UHPLC-MS profiles and antidiarrheal activity of Quercus coccinea Münchh. and Quercus robur L. employing in vivo technique

<strong>ABSTRACT</strong> <strong>Introduction</strong><em>: Quercus</em> L. genus (Oak) belongs to the family Fagaceae and their galls are used commercially in leather tanning, dyeing, and ink preparation. Several <em>Quercus</em> species were traditionally used to manage wound healing, acute diarrhea, hemorrhoid, and inflammatory diseases. The present study aims to investigate the phenolic content of the 80% aqueous methanol extract (AME) of <em>Q. coccinea</em> and <em>Q. robur</em> leaves as well as to assess their anti-diarrheal activity. <strong>Methods</strong>: Polyphenolic content of <em>Q. coccinea</em> and <em>Q. robur </em>AME were investigated using UHPLC/MS. The antidiarrheal potential of the obtained extracts was evaluated by conducting a castor oil-induced diarrhea <em>in-vivo</em> model, <strong>Result and Discussion</strong>: Twenty-five and twenty-six polyphenolic compounds were tentatively identified in <em>Q. coccinea</em> and <em>Q. robur </em>AME, respectively. The identified compounds are related to quercetin, kaempferol, isorhamnetin, and apigenin glycosides and their aglycones. In addition, hydrolyzable tannins, phenolic acid, phenyl propanoides derivatives, and cucurbitacin F were also identified in both species AME of <em>Q</em>.<em> coccinea</em> (250, 500, and 1000 mg/kg) exhibited a significant prolongation in the onset of diarrhea by 17.7 %, 42.6%, and 79.7% respectively while AME of <em>Q robur</em> at the same doses significantly prolonged the onset of diarrhea by 38.6%, 77.3%, and 2.4 folds respectively as compared to the control. Moreover, the percentage of diarrheal inhibition of <em>Q. coccinea </em>was 23.8%, 28.57%, and 42,86% respectively, and for<em> Q robur </em>33.34%, 47.3%, and 57.14% respectively as compared to the control group. Both extracts significantly decreased the volume of intestinal fluid by 27%, 39.78%, and 50.1% for <em>Q coccinea</em> respectively; and by 38.71%, 51.19%, and 60% for <em>Q robur </em>respectively as compared to the control group. In addition, AME of <em>Q. coccinea</em> exhibited a peristaltic index of 53.48, 47.18, and 42.28 with significant inhibition of gastrointestinal transit by 18.98%, 28.53%, and 35.95 % respectively; while AME of <em>Q robur</em> exhibited a peristaltic index of 47.71, 37, and 26.41 with significant inhibition of gastrointestinal transit by 27.72%, 43.89%, and 59.99% respectively as compared with the control group. Notably, <em>Q. robur </em>showed a better antidiarrheal effect in comparison with <em>Q. coccinea </em>and, the highest effect was observed for <em>Q. robur</em> at 1000 mg/kg as it was nonsignificant from the loperamide standard group in all measured parameters.