Seasonal variation of antioxidant activity and bioactive compounds in Acer tegmentosum stems

Acer tegmentosum , traditionally used in East Asian ethnomedicine to treat liver-related disorders, is a deciduous tree whose stems are gaining interest for their pharmacological potential. To provide scientific evidence supporting traditional uses and optimize harvesting practices, this study evaluated the seasonal variation in antioxidant activity and phytochemical contents of A. tegmentosum stems. Monthly samples from May to September were extracted using 70% ethanol and analyzed for DPPH radical scavenging activity and levels of salidroside, catechin, and epicatechin gallate using HPLC. Antioxidant activity increased progressively with harvest time, from 51.4% in May to 70.1% in September at 40 ppm. Similarly, total phenolic content increased from 457.1 to 482.6 μg GAE/g. Among the quantified compounds, salidroside—a phenylethanoid glycoside known for hepatoprotective effects—showed a significant increase from 56.02 to 61.48 mg/g. In contrast, catechin and epicatechin gallate levels remained relatively unchanged.These results provide a scientific rationale for traditional knowledge recommending late-summer harvesting to enhance medicinal efficacy. The study highlights how seasonal factors influence the pharmacological quality of plant materials and reinforces the importance of aligning modern analytical techniques with ethnopharmacological insights. This research contributes to the evidence-based validation of herbal medicines and supports the sustainable development of functional botanical products derived from A. tegmentosum . Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany