Antibacterial Effects of Hydroalcoholic and Aqueous Extracts of Two Medicinal Plants in Comparison with Popular Antibiotics: An in Vitro Study

Background: Acinetobacter baumannii is considered a dangerous and drug-resistant hospital-acquired infection. Nowadays, there has been an increasing interest in the use of herbal drugs. Objectives: This in vitro study was conducted to determine the antimicrobial effects of Rumex acetosella L. and Cucurbita maxima L. on Acinetobacter baumannii in comparison with popular antibiotics. Methods: In this experimental study, after extraction, the antibacterial effects of extracts were determined based on MIC and MBC using broth microdilution. The effects of different concentrations of the extracts on A. baumannii growth were also investigated by the disk diffusion method. The results were compared with choice antibiotics. Results: The results of the study indicated that in broth microdilution, the MIC and MBC of the hydroalcoholic extract of C. maxima and the aqueous extract of R. acetosella were equal (64 and 128 µg/mL, respectively). The MIC and MBC of the hydroalcoholic extract of R. acetosella and the aqueous extract of C. maxima were 128 and 256 µg/mL, respectively, which indicated the weaker effects of these extracts. In the disk diffusion method, the greatest mean diameter of inhibition zone was obtained for R. acetosella extracts (24.83 ± 0.29 and 21.83 ± 0.29 mm for hydroalcoholic and aqueous extracts, respectively). Also, the lowest mean diameter was obtained for C. maxima extracts (10.33 ± 0.58 and 8 mm for hydroalcoholic and aqueous extracts, respectively). Conclusions: This study showed the potent antibacterial effects of R. acetosella and C. maxima. They were even more potent than commonly used antibiotics. Therefore, the plants can be used as antimicrobial agents, as well as pharmaceutical supplements and alternative therapies.