Enhanced Potency of Phenolic Compounds from Cleodendrum myricoides and Olinia rochetiana in Combination with Oleic acid against Antibiotic Resistance Bacteria

Antimicrobial resistance (AMR) is a growing global threat, with multidrug-resistant pathogens emerging as a major challenge for public health. Combination therapy of bioactive compounds is a novel strategy towards reversing antibiotic resistance. In this study, we investigated the antibacterial activities of extracts, fractions, and isolated compounds from Cleodendrum myricoides and Olinia rochetiana . Fresh plants were collected from the field, dried and the extracts obtained using different solvents. Sequential extracts, fractions, and compounds obtained were screened for antibacterial activities using disc diffusion and broth micro-dilution methods. Nine strains of bacteria were used including the resistant Esbl Escherichia coli and methicillin resistant (MR) Staphylococcus aureus . Pure chemical compounds were obtained using bioassay guided isolation of bioactive extracts and fractions. Structural elucidation of isolated compounds was carried out using nuclear magnetic resonance (NMR) and through comparison of the spectroscopic data with published values. Synergism between the two compounds, and previously reported antibacterial oleic acid were determined against the selected bacteria. Two phenolic compounds, cis 4′′- O -acetyl martinoside ( 1 ) from C. myricoides and 4- β -D-glucopyranosyl ferullic acid ( 2 ) from O. rochetiana were isolated and identified. 4- β -D-glucopyranosyl ferullic acid ( 2 ) was found more active (Inhibition zone = 11.36 mm) compared to Cis 4′′- O -acetyl martynoside ( 1 ) with IZ of 10.40 mm against MR. Staphylococcus aureus . Interestingly, combination of the two compounds (1and 2), with antibacterial oleic acid presented a promising approach to combating antibiotic-resistant bacteria. The combination promoted synergistic effect with an inhibition one of 18.80 mm against the same microorganism. Synergism and isolation of these compounds from the selected medicinal plants are reported in this work for the first time. Understanding the synergy of bioactive compounds can lead to development of new, more effective antimicrobial therapies.