Comparative study of the antibacterial activity of propolis from different geographical and climatic zones

Abstract

Propolis is a natural substance produced by honeybees upon collection and transformation of resins and exudates from plants. Comparative studies on propolis collected from a wide range of countries are crucial for linking its provenance to antibacterial activity and thus ensuring that the beneficial properties of propolis are used more efficiently by the general public. This study reports the in vitro screening of ethanol extracts of propolis (n = 40), collected from a wide range of countries within the tropical, subtropical and temperate zones, and on the comparison of their activity against a range of Gram-positive and Gram-negative bacteria using a broth microdilution assay. The results obtained revealed that propolis extracts were mostly active against Gram-positive bacteria. The samples were subjected to principal component analysis (PCA) in order to model their activity against Gram-positive microorganisms. Three distinct clusters were distinguished in the PCA mapping based on MIC values, categorizing samples with strong (MIC range 3.9-31.25 mg/L), moderate (MIC range 31.25-> or =500 mg/L) and weak antibacterial activity or inactivity (MIC > or = 500 mg/L only). It is hypothesized that for samples of tropical provenance differences in the activity profiles may depend on the climatic characteristics of the collection sites. High antibacterial activity was observed for samples from locations characterized by a wet-tropical rainforest-type climate.

Antimicrobial Activity of Propolis From Tabora and Iringa Regions, Tanzania and Synergism with Gentamicin

“…In this study, the ethanolic extract of propolis obtained from Tabora displayed activity on almost all tested microorganisms (MIC 0.42 -1.67 mg/ml) with only Pseudomonas aeruginosa being resistant to this extract. This is in agreement with a previous study on Tanzanian propolis; although in that study the specific area where propolis was collected was not indicated (Seidel et al, 2008). On the other hand the ethanolic extract of propolis from Iringa was able to inhibit growth of five out of nine microorganisms tested, with MICs ranging from 1.67 to 6.67mg/ml.…”

“…This extract was not active against S. aureus, S. typhi, P. aeruginosa and S. faecalis at the tested concentrations. The observed MICs for both samples were several times higher when compared to a previous report on Tanzanian propolis (Seidel et al, 2008), where MICs ranged from 15.62 to 250 mg/l for Gram +ve bacteria. The MICs observed in this study were somehow similar to those reported in another study on propolis from Italy (Scazzocchio et al, 2006).…”

“…A study conducted on propolis from various countries, reported that a sample from Tanzania exhibited antimicrobial activity, with a MIC of 15.62 μg/ml against standard strains of Gram positive bacteria including, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Enterococcus faecalis and Bacillus subtilis (Seidel et al, 2008). However, the exact collection area of the studied propolis sample was not indicated.…”

Natural products modulate Shigella–host-cell interaction

“…Compounds 1-5 were from Sigma-Aldrich; compound 6 was isolated from propolis (Raghukumar et al, 2010) and 7-9 were purified from plants (Gordien et al, 2009;Shilpi et al, 2010). These compounds were selected because they had previously demonstrated some antimicrobial activity (Seidel et al, 2008;Shilpi et al, 2010) and/or because they were part of our laboratory database of authentic standards available in sufficient amounts for biological screening. All compounds were dissolved in DMSO (2 mg ml 21 ) to prepare stock solutions and diluted with cellculture medium to 18 mg ml 21 (i.e.…”

“…A broth microdilution method was used to determine MICs, as described previously (Seidel et al, 2008).…”