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Radical scavenging potential of pumpkin seed oil

Pumpkin (Cucurbita pepo L.) seed oil is a common salad oil in a northern part of Croatia. Besides the traditional production method (crushing the seeds, roasting and pressing at elevated temperatures) cold production method (crushing the seeds, roasting and pressing at max. 40°C) recently apeared. As a result, pumpkin seed oils differing in organoleptical, as well as, chemical characterists, were produced. In this work, antioxidant activity of several pumpkin seed oil samples, differing in production method, was investigated by electron spin resonance (ESR) and UV-VIS spectroscopy. Galvinoxyl radical (GO) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) were used as scavenging object for the ESR. GO was dissolved in isooctane with the radical concentration of 0.15 mmol/L while DPPH solution with the radical concentration of 0.10 mmol/L was prepared using ethyl acetate as solvent. The freshly prepared radical solution was added to the pumpkin-seed oil samples in order to obtain 3 and 4% (w/v) oil solution. The moment at which the radical solution was put in contact with oil sample was taken as t = 0. ESR measurements were performed at room temperature and the loss of the signal intensity was measured as a function of time. DPPH was applied as scavenging object for UV-VIS measurements. The absorbance was measured at l = 515 nm as a function of the time past from the addition of DPPH solution (0.10 mmol/L) to oil samples. The inhibition of GO, as well as DPPH, in the case of the traditionally produced pumpkin-seed oils was very rapid, and better comparing cold method produced oil samples. Although the reaction of inhibition during the first minute of scavenging reaction was similar between differently produced oil samples, it differ significantly comparing end time point. For each oil sample, scavenging mechanisms were similar, comparing ESR scavenging object, as well as, radical-scavenging activity methods.

Radical scavenging potential; pumpkin seed oil; ESR; UV-VIS

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