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Nutritional composition and antioxidant capacity in edible flowers: characterisation of phenolic compounds by HPLC-DAD-ESI/MSn.

Navarro-González I, González-Barrio R, García-Valverde V, Bautista-Ortín AB, Periago MJ - Int J Mol Sci (2014)

Bottom Line: In relation to the nutritional value, the edible flowers had a composition similar to that of other plant foods, with a high water and TDF content, low protein content and very low proportion of total fat-showing significant differences among samples.The levels of TPC compounds and the antioxidant capacity were significantly higher in T. erecta, followed by S. oleracea and T. majus.In T. erecta small proportions of gallotannin and ellagic acid were also identified.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Technology, Food Science and Nutrition, Faculty of Veterinary Sciences, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, Espinardo 30071 (Murcia), Spain. inmanago@yahoo.es.

ABSTRACT
Edible flowers are commonly used in human nutrition and their consumption has increased in recent years. The aim of this study was to ascertain the nutritional composition and the content and profile of phenolic compounds of three edible flowers, monks cress (Tropaeolum majus), marigold (Tagetes erecta) and paracress (Spilanthes oleracea), and to determine the relationship between the presence of phenolic compounds and the antioxidant capacity. Proximate composition, total dietary fibre (TDF) and minerals were analysed according to official methods: total phenolic compounds (TPC) were determined with Folin-Ciocalteu's reagent, whereas antioxidant capacity was evaluated using Trolox Equivalent Antioxidant Capacity (TEAC) and Oxygen Radical Absorbance Capacity (ORAC) assays. In addition, phenolic compounds were characterised by HPLC-DAD-MSn. In relation to the nutritional value, the edible flowers had a composition similar to that of other plant foods, with a high water and TDF content, low protein content and very low proportion of total fat-showing significant differences among samples. The levels of TPC compounds and the antioxidant capacity were significantly higher in T. erecta, followed by S. oleracea and T. majus. Thirty-nine different phenolic compounds were tentatively identified, with flavonols being the major compounds detected in all samples, followed by anthocyanins and hydroxycynnamic acid derivatives. In T. erecta small proportions of gallotannin and ellagic acid were also identified.

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Identification of the edible flowers and the proportions of the individual phenolic compounds as part of the total compounds identified by HPLC-DAD-ESI/MSn.
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ijms-16-00805-f002: Identification of the edible flowers and the proportions of the individual phenolic compounds as part of the total compounds identified by HPLC-DAD-ESI/MSn.

Mentions: The main phenolic compounds detected in the methanolic extract of T. majus are shown in Figure 1 and Figure 2 and Table 4, and were identified as flavonol-glycosides and hydroxycinnamic acid derivatives (581 and 124 µg/g, respectively, data not shown). In addition one anthocyanin was also characterised (105.8 µg/g, data not shown). Peaks 1–5 and 7 had UV spectra with λmax between 305 and 325 nm, characteristic of hydroxycinnamic acids. The mass spectral analysis revealed that they had a negatively charged quasi-molecular ion ([M-H]−) at m/z 353 and 337 (Table 4 and Figure 1). By comparison of their fragmentation pattern with spectrometric characteristics previously reported in the literature, these peaks were identified as isomeric forms of caffeoylquinic acid and p-coumaroylquinic acid [36,37,38,40]. A total of seven flavonol-glycosides were also identified in the flowers of T. majus according to their UV spectra, with λmax between 347 and 355 nm. Peaks 6, 9 and 10 had an [M-H]− at m/z 641, 625 and 609, respectively. The MS2 analyses showed fragment ions corresponding to the loss of 180 amu [M-H-180]−, which is characteristic of the loss of the terminal glucose from a sophorosyl moiety [41]. Other fragments at m/z 317, 301 and 285 correspond to the mass of myricetin, quercetin and kaempferol (i.e., the aglycons without the sophorosyl moiety), respectively, indicating that peaks 6, 9 and 10 are myricetin-3-O-sophoroside, quercetin-3-O-sophoroside and kaempferol-3-O-sophoroside, respectively. The loss of 180 amu was also observed for peak 11, which allowed the presence of a sophorosyl moiety in the structure to be determined. This peak displayed a UV spectrum similar to that of peak 10; however, peak 11 had an [M-H]− at m/z 651, indicating that this peak is kaempferol-3-O-acetylsophoroside.


