EGCG and quercetin are flavonoids which usually co-exist in edible plants and they exhibit anti-diabetes effects. This study aimed to explore the mechanisms by which quercetin and EGCG synergistically protected pancreatic β-cells from streptozotocin-induced apoptosis. EGCG, quercetin, and their combinations (both 15 μM) all reversed STZ-induced cells damage and enhanced glucose-stimulated insulin secretion, with the combination being more effective than a single compound. At the molecular level, the EGCG-quercetin combination upregulated BCL-2 expression and caused a greater reduction in miR-16-5p level than EGCG alone or quercetin alone. Overexpression of miR-16-5p could offset the down-regulated apoptotic genes caused by the synergistic action of the combination. These findings suggest that EGCG and quercetin exert synergistic anti-diabetes effect, possibly via decreasing the expression of miR-16-5p that targets directly BCL-2. This is the first report on a miRNA-based mechanism underlying the synergistic protective effect of EGCG and quercetin against pancreatic cell damage.

EGCG和槲皮素是黄酮类化合物，通常共存于食用植物中，具有抗糖尿病作用。本研究旨在探讨槲皮素和 EGCG 协同保护胰腺 β 细胞免受链脲佐菌素诱导的细胞凋亡的机制。EGCG、槲皮素及其组合（均为 15 μM）均能逆转 STZ 诱导的细胞损伤并增强葡萄糖刺激的胰岛素分泌，并且该组合比单一化合物更有效。在分子水平上，与单独的 EGCG 或单独的槲皮素相比，EGCG-槲皮素组合上调 BCL-2 表达并导致 miR-16-5p 水平的更大降低。miR-16-5p 的过表达可以抵消由组合的协同作用引起的下调的凋亡基因。通过降低直接靶向 BCL-2 的 miR-16-5p 的表达。这是关于基于 miRNA 的机制的第一份报告，该机制是 EGCG 和槲皮素对胰腺细胞损伤的协同保护作用的基础。