Determination of the phytoalexin resveratrol (3,5,4′-trihydroxystilbene) in peanuts and pistachios by high-performance liquid chromatographic diode array (HPLC-DAD) and gas chromatography-mass Spectrometry (GC-MS)

The phytoalexin resveratrol (3,5,4'-trihydroxystilbene) in edible peanut (Arachis hypogaea L.) and pistachio (Pistacia vera L.) varieties grown in Turkey was analyzed by high-performance liquid chromatographic diode array and gas chromatography-mass spectrometric detection. trans-resveratrol in six peanut varieties, five pistachio varieties, and four market samples ranged between 0.03 and 1.92 mu g/g. The qerezlik 5025 peanut (1.92 +/- 0.01 mu g/g) and Ohadi pistachio genotype (1.67 +/- 0.01 mu g/g) had significantly higher trans-resveratrol contents. Peanuts contained 0.03-1.92 mu g/g (av = 0.84 mu g/g) of trans-resveratrol, whereas pistachio contained 0.09-1.67 mu g/g (av = 1.15 mu g/g). With exposure to UV light for 1 min, trans-resveratrol concentrations of samples ranged from 0.02 to 1.47 mu g/g and those of cis-resveratrol from 0.008 to 0.32 mu g/g. The occurrence of resveratrol in peanut and pistachio was confirmed by total ion chromatograms (TIC) of bis[trimethylsilyl]trifluoroacetamide derivatives of resveratrol isomers and comparison of the mass spectral fragmentation data with those of a resveratrol standard. Formation of the cis-isomer in pistachios was higher than in peanuts.