The association constants determined by diffusion experiments (DOSY) revealed that PLC/EPC interactions are larger at pH 10.0 than at pH 5.5 due to an increase in PLC/EPC interaction and the PLC preference for the aqueous phase at pH 5.5. The STD-NMR technique was also applied to a pioneer study of the Quorum Sensing using (S)-N-(3-oxo-octanoyl)-HSL and a strain of A. tumefaciens NTL4(pZLR4). Liposome vesicles were used as membrane model to study the Quorum Sensing mechanism. Finally, it was concluded that of diffusion acyl-HSLs through the lipidic part of the bacterial cell membrane is an important event for a successful bacterial communication.DoutoradoQuimica OrganicaDoutor em Ciência

Sintese e caracterização de novas quinazolinas polissubstituidas

Orientador: Roberto Rittner NetoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuimicaMestradoQuimica OrganicaMestre em Químic

Combining nuclear magnetic resonance with molecular dynamics simulations to address sumatriptan interaction with model membranes

The goal of this work is to obtain a complete map on the interactions between sumatriptan, an amphiphilic ionizable anti-migraine drug, with lipid bilayers. To this end, we combined two physico-chemical techniques – nuclear magnetic resonance and molecular dynamics simulations – to obtain a detailed picture at different pH values. Both approaches were used considering the strength and constraints of each one. NMR experiments were performed at pH 7.4 where at least 95% of the drug molecules are in their protonated state. From NMR, sumatriptan shows partition on the interfacial region of model membranes (near the head groups and intercalating between adjacent lipids), inducing changes in chemical environment and affecting lipid dynamics of liposomes, in a dose dependent manner. Due to the experimental instability of lipid bilayers at high pH, we took advantage of the molecular dynamics power to emulate different pH values, to simulate sumatriptan in bilayers including at fully uncharged state. Simulations show that the neutral species have preferential orientation within the bilayer interface while the distribution of protonated drugs is independent on the initial conditions. In summary, several properties depicted the interfacial partition of the anti-migraine drug at the water-lipid interface at different conditions. Both techniques were found complementary to shed light on the structural and dynamics of sumatriptan-lipid bilayer interactions.Fil: Wood, Irene. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Fabian, Lucas Emanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: Moglioni, Albertina Gladys. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: Cabeça, Luis Fernando. Universidade Tecnologia Federal Do Parana.; BrasilFil: de Paula, Eneida. Universidade Estadual de Campinas; BrasilFil: Pickholz, Mónica Andrea. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

Inclusion Complex between Local Anesthetic/2-hydroxypropyl-β-cyclodextrin in Stealth Liposome

The drugs delivery system in the treatment of diseases has advantages such as reduced toxicity, increased availability of the drug, etc. Therefore, studies of the supramolecular interactions between local anesthetics (LAs) butamben (BTB) or ropivacaine (RVC) complexed with 2-hydroxypropyl-β-cyclodextrin (HP-βCD) and carried in Stealth liposomal (SL) are performed. 1H-NMR nuclear magnetic resonance (DOSY and STD) were used as the main tools. The displacements observed in the 1H-NMR presented the complexion between LAs and HP-βCD. The diffusion coefficients of free BTB and RVC were 7.70 × 10−10 m2 s−1 and 4.07 × 10−10 m2 s−1, and in the complex with HP-βCD were 1.90 × 10−10 m2 s−1 and 3.64 × 10−10 m2 s−1, respectively, which indicate a strong interaction between the BTB molecule and HP-βCD (98.3% molar fraction and Ka = 72.279 L/mol). With STD-NMR, the encapsulation of the BTB/HP-βCD and RVC/HP-βCD in SL vesicles was proven. Beyond the saturation transfer to the LAs, there is the magnetization transfer to the hydrogens of HP-βCD. BTB and RVC have already been studied in normal liposome systems; however, little is known of their behavior in SL

Improvement Of Tetracaine Antinociceptive Effect By Inclusion In Cyclodextrins.

Local anesthetics (LA) are among the most important pharmacological compounds used to attenuate or eliminate pain. However, systemic toxicity is still a limitation for LA application, especially for ester-type drugs, such as tetracaine (TTC) that presents poor chemical stability (due to hydrolysis by plasma esterases). Several approaches have been used to improve LA pharmaceutical properties, including the employment of drug-delivery systems. Here we used beta-cyclodextrin (β-CD) or hydroxypropyl-beta-cyclodextrin (HP-β-CD) to develop two new TTC formulations (TTC:β-CD and TTC:HP-β-CD). The inclusion complexes formation, in a 1:1 stoichiometry, was confirmed by differential scanning calorimetry, X-ray diffraction, UV-VIS absorption and fluorescence. Nuclear magnetic resonance (DOSY experiments) revealed that TTC association with HP-β-CD is stronger (Ka=1200 mol/L(-1)) than with β-CD (Ka=845 mol/L(-1)). Moreover, nuclear Overhauser effect (NOE) experiments provided information on the topology of the complexes, where TTC aromatic ring is buried inside the CD hydrophobic cavity. In vitro tests with 3T3 fibroblast cells culture revealed that complexation decreased TTC cytotoxicity. In addition, the total analgesic effect of TTC, tested in rats through the infraorbital nerve test, was improved in 36% with TTC:β-CD and TTC:HP-β-CD. In conclusion, these formulations presented potential for future clinical use, by reducing the toxicity and increasing the antinociceptive effect of tetracaine.2085-9