Analysis of Fatty Acid Esters of Hydroxyl Fatty Acid in Selected Plant Food.

Metabolic syndrome, characterized by obesity, low-grade inflammation, insulin resistance, hyperglycemia, dyslipidemia and hypertension, is a major risk factor for cardiovascular mortality. Preclinical studies on recently discovered classes of lipids - fatty acid esters of hydroxy fatty acids (FAHFA) have revealed their anti-inflammatory and insulin-sensitizing potential. The FAHFA levels are significantly decreased in insulin-resistant individuals, their application exhibited anti-inflammatory effects and restoring the glucose-insulin homeostasis. The aim of our research was to analyze the overall FAHFA composition in a common diet, as only a partial FAHFA composition has been revealed so far (only the PAHSA subclass was analyzed in a few foods). A new approach to the FAHFAs analysis includes nano-LC and post-column modifier followed by negative ion mass spectrometry, in order to obtain maximum sensitivity. Analysis of different foods - oat (whole grain, coarse flakes and fine flakes), apple, clementine, lemon, strawberry, blueberry, mango, kiwi, avocado, pineapple, banana, onion, garlic, cherry tomato, carrot, parsley root, pepper and radish - exhibited wide inter-food variation in the FAHFA profiles. Sixteen analyzed FAHFAs (palmitic, oleic, palmitoleic and stearic hydroxy-esters) showed microgram to low nanogram levels (0.165 ng/g - 32 μg/g FW), with the highest abundancy in oat, clementine, garlic and pineapple. Stearic acid hydroxy stearic acid (SAHSA) was the most abundant FAHFA, especially in the food with antioxidative, anti-inflammatory and beneficial metabolic effects. In contrary, the PAHSA - previously proven to have the strongest antihyperglycemic and insulin-sensitizing effects, was not present in some foods (radish, avocado, mango, lemon, cherry tomato, kiwi). Our study proves the importance of overall FAHFA analysis in food (especially in a functional food), because of their potential metabolic benefits and possible future incorporation in special diets.