Caffeoylquinic Acids From Lonicera japonica Thunb. as Hypoglycemic Agents: Network Pharmacology and Pharmacological Validation

The global increase in Type 2 diabetes (T2D) presents a serious public health challenge. Lonicera japonica Thunb., a traditional medicinal and edible plant, is a rich source of caffeoylquinic acids (CQAs), which are naturally occurring polyphenols that have drawn considerable research interest due to their diverse biological activities, particularly their potential in the management of T2D. In this study, six CQAs were isolated from the flower buds of L. japonica using preparative HPLC, with a total yield of 0.0555 mg/g. These compounds were identified as 3-CQA, 4-CQA, 5-CQA, 3,4-DCQA, 3,5-DCQA, and 4,5-DCQA, and their structures were characterized by LC-DAD-ESI-QTOF-MS and NMR. Hypoglycemic activity was then assessed using α-glucosidase/α-amylase inhibition, glucose uptake, and hepatic glucose production assays. Network pharmacology predicted potential targets and pathways, which were then validated by dual-luciferase reporter and Western blot analyses. Results showed that CQAs selectively inhibited α-glucosidase (not α-amylase), enhanced glucose uptake, and suppressed hepatic glucose production. Among them, the di-CQAs, particularly 4,5-DCQA and 3,5-DCQA, were the most potent α-glucosidase inhibitors, with IC₅₀ values of 5.49 and 7.96 mM, respectively. Network analysis identified AKT1, PEPCK, and INSR as core targets, and PI3K/AKT, insulin, and FoxO signaling pathways as key pathways. Mechanistically, 3,5-DCQA suppressed gluconeogenesis by inhibiting PEPCK (at both promoter activity and protein levels) and downregulating CREB. It also enhanced insulin signaling via upregulation of INSR, IRS-1, and p-AKT. In conclusion, our study demonstrates that 3,5-DCQA, a key bioactive constituent of L. japonica, exerts multitarget hypoglycemic effects by coordinately regulating gluconeogenesis and insulin signaling. These findings not only provide a direct pharmacological basis for the antidiabetic potential of CQA-rich herbs but also highlight 3,5-DCQA as a promising candidate for developing novel therapeutics or adjuncts for T2D management.