Isolation and Tandem Mass Spectometric Characterization of Selected Crocus sativus L. (Saffron) Bioactive Compounds
Saffron, the dried stigmas of Crocus sativus L., is an expensive spice that is used mainly as a medicine or food coloring and flavoring agent in different parts of the world. The major biologically active ingredients of saffron are crocin analogues, including crocins 1–4, which are all glycosides of trans-crocetin, a carotenoid derivative. cis-Crocetin and its glycosides are also present, although they make up the minor components in saffron [1, 2]. In addition, saffron also contains the flavonoid derivatives, picrocrocin and its aglycone safranal, in lower quantities. In this study, extraction of saffron was carried out using 50% methanol and was evaluated qualitatively using HPLC-DAD profiling. According to the Rt and UV spectra, crocin analogues (cis and trans), kaempherol glycosides, picrocrocin and safranal were detected. The analytical method that was used for the profiling was transferred to preparative MPLC and HPLC scale and was used for the fractionation and purification of the aforementioned constituents, respectively. The complete identification of the purified compounds was performed using NMR (1 & 2D) and HRMS/MS spectrometric methods. Fingerprinting of crocus extracts was performed by LC-electrospray (ESI) mass spectrometry (MS) on Orbitrap and QqRTOF systems. Moreover, selected saffron compounds (e.g., trans-crocin, cis-crocin and picrocrocin) were further characterized by various tandem mass spectrometric techniques such as vacuum MALDI-TOF/RTOF-MS in combination with collision-induced dissociation intermediate pressure MALDI-QqRTOF-MS/MS, ESI-QqRTOF-MS/MS, ESI-LTQ-orbitrap-MS/MS and ESI-IT-MS/MS. Furthermore, high-energy CID on the stable [M+Na]+ adduct ions yielded the highest content of structural information.
References: 1. Choi HJ et al. (2001) Dyes Pigment 49: 15–20.
2. Tarantilis AP et al. (1995)J Chromatogr A 699: 107–118.