UPLC-QTOF-MS/MS analysis of saponin-enriched fractions from Calliandra umbellifera Benth and evaluation of antibacterial activity against multidrug-resistant bacteria

The genus Calliandra, rich in diterpenes, flavonoids, tannins and saponins, has several species with medicinal use. The species Calliandra umbellifera has abundant saponins in its composition, it is a glycoside that acts in defense against insects and pathogens. Due to these properties, saponins have been described to have antibacterial, antifungal, antiparasitic, anti-inflammatory and antiviral activity. Thus, the present work aimed to isolate the saponin-rich fraction of the Calliandra umbellifera species (FRSCu) and to evaluate the antibacterial activity against standard and multidrug-resistant bacterial species. The fraction was obtained from the preparation of the ethanolic extract of the species, being characterized by chromatography, using the method ultra-efficient liquid chromatography coupled to quadrupole/time of flight system (UPLC-QTOF-MS/MS). Minimum inhibitory concentration (MIC) assays were performed to verify the inhibition of bacterial growth for standard and multiresistant strains of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, as well as the evaluation of the activity when combined with the antibiotics: gentamicin, norfloxacin and ampicillin. The chemical analysis of FRSCu allowed the identification of the presence of phenolic compounds, flavonoids, condensed tannins and saponins. The intrinsic antibacterial activity of FRSCu did not show relevant results against the bacteria used. However, it showed promising results when combined with antibiotics, enhancing the effect of gentamicin against two gram-negative strains E. coli and P. aeruginosa and also when combined with norfloxacin against P. aeruginosa. Thus, this work presents an innovative and biotechnological potential that can contribute to future pharmaceutical formulations and knowledge about the C. umbellifera species.