Abstract: |
The worldwide crises from multi-drug-resistant (MDR) bacterial infections are pushing
us to search for new alternative therapies. The renewed interest in medicinal plants has gained the
attention of our research group. Tamarindus indica L. (T. indica) is one of the traditional medicines used
for a wide range of diseases. Therefore, we evaluated the antimicrobial activities of ethanolic extract
of T. indica. The inhibitions zones, minimum inhibitory concentration (MIC), minimum bactericidal
concentration (MBC), and fractional inhibitor concentration indices (FICI) against Gram+ve and −ve
pathogens were detected. The bioactive compounds from T. indica extract were identified by mass
spectroscopy, thin-layer chromatography, and bio-autographic assay. We performed scanning electron
microscopy (SEM) and molecular docking studies to confirm possible mechanisms of actions and
antivirulence activities, respectively. We found more promising antimicrobial activities against MDR
pathogens with MIC and MBC values for Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa
(P. aeruginosa), i.e., (0.78, 3.12 mg/mL) and (1.56, 3.12 mg/mL), respectively. The antimicrobial
activities of this extract were attributed to its capability to impair cell membrane permeability,
inducing bacterial cell lysis, which was confirmed by the morphological changes observed under
SEM. The synergistic interactions between this extract and commonly used antibiotics were confirmed
(FICI values < 0.5). The bioactive compounds of this extract were bis (2-ethylhexyl)phthalate, phenol,
2,4-bis(1,1-dimethylethyl), 1,2-benzenedicarboxylic acid, and bis(8-methylnonyl) ester. Additionally,
this extract showed antivirulence activities, especially against the S. aureus protease and P. aeruginosa
elastase. In conclusion, we hope that pharmaceutical companies can utilize our findings to produce a
new formulation of T. indica ethanolic extract with other antibiotics.
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