Functional, Antioxidant, Antibacterial, and Antifungal Activity of Edible Flowers

Edible flowers have been used since ancient times, but their potential for improving human health has not been explored. This study aimed to evaluate the profile of bioactive compounds (organic acids, phenolics, and carotenoids) and the antioxidant and antimicrobial activity of nine flower varieties with high concentrations of carotenoids or total phenolic compounds. Ninety-three edible flowers were analysed for physicochemical characteristics, total phenolic and carotenoid concentrations, and antioxidant activity (ABTS). Bioactive profiles were determined by rapid resolution liquid chromatography (RRLC), and antimicrobial activity was determined against <i>Escherichia coli</i>, <i>Staphylococcus aureus</i>, <i>Pseudomonas aeruginosa</i> and <i>Streptococcus mutans</i>, and <i>Candida albicans</i> and <i>Candida tropicalis. Chrysanthemum x hybrid</i> orange, <i>Helianthus annuus</i> yellow, <i>Tagetes patula</i> orange, <i>Canna indica</i> red, and <i>Hibiscus rosa-sinensis</i> (orange1 and yellow) showed significant concentrations of total carotenoids. In contrast, <i>Pelargonium hortorum</i> orange2, <i>Hibiscus rosa-sinensis</i> red1, and <i>Rosa x hybrid</i> variety medium yellow showed high levels of total phenolics. The predominant compounds in these species were citric acid (991.4 mg/g DW in <i>Hibiscus rosa-sinensis</i> red1), 4-hydroxybenzoic acid (936.2 mg/100 g DW in <i>P. hortorum</i> orange2), kaempferol (971. 9 mg/100 g DW in <i>T. patula</i> orange), quercetin glucoside (958.8 in <i>C. x hybrid</i>), quercetin (919.3 mg/100 g DW in <i>T. patula</i>), α-carotene, and β-carotene in <i>T. patula</i> orange (989.5 and 601.2 mg/100 g DW, respectively). Regarding antimicrobial activity, <i>T. patula</i> orange and <i>P. hortorum</i> orange2 inhibited bacterial growth, while <i>C. x hybrid</i> orange and <i>P. hortorum</i> orange2 inhibited <i>Candida albicans,</i> and the latter inhibited <i>Candida tropicalis</i>. These results indicate the potential of edible flowers as a natural source of bioactive compounds and as a tool in the fight against antimicrobial resistance.