Plantago asiatica L. is a natural medicinal plant that has been widely used for its various pharmacological effects such as
antidiarrheal, anti-inflammatory, and wound healing. This study aims to explore the
antidiarrheal active ingredients of Plantago asiatica L. that can be used as quality markers to evaluate P. asiatica L. superfine
powder (PSP). Molecular docking experiment was performed to identify the effective components of P. asiatica L., which were further evaluated by an established mouse
diarrhea model. Na+/K+-
ATPase and
creatine kinase (CK) activities and the Na+/K+ concentrations were determined. The gene expression of ckb and Atp1b3 was detected. PSP was prepared and evaluated in terms of the tap density and the angle of repose. The structures of PSPs of different sizes were measured by infrared spectra. The active ingredient contents of PSPs were determined by HPLC. The results indicated that the main
antidiarrheal components of P. asiatica L. were
luteolin and
scutellarein that could increase the concentration of Na+ and K+ by upregulating the activity and gene level of CK and Na+/K+-
ATPase. In addition,
luteolin and
scutellarein could also decrease the volume and weight of small intestinal contents to exert
antidiarrheal activity. Moreover, as the PSP size decreased from 6.66 to 3.55 μm, the
powder tended to be amorphous and homogenized and of good fluidity, the content of active compounds gradually increased, and the main structure of the molecule remained steady. The optimum particle size of PSP with the highest content of active components was 3.55 μm, and the lowest effective dose for antidiarrhea was 2,000 mg/kg. Therefore, the
antidiarrheal active ingredients of PSP were identified as
luteolin and
scutellarein that exert
antidiarrheal activity by binding with Na+/K+-
ATPase. PSP was successfully prepared and could be used as a new
dosage form for the
diarrhea treatment.