Phenolic content and profile alterations during seedling growth in supina bluegrass and bermudagrass

Poaceae encompasses many species with substantial regrowth potential, providing a sustainable source of bioactive agents. Research remains limited on the type of grass providing the highest bioactive yields, the optimal harvest time, and the agents present at these times. Therefore, the objective of this study was to evaluate two amenity grasses, supina bluegrass (Poa supina Schrad.) and bermudagrass [Cynodon dactylon (L.) Pers.], as novel sources of dietary bioagents. Considering that bioactives are typically extracted from seedlings, this investigation evaluated alterations in soluble phenolic content or composition and antioxidative capacity during seedling growth (0–21 d). Both supina bluegrass and bermudagrass seedlings contained total soluble free phenols (TSFP) levels comparable with those present in fruits and vegetables. In bermudagrass, the most apparent changes occurred after 21 d of growth, exhibiting a significant spike in TSFP (7.7 mg gallic acid equivalents g⁻¹), total soluble free flavonoids (TSFF, 3.0 mg catechin equivalents g⁻¹), and antioxidant capacity values (96.6 mg trolox equivalents g⁻¹). Kaempferol was abundant throughout the stages and increased to 1.97 mg g⁻¹ at 21 d. Only subtle differences in TSFP, TSFF, and antioxidant capacity were detected during supina bluegrass seedling growth. Analysis of the phenolic profile of supina bluegrass showed increasing ferulic acid (7.75 μg g⁻¹ fresh wt. at 21 d) and caffeic acid (2.15 μg mL⁻¹ fresh wt. at 21 d) over time. These results support that bermudagrass and supina bluegrass seedlings are viable sources for phenolic bioactives.