Inhibitory Effect of Ranunculus kotschyi Boiss. Extract on Multidrug Resistant Acinetobacter baumanii and Other Pathogenic Bacteria

Emergence of multi-drug-resistant bacteria poses an imminent and clear threat to human health. Acinetobacter baumanii is such an organism, which may cause up to 40% mortality due to bacteremia. Ranunculus kotschyi, a widespread herb, is utilized in Türkiye for treatment of rheumatism, leg pain and bruises in folk medicine, and also consumed as food. Molecular identification of Ranunculus kotschyi was performed using ITS1 partial sequence, 5.8S and ITS2 partial sequence. Phylogenetic analyses of the plant were conducted. The plant sample was extracted and fractioned using activity guided fractionation to yield an active fraction (RK4A). RK4A was analysed using LC-QTOF-MS and the presence of syringic acid in RK4A was revealed. The antimicrobial effects of RK4A and syringic acid against multi-drug-resistant Acinetobacter baumanii, as well as other pathogens, namely Klebsiella pneumonia, Escherichia coli, Staphylococcus aureus and Enterococcus faecalis, were screened in broth media. Minimum inhibitory concentration (MIC) values were determined using microdilution method. Our results revealed that RK4A and syringic inhibited growth of all tested bacteria in broth. The MIC values of RK4A against Acinetobacter baumanii, Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Enterococcus faecalis were 500, 62.5, 31.25, 125 and 15.525 µg/ml, respectively. The MIC values of syringic acid against Acinetobacter baumanii, Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Enterococcus faecalis were 1000, 62.5, 62.5, 125 and 31.25 µg/ml, respectively. Our results suggest that Ranunculus kotschyi and syringic acid may provide alternatives in the treatment of infections caused by A. baumanii and other multidrug-resistant bacteria. Further research is needed in order to discover action mechanisms of the reported antimicrobial effects and enhance the observed effects of RK4A and syringic acid.