Phenolic Composition and Antioxidant Activity of Edible Flowers: Insights from Synergistic Effects and Multivariate...

The phenolic composition and antioxidant activity of four edible flowers-Orange marigold, yellow marigold, rose geranium, and Rosa de Santa Teresinha-were evaluated to explore their potential as natural antioxidants. Rosa de Santa Teresinha exhibited the highest total phenol content (83.34 ± 2.09 mg GA g^-1 DW) and ortho-diphenol content (168.91 ± 0.15 mg GA g^-1 DW), while the marigolds showed significantly lower levels (~17 mg GA g^-1 DW for total phenols). Antioxidant activity, determined via ABTS, DPPH, and FRAP assays, ranged from 0.11 to 0.96 mmol Trolox g^-1 DW, with rose geranium and Rosa de Santa Teresinha achieving the highest values. Theoretical antioxidant contributions, calculated based on the identified phenolic compounds, accounted for only a small fraction of the measured activity, with observed values exceeding predictions by factors of 56 to 1416, indicating the presence of synergistic interactions and additional bioactive compounds. Multivariate analyses (PCA and PLS regression) identified luteolin-7-O-glucoside and quercetin-3-O-galactoside as primary contributors to antioxidant capacity. These results underscore the importance of synergistic effects in edible flowers and highlight their potential as functional ingredients for nutraceutical applications.