Síntese e caracterização de sistema de liberação a base de vitexina e ZIF-8

Abstract

The objective of this work was to plan the synthesis of ZIF-8 and carry out its characterization, as well as carry out the characterization of vitexin (VIT) and to obtain and characterize (physical-chemical and pharmacological) a system based on vitexin and ZIF-8. For the synthesis of ZIF-8, a 32 factorial design was used and the ZIF-8 was characterized by techniques such as FT-IR, TG, DSC and SEM. VIT was obtained from the leaves of Jatropha mutabilis and was characterized by the techniques already mentioned; UV-vis and HPLC-DAD calibration curves were obtained, their release profile was evaluated, and their quantitative solubility was verified. For the synthesis of VIT@ZIF-8 system, a 22 factorial design was used; the characterization was performed by the tests mentioned above and the pharmacological action was verified in a murine model of primary dysmenorrhea. Among the reaction conditions used for the synthesis of ZIF-8, the one that provided the best yield was the one with reagents in a 1:2 ratio and occurred for 12 h; FT-IR analysis showed the characteristic bands present in 2-methylimidazole; SEM analyzes revealed the standard appearance of the MOF under study; TG analysis revealed mass loss thermal events related to water desorption, degradation of unbound 2-methylimidazole molecules and degradation of ZIF-8; the ZIF-8 DSC curve revealed no signs. Regarding vitexin, its structure was confirmed by NMR and FT-IR, with the presence of published characteristic signals and bands; its solubility proved to be low; the constructed calibration curves were linear, and their release did not exceed 35%; TG analysis revealed mass loss thermal events related to adsorbed water loss, melting and degradation; the DSC curve revealed a single endothermic event related to its fusion; SEM analysis revealed crystal morphology into spheres of different sizes. On VIT@ZIF-8, it was evidenced that the conditions that provide the best results for yield and incorporation rate were achieved at high levels; FT-IR revealed characteristic signals for VIT and ZIF-8, in addition to a new signal at 1743 cm-1 that can be considered evidence of system formation; TG and DSC data evidenced the characteristic events for both test substances, and a new thermal pattern was revealed for VIT@ZIF-8; the release test revealed that VIT@ZIF-8 releases 100% of the vitexin incorporated into the net within 1 min; regarding the pharmacological action, vitexin and VIT@ZIF-8 were able to reduce abdominal contortions orally at concentrations of 3 and 30 mg/kg, however, intraperitoneally this effect was only observed at a concentration of 30 mg/ kg. The work brought new data, which reaffirms its importance and originality.