Abstract: Purpose: The aim of this study was to reveal the protective effect and underlying mechanism of Prunella vulgaris honey (PVH) extract on dextran sulfate sodium (DSS)-induced human colon epithelial cell (Caco-2) injury at cellular and molecular levels. Methods: The contents of total polyphenols and flavonoids in PVH and acacia honey (AH) as a control were determined by Folin-phenol reagent method and aluminum nitrate method, respectively. 2,2’-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, 50% maximum inhibitory concentration (IC50), and ferric ion reducing antioxidant power (FRAP) were used to evaluate in vitro antioxidant activity of the two honeys. Then, the protective effect of PVH on ulcerative colitis in rats was studied using a rat model of DSS-induced ulcerative colitis by real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting and Transwell migration analysis. Results: The contents of total phenolic acid and total flavonoids in PVH were respectively (52.4 ± 0.4) and (7.0 ± 0.3) μg/g. PVH extract at concentrations of 50–100 μg/mL could significantly alleviate the decrease of cell viability caused by 2.5% (V/V) DSS treatment. Based on RT-qPCR analysis, PVH significantly up-regulated the mRNA expression of antioxidant cytokine genes such as NQO-1, Txnrd1 and Nrf2 and tight junction gene such as ZO-1. Based on immunofluorescence analysis, PVH extract could protect the key tight junction protein ZO-1 in Caco-2 cell monolayers against DSS-induced damage. In addition, PVH extract could significantly up-regulate the expression of antioxidant proteins such as NQO-1, Txnrd1 and Nrf2 as evaluated by Western blot assay. Conclusion: PVH has great potential for development and utilization in alleviating DSS-induced damage to the barrier function of intestinal epithelial cells.

Key words: Prunella vulgaris honey; tight junction; antioxidant