UHPLC-Orbitrap MS characterization of total phenolics in French marigold (Tagetes patula L.) extracts

Abstract

Aqueous, ethanol and methanol extracts of aerial parts of ornamental French marigold (Tagetes patula L.), which consist mostly of flavonoids, have been reported to exhibit different biological activities, including cytotoxic effect on various human cancer cell lines. However, some of the most potent flavonoids characteristic for the genus Tagetes, such as quercetagetin and patuletin, are rare in nature. Thus, optimization of extraction process together with employment of sensitive techniques and detection equipment should be of interest in gaining information about marigold biologically active compounds. In the present study, separate extracts of leaves and flowers were obtained from dry plant material by overnight incubation in methanol, dichloromethane or hot (60 °C) water, followed by ultrasonic bath maceration. UHPLC–LTQ/orbitrap/MS, employed for separation and identification, revealed the presence of 68 different compounds in total, belonging to phenolic acids (20 compounds), flavonoid glycosides (37 compounds), and flavonoid aglycones (11 compounds). The highest number of compounds was detected in methanol extracts, i.e. 55 in flowers and 60 in leaves, while after the extraction in dichloromethane only 23 compounds were detected in leaves and 24 in flowers. In both leaves and flowers, the most diversified were flavonoid glycosides with quercetin and patuletin in 3, 7 or 3,7 di-O- derivativeforms. Aglycon patuletin was detected in all analyzed extracts, while quercetagetin was detected only in methanol and dichloromethane extracts of flowers. Obtained data confirmed T. patula extracts as a rich source of compounds with biological and potential pharmacological values.