A comparative analysis of the composition of the primary bioactive molecules, antioxidant activities, and anti-inflammation abilities of the roots of Zanthoxylum nitidum harvested at different years of cultivation.

Zanthoxylum nitidum is a traditional medicinal herb prevalent in China and Southeast Asia. However, despite being a widely cultivated perennial woody plant, an accurate reference and guide for determining the appropriate harvesting age in lacking. This study employed high-performance liquid chromatography (HPLC) and ultraviolet-visible (UV-Vis) spectrophotometry, along with in vitro antioxidant and in vivo anti-inflammatory assays, to comprehensively analyze and compare the roots of Z. nitidum at 1–9 and 14 years. The results indicated a positive correlation between the increase in age and the root biomass. The highest decoction rates were observed in the roots of the 5- (44.08 %) and 4-year-old plants (40.42 %). However, the total alkaloid content (TAC) and the levels of nitidine chloride (NC), chelerythrine, and sanguinarine chloride initially increased but then decreased; their highest contents were 1.49 % (3-year-old), 0.50 % (7-year-old), 0.50 % (5-year-old), and 0.061 % (6-year-old), respectively. The levels of magnoflorine exhibited a trend of 3-year peaks; the respective contents were 0.36 % (3-year-old), 0.30 % (5-year-old), and 0.33 % (14-year-old). The change in the in vitro antioxidant potency composite index correlated with the wave-like trends in the total flavonoid content (TFC) and total phenolic acid (TPA). The indices for 9-, 5-, and 3-year-olds ranked among the top three and were >90. Extracts of Z. nitidum roots demonstrated a therapeutic effect in dextran sulfate sodium-induced ulcerative colitis mice, with that from the roots of 5-year-old plants showing the highest impact. Overall, the Z. nitidum roots of 4–6-year-old plants can be harvested as high-quality raw materials that meet the Pharmacopoeia of the People's Republic of China standards. This study provides scientific references for aspects such as the rational harvesting of Z. nitidum during artificial cultivation, the optimal utilization of land resources, and clinical use. [Display omitted] • First comparative evaluation this species at different growth years. • Alkaloid contents showed uni or bimodal patterns of variation. • Anti-oxidant capacity fluctuated. • The highest in vivo anti-inflammation effect was exhibited by five-year-old plants. [ABSTRACT FROM AUTHOR]