Assessment of phytochemicals, nutritional compositions and metabolite profiling using GCMS– from annual edible flowers

Abstract

In this work, the nutritional value and phytochemical content of the six annual flower petals such as Pansy (Viola wittorckiana), Dianthus (Dianthus chinensis), Cosmos (Cosmos bipinnatus), Calendula (Calendula officinalis), Petunia (Petunia hybrida), and Geranium (Pelargonium hortorum), were assessed. Gas Chromatography-Mass spectrometry (GC–MS) was utilized to characterize their metabolites in addition to assessing their antioxidant and antibacterial activities. Dianthus chinensis was found to have the highest concentrations among all six annuals' components, including total protein (19.5 gm/100 g), ascorbic acid (100 mg/100 g), anthocyanin (1.23 mg Cyn. H./g), total reducing capacity (9.47 mg GAE/g), and hydrolysable tannin (36.96 mg TAE/g). While TPC and TFC values in all of the studied flowers ranged from 13.94 to 107.9 mg catechol/g and 13.3 to 135.84 mg rutin /g, respectively. Maximum TPC was found in geranium flowers (107.9 mg catechol/g). The pansy was shown to have a minimum amount of total phenol (13.9 mg catechol/g). Calendula has the highest level of β-carotene (0.85 mg/g), whereas the cosmos has the highest amount of carotenoid (18.8 µg/g) and lycopene (0.55 µg/g) among the flowers. Petunia flowers showed the highest antioxidant activity (98.3 %), according to the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, followed by pansies (87.6 %), cosmos (65 %), geraniums (56.3 %), and calendula (46.4 %), with the exception of Dianthus. The concentration of micronutrients differed significantly among all six flowers which accumulated nutrients in descending order from (highest to lowest) Fe (1771 ppm) > Zn (143 ppm)>Cu (21.1 ppm) with maximum concentration obtained in Cosmos, Dianthus, and Calendula, respectively. It was found that Petunia extracts exhibited the highest antimicrobial properties, with a maximum growth inhibition zone against Salmonella typhi A (S. typhi A), S. typhi B, Enterobacter, and Pseudomonas with hexane extract, except for S. typhi. However, Dianthus extracts exhibited the highest growth inhibition zones against Enterobacter. Several bioactive metabolites were found in the petals during GC–MS analysis. Among others, notable metabolites include ß-Amyrin, Caryophyllene, 2,4-Di‑tert-butylphenol, ß-Sitosterol, and Stigmasterol, while brewing samples include significant amounts of phenylethyl alcohol, indole, 4-Vinylphenol,.tau.-Muurolol, and 2-Methoxy-4-Vinylphenol. The results are significant information that may be utilized to promote the consumption of annual edible flowers and to recognize their usage as flower infusions or as tea supplements.