Anti-pseudomonas activity of essential oil, total extract, and proanthocyanidins of Pinus eldarica Medw. bark

Abstract

Pinus eldarica Medw. (Iranian pine) is native to Transcaucasian region and has been vastly planted in Iran, Afghanistan, and Pakistan. Various parts of this plant have been widely used in traditional medicine for the treatment of various diseases including infectious conditions (e.g. infectious wounds). In this study we aimed to investigate the antibacterial activity of P. eldarica bark extract, essential oil and proanthocyanidins on three important bacteria, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Antibacterial analysis was performed using standard disk diffusion method with different concentrations of essential oil, bark total hydroalcoholic extract, and bark proanthocyanidins (0.5, 1, 2 and 3 mg/ml). After incubation at 37°C for 24 h, the antibacterial activity was assessed by measuring the zone of growth inhibition surrounding the disks. The results indicated that the essential oil, total hydroalcoholic extract, and proanthocyanidins of the bark of the P. eldarica were effective against the gram negative bacteria, P. aeruginosa, and significantly inhibited its growth in disk diffusion method (P<0.001) of which the essential oil had the most potent inhibitory effect. However, none of the bark preparations could significantly inhibit the growth of S. aureus or E. coli. Our findings showed that P. eldarica bark components have significant anti-pseudomonas activity having potentials for new sources of antibacterial agents or antibacterial herbal preparations.

Keywords: Anti-pseudomonas; Antibacterial activity; Disk diffusion; Pinus eldarica; Proanthocyanidins.

Fig. 1

Antibacterial effects of Pinus eldarica bark essential oil (PEEO) on Pesudomonas aeroginosa determined by disc diffusion method. Values are expressed as mean ± S.E.M. PEEO and vancomycin samples have significantly increased the growth inhibition zone compared to the blank sample (P<0.001). **P<0.01 compared with vancomycin disc; ***P<0.001 compared with vancomycin disc, Statistical analyses performed with one-way ANOVA and Tukey's post hoc test.

Fig. 2

Antibacterial effects of Pinus eldarica bark proanthocyanidins (PEPa) on Pesudomonas aeroginosa determined by disc diffusion method. Values are expressed as mean ± S.E.M. PEPa and vancomycin samples have significantly increased the growth inhibition zone compared to the blank sample (P<0.001). **P<0.01 compared with vancomycin disc; ***P<0.001 compared with vancomycin disc, Statistical analyses performed with one-way ANOVA and Tukey's post hoc test.

Fig. 3

Antibacterial effects of Pinus eldarica bark total hydroalcoholic extract (PETE) on Pesudomonas aeroginosa determined by disc diffusion method. Values are expressed as mean ± S.E.M. PETE and vancomycin samples have significantly increased the growth inhibition zone compared to the blank sample (P<0.001). **P<0.01 compared with vancomycin disc; ***P<0.001 compared with vancomycin disc, Statistical analyses performed with one-way ANOVA and Tukey's post hoc test.