Inhibitory effects of bioactive leads isolated from Pseudomonas aeruginosa PS3 and Pseudomonas fluorescens PS7 on MAP kinases and down regulation of pro inflammatory cytokines (TNF-α, IL-1β) and mediators (NO, iNOS and COX)

Volatile Nitrogenous Compounds from Bacteria: Source of Novel Bioactive Compounds

Bacteria can produce nitrogenous compounds via both primary and secondary metabolic processes. Many bacterial volatile nitrogenous compounds produced during the secondary metabolism have been identified and reported for their antioxidant, antibacterial, antifungal, algicidal and antitumor activities. The production of these nitrogenous compounds depends on several factors, including the composition of culture media, growth conditions, and even the organic solvent used for their extraction, thus requiring their identification in specific conditions. In this review, we describe the volatile nitrogenous compounds produced by bacteria especially focusing on their antimicrobial activity. We concentrate on azo-compounds mainly pyrazines and pyrrolo-pyridines reported for their activity against several microorganisms. Whenever significant, extraction and identification methods of these compounds are also mentioned and discussed. To the best of our knowledge, this is first review describing volatile nitrogenous compounds from bacteria focusing on their biological activity.

Attenuation of TNF-α secretion by L-proline-based cyclic dipeptides produced by culture broth of Pseudomonas aeruginosa

To identify small molecule inhibitors of TNF-α, bioassay- and LC-MS-guided chemical investigation on EtOAc extract of Pseudomonas aeruginosa ABS-36 culture broth (EEPA) was performed, which yielded four proline-based cyclic dipeptides, cyclo(Gly-l-Pro) (1), cyclo(l-Pro-l-Phe) (2), cyclo(trans-4-hydroxy-l-Pro-l-Phe) (3) and cyclo(trans-4-hydroxy-l-Pro-l-Leu) (4). Compounds 1 and 3 exhibited potent inhibition of TNF-α release with IC50 values of 4.5 and 14.2μg/mL, respectively, while EEPA showed IC50 of 38.8μg/mL under lipopolysaccharide treated RAW 264.7 cell ELISA assay. Also, marked attenuation of mRNA-expression of TNF-α was shown by all compounds. In vivo testing in rats of EEPA and chemically synthesized 4 validated significant TNF-α reduction with 51% (500mg/kg) and 79% (50mg/kg), respectively. In addition, all compounds exhibited significant diminution of IL-1β and IL-6 mRNA-expression levels and NO production. All samples displayed only weak toxicity to lipopolysaccharide-induced RAW 264.7 cells.

Anti-inflammatory effects of secondary metabolites of marine Pseudomonas sp. in human neutrophils are through inhibiting P38 MAPK, JNK, and calcium pathways

Activated neutrophils play a significant role in the pathogenesis of many inflammatory diseases. The metabolites of marine microorganisms are increasingly employed as sources for developing new drugs; however, very few marine drugs have been studied in human neutrophils. Herein, we showed that secondary metabolites of marine Pseudomonas sp. (N11) significantly inhibited superoxide anion generation and elastase release in formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP)-activated human neutrophils, with IC50 values of 0.67±0.38 µg/ml and 0.84±0.12 µg/ml, respectively. In cell-free systems, neither superoxide anion-scavenging effect nor inhibition of elastase activity was associated with the suppressive effects of N11. N11 inhibited the phosphorylation of p38 MAP kinase and JNK, but not Erk and Akt, in FMLP-induced human neutrophils. Also, N11 dose-dependently attenuated the transient elevation of intracellular calcium concentration in activated neutrophils. In contrast, N11 failed to alter phorbol myristate acetate-induced superoxide anion generation, and the inhibitory effects of N11 were not reversed by protein kinase A inhibitor. In conclusion, the anti-inflammatory effects of N11 on superoxide anion generation and elastase release in activated human neutrophils are through inhibiting p38 MAP kinase, JNK, and calcium pathways. Our results suggest that N11 has the potential to be developed to treat neutrophil-mediated inflammatory diseases.