Background: Macrothelypteris torresiana (Gaudich) is a species of fern having a wide range of reputed medicinal properties for the treatment of inflammation, fever, renal failure, stomach problems, etc. Objective: The present investigation focused on the evaluation of toxicity profile and diuretic and laxative activities of ethanol extract from M. torresiana aerial parts (EEMTAP), with in silico docking studies of polyphenolic compounds on carbonic anhydrase (CA)‑II, an enzyme target for diuretic activity. Materials and Methods: Acute and subacute toxicity was performed according to the Organization for Economic Co‑operation and Development guidelines. EEMTAP at doses of 200, 400, and 600 mg/kg, p.o., employed for the assessment of diuretic and laxative activities with loperamide‑induced constipation in Wistar albino rats. Furosemide (10 mg/kg, p.o.), agar‑agar (300 mg/kg, p.o.), and sodium picosulfate (5 mg/kg, p.o) were used as reference standards, respectively, for activity comparison. During saluretic activity study, total urine volume, body weight before and after the experiment, and urinary levels of Na+, K+ (by flame photometry), and Cl− (by titrimetry) were estimated. Polyphenolic compounds such as caffeic acid and quercetin were successfully detected through chromatographic method of EEMTAP, and to rationalize the results obtained in diuretic activities, we carried out docking studies of the natural phenolic compounds against CA‑II enzyme co‑complexed with furosemide (Protein Data Bank ID: 1Z9Y CA‑II in complex with furosemide as sulfonamide inhibitor). Results: In acute toxicity study, no mortality was observed at 2000 mg/kg, p.o., and in subacute toxicity study, the extract‑treated group did not show any significant changes in body weight and organ weights. The hematological and biochemical parameters did not show any significant changes in the sample‑treated groups when compared with the control group animals. The laxative activity of the extract was found to be in a dose‑dependent increase in fecal output of rats at selected dose levels; similarly, EEMTAP significantly increased the urinary output as well as urinary electrolyte concentration in a dose‑dependent manner. The molecular docking studies of phenolic compounds (caffeic acid and quercetin) into the binding site of CA II enzyme reveals that these analogues are having more favourable interaction when compared to the furosemide with better docking scores and hydrogen bonding interactions. Conclusion: The result demonstrated that the EEMTAP possesses a reasonable safety profile and shows promising diuretic and laxative activities in a dose‑dependent manner.