Nutritional composition and antioxidant capacity in edible flowers: characterisation of phenolic compounds by HPLC-DAD-ESI/MSn.

Navarro-González I, González-Barrio R, García-Valverde V, Bautista-Ortín AB, Periago MJ - Int J Mol Sci (2014)

Identification of the edible flowers and the proportions of the individual phenolic compounds as part of the total compounds identified by HPLC-DAD-ESI/MSn.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4307276&req=5

ijms-16-00805-f002: Identification of the edible flowers and the proportions of the individual phenolic compounds as part of the total compounds identified by HPLC-DAD-ESI/MSn.
Mentions: The main phenolic compounds detected in the methanolic extract of T. majus are shown in Figure 1 and Figure 2 and Table 4, and were identified as flavonol-glycosides and hydroxycinnamic acid derivatives (581 and 124 µg/g, respectively, data not shown). In addition one anthocyanin was also characterised (105.8 µg/g, data not shown). Peaks 1–5 and 7 had UV spectra with λmax between 305 and 325 nm, characteristic of hydroxycinnamic acids. The mass spectral analysis revealed that they had a negatively charged quasi-molecular ion ([M-H]−) at m/z 353 and 337 (Table 4 and Figure 1). By comparison of their fragmentation pattern with spectrometric characteristics previously reported in the literature, these peaks were identified as isomeric forms of caffeoylquinic acid and p-coumaroylquinic acid [36,37,38,40]. A total of seven flavonol-glycosides were also identified in the flowers of T. majus according to their UV spectra, with λmax between 347 and 355 nm. Peaks 6, 9 and 10 had an [M-H]− at m/z 641, 625 and 609, respectively. The MS2 analyses showed fragment ions corresponding to the loss of 180 amu [M-H-180]−, which is characteristic of the loss of the terminal glucose from a sophorosyl moiety [41]. Other fragments at m/z 317, 301 and 285 correspond to the mass of myricetin, quercetin and kaempferol (i.e., the aglycons without the sophorosyl moiety), respectively, indicating that peaks 6, 9 and 10 are myricetin-3-O-sophoroside, quercetin-3-O-sophoroside and kaempferol-3-O-sophoroside, respectively. The loss of 180 amu was also observed for peak 11, which allowed the presence of a sophorosyl moiety in the structure to be determined. This peak displayed a UV spectrum similar to that of peak 10; however, peak 11 had an [M-H]− at m/z 651, indicating that this peak is kaempferol-3-O-acetylsophoroside.

Bottom Line: In relation to the nutritional value, the edible flowers had a composition similar to that of other plant foods, with a high water and TDF content, low protein content and very low proportion of total fat-showing significant differences among samples.The levels of TPC compounds and the antioxidant capacity were significantly higher in T. erecta, followed by S. oleracea and T. majus.In T. erecta small proportions of gallotannin and ellagic acid were also identified.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Technology, Food Science and Nutrition, Faculty of Veterinary Sciences, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, Espinardo 30071 (Murcia), Spain. inmanago@yahoo.es.

ABSTRACT
Edible flowers are commonly used in human nutrition and their consumption has increased in recent years. The aim of this study was to ascertain the nutritional composition and the content and profile of phenolic compounds of three edible flowers, monks cress (Tropaeolum majus), marigold (Tagetes erecta) and paracress (Spilanthes oleracea), and to determine the relationship between the presence of phenolic compounds and the antioxidant capacity. Proximate composition, total dietary fibre (TDF) and minerals were analysed according to official methods: total phenolic compounds (TPC) were determined with Folin-Ciocalteu's reagent, whereas antioxidant capacity was evaluated using Trolox Equivalent Antioxidant Capacity (TEAC) and Oxygen Radical Absorbance Capacity (ORAC) assays. In addition, phenolic compounds were characterised by HPLC-DAD-MSn. In relation to the nutritional value, the edible flowers had a composition similar to that of other plant foods, with a high water and TDF content, low protein content and very low proportion of total fat-showing significant differences among samples. The levels of TPC compounds and the antioxidant capacity were significantly higher in T. erecta, followed by S. oleracea and T. majus. Thirty-nine different phenolic compounds were tentatively identified, with flavonols being the major compounds detected in all samples, followed by anthocyanins and hydroxycynnamic acid derivatives. In T. erecta small proportions of gallotannin and ellagic acid were also identified.

Show MeSH