Assessments of protodioscin's antinociceptive and antidiarrheal properties: in vivo and in silico investigations on macromolecule binding affinity and modulatory effects.

Protodioscin (PRO) is a furostanol saponin with antioxidant and anti-inflammatory properties. However, there is no proof against nociception and diarrhea. The study aims to investigate the antinociceptive and antidiarrheal effects of PRO, comparing its efficacy with diclofenac sodium (DFS) and loperamide (LOP) using in vivo and in silico methods. Antinociceptive activity was evaluated using the acetic acid-induced writhing and formalin-induced paw licking tests, and antidiarrheal effects were assessed via castor oil-induced diarrhea in mice. Mice were divided into groups receiving PRO (2.5 and 10 mg/kg, p.o.), DFS (25 mg/kg, p.o.), LOP (3 mg/kg, p.o.), or combinations. Molecular docking studies were conducted on COX-1, COX-2 enzymes, and the Mu-opioid receptor (MOR), with toxicity predictions performed for safety profiling. In vivo results demonstrated that PRO significantly (p < 0.05) reduced pain and diarrhea in animals. PRO at 10 mg/kg, showed comparable efficacy to DFS and LOP (25 and 3 mg/kg) in both models. Molecular docking revealed that PRO had stronger binding affinities with COX-1 (‒10.0 kcal/mol), COX-2 (‒9.6 kcal/mol) enzymes, and MOR (‒7.7 kcal/mol) compared to standard drugs. Toxicity predictions indicate PRO is relatively safe in some toxicity parameters. PRO exhibits significant antinociceptive and antidiarrheal activities comparable to DFS and LOP, making it a promising natural alternative for managing pain and diarrhea. Additional clinical trials and pharmacokinetic assessments are required to evaluate its long-term safety for use.