LEVELS OF PYRROLOQUINOLINE QUINONE IN VARIOUS FOODS

The levels of free pyrroloquinoline quinone (PQQ) in various foods wer e examined by the use of gas chromatography-mass spectrometry. PQQ was extracted from the samples, after addition of [U-C-13]PQQ as internal standard, with n-butanol and Sep-Pak C-18 cartridges. After derivatiz ation of PQQ with phenyltrimethylammonium hydroxide, molecular peaks a t m/z 448 and 462 were used for detection of PQQ and [U-C-13]PQQ respe ctively, by selected ion monitoring. Free PQQ could be detected in eve ry sample in the range 3.7-61 ng/g or ng/ml. Since its levels in human tissues and body fluids are 5-10 times lower than those found in food s, it is probable that PQQ existing in human tissues is derived, at le ast partly, from the diet.