Title: Fractionation of the secondary metabolites of orange (Citrus sinensis L.) leaves by fast centrifugal partition chromatography Author
Submitted to: Florida State Horticultural Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 16, 2010
Publication Date: N/A
Technical Abstract: There is interest in the detection of changes in secondary metabolites in orange leaves in response to citrus greening disease. Conventional HPLC analysis readily provides detection of major phenolic compounds, but further, more detailed chromatographic analyses show many more compounds, to an extent where peak overlap prevent distinct detection and reliable quantitation of these numerous minor constituents. Hence, to achieve a more complete chromatographic analysis of orange leaf compounds, further fractionation of the complex compound profiles of orange leaves is needed, and this was achieved by Fast Centrifugal Partition Chromatography (FCPC). Separations by FCPC were accomplished with the biphasic system of ethanol/butanol/water (20/80/100). Distribution coefficients, Kd (Kupper/lower), ranged from 0.20 to >10 for the polar to nonpolar compounds. Kd values did not always correlate with compound polarity estimated by elution times on reversed phase columns. Early eluted fractions provided recoveries of polar and midpolar hydroxycinnamates. Later eluting fractions contained various clusters of polar and midpolar flavones, many of which, in the intact extract, significantly overlapped. Components of the notorious “humptogram” of leaf extracts were resolved into their flavone and hydroxycinnamate constituents. Such resolution helps provide better chromatographic detection of individual components in this complex region of orange leaf HPLC chromatograms.