# Phytochemicals and Antioxidant Properties of Edible Flowers
## 2 Phytochemicals
### Phenolic Compounds
#### 2.1.3 Flavonoids  
Flavonoids, a class of low-molecular-weight phenolic compounds, are an important group of natural products, which are characteristic compounds and the largest group of secondary metabolites in plants [27]. In plants, flavonoids, as all the phenolic compounds, participate in the mechanisms of growth and protection. Many flavonoids are the main flower pigments in most plants. Flavonoids can be easily divided in several subgroups; however, this review will be focus on anthocyanins, flavones and flavanones, and flavanols. The total flavonoid content (TFC) of more than 100 edible flowers is presented in Tables 5 and 6. The TFC of 65 edible flowers showed a wide variation from 0.7 to 85.3 mg CAE (catechin equivalents)/g DW, with a more than 120-fold difference. The highest TFC was reported in flowers of _Osmanthus fragrans_ (85.3 mg CAE/g DW), _Lonicera japonica_ (52.5 mg CAE/g DW), _Coreopsis tinctoria_ (29.3 mg CAE/g DW), _Helichrysum bracteatum_ (28.59 mg CAE/g DW) and _Armeniaca mume_ (28.50 mg CAE/g DW). On the other hand, the lowest TFC was reported in _Cucumis sativus_ Linn. (0.7 mg CAE/g DW), _Hylocereus undatus_ (0.8 mg CAE/g DW) and _Hemerocallis citrina_ (0.9 mg CAE/g DW). This study concluded that Chrysanthemum species may contain higher flavonoids than Rosa species [20]. The TFC of 23 edible flowers, expressed as mg rutin equivalents per gram of dry weight (mg RE/g DW) varied from 0.5 to 71.5 mg RE/g DW with a 159-fold difference. _Osmanthus fragrans_ (Thunb.) [PERSON] had the highest total flavonoid content (71.5 mg RE/g DW), followed by _Lavandula angustifolia_ Mill (27.4 mg RE/g DW), _Rosmarinus officinalis_ L. (18.8 mg RE/g DW), _Perennial chamonille_ (16.0 mg RE/g DW) and _Chamonilia_ (15.7 mg RE/g DW). _Gomplrena globose_ Linn had the lowest TFC (0.5 mg RE/g DW), followed by _Redarfulplum tea_ (0.7 mg RE/g DW) [18]. Figure 3: The major hydroxycinnamic and hydroxybenzoic acids. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Flower** & **TFC** & **Flower** & **TFC** & **Flower** & **TFC** \\ \hline mg RE/g DW [18] & & & & \\ \hline _Calendula officinalis_ L. & 3.0 & _Jasntium samuc_ (L.) Ait & 3.8 & _Perennial chamomile_ & 16.0 \\ _Chmomilia_ & 15.7 & _Lavandula angustifolia_ Mill. & 27.4 & _Radix Gentiane_ & 6.9 \\ _Chimonanthus praecox_ (L.) & 6.0 & _Lilium broxmi_ var. & 1.9 & _Redraftplum tea_ & 0.7 \\ Link & & _viridulum_ & 1.9 & _Rosa rugosa_ Thumb (pink) & 3.4 \\ _Chrysanthemum morifolium_ & 10.4 & _Matricaria recutita_ & 17.6 & _Rosa rugosa_ Thumb (pink) & 3.4 \\ _Dendranthema morifolium_ & 9.6 & _Myostis sylvatica_ & 4.3 & _Rosa rugosa_ Thumb (purple) & 6.6 \\ _Dianthus carophyllus_ & 1.4 &
\begin{tabular}{c} _Osnanthus fragrans_ \\ (Thumb.) [PERSON]. \\ \end{tabular} & 71.5 & _Rosmarinus officinalis_ L. & 18.8 \\ _Gombrena globosa_ Linn. & 0.5 & _Paorenia lactiflora_ Pall. & 13.8 & _Siriatia grosvenorii_ & 4.5 \\ _Hibiscus sabdarififa_ L. & 1.9 & & \\ \hline mg QE/g DW [14] & & [14] & & \\ \hline _Allium schoneprossum_ L. & 4.6 & _Hemercollis hybrida_ hort & 9.6 & _Agave salniana_ & 4.6 \\ _Begonia tuberhybrida_ [PERSON]. & 22.0 & _Lavandula angustifolia_ Mill. & 2.1 & _Aloe vera_ & 7.8 \\ _Calendula officinalis_ L. & 7.8 & _Rosa rugosa_ & 14.4 & _Erythrina Americana_ & 25.3 \\ _Centaurea cyanus_ L. & 4.8 & _Sambucus nigra_ L. & 2.1 & _Myrtillocatus geometrizans_ & 72.4 \\ _Chrysanthemum_ & 5.7 & _Tagates_ L. & 14.7 & & \\ _Cucutbita pepo_ L. & 3.6 & _Tropaculum majus_ & 0.8 & & \\ _Dianthus_ L. & 11.9 & _Viola tricolor_ L. & 1.5 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Total flavonoid content (mg RE/g DW or mg QE/g DW) of several edible flowers.