Phuntila TharabenjasinRonaldo P. FerrarisKiattawee ChoowongkomonPawin PongkorpsakolNichakorn WorakajitSutthipong SawasvirojwongNoel PabalanKesara Na-BangchangChatchai MuanprasatChulabhorn Royal AcademyKasetsart UniversityFaculty of Medicine Ramathibodi Hospital, Mahidol UniversityThammasat UniversityRutgers New Jersey Medical SchoolFaculty of Medicine, Chulalongkorn University2022-08-042022-08-042021-10-01Biomedicine and Pharmacotherapy. Vol.142, (2021)19506007075333222-s2.0-85113682872https://repository.li.mahidol.ac.th/handle/20.500.14594/78944Oriental herbal medicine with the two bioactive constituents, β-eudesmol (BE) and atractylodin (AT), has been used as a remedy for gastrointestinal disorders. There was no scientific evidence reporting their antidiarrheal effect and underpinning mechanisms. Therefore, we aimed to investigate the anti-secretory activity of these two compounds in vitro. The inhibitory effect of BE and AT on cAMP-induced Cl- secretion was evaluated by Ussing chamber in human intestinal epithelial (T84) cells. Short-circuit current (ISC) and apical Cl- current (ICl-) were measured after adding indirect and direct cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel activator. MTT assay was used to determine cellular cytotoxicity. Protein-ligand interaction was investigated by in silico molecular docking analysis. BE, but not AT concentration-dependently (IC50 of ~1.05 µM) reduced cAMP-mediated, CFTRinh-172 inhibitable Cl− secretion as determined by transepithelial ISC across a monolayer of T84 cells. Potency of CFTR-mediated ICl- inhibition by BE did not change with the use of different CFTR activators suggesting a direct blockage of the channel active site(s). Pretreatment with BE completely prevented cAMP-induced ICl-. Furthermore, BE at concentrations up to 200 µM (24 h) had no effect on T84 cell viability. In silico studies indicated that BE could best dock onto dephosphorylated structure of CFTR at ATP-binding pockets in nucleotide-binding domain (NBD) 2 region. These findings provide the first evidence for the anti-secretory effect of BE involving inhibition of CFTR function. BE represents a promising candidate for the therapeutic or prophylactic intervention of diarrhea resulted from intestinal hypersecretion of Cl-Mahidol UniversityPharmacology, Toxicology and PharmaceuticsArticleSCOPUS10.1016/j.biopha.2021.112030