Developing new antimicrobial therapies: Are synergistic combinations of plant extracts/compounds with conventional antibiotics the solution?

Abstract

The discovery of penicillin nearly 90 years ago revolutionized the treatment of bacterial disease. Since that time, numerous other antibiotics have been discovered from bacteria and fungi, or developed by chemical synthesis and have become effective chemotherapeutic options. However, the misuse of antibiotics has lessened the efficacy of many commonly used antibiotics. The emergence of resistant strains of bacteria has seriously limited our ability to treat bacterial illness, and new antibiotics are desperately needed. Since the discovery of penicillin, most antibiotic development has focused on the discovery of new antibiotics derived from microbial sources, or on the synthesis of new compounds using existing antibiotic scaffolds to the detriment of other lines of discovery. Both of these methods have been fruitful. However, for a number of reasons discussed in this review, these strategies are unlikely to provide the same wealth of new antibiotics in the future. Indeed, the number of newly developed antibiotics has decreased dramatically in recent years. Instead, a reexamination of traditional medicines has become more common and has already provided several new antibiotics. Traditional medicine plants are likely to provide further new antibiotics in the future. However, the use of plant extracts or pure natural compounds in combination with conventional antibiotics may hold greater promise for rapidly providing affordable treatment options. Indeed, some combinational antibiotic therapies are already clinically available. This study reviews the recent literature on combinational antibiotic therapies to highlight their potential and to guide future research in this field.

An Interactive Antimicrobial Activity of Embelica officinalis Gaertn. Fruit Extracts and Conventional Antibiotics against Some Bacterial Triggers of Autoimmune Inflammatory Diseases

“…Bacterial susceptibility to antibiotics and to plant extracts may vary widely between different strains of bacteria, even within the same species. 1 Mutations may occur in bacterial DNA, providing the cell resistance to specific antibiotic(s). Alternatively, bacterial cells may incorporate DNA from other bacteria in their environment via conjugation or transformation and also develop resistance.…”

“…1 There are now limited therapeutic options for the diseases caused by these pathogens and the development of alternative antibiotic chemotherapies is considered by the World Health Organisation (WHO) to be one of the most serious challenges facing medical science. 2 Previously, much antibiotic drug development has focussed on microbial derived compounds with antibiotic activity (e.g.…”

Piper novae-hollandiae Miq. Leaf Extracts Lack Antibacterial activity and are Non-Toxic in vitro

“…Due to recent increases in bacterial resistance to many antibiotics, the development of new antibiotic chemotherapies is a high priority for medical science. 6,7 A concurrent decrease in the discovery of new antibiotic medicines by conventional strategies has increased interest in re-evaluating medicinal plants for new antibiotic chemotherapies. 24 P. novae-hollandiae was used by the first Australians to treat a number of diseases, some of which are caused by bacterial pathogens.…”

“…Indeed, the development of alternative antibacterial treatment modalities has become crucial and is considered by the World Health Organisation (WHO) to be one of the most serious challenges currently facing medical science. 7 For a number of reasons reviewed elsewhere, 6 it is unlikely that the previous methods of antibiotic discovery/development will be as successful in the future and new treatment modalities are urgently required. Traditional medicines and herbal remedies have great potential for antimicrobial drug development and there has recently been a substantial increase in interest in this field.…”

Small Molecule Inhibitors of the Response Regulator ArsR Exhibit Bactericidal Activity against Helicobacter pylori

“…We analysed the in vitro bactericidal effect of lithocholic acid in combination with other recognized anti-H. pylori substances including the conventional antibiotics clarithromycin, metronidazole and levofloxacin, as well as the flavonoid chrysin [16], by the checkerboard method [16,17,24,28]. According to this approach, when two antimicrobial substances are used together in a fixed concentration ratio against a certain microbial strain, and the combinatory action of both drugs noticeably increases the activity of each drug when they act separately against the same strain, we could infer that these substances exhibit a synergistic interaction in their antimicrobial action.…”