Patchouli Alcohol: a Natural Sesquiterpene Against Both Inflammation and Intestinal Barrier Damage of Ulcerative Colitis

Ulcerative colitis (UC) is a chronic and relapsing inflammatory disorder of the gastrointestinal tract, characterized by diarrhea, hematochezia, abdominal distension, and abdominal pain. The perpetuation of inflammation and the impairment of the intestinal barrier are part of the main courses of UC, responsible for the deteriorating inflammatory condition. Patchouli alcohol (PA), extracted from Pogostemon cablin Benth., is employed to treat both inflammation and intestinal barrier damage. Its curative effect on UC was testified firstly by TNBS-induced UC, a chemically induced colitis, and further tested by DSS-induced UC, an acute attack stage of UC in which the clinical course of human UC occurs frequently. PA reduced the levels of TNF-α, IFN-γ, IL-1β, IL-6, and IL-17 in serum and decreased the mRNA expression of pro-inflammatory cytokines (e.g., iNOS, COX-2, TNF-α, IL-1β, and IL-6). Concurrently, PA upregulated the expression of tight junction protein (e.g., ZO-1, ZO-2, claudin-1, and occludin) and the mRNA of mucin-1 and mucin-2 in both animal models. Further, PA ameliorated both histological damage and clinical parameters. Thus, PA could credibly reduce the expression of pro-inflammatory cytokines, protect the integrity of intestinal epithelial barrier, and repair the macroscopic colon lesions in both colitis models.