Aplicação de cromatografia a líquido de alta eficiência preparativa para isolamento de alcaloides de Cissampelos sympodialis Eichl. e estudo de farmacocinética preliminar de Warifteína

Abstract

The application of preparative high pressure liquid chromatography (PREP-HPLC) in the isolation of natural products is shown as a robust, versatile and fast technique that ensures the purification and isolation of substances in complex matrices, as natural products. This technique is a powerful tool in an area in which purification and obtainment of samples in large amount is somewhat laborious, and often, there is a need for re-isolation of samples; thus, its reproducibility is a great advantage. The combination of HPLC with mass spectrometry allows merging the advantages of chromatography, such as the high selectivity and separation efficiency, with the mass spectrometry advantages, as information related to molecular structure, the molar mass and enhancement of additional selectivity. Cissampelos sympodialis Eichl. is a Brazilian species and the infusion of this plant is traditionally used in the northeast of Brazil to treat asthma, bronchitis and rheumatism, between other inflammatory diseases. The objective of this work to develop a rapid and reproducible method for isolation of established chemical biomarkers of plant and other alkaloids from C. sympodialis Eichl., and use the standard of warifteine in quantification of it in biological fluids to determine the pharmacokinetic parameters of the alkaloid after administration of it in rats in vivo. The chromatographic method consisted of a gradient from 0-15 min (75 % B), 15-20 min (80 % B), 20-25 min (100 % B),  278 nm, and flow of 5.0 mL/min during 20 min, with mobile phase of methanol (B) and water (A) basified with ammonium to reach pH 8.0, and the amount of sample mass injected per experiment was 800 mg. The alkaloids isolated were warifteine (99.79 % of purity), methyl-warifteine (98.52 % of purity), the mixture of epimers of desmethyl-roraimine, and a new alkaloid not referred in literature that was elucidated and named as Sousine. Animals from Ratus novergicus species received an intravenous single dose of warifteine of 1.0 mg/Kg, and the blood samples were collected in 5, 15, 30, 60, 120 and 180 minutes. The blood samples were centrifuged to obtain the plasma and then were extracted by protein precipitation with acetonitrile. The pharmacokinetic parameters were calculated based on plasmatic concentrations versus time curves using non-compartmental model. The linearity range to chromatographic method was between 10 and 500 ng/mL e the kinetic parameters were Cmáx 16.08 μg/mL, Tmáx 12.5 min-1, Kel 0.01355 min-1. The method developed to isolation of alkaloids from C. sympodialis Eichl. is a practical, rapid and robust one. The HPLC-MS/MS method enabled to quantify warifteine in rat plasma with samples extraction by protein precipitation, yet, there was a great variability between animals in the kinetics experiment.