Identification and quantification of flavonols, anthocyanins and lutein diesters in tepals of Crocus sativus by ultra performance liquid chromatography coupled to diode array and ion trap mass spectrometry detections

Ultra performance liquid chromatography coupled to diode array detection (UPLC DAD) and ion trap mass spectrometry with either electrospray ionization (ESI-MSn) or atmospheric pressure chemical ionization (APCI-MSn) interface were used to investigate flavonols, anthocyanins and lutein diesters in tepals from Crocus sativus. Extraction by methanol/water (1:1, v/v) containing 1% hydrochloric acid was selected as the optimal solvent mixture for a quantitative extraction of flavonols and anthocyanins. A UPLC method for separation of nineteen flavonols: kaempferol, quercetin and isorhamnetin glycosides as mono-, di- or tri-glycosides and five anthocyanins reported as delphinidin, petunidin and malvidin glycosides was achieved. Kaempferol glycosides were the major flavonols (84.0% of total flavonol content) in C. sativus tepals, the main compound was kaempferol 3-O-sophoroside. Isorhamnetin 3-O-sophoroside, kaempferol 3-O-rutinoside and quercetin 3-O-glucoside 7-O-rhamnoside in C. sativus tepals were newly identified. Anthocyanins were quantified for the first time in C. sativus tepals (4804 ± 233 μg g−1 DW), the main anthocyanin identified was delphinidin 3,7-O-diglucoside. For the first time, (E) and (Z) isomers of lutein diesters with lauric, myristic, palmitic and stearic acids were found in C. sativus and characterized by UPLC DAD/APCI-MS. A gradient programme consisting of methanol/water (8:1, v/v) and ethyl acetate was developed for their qualitative and quantitative analyses. Lutein diesters’ content (21.46 ± 0.98 mg 100 g−1 DW) in tepals from C. sativus was comparable to food products, lutein diesters represented 69% of the total lutein diesters’ content.

► Analysis of flavonoids and carotenoids in Crocus sativus tepals by UPLC DAD/MSn. ► Three kaempferol glycosides were newly identified in C. sativus tepals. ► First report of the anthocyanin content in tepals from C. sativus. ► For the first time lutein diesters were identified in C. sativus. ► C. sativus tepals are a workable by-product of the saffron industry.