Résumé
Citrus are rich in flavonoids such as flavones and flavanones. Recent studies have shown that these phytonutrients play a beneficial role for human health. Citrus plants can contain high levels of hesperidin, a flavanone which is effective in the treatment of chronic venous insufficiency. Nobiletin and tangeretin are two polymethoxylated flavones. Nobiletin has been shown to increase hepatic insulin sensitivity and decrease atherosclerosis. Tangeretin may have antiproliferative and anticarcinogenic effects by blocking MAPKs activation and ROS generation. Studies on flavonoids from citrus are generally focussed on ripe fruits and on one group of metabolites. The aim of this study is to quantify accurately all groups of flavonoid from leaves of mandarin (Citrus deliciosa). Flavones and flavanones analysis was carried out by liquid chromatography and mass spectrometry (LC-MS) using a new generation column. Moreover, a specific gradient was designed to evaluate both flavanones and methoxylated flavones. This method was applied to leaves from mandarin tree. All leaves were fully-expanded, and were about one-year-old from the spring flush of the previous season. They were of similar height above the ground, had the same east orientation and experienced similar exposure to light. Comparison of metabolite levels revealed that mandarin leaves were rich in hesperidin, nobiletin and tangeretin. Interestingly, nobiletin and tangeretin also accumulated in high level. (Texte integral)