Plant Maturity Differentially Affects the Phenolic Composition and Antioxidant Properties of Green Basil (<i>Ocimum basilicum</i> L.) Cultivars

Basil is an aromatic herb of culinary importance as well as a rich source of phenolic compounds, secondary plant metabolites with strong antioxidant properties that are associated with dietary health benefits. Although basil is cultivated worldwide, little is known about how its phytochemical content changes as the plant matures, information that is useful to identify harvest strategies that maximize the herb's nutritional value. Therefore, the aim of this study was to determine the effects of plant development on the phenolic composition and antioxidant properties of three green basil cultivars (Genovese, Spicy, and Tuscany) that were harvested weekly throughout the vegetative stage. Average total phenolic content (TPC), individual phenolic acid concentrations, and antioxidant capacity values showed significant cultivar × plant maturity interactions, indicating that these properties change with plant growth in genotype-specific ways. TPC values and the concentrations of rosmarinic, caffeic, and caftaric acids generally increased as basil plants matured. Caffeic acid had the highest concentrations (0.71-5.00 mg/100 g dry weight, depending on the cultivar) and levels correlated strongly with basil height (<i>r</i> _s = 0.717; <i>p</i> < 0.001) and leaf mass (<i>r</i> _s = 0.676; <i>p</i> < 0.001), suggesting that its accumulation is closely associated with plant growth. Hierarchical cluster analysis revealed that the genotype exerts a greater influence than plant maturity on the phenolic composition of Genovese and Tuscany basils. In contrast, the chemical properties of Spicy basil varied greatly with developmental stage, implying that plant maturity plays a larger role in the phytochemical profile of this cultivar.