Abstract:

A method for the determination of trigonelline in pumpkin flesh was established using high performance liquid chromatography (HPLC). Samples were defatted in a Soxhlet extractor with absolute ethyl ether as solvent and extracted with 70% aqueous ethanol with microwave assistance. An Agilent Zorbax SB-C18 column kept at ambient temperature was used for the chromatographic separation with 0.40 mmol/L aqueous solution of phosphoric acid (pH 3.2) as a mobile phase at a flow rate of 0.6 mL/min. The injection volume was 10 μL. The detection wavelength was set at 265 nm. Results showed that the developed standard curve of trigonelline exhibited good linearity over the concentration of 5.6 to 134.4 μg/mL, with a correlation coefficient of 0.9999 (n = 5). The average recovery for trigonelline in a total of 6 real samples spiked at 3 levels repeated twice each in 5 replicates was 97.09%, with a relative standard deviation of 1.02%. This method proved to be simple, accurate and of good repeatability so as to be most suitable for the determination of trigonelline in pumpkin pulp. Thirteen cultivars of pumpkin pulp were determined by the method to have very different trigonelline contents ranging between 172.5μg/g and 475.5 μg/g.

Key words: pumpkin, trigonelline, high performance liquid chromatography