The therapeutic mechanism of bornyl acetate in alleviating ulcerative colitis by regulating the intestinal flora.

Pine needle essential oil (PNEO) significantly inhibited pro-inflammatory mediators but showed only modest therapeutic efficacy against UC.

• PNEO significantly inhibited pro-inflammatory mediators including NO and TNF-α in vitro and in vivo models.
• Despite its anti-inflammatory properties, PNEO's therapeutic efficacy against UC was described as 'modest' compared to its key constituent bornyl acetate.
• The study used an integrated approach combining in vitro and in vivo models with 16S rRNA sequencing.

Bornyl acetate (BA) exerted potent anti-inflammatory effects by downregulating the transcriptional activity of p65 in the NF-κB pathway.

• BA is a monocyclic diterpene derived from pine needle essential oil (PNEO).
• BA downregulated the transcriptional activity of the p65 subunit of the NF-κB pathway.
• BA demonstrated more potent anti-inflammatory effects than PNEO overall.
• The mechanism was investigated using both in vitro and in vivo UC models.

BA enhanced the transcription and expression of tight junction proteins, thereby restoring intestinal barrier integrity in UC mice.

• BA upregulated the expression of ZO-1, claudin-1, and occludin.
• Enhancement occurred at both the transcriptional and protein expression levels.
• These tight junction proteins are critical components of intestinal barrier integrity.
• The effect was demonstrated in an in vivo mouse model of UC.

BA treatment suppressed the expansion of opportunistic pathogens while significantly promoting the proliferation of the potential probiotic Akkermansia.

• BA suppressed abnormal expansion of Erysipelotrichaceae, Saccharimonadaceae, Escherichia-Shigella, Turicibacter, Ruminococcus, and Candidatus Saccharimonas.
• BA significantly promoted the proliferation of Akkermansia, described as a 'potential probiotic.'
• Microbiota changes were characterized using 16S rRNA sequencing.
• These findings were obtained from the in vivo UC mouse model.

Spearman correlation analysis revealed that Akkermansia abundance was negatively correlated with p65 transcriptional activity and positively correlated with anti-inflammatory markers.

• Akkermansia abundance was negatively correlated with p65 transcriptional activity in the NF-κB pathway.
• Akkermansia abundance was positively correlated with anti-inflammatory cytokine IL-10.
• Akkermansia abundance was positively correlated with mRNA levels of barrier proteins ZO-1 and occludin.
• These correlations were identified through Spearman correlation analysis linking microbiota composition to molecular inflammatory and barrier markers.