RESUMO
In this work a multivariate statistical tool (Derringer and Suich optimization) was proposed for the separation of seventeen capsinoids (natural and synthetic) using the UHPLC-DAD chromatography. Capsinoids were analyzed at 280 nm. The variables optimized were the mobile phase (water (0.1% acetic acid as solvent A) and acetonitrile (0.1% as solvent B)), gradient time and flow rate. Two columns with different length (50 and 100 mm) were used for the chromatographic separation. The two columns used properly separated the seventeen capsinoids, however the 100 mm column length showed a better chromatographic separation with a shorter run time and smaller peak widths. These results provided better values of limit of detection and quantification for the 100 mm column length. The better conditions of separation with the 100 mm column length were established with: initial mobile phase with 41.8% of solvent B; 3.96 min of linear gradient time to reach 100% of solvent B; flow rate of 0.679 mL min(-1). A validation of the method has been done with excellent values of repeatability (RSD<1.92) and intermediate precision (RSD<3.92). The developed method has been applied to real samples. Capsiate has been identified and quantified in some varieties of peppers.
Assuntos
Capsaicina/análogos & derivados , Capsaicina/isolamento & purificação , Capsicum/química , Cromatografia Líquida de Alta Pressão/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Análise Fatorial , Limite de Detecção , Reprodutibilidade dos TestesRESUMO
A bio-guided optimization of the extraction of bioactive components from Annona glabra leaves has been developed using the etiolated wheat coleoptile bioassay as the control method. The optimization of an ultrasound-assisted extraction of bioactive compounds using allelopathy results as target values has been carried out for the first time. A two-level fractional factorial experimental design was applied to optimize the ultrasound-assisted extraction. The solvent was the extraction variable that had the most marked effect on the resulting bioactivity of the extracts in the etiolated wheat coleoptile bioassay. Extraction time, extraction temperature and the size of the ultrasonic probe also influenced the bioactivity of the extracts. A larger scale extraction was carried out in the next step in the allelopathic study, i.e., the isolation of compounds from the bioactive extract and chemical characterization by spectroscopic techniques, including NMR. Eight compounds were isolated and identified from the active extracts, namely two steroids (ß-sistosterol and stigmasterol), five diterpenes with the kaurane skeleton (ent-kaur-16-en-19-oic acid, ent-19-methoxy-19-oxokauran-17-oic acid, annoglabasin B, ent-17-hydroxykaur-15-en-19-oic acid and ent-15ß,16ß-epoxy-17-hydroxy-kauran-19-oic acid) and the acetogenin asimicin. The most active compound was annoglabasin B, which showed inhibition with values of -95% at 10(-3) M, -87% at 5×10(-4) M and greater than -70% at 10(-4) M in the etiolated wheat coleoptile bioassay.