## 4 Discussion  
Plant development stages significantly influence the accumulation of specialized metabolites, with different compounds often peaking at specific growth phases to support functions like defense, signaling, or reproduction [26]. Thus, preparations for potential medicinal use may vary in their properties depending on the plant's developmental stage, as the concentration and composition of bioactive compounds fluctuate throughout growth [26]. Herein, we compared ginkgo leaf infusions prepared from green leaves collected in spring and yellow leaves harvested in autumn, both directly from the tree and from fallen leaves. Collecting leaves after they have fallen, rather than harvesting them directly from the tree, can lower labor requirements and prevent damage to the tree, offering a more sustainable approach to leaf collection. The total polyphenol and flavonoid content followed a similar pattern, with significantly higher amounts found in both types of yellow leaves. A similar trend was reported by [PERSON] et al. [15], who compared the polyphenol and flavonoid content in PBS/ethyl acetate fractions of green and yellow ginkgo leaves, finding nearly double the content in yellow leaf extracts. [PERSON] et al. [27] also reported higher flavonoid content in yellow than in green leaves. This aligns with our results, where yellow leaves--both from trees and fallen--showed approximately 3.2-fold and 2.5-fold higher polyphenol and flavonoid content, respectively, compared to infusions made from green leaves. In total polyphenol and flavonoid content, we observed slightly higher amounts in yellow leaves collected directly from the trees, suggesting that some degradation of these compounds occurs in fallen leaves. Nevertheless, the levels in fallen leaves remained higher than those found in spring leaves. Although some published re  
Figure 5: DPPH radical inhibition (%) by infusions prepared from different ginkgo leaf types. Data labeled with different letters differed significantly at \(p<0.05\). ports [12] suggest that infusions contain fewer polyphenols compared to extracts prepared with organic solvents, our current results are consistent with previously published findings on the total flavonoid and polyphenolic content in ginkgo leaf extracts prepared with 80% methanol [28] and 70-80% ethanol [14; 29; 30]. [PERSON] et al. [13] compared total polyphenol content in infusions and 12% ethanol extracts and reported higher content in infusions. In our study, HPLC-DAD analysis of the infusions did not detect biflavonoids, a group of dimeric flavonoids that were among the most abundant flavonoids identified in ginkgo leaf extracts prepared with 70% ethanol [14] and 80% methanol [19], as well as in those prepared using deep eutectic solvents [28]. This absence is likely due to their insolubility in water [31]. The flavonoids found in the infusions can be annotated as monomeric flavonoids and flavonoid glycosides (Supplementary Materials), with a higher abundance observed in yellow leaves, as confirmed by spectrophotometric methods. In the salivary phase for green leaves, we noted lower bioaccessibility compared to yellow leaves. However, after all three digestion phases, we did not observe a significant reduction during the intestinal digestion phase. [PERSON] et al. [32] evaluated the in vitro digestion of ginkgo leaf decoction and commercial capsules, noting that individual compounds underwent more significant changes during the intestinal and complete digestion stages, while antioxidant activity increased following in vitro digestion. Polyphenol and flavonoid content in plants often correlates well with antioxidant activity, as these compounds are known to possess strong antioxidant properties. Our results similarly show higher antioxidant activity in yellow leaves, both fallen and those collected directly from trees. This trend aligns with previous findings by [PERSON] et al. [13], who reported higher DPPH inhibition capacity in infusions prepared from leaves collected in autumn.