Gonçalves, M., Madureira, A. M., Catarino, L., Monteiro, A. & Teixeira, G. (2021) In vitroassessment of the synergism between extracts of Zanthoxylum zanthoxyloidesand Zanthoxylum leprieurii and some standard antibiotics. Global J Pharmacy & Pharmaceutical Sciences, 8(4), 1-8. DOI:10.19080/GJPPS.2021.08.555742.
Purpose: To survive in harsh environments, plants developed functional and metabolic adaptive mechanisms. One of the most relevant defense strategies is the biosynthesis of secondary metabolites, including terpenoids, alkaloids, flavonoids, and phenolics that are accumulated in cellular organelles or secretory structures. Hence, plants are recognized as a valuable source of natural products and for thousands of years very diverse herbal formulations were created to treat several diseases. Zanthoxylum zanthoxyloides and Zanthoxylum leprieurii, two Rutaceae species native to Guinea-Bissau, are well known for their ethnopharmacological relevance.
Methods: In the present study, the in vitro antimicrobial activity of these plants against human pathogens was assessed and the phytochemical profile was screened. The extracts of roots and young leaves were obtained by sequential extraction of increasing polarity (n-hexane, CH2Cl2, EtOAc, MeOH and H2O) and tested against Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined, as well as the evaluation of the synergic potential of the extracts.
Results: Z. leprieurii leaves extracts, the most apolar ones, had the highest antimicrobial activity, being able to inhibit the growth of Enterococcus hirae and all the Staphylococcus strains assayed, including the resistant ones. A synergic effect between the Zanthoxylum species extracts and standard antibiotics was found, reverting the activity of resistant strains. The phytochemical screening revealed the presence of terpenes, flavonoids, and phenolic compounds, known to have antibacterial properties.
Conclusions: The obtained results point to the validation of their use in tradition medicine and emphasize the worthwhile of additional studies of these species to better understand the compounds and mechanisms that may be valuable to restore antibacterial activity.