Microbial biofilm are communities of surface-adhered cells enclosed in a matrix of extracellular polymeric substances. Extensive use of antibiotics to treat biofilm associated infections has led to the emergence of multiple drug resistant strains. Pseudomonas aeruginosa is recognised as a model biofilm forming pathogenic bacterium. Vitexin, a polyphenolic group of phytochemical with antimicrobial property, has been studied for its antibiofilm potential against Pseudomonas aeruginosa in combination with azithromycin and gentamicin. Vitexin shows minimum inhibitory concentration (MIC) at 260 μg/ml. It’s antibiofilm activity was evaluated by safranin staining, protein extraction, microscopy methods, quantification of EPS and in vivo models using several sub-MIC doses. Various quorum sensing (QS) mediated phenomenon such as swarming motility, azocasein degrading protease activity, pyoverdin and pyocyanin production, LasA and LasB activity of the bacteria were also evaluated. Results showed marked attenuation in biofilm formation and QS mediated phenotype of Pseudomonas aeruginosa in presence of 110 μg/ml vitexin in combination with azithromycin and gentamicin separately. Molecular docking of vitexin with QS associated LuxR, LasA, LasI and motility related proteins showed high and reasonable binding affinity respectively. The study explores the antibiofilm potential of vitexin against P. aeruginosa which can be used as a new antibiofilm agent against microbial biofilm associated pathogenesis.

The recurrence of breast cancer in patients is a persistent challenge to the medical fraternity. Breast tumor contains a small population of cells with high tumor initiating and metastatic potential, known as cancer stem cells (CSCs), which are resistant to existing chemotherapeutics. CSCs contribute to the aggressiveness of triple negative breast cancers (TNBCs), thereby necessitating the identification of molecular targets on breast CSCs. TNBC cell line MDA-MB-231, in comparison with MCF-7, demonstrated a higher expression of epidermal growth factor receptor (EGFR). Thus, the naturally occurring flavanone, chrysin, with limited potential as a chemotherapeutic agent, was structurally modified by designing an analog with EGFR binding affinity using a molecular docking approach and subsequently synthesised. Chrysin analog CHM-09 and known EGFR inhibitors demonstrated a comparable anti-proliferative, anti-migratory activity along with the induction of apoptosis and cell cycle arrest in MDA-MB-231. Furthermore, sorted CD24 /CD44 -breast CSCs and CD24 -breast cancer cells from MDA-MB-231 demonstrated a markedly high expression of EGFR in the former than in the latter. CHM-09 and EGFR inhibitors could perturb EGF-induced EGFR signalling of breast CSC proliferation, migration, mammosphere formation and mesenchymal tri-lineage differentiation. CHM-09 or EGFR inhibitors not only led to inactivation of EGFR downstream signalling pathways such as Akt, extracellular signal regulated kinase and signal transducer and activator of transcription 3, but also induction of mesenchymal-epithelial transition as confirmed by decreased N-cadherin and increased E-cadherin expression. Finally, combinatorial treatment of EGFR inhibitors and doxorubicin led to significant increase in breast CSCs responsiveness to a chemotherapeutic drug. The results of the present study suggest that EGFR is a therapeutic target in breast CSCs and that abrogation of EGFR signalling along with chemotherapeutic drugs is an effective approach against breast cancer.

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Parkia javanica is a well-known ethno-botanical plant of the north-east region of India. Ethnic communities of the region use several parts, including fruits, of this plant for the treatment of various ailments like diarrhoea, dysentery, cholera, food poisoning etc. In addition fruits are consumed by the local tribes of the north-east as food supplements. With this background we have performed chemical characterisation, and investigated the antimicrobial and antibiofilm potentiality of ethyl acetate fraction of Parkia javanica fruit extract (PJE) against model biofilm-causing microorganism Pseudomonas aeruginosa. PJE was initially prepared from fruit extract, and assayed by IR and UV spectroscopy and HPLC to confirm the presence of compounds. HPLC and NMR analysis reveals that PJE contains flavone compounds baicalein, quercetin and chrysin. PJE, baicalein, quercetin and chrysin were then tested for antimicrobial and antibiofilm activity against P. aeruginosa. PJE showed very significant antimicrobial activity against P. aeruginosa wherein the minimum inhibitory concentration was found at 180 mg mL À1. Interestingly, the antibiofilm study illustrates that minimum concentration of PJE (30 mg mL À1 ) exhibited maximum activity whereas maximum concentration of PJE (90 mg mL À1 ) exhibited minimum antibiofilm activity. It was also observed that compounds baicalein, quercetin and chrysin separately show lower to moderate antibiofilm activity in comparison to PJE. Molecular docking study indicates that baicalein, quercetin and chrysin have good binding affinity with bacterial quorum sensing and motility associated proteins. Furthermore, we have also observed that in comparison with higher concentration, lower concentration of PJE exhibited better attenuation in swarming motility, secretion of proteases and virulence factors like pyoverdin and pyocyanin. AFM study reveals that aggregates in PJE are smaller in size at low concentrations than at higher concentrations. Observations in the present study suggest that PJE as a whole shows higher antibiofilm activity at low concentration whereas individual compounds have comparatively lower antibiofilm activity. This validates the phytomedicinal significance of Parkia javanica against bacterial biofilms.

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