Identification of Flavonoids and Hydroxycinnamic Acids in Pak Choi Varieties ( Brassica campestris L. ssp. chinensis var. communis) by HPLC–ESI-MS ⁿ and NMR and Their Quantification by HPLC–DAD

Abstract

Twenty-eight polyphenols (11 flavonoid derivatives and 17 hydroxycinnamic acid derivatives) were detected in different cultivars of the Chinese cabbage pak choi ( Brassica campestris L. ssp. chinensis var. communis) by HPLC-DAD-ESI-MS(n). Kaempferol was found to be the major flavonoid in pak choi, glycosylated and acylated with different compounds. Smaller amounts of isorhamnetin were also detected. A structural determination was carried out by (1)H and (13)C NMR spectroscopy for the main compound, kaempferol-3-O-hydroxyferuloylsophoroside-7-O-glucoside, for the first time. Hydroxycinnamic acid derivatives were identified as different esters of quinic acid, glycosides, and malic acid. The latter ones are described for the first time in cabbages. The content of polyphenols was determined in 11 cultivars of pak choi, with higher concentrations present in the leaf blade than in the leaf stem. Hydroxycinnamic acid esters, particularly malic acid derivatives, are present in both the leaf blade and leaf stem, whereas flavonoid levels were determined only in the leaf blade.

Application of ultra performance liquid chromatography-photodiode detector-quadrupole/time of flight-mass spectrometry (UPLC-PDA-Q/TOF-MS) method for the characterization of phenolic compounds of Lepidium sativum L. sprouts

“…The sinapic acid was identified by UPLC-PDA-MS-MS method by comparison with standards. The molecular mass identified for sinapic acid by MS is the same as reported by Harbaum et al [22]. This compound was previously reported in L. sativum by other researchers [16].…”

“…In positive mode of ions, the breakdown into fragments of ethyl ester of sinapic acid (loss of trimethyl amine) [29] and into fragments of sinapic acid (loss of H 2 O and CH 3 OH) was observed at m/z 207.0647 and 175.0392. The molecular mass for sinapine calculated by MS is the same as reported by Harbaum et al [22].…”

Strategies for differentiation of isobaric flavonoids using liquid chromatography coupled to electrospray ionization mass spectrometry

“…Upon evaluating the MRM transitions corresponding to the 287xxx the results indicates (see Figure S5) that most likely more than 10 cyanidin containing compounds are present in the red onion sample. Peak nr 3,5,6,8,10,14,15,17,20,21,27,29,34,35, and 39 (see Figure S5), all show MRM patterns that are similar to the cyanidin standards that were analyzed in this study. The peak in Figure S5 with a retention time of 24.3 min (compound 10) has a retention time close to one of the available standards, Cy-3-rut entry 9 in Table 3, however, method 2 indicates that m/z 611 is the parent ion and not m/z 595.…”

“…One approach found in the literature for achieving this utilizes basic and acidic hydrolysis in such a way that substituents are cleaved off, more or less completely, before chromatographic analysis. [8,[20][21][22] One limitation with this approach is that information about the number of flavonoids with a specific aglycone could not directly be obtained. Furthermore, C-linked substituents are more resistant against hydrolysis [8] , thus identity of those aglycones will not be obtained.…”

“…287.1/213.1 (20) 287.1/137.1 (16) 128 (38) 157 (35) 139 (26) 121 (11) 213 (11) 449287 (100) 213 (23) 241 (23) 145 (15) 157 (12) (37) 127 (33) 173 (30) 115 (30) 465.1/303.1 (100) 627.1/303.1 (30) 465303 (100) 257 (11) 229 (10) 285 (8) 165 (5) 22 (47) 203 (47) 229 (27) 479.1/317.1 (100) 479317 (100) 285 (43) 302 (34) 139 (19) 261 (14) ? n.d. not detected.…”