BACKGROUND: Fructose consumption has been suggested to contribute to metabolic diseases including metabolic dysfunction-associated steatotic liver disease (MASLD), at least in part, by disturbing intestinal barrier function and intestinal nitric oxide (NO) homeostasis. Honokiol, a neolignan found in Magnolia officinalis, has been suggested to affect intestinal integrity and barrier function. OBJECTIVE: We assessed whether honokiol affects fructose-induced small intestinal permeability in settings of early MASLD. METHODS: Female 8-10 weeks old C57BL/6J mice (n=7/group) received either a 30% fructose solution + vehicle (Fru) or plain drinking water + vehicle ± honokiol (Hon, 10 mg/kg bw/day) for four weeks. Liver damage (e.g., NAFLD activity score (NAS), number of neutrophils, interleukin-6 (IL6) protein concentration), markers of intestinal permeability (bacterial endotoxin, tight junction proteins), and NO homeostasis in small intestine were determined in vivo as well as ex vivo in an everted sac model and in Caco-2 cells. One-way and two-way ANOVA were performed, respectively. RESULTS: Honokiol diminished the development of MASLD, which was associated with a significant lower NAS (-38%), number of neutrophils (-48%) and IL6 protein concentrations (-38%) in livers of Fru-fed mice. Honokiol also attenuated fructose-induced alterations of markers of intestinal barrier function with Fru+Hon-fed mice showing lower bacterial toxin levels in portal plasma (-29%, p=0.075), higher tight junction protein concentrations (+2.4-fold, p<
0.05), and lower NOx concentration (-44%, p<
0.05) as well as NOS activity (-35%) in the small intestine compared to Fru+vehicle-fed mice. Moreover, the decrease in AMPK phosphorylation found in small intestine of Fru-fed mice was significantly attenuated (+5.3-fold) by the concomitant treatment with honokiol in Fru-fed mice. In support of the in vivo findings, honokiol significantly attenuated Fru-induced intestinal permeability ex vivo and in Caco-2 cells. CONCLUSIONS: Our data suggest that honokiol diminished the development of fructose-induced early MASLD by alleviating impairments in intestinal barrier function.