Scale-up of polyphenolic isolation by HPLC from Uncaria guianensis leaves by applying chromatographic models

Uncaria guianensis (UG) (Rubiaceae) is a species widely used in traditional medicine. The EtOH extract of their leaves has demonstrated anti-inflammatory and anti-allergic activities. In this work Semi-Prep-HPLC was employed to separate the polyphenolic compounds present in the UG EtOH leaf extract by applying chromatographic models. Polyphenolic enriched fractions previously obtained by RP-CC were analyzed in an Inertsil Prep-ODS column (250×6mm, 10µm), 30°C, flow rate 1.4 mL/min, isocratic mode of CH₃CN:H₂O at five different compositions (3% to 20% v/v) and UV detection at 265 and 280nm. From the retention times and the peak widths, the parameters k (capacity) and h (reduced plate height) were determined. From the application of the k data in four different models those based on linear and squared equations have shown correlation coefficient above 0.99 thus well representing the retention. Average h value was adopted. The prediction of the retention and efficiency of the compounds under unevaluated conditions was then possible. By applying two chromatographic models expressed by statistical moments, the simulation of the chromatograms under volume overload indicated the best conditions to isolate the compounds in each fraction. Kaempferitrin (˜98% pure by ¹H NMR) and other minor polyphenolic compounds were separated and their structures are currently under characterization.