The Synergistic Effect of Triterpenoids and Flavonoids-New Approaches for Treating Bacterial Infections?

Currently, the pharmaceutical industry is well-developed, and a large number of chemotherapeutics are being produced. These include antibacterial substances, which can be used in treating humans and animals suffering from bacterial infections, and as animal growth promoters in the agricultural industry. As a result of the excessive use of antibiotics and emerging resistance amongst bacteria, new antimicrobial drugs are needed. Due to the increasing trend of using natural, ecological, and safe products, there is a special need for novel phytocompounds. The compounds analysed in the present study include two triterpenoids ursolic acid (UA) and oleanolic acid (OA) and the flavonoid dihydromyricetin (DHM). All the compounds displayed antimicrobial activity against Gram-positive ( ATCC 6538, ATCC 12228, and ATCC 19115) and Gram-negative bacteria ( ATCC 25922, ATCC 15442, and ATCC 33560) without adverse effects on eukaryotic cells. Both the triterpenoids showed the best antibacterial potential against the Gram-positive strains. They showed synergistic activity against all the tested microorganisms, and a bactericidal effect with the combination OA with UA against both strains. In addition, the synergistic action of DHM, UA, and OA was reported for the first time in this study. Our results also showed that combination with triterpenoids enhanced the antimicrobial potential of DHM.