# Phytochemicals and Antioxidant Properties of Edible Flowers
## 2 Phytochemicals
### Phenolic Compounds
#### 2.1.3 Flavonoids
(light red color and 3.7 \(\upmu\)g/g FW). _Cosmos sulphureus_ Cav., _Clitoria ternatea_ L. and _Dianthus chinensis_ L. were the edible flowers with the highest content of both flavanones (hesperidin and naringenin). However, the same study reported a low bioaccessibility of these flavanones compared to other phenolic compounds, with the highest value of 11% detected in _Dianthus chinensis_ L. It is well-known that hesperidin, as a rutinoside, is more difficult to be absorbed, compared to hesperitin, which can be absorbed directly in the small intestine. Hesperidin should be first fermented by the intestinal microorganisms in order to become more easily absorbed. The flavanone composition of 70 edible flowers from China revealed mainly hesperitin (up to 2162 \(\upmu\)g/g DW), naringin (up to 28,001 \(\upmu\)g/g DW) and naringenin (up to 1187 \(\upmu\)g/g DW) [36]. Hesperitin was detected in the majority of edible flowers, followed by naringin and naringenin. However, among the 70 flower samples, hesperitin was only detected in seven, naringin in four, and naringenin in three. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Flavones/Flavanones** & **Flower** & **Reference** \\ \multicolumn{2}{c}{**(and Their Derivatives)**} \\ \hline Acacetin & _Chrysanthemum morifolium_ & [40] \\ \hline Apigenin & _Chrysanthemum indicum_ L., _Chrysanthemum lavandulfolium_, _Chrysanthemum morifolium_, _Chrysanthemum morifolium_, _Clitoria ternatea L., _Florists chrysanthemum_, _Helichrysum bractatum_, _Matthiola incana_, _Nelumbo nucifera_ [PERSON], _Rosa_ & [36; 41; 42] \\ \hline Chrysoeriol & Tree peony flowers, _Hemerocallis fulva_ & [43; 44] \\ \hline Chrysin & _Chrysanthemum morifolium_, _Helichrysum bracteatum_ & [36] \\ \hline Eriddictytol & _Fengdan Bai_ (tree peony), _Impatiens valleriana_, _Chrysanthemum morifolium_ & [45; 46; 47] \\ \hline Hesperetin & _Amygdala persica_, _Chrysanthemum indicum_, _Chrysanthemum_ \\  & _lavandulfolium_, _Chrysanthemum morifolium_, _Cirtus aurantium_ L., _Gombrena globose_, _Hylocereus undatus_, _Musa busjo_ [PERSON]. et Zucc. \\ \hline Hesperidin & _Cirtus aurantium_ L., _Rosa chinensis_, _Torenia fournieri_, _Clitoria ternatea_ L. & [39; 48] \\ \hline Luteolin & _Chrysanthemum indicum_ L., _Chrysanthemum morifolium_, _Glycyrrhiza_ & [41; 47; 49; 50] \\ \hline Naringenin & _Anygdala persica_, _Helichrysum bracteatum_, _Nymphaea hybrid_, _Begonia_\(\times\)_tubchybrida_ Voss., _Rosa chinensis_, _Torenia fournieri_, _Clitoria_ & [36; 39] \\ \hline Naringin & _Cirtus aurantium_, _Rhododendon simsi planch_, _Rosa chinensis_, _Nymphaea_ & [36] \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Major flavones and flavanones detected in several edible flowers. Flavonols  
Flavonols are usually the group of flavonoids with the higher content in edible flowers, even among total phenolic compounds [7; 51]. This group of flavonoids has a double bond between C2 and C3 and a carbonyl at C4. Glycoslation normally occurs at C3 as mono-, di-, or triglycerides, while there is also the possibility for glucuronidation [10]. The most frequently determined flavonoids in edible flowers are quercetin, quercetin and isoquercitrin, hyperoside, rutin and other quercetin derivatives, kaemberol and its derivatives, isorham-nein and its derivatives and myricetin and its derivatives (Table 8). Although almost all flowers present high (>2200 mg/100g _Diantthus pavonius_) or low concentrations of flavonoids (<1 mg/100 g), according to [PERSON] et al., [17], flowers of _Centaurea cyanus_ (0.9 mg/100 g), _Taraxecum officinal_ (1.8 mg/100 g), _Tagetes patula_ (0.5 mg/100 g) and _Calendula officinalis_ (1.7 mg/100 g), are very poor in flavonoids, while in flowers of _Bellis perennis_, _Salvia pratensis_ and _Borago officinalis_, flavonoids are lacking completely.