Biology subjects

Neelakantan, P.

Publications and source records attributed to Neelakantan, P..

4 recordsLinked to original sources

bioRxiv2021

Trans -cinnamaldehyde attenuates Enterococcus faecalis virulence and inhibits biofilm formation

Enterococcus faecalis as an important nosocomial pathogen is critically implicated in the pathogenesis of endocarditis, urinary tract and surgical wound infections. Its major virulence attributes (biofilm formation, production of proteases and hemolytic toxins) enable it to cause extensive host tissue damage. With the alarming increase in enterococcal resistance to antibiotics, novel therapeutics are required to inhibit E. faecalis biofilm formation and virulence. Trans-cinnamaldehyde (TC), the main phytochemical in cinnamon essential oils has demonstrated promising activity against a wide range of pathogens. Here, we comprehensively investigated the effect of TC on planktonic growth, biofilm formation, proteolytic and hemolytic activities, as well as gene regulation in E. faecalis. Our findings revealed that sub-inhibitory concentrations of TC reduced biofilm formation, biofilm exopolysaccharides as well as its proteolytic and hemolytic activities. Mechanistic studies revealed significant down regulation of the quorum sensing fsr locus and downstream gelE, which are major virulence regulators in E. faecalis. Taken together, our study highlights the potential of TC to inhibit E. faecalis biofilm formation and its virulence.

microbiology↗

bioRxiv2021

Design of a novel DNA Gyrase B inhibitor with a rhodanine scaffold: in silico and in vitro approaches

Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin intermediate-resistant Staphylococcus aureus (VRSA) is one among the WHO high priority pathogens. Among these two, MRSA is the most globally documented pathogen that necessitates the pressing demand for new classes of anti-MRSA drugs. Bacterial gyrase targeted therapeutics are unique strategies to overcome cross-resistance as they are present only in bacteria and absent in higher eukaryotes. The GyrB subunit is essential for the catalytic functions of the bacterial enzyme DNA Gyrase, thereby constituting a promising druggable target. The current study performed a structure-based virtual screening to designing GyrB target-specific candidate molecules. The de novo ligand design of novel hit molecules was performed using a rhodanine scaffold. Through a systematic in silico screening process, the hit molecules were screened for their synthetic accessibility, drug likeliness and pharmacokinetics properties in addition to its target specific interactions. Of the total 374 hit molecules obtained through de novo ligand design, qsl-304 emerged as the most promising ligand. qsl-304 was synthesized through a one-step chemical synthesis procedure, and the in vitro activity was proven, with an IC50 of 31.23 g/mL against the novobiocin resistant clinical isolate of Staphylococcus aureus sa-P2003. Further studies on time-kill kinetics showed the bacteriostatic nature with the diminished recurrence of resistance.

microbiology↗

bioRxiv2020

Curcumin-Sophorolipid nano-conjugate inhibits Candida albicans filamentation and biofilm development

Candida albicans is an opportunistic fungal pathogen that is highly resistant to contemporary antifungals, and a major reason for this appears to be their predominant, filamentation-mediated, biofilm lifestyle. Hence, agents that inhibit biofilms and filamentation of the yeast offer promise as next-generation antifungals. Curcumin is a natural polyphenol with several beneficial pharmacological attributes, yet limitations such as poor solubility, acid, and enzyme tolerance have impeded its practical utility. Sophorolipids are biologically-derived surfactants that serve as efficient carriers and delivery agents of hydrophobic molecules, such as curcumin, into biofilms. The aim of this study was to investigate the effects of a novel, curcumin-sophorolipid (CU-ASL) nano-conjugate on Candida albicans biofilms and filamentation. The effects of CU and ASL, in combination, and alone, were investigated on planktonic cells of the yeast. The effects of sub-inhibitory concentrations of the compounds were investigated on biofilm biomass and biofilm architecture. Their effects on filamentation was compared by scanning electron microscopic imaging, and gene expression analysis by qRT-PCR. Our results demonstrated that sub-inhibitory concentration of CU-ASL (9.37 {micro}g/mL) significantly inhibited candidal adhesion to substrates, and subsequent biofilm development, maturation, and filamentation. This effect was associated with significant downregulation of a select group of biofilm, adhesins, and hyphal regulatory genes. In conclusion, the curcumin-sophorolipid nano-conjugate is a potent inhibitor of the two major virulence attributes of C. albicans, biofilm formation and filamentation, thus highlighting its promise as a putative anti-candidal agent with low toxicity and biofilm penetrative potential.

microbiology↗

bioRxiv2020

Trans-cinnamaldehyde potently kills Enterococcus faecalis biofilm cells and prevents biofilm recovery

Enterococcus faecalis is a biofilm-forming, nosocomial pathogen that is frequently isolated from failed root canal treatments. Contemporary root canal disinfectants are ineffective in eliminating these biofilms and preventing reinfection. As a result, there is a pressing need to identify novel and safe antibiofilm molecules. The effect of short-term (5 and 15 min) and long-term (24 h) treatments of TC on the viability of E. faecalis biofilms was compared with currently used root canal disinfectants. Treatment for 15 min with TC reduced biofilm metabolic activity as effective as 1% sodium hypochlorite and 2% chlorhexidine. Treatment with TC for 24 h was significantly more effective than 2% chlorhexidine in reducing the viable cell counts of biofilms. This serendipitous effect of TC was sustained for 10 days under growth-favoring conditions. For the first time, our study highlights the strong antibacterial activity of TC against E. faecalis biofilms, and notably, its ability to prevent biofilm recovery after treatment.

microbiology↗