Phytochemical profile and Allelopathic Potential of Globularia alypum L
摘要
Leaf extracts of Globularia alypum were investigated for their phytochemical profile, antioxidant capacity, and allelopathic potential. Methanolic extracts showed an extraction yield 45% higher than aqueous extracts and contained 2- and 1.8-fold higher total phenolic and flavonoid contents, respectively. Accordingly, the aqueous extract exhibited an IC₅₀ nearly twice that of the methanolic extract, indicating lower radical-scavenging capacity. The allelopathic effects of G. alypum aqueous leaf extract were evaluated in canary grass (Phalaris canariensis L.) and radish (Raphanus sativus L.) under controlled conditions. Seeds were germinated for seven days in the presence of increasing extract concentrations (0–125 g L-1). A strong dose-dependent inhibition of germination and seedling growth was observed. Canary grass was particularly sensitive, showing a 42% reduction in germination rate at 25 g L⁻¹ and up to 99% inhibition at 125 g L⁻¹. In contrast, radish exhibited greater tolerance at low concentrations (25 and 50 g L⁻¹). Growth inhibition was associated with oxidative stress, as evidenced by increased hydrogen peroxide levels, lipid peroxidation, and NADPH-oxidase activity. At 125 g L-1, NADPH-oxidase activity increased by 227% in canary grass and 155% in radish. At concentrations ≥ 75 g L⁻¹, key antioxidant enzymes declined markedly, with reductions of 64%, 50%, and 74% in ascorbate peroxidase, monodehydroascorbate reductase, and glutathione reductase activities, respectively, in canary grass at 100 g L⁻¹. These alterations led to a pronounced decrease in the redox ratios of ascorbate, glutathione, and NADPH pools. In contrast, radish seedlings maintained a more stable redox balance at low and moderate extract concentrations (25 and 50 g L⁻¹). Overall, G. alypum exhibits selective allelopathic activity, highlighting its potential as a natural biopesticide.