An insight into pyocyanin: production, characterization, and evaluation of its in vitro antibacterial, antifungal, antibiofilm and in vivo anti-schistosomal potency.

backgroundTackling the high demand for alternative therapeutic options, especially for multi-drug-resistant organisms, has awakened interest in naturally originated biomolecules such as pyocyanin (PYO). Herein, PYO-producing bacterium was isolated and PYO was extracted, characterized, and its antagonistic potency was scrutinized against a vast array of prokaryotic and eukaryotic water pathogens, either in free-living or biofilm lifestyles, both in vitro and in vivo.

resultsInitially, Pseudomonas sp. MPF-2 that was screened from agricultural soil for PYO production, was characterized and identified. On King’s-A broth, the maximum productivity of PYO recorded 31.35 µg\ mL within 72 h. Subsequently, the extracted PYO exhibited maximum absorbance peaks at 277, 383 and 522 nm using UV–vis spectrophotometry. While FTIR spectrum accentuated the involvement of the main hallmark functional groups that characterize phenazine including O–H, C = N, aromatic C-H, C = C, CH3, C-O and C– O–C. Additionally, GC-MS analysis showed the major peaks of 1-hydroxyphenazine (hemi pyocyanin) and phenazine fractions at 206.1, 196.1 and 168.1 m/z. Upon employing it as an antibacterial agent, the crude PYO showed the lowest MIC (15.6 µg/mL) against S. pneumoniae, the highest MIC (500 µg/mL) versus P. vulgaris. While a considerable mycocidal potency was noticed against C. albicans and C. tropicalis at 125 and 62.5 µg/mL, respectively. As an antibiofilm agent, PYO displayed 98.11 ± 1.7, 88.04 ± 1.37 and 90.99 ± 2.13% inhibition for B. cereus, P. vulgaris and C. albicans biofilms, in that same order. Whereas, 61.65 ± 2.09, 40.86 ± 2.81 and 48.68 ± 2.56% eradication was detected at 1000 µg/mL for the pre-established biofilms of B. cereus, P. vulgaris and C. albicans, sequentially. Meanwhile, it didn’t show any significant toxicity regarding serum kidney and liver functions in orally treated mice at 25 mg/kg for 5 days. For antiparasitic potency, PYO-treated mice, at the juvenile stage, exhibited a significant reduction (p ≤ 0.05) in the total worm load (23.83 ± 2.79), with a reduction percentage of 34.41%, while PZQ-treated mice failed to show any significant reduction. Moreover, SEM micrographs emphasized the ultrastructural changes in S. mansoni juvenile and adult worms recovered from the PYO-treated mice. To the best of our knowledge, this is the first in vivo study to assess orally administered PYO as a therapeutic option against S. mansoni.

conclusionThe promising results encourage the recruiting of PYO in conquering the virulence of other pathogens in different environmental, medical and industrial applications.