RESUMEN
Abstract Polyelectrolyte complexes (PECs) as drug delivery systems are widely explored since they are easily obtained by coacervation and biopolymers can be associated. However, particle distribution is a challenging critical parameter that has been infrequently focused. This work evaluated the effect of NaCl concentration on the physicochemical properties of PECs based on chitosan and hypromellose loaded with methotrexate. The particle size, zeta potential and polydispersity index (PdI) were determined by DLS, besides of drug entrapment efficiency (EE) and in vitro drug release profile determination. Particle size decreased while NaCl concentration rised, achieving a narrower size distribution of (345±79 nm) and PdI (0.285±0.067) with 200 mmol/L NaCl. The higher the NaCl concentration, the lower the zeta potential at acid pH. The EE was kept similar ((28.2±4.5) %) from 0 to 300 mmol/L NaCl, while 400 mmol/L NaCl impaired the drug entrapment. The addition of (200 and 300) mmol/L NaCl did not affect the drug release profile, but it was faster with (100 or 400) mmol/L. In conclusion, the addition of 200 mmol/L NaCl reduced particle size and PdI with no changes in the EE and drug release. Therefore, the ionic strength plays an important role on PECs development.
RESUMEN
To explore in vivo application of quantum dots (QDs), it is essential to understand the dynamics and energetics of interactions between QDs and proteins. Here, surface plasmon resonance (SPR) and molecular docking were employed to investigate the kinetics and thermodynamics of interactions between human serum albumin (HSA) and CdTe QDs (~3 nm) functionalized with mercaptopropionic acid (MPA) or thioglycolic acid (TGA). Kinetic analysis showed that HSA-QD interactions involved transition-complex formation. Despite the structural similarities between MPA and TGA, the [HSA-CdTe@TGA] formation by association of free HSA and QDs demanded 70% more energy and higher entropic gain (Ea-TGA= 65.10 and T∆Sa-TGA= 28.62 kJ mol-1) than the formation of [HSA-CdTe@MPA] (Ea-MPA = 38.13 and T∆Sa-MPA = 0.53kJ mol-1). While the [HSA-CdTe@MPA]° dissociation required higher energy and lower entropy loss (Ed-MPA = 49.96 and T∆Sd-MPA = - 32.18kJ mol-1) than the [HSA-CdTe@TGA]° dissociation (Ed-TGA= 30.78 and T∆Sd-TGA= - 51.12 kJ mol-1). The stability of [HSA-QDs]° was independent of the temperature and functionalizing group. However, the enthalpic and entropic components were highly affected by the substitution of MPA (ΔH° = - 11.83 and TΔS° = 32.72 kJ mol-1) with TGA (ΔH° = 34.31 and TΔS° = 79.73 kJ mol-1). Furthermore, molecular docking results indicated that the metal site on the QDs contributes to the stabilization of [HSA-QDs]°. Therefore, differences in QD functionalization and surface coverage densities can alter the HSA-QD interaction, thus their application.
Asunto(s)
Compuestos de Cadmio/farmacología , Albúmina Sérica Humana/metabolismo , Compuestos de Sulfhidrilo/química , Telurio/farmacología , Tioglicolatos/química , Compuestos de Cadmio/química , Entropía , Humanos , Cinética , Simulación del Acoplamiento Molecular , Puntos Cuánticos , Albúmina Sérica Humana/química , Resonancia por Plasmón de Superficie , Telurio/química , TermodinámicaRESUMEN
There is some evidence in the literature of the photocyclization reaction of Tagitinin C (1) to Tagitinin F (2). Compound 2 has high pharmacological potential, but it is not easy to obtain, while compound 1 is easily obtained from a widespread plant, Tithonia diversifolia. Among different reaction conditions monitored, one was found that allowed the cyclization of 1 into 2 in <15 min in a photo-dependent reaction. Scaling-up the photocyclization of the pure compound 1 into 2 demonstrated 100% yield, and the isolation of 2 from a UV-irradiated extract was eight-fold higher than the quantity isolated from the non-UV-irradiated extract. We were also able to better understand the process of photoconversion and determine methods to isolate and quantify these compounds, which are known for their important antitumoral activities among other important pharmacological properties.
Asunto(s)
Procesos Fotoquímicos , Extractos Vegetales/química , Sesquiterpenos/aislamiento & purificación , Cromatografía Líquida de Alta Presión , Ciclización , Espectroscopía de Resonancia Magnética , Espectrometría de Masas/métodos , Reproducibilidad de los Resultados , Sesquiterpenos/química , Espectrofotometría Ultravioleta , Rayos UltravioletaRESUMEN
O presente estudo teve como objetivo avaliar o efeito hipolipidêmico do flavonóide rutina, do medicamento colestiramina, do corante natural betalaína, bem como verificar o sinergismo entre o flavonóide rutina associado à betalaína investigando seus efeitos em coelhos. Os resultados foram significativos para o flavonóide e betalaína isoladamente e associados, ou seja, verificando-se o efeito hipolipidêmico e sinérgico destas substâncias nos parâmetros analisados de colesterol total, colesterol-DDL, colesterol-LDL e triacilgliceróis