Synergistic antimicrobial activity between pentacyclic triterpenoids and antibiotics against Staphylococcus aureus strains

Abstract

BackgroundThere has been considerable effort to discover plant-derived antibacterials against methicillin-resistant strains of Staphylococcus aureus (MRSA) which have developed resistance to most existing antibiotics, including the last line of defence, vancomycin. Pentacyclic triterpenoid, a biologically diverse plant-derived natural product, has been reported to show anti-staphylococcal activities. The objective of this study is to evaluate the interaction between three pentacyclic triterpenoid and standard antibiotics (methicillin and vancomycin) against reference strains of Staphylococcus aureus.Methods and ResultsThe activity of the standard antibiotics and compounds on reference methicillin-sensitive and resistant strains of S. aureus were determined using the macrodilution broth method. The minimum inhibitory concentration (MIC) of the compounds was compared with that of the standard antibiotics. The interaction between any two antimicrobial agents was estimated by calculating the fractional inhibitory concentration (FIC index) of the combination. The various combinations of antibiotics and compounds reduced the MIC to a range of 0.05 to 50%.ConclusionPentacyclic triterpenoids have shown anti-staphylococcal activities and although individually weaker than common antibiotics produced from bacteria and fungi, synergistically these compounds may use different mechanism of action or pathways to exert their antimicrobial effects, as implicated in the lowered MICs. Therefore, the use of current antibiotics could be maintained in their combination with plant-derived antibacterial agents as a therapeutic option in the treatment of S. aureus infections.

Assessing the Therapeutic Role of Joshanda: Phytochemical, Antioxidant, Anti-Inflammatory and Antimicrobial Activities

“…Secondary metabolite such as alkaloids, tannins, flavonoids are known to have activity against pathogens and therefore aid the antimicrobial activities of medicinal plants [24] which contribute significantly towards the biological activities of medicinal plants such as hypoglycemic, anti-diabetic, antioxidant, antimicrobial, antiinflammatory, anti-carcinogenic, anti-malarial, anti-cholinesterase, anti-leprosy activities etc [25][26][27][28][29][30][31][32]. From the present study, it is found that the decoction of joshanda contains flavonoids, alkaloid, tannin, phenol, glycosides, and terpenoids which are of great importance in the field of drug research.…”

Ayurvedic, Phytochemical and Pharmacological Review of Schleichera Oleosa (Lour.) Oken: A Traditional Plant With Enormous Biological Activity

“…[22] Though the exact mechanism of triterpenoids for inhibiting microbial growth was not fully understood but it could be hypothesized that these constituents inhibit DNA synthesis in microbes by preventing cell division. [39] www.wjpr.net Vol 6, Issue 10, 2017. 302…”

“…Inhibit bacterial enzyme, Inhibit oxidative phosphorylation, Inhibition of DNA gyrase, [36,,37] prevent cell division to inhibit DNA synthesis [39] Antioxidant activity Metal-chelating complex, Antiradical activity and Inhibition of free radical generation [44,,45] www.wjpr.net …”

Evaluation of some Antibiotics in Combination Activity Against Isolates of Staphylococcus aureus and Pseudomonas aeruginosa

“…The antibiotics were combined at concentrations ranging from 1/8 x MIC to 2xMIC, then inoculated with bacterial cultures and incubated for 24h at 37 ºC after which the MIC values were estimated. The fractional inhibitory concentration (FIC) was derived from the lowest concentration of antibiotic combination permitting no visible growth of the test organism in the tube and was calculated for each antimicrobial concentration as follows: Combination between antibiotics according to accepted criteria [16] as follows: ≤ 1.5, synergy; 1.5 to 1.1, additive; 1.1 to 4.1, indifference; and > 4, antagonism.…”