# Phytochemicals and Antioxidant Properties of Edible Flowers
## 1 Introduction  
The word phytochemicals is derived from two Greek words \"\(\varphi\)\" and \"\(\varphi\)\"\(\varphi\)\", which mean plants and chemicals, respectively. Therefore, phytochemicals are chemical compounds that are derived from plants. According to the most common definition, _phytochemicals are defined as bioactive non-nutrient plant compounds in fruits, vegetables, grains, and other plant foods that have been linked to reducing the risk of major chronic diseases_[1]. However, in plants they are produced through secondary biochemical pathways due to environmental stimulations and as a response to various challenges. They play several roles during all stages of plant growth and are essential for their survival (Figure 1) [2]. These roles may explain several characteristics and properties of phytochemicals such as their taste, color or even aroma. In the case of taste, phytochemicals may be bitter or even toxic (in interactions with nervous systems of animals) in order to limit their consumption from herbivores. Some of them present characteristic colors and aromas in order to attract the necessary pollinators or the enemies of herbivores by producing a mixture of phytochemicals as a response to tissue damage [2].  
Flowers are parts of plants that also contain amounts of several phytochemicals, and therefore they have been used since ancient times for their potential therapeutic properties in medicine or for culinary purposes [3]. Nowadays, the results of several research studies support these potential health properties of edible flowers, known since ancient times. In addition, these studies concluded that it is mainly the antioxidant activities of such compounds that are responsible for these health benefits, since they are linked with the prevention of several diseases (Figure 2). Therefore, various recent review articles are available reporting the potential health benefits of phytochemicals from edible flowers [3, 4, 5, 6].  
Edible flowers are sources of a variety of bioactive compounds, and the most common include phenolic acids, flavonoids, carotenoids, tools and terpene compounds. However,some other compounds in lower concentrations may also be detected, such as alkaloids, nitrogen-containing compounds and organosulfur compounds [7,8].  
As already mentioned, there are several works available regarding the functional characteristics of edible flowers; however, the majority of them focus on the health benefits, and in some of them a brief description of the main compounds is presented [3, 4, 5, 6, 7, 8]. The aim of the present study is to provide a detailed presentation of the main compounds detected in edible flowers and the possible antioxidant activity. In the present work, more than 200 edible flowers, analyzed in different studies, have been collected and presented.  
This comprehensive review was based on a search in electronic databases such as Scopus and Google Scholar and related articles regarding edible flowers, as well as their total phenolic content and antioxidant activity. The keywords used were 'edible flower' and each one of the terms 'antioxidant', 'total phenolic content', 'total flavonoid content', 'phenolic acids', 'flavonoids', 'carotenoids', 'tocols' and 'terpenes', found in the title/abstract/keywords. Subsequently, a systematic review related to the phenolic compounds of edible flowers and their antioxidant properties was performed. An attempt was made to mainly include works from the last 5-10 years.  
Figure 1: Phytochemicals and their role in plants.