Metabolomic and phytochemical insights into tree age effects on Lycium barbarum fruits quality.

Tree age plays a crucial role in determining metabolite accumulation in Lycium barbarum L. fruits (LBF), yet the optimal age for achieving peak nutraceutical value remains unclear. In this study, we systematically investigated the effects of tree age (2, 4, 6, 8, 10, and 15 years; Y2-Y15) on the bioactive compounds and metabolic profiles of LBF. The results revealed pronounced age-dependent variations: total polysaccharides and carotenoids peaked at Y6 and Y8, whereas total polyphenols and flavonoids reached their highest levels at Y10. Distinct accumulation patterns were also observed for individual metabolites, with zeaxanthin dipalmitate (ZDP) showing a maximum at Y6, AA-2βG at Y8, and betaine at Y10. Non-targeted metabolomic analysis further indicated highly similar metabolic profiles among Y4-Y10, as reflected by their close clustering in the PCA model. Polysaccharides extracted from Y6-Y8 exhibited the strongest hepatoprotective activity, significantly improving oxidative stress markers and liver injury indicators. Specifically, high-dose polysaccharides extracted from Y8 reduced MDA levels by over 40 %, while those from Y6 decreased ALT and AST levels by approximately 32 % and 40 %, respectively, relative to the model group. Collectively, these findings identify Y6-Y10 as the optimal harvesting window for obtaining LBF with superior nutraceutical potential.