Ornamental Asteraceae Species as New Sources of Secondary Metabolites

Abstract:

Objective: This paper presents the results regarding the morphological characters, the content in total phenols, the metabolites profile and the antioxidant activity of outdoor cultivated Rudbeckia hirta var. Goldilocks and Tagetes erecta plants. Material and Methods: The plant material was represented by flower buds and fully bloomed inflorescences taken from Rudbeckia hirta var. Goldilocks and Tagetes erecta. Morphological assessment was carried using microscopy, while chemical assessment used thin layer chromatography (TLC) and UHPLC methods. The total phenolic content was established with Folin- Ciocalteu method. The antioxidant activity was evaluated with DPPH radical scavenging tests. The secondary metabolites were evaluated in two different nutritional statuses. Results: The results indicated that the studied ornamental Asteraceae species represent rich sources of phenols. However, the fertilization lowers the plant’s biosynthetic capacity for polyphenols for both Rudbeckia and Tagetes flowers. Thus, by fertilizing, the flowers of Tagetes lose components such as polyphenolic acids, modifying their spectrum. Regarding the antioxidant activity, Tagetes erecta showed a promising activity against free radicals. Conclusion: The concentration of plant secondary metabolites was found to be influenced by the nutritional status. Both species represent a good source for secondary metabolites, but their biological potential remains to be established.

Key words: Rudbeckia, Tagetes, Secondary metabolites, Ornamental plants, Antioxidant activity.