Abstract:
In continuation of our search for new bioactive compounds from soil microbes, a
fluorescent Pseudomonas strain isolated from paddy field soil of Kuttanad, Kerala,
India was screened for the production of bioactive secondary metabolites. This strain
was identified as Pseudomonas mosselii through 16S rDNA gene sequencing followed
by BLAST analysis and the bioactive metabolites produced were purified by column
chromatography (silica gel) and a pure bioactive secondary metabolite was isolated.
This bioactive compound was identified as Pseudopyronine B by NMR and HR-ESI-MS.
Pseudopyronine B recorded significant antimicrobial activity especially against Grampositive
bacteria and agriculturally important fungi. MTT assay was used for finding
cell proliferation inhibition, and Pseudopyronine B recorded significant antitumor activity
against non-small cell lung cancer cell (A549), and mouse melanoma cell (B16F10). The
preliminary MTT assay results revealed that Pseudopyronine B recorded both doseand
time-dependent inhibition of the growth of test cancer cell lines. Pseudopyronine B
induced apoptotic cell death in cancer cells as evidenced by Acridine orange/ethidium
bromide and Hoechst staining, and this was further confirmed by flow cytometry
analysis using Annexin V. Cell cycle analysis also supports apoptosis by inducing
G2/M accumulation in both A549 and B16F10 cells. Pseudopyronine B treated cells
recorded significant up-regulation of caspase 3 activity. Moreover, this compound
recorded immunomodulatory activity by enhancing the proliferation of lymphocytes.
The production of Pseudopyronine B by P. mosselii and its anticancer activity in
A549 and B16F10 cell lines is reported here for the first time. The present study has
a substantial influence on the information of Pseudopyronine B from P. mosselii as
potential sources of novel drug molecule for the pharmaceutical companies, especially
as potent antimicrobial and anticancer agent
