Exploring wild edible flowers as a source of bioactive compounds: New perspectives in horticulture

The increasing interest in healthy and natural foods has raised the attention towards uncommon or unexplored ingredients, such as edible flowers. These products are proven to be a rich source of bioactive compounds, for example, vitamins or polyphenols that play an important role in health promotion and disease prevention. However, plant species with edible flowers are numerous and most of them still need to be studied with this aim. The high species richness of North-Western Italy provides interesting perspectives in the use of wild edible flowers, which are currently underutilized, but can be a valuable food source or food supplement for healthy diets. In this framework, the phytochemical composition of 22 wild edible flowers was analysed and compared with that of four cultivated species (Borago officinalis L., Calendula officinalis L., Tagetes patula L. and Tropaeolum majus L.) to evaluate their potentiality as sources of bioactive compounds. The total polyphenol content (TPC) and antioxidant activity of the fresh flowers were assessed, together with their phenolic profiles and vitamin C content, through spectrophotometric and chromatographic analyses. The evaluated parameters varied widely among species, with Paeonia officinalis L. and Rosa pendulina L. showing the highest values of polyphenols (1,930 mg gallic acid equivalents (GAE) · 100 g-1 and 1,774 mg GAE · 100 g-1, respectively), followed by Rosa canina L. (1,397 mg GAE · 100 g-1) and Geranium sylvaticum L. (1,268 mg GAE · 100 g-1). The same species also showed the highest antioxidant activity, measured with three different assays [ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS)]. The phenolic profile differed among the studied species, with Dianthus pavonius Tausch and R. pendulina having the highest sum of detected polyphenols (2,522 mg · 100 g-1 and 2,366 mg · 100 g-1, respectively). Vitamin C was identified in all but two flowers (Allium ursinum L. and B. officinalis) and Primula veris L. had the highest amount (45 mg · 100 g-1). The study showed that wild edible flowers outperformed the cultivated species, except for T. majus, providing new insights for the use of wild edible flowers as sources of bioactive compounds.