Data from the specialized literature confirm that plants and their natural products represent promising sources of antibacterial agents and that their exploration represents a productive trajectory. One of the future challenges for many phytochemicals is to find efficient routes and forms of administration, capable of delivering the active substance, the antimicrobial compound at the target site. The association between gut microbiota and some types of cancer is evident. Among the potential pro-carcinogenic effects of bacterial species: Helicobacter pylori, Enterococcus faecalis, Clostridium septicum, Fusobacterium spp. and Escherichia coli are genotoxicity, inflammation, oxidation, modulation of antioxidant defense, etc. Certain natural compounds of plant origin, such as essential oils, alkaloids, lectins, polypeptides, flavones, flavonols, coumarins, terpenoids and tannins, have become potential therapeutic tools. Polyphenols of vegetable origin have various biological effects, including antioxidant, anticarcinogenic, anti-inflammatory and antimicrobial activities. In the regulation of side effects during anticancer therapy, complementary and integrative approaches are becoming more current. To highlight the antimicrobial properties of some plants with anticancer properties against agents of the E. coli genus 5 indigenous medicinal plants were used: Chelidonium majus, Viscum album, Artemisia absinthium, Xanthium spinosum and Acorus calamus, prepared in 4 forms: decoction, infusion, alcoholic tincture and cold maceration. Evaluation of their antimicrobial activity was performed using the well diffusion method. The diameter of the zones of cell growth inhibition around the wells depends on the degree of sensitivity of the reference culture to antibiotics: zone diameter up to 10 mm is considered low sensitivity; 11-15 mm – medium sensitivity; 15-25 mm – sensitive; greater than 25 mm – increased sensitivity. Chelidonium majus demonstrated the most pronounced antibacterial activity in the case of the decoction form – sensitive area according to the gradation of М. Birgher and tincture – medium sensitivity. Viscum album in the form of infusion and maceration showed medium sensitivity, while the forms of decoction and tincture – low sensitivity. Artemisia absinthium proved to be more effective in the form of tincture and infusion (sensitive area), also having the highest inhibition zone values compared to the other herbs. E. coli culture sensitivity in the infusion and maceration of Xanthium spinosum were higher, compared to the form of decoction and tincture, which both demonstrated an average sensitivity, and Acorus calamus in the forms of decoction, infusion and maceration – on the border between low and medium sensitivity. Thus, the forms of preparation of tested medicinal plants were identified, which demonstrated in vitro a significant antimicrobial potential against E. coli, due to phytoconstituents with antibacterial action, among which the most active are polyphenols and terpenes, a fact that will allow their use in the process of further development of phytooncoprotectors.