Insights Into Antivirulence Applications of <i>Macrochloa tenacissima</i> (L.) Kunth (Poaceae) From In Vitro and In Silico Assessments

Macrochloa tenacissima (Stipa tenacissima) is an economically important species, but its biochemical properties remain underexploited. This study reports the phenolic composition of M. tenacissima ethanolic extract (MTEE) and evaluates its antimicrobial virulence potential. Total phenolic (7.42 ± 0.46 mg GAE/g) and flavonoid (6.49 ± 0.36 mg QE/g) contents were determined. LC-ESI-MS/MS revealed quinic acid (5.699 mg/g), p-coumaric acid (0.639 mg/g), protocatechuic acid (0.473 mg/g), protocatechuic aldehyde (0.319 mg/g), and vanillin (0.354 mg/g) as the most abundant phenolics. Minimal inhibitory concentration (MIC) against Staphylococcus aureus, Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, Candida albicans, and Chromobacterium violaceum indicated S. aureus and C. albicans as the most susceptible, with MICs of 0.312 mg/mL. The MTEE inhibited violacein production by C. violaceum CV12472, ranging from 50.06% ± 0.55% (MIC) to 9.06% ± 0.89% (MIC/4), and antiquorum sensing activity (7.0 ± 0.0 mm) against C. violaceum CV026 at MIC. Antibiofilm activity at MIC was 81.23% ± 1.15% (S. aureus), 80.91% ± 2.37% (C. albicans), 75.50% ± 2.68% (E. coli), and 71.84% ± 1.43% (S. typhi) and decreased in a concentration-dependent manner. MTEE inhibited swarming and swimming motilities against P. aeruginosa. Molecular docking experiments indicated favorable interactions, and the negative binding energies substantiate the in vitro antimicrobial virulence effects of M. tenacissima. Further, molecular dynamics simulations (MDs) have been carried out to investigate the stability of compounds in the binding of the chosen targets. The ADMET study has been performed to estimate the drug-likeness and the toxicity of the MTEE components.