The degree of esterification influences the bioactivity of pectic polysaccharides isolated from Lithocarpus litseifolius

Pectic polysaccharides are the mainly bioactive components in <i>Lithocarpus litseifolius</i> (sweet tea) leaves. Nevertheless, owing to their diverse and complex chemical structures, the detailed structure-function relationships (SFR) of pectic polysaccharides from sweet tea (STP) are still unclear. Herein, the influence of STP's esterified degree on its diverse biological functions was uncovered. The results showed that the de-esterified STPs with a middle-esterified degree (33.53 %) and a low-esterified degree (7.66 %) were successfully prepared when compared with the original high-esterified STP (47.01 %), and their primary structural features were almost stable after the controllable de-esterification treatment. Furthermore, the findings inferred that STP's antioxidant, anti-diabetic, and immunostimulatory functions showed inverse correlations with the esterified degree. Moreover, the de-esterified STP with a lower-esterified degree could be more easily utilized by intestinal microorganisms to positively regulate the gut microbial composition. Overall, these findings can provide valuable insights for elucidating STP's precise SFR.