It is well known that the biological activity of gallated proanthocyanidins (PAs) is highly structure-dependent. Polymerization degree (DP) and linkage types affect their biological activity greatly. Positions and orientations of gallated PAs in lipid bilayer reveal their structure-function activity at the molecular level. The present work aimed at determining the locations and orientations of epigallocatechin-3-gallate (EGCG) and its derivatives: A-type and B-type EGCG dimers and trimers in 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC) and 1-palmitoyl-2-oleoyl phosphatidylethanolamine (POPE) lipid bilayer via molecular dynamic (MD) simulations. The results showed that EGCG and its derivatives localized in the lipid bilayer or on the bilayer/water interface. Their penetration depths and orientations depended on both DP and linkage types. The penetration depths decreased with the increase of DP, sequencing to be EGCG > EGCG dimers > EGCG trimers. Spatially stretched A-type PAs could form more hydrogen bonds (H-bonds) with deep oxygen atoms of lipid bilayer and have higher affinity to the lipid bilayer than B-type PAs. Our results will provide an explicit evidence for PAs’ distinct biological activities.

Shepherd’s purse (Capsella bursa-pastoris (L.) Medik.), a wild herb as a traditional herbal medicine, has been proved with multiple healthy benefits. In this study, the chemical constituents of shepherd’s purse were identified by UPLC-QTOF-MS/MS. The antioxidative and anti-inflammatory potential of shepherd’s purse extract (SPE) were also investigated applying lipopolysaccharide- (LPS-) induced inflammation in RAW 264.7 macrophages and a carrageenan-induced mice paw edema model. Twenty-four chemical compounds were identified mainly including phenolic acids and flavonoids. The data also indicated SPE inhibited the productions of NO, PGE₂, TNF-α, and IL-6 stimulated with LPS. In addition, SPE inhibited the increase of reactive oxygen species (ROS) and upregulated the expression of heme oxygenase-1 (HO-1). We further found that SPE inhibited the phosphorylation of P38 MAPK and activation of NF-κB. In vivo mice model also indicated that SPE showed strong antioxidative and anti-inflammatory activity.