Isolation of Phytoecdysteroids: Ajugasterone C and 20-Hydroxyecdysone, from Sida alba Linn

Medicinal plants are employed in folk medicine as enormous reservoirs of secondary metabolites, with varied and distinctive chemical and biological properties, that can prevent, treat, or cure diseases. Consequently, the validation of traditional remedies has remained a prominent harbinger to modern drug discovery. Herein, the aerial parts of the Sida alba Linn. (Malvaceae) plant were subjected to maceration in methanol, fractionation in mixed solvent systems, and solvent-gradient column chromatography to furnish 20-hydroxyecdysone 8 and ajugasterone C 24 as pale-yellow and yellow powders in 0.62% and 0.25% yields, respectively. The crude methanol extract and fractions were assayed against Escherichia coli ATCC 25922, enterohemorrhagic E. coli (EHEC) O157:H7, Shigella flexneri ATCC 12022, Salmonella Typhi ATCC 13311, and coded clinical diarrheagenic E. coli isolates: DEC ANI and DEC 134, to assess in vitro antidiarrheal activity. The extract exhibited an MIC of 17.5 mg/mL against DEC ANI, whereas fraction F11 recorded an MIC of 8.75 mg/mL against EHEC and S. flexneri. The docking studies of compounds 8 and 24 with proteins of S. Typhi (PDB id: 4KRA) and EHEC (PDB id: 1AB4) revealed higher binding affinities of -12.12 kcal/mol and -12.70 kcal/mol, respectively, against the S. Typhi protein, compared to -11.09 kcal/mol of ciprofloxacin (reference drug), indicating potential antidiarrheal properties.