Binding and potential antibiofilm activities of Amaranthus proteins against Candida albicans.

In the present study evaluation of structural, thermal and antifungal properties of Amaranthus hypochondriacus laboratory protein isolate (ALMA) and commercially available Amaranthus protein dietary antidepressant (APGM) was done by differential scanning calorimetry (DSC), Fourier Transform Infrared (FTIR) and fluorescence spectroscopy and antibiofilm activities against Candida albicans. The results exhibited thermal stability and antioxidant activity for the isolates. Fluorescence measurements showed that they bind to human serum albumin through a static quenching mechanism, decreasing its fluorescence intensity. FTIR spectra showed amides I, II and III shifts, but it does not modify the structural and bioactive properties against C. albicans despite of its infections which is difficult to treat due to virulence expression and biofilm formation that protects of therapeutic drugs. Both isolates had the potential to assuage two virulence factors such as biofilm formation and yeast to hyphal transition of C. albicans. The biofilm inhibitory concentration of the protein isolates was determined to 10 and 30 µg mL-1 with 50% inhibition, while morphogenic transition of the yeast leads to host tissue damage was significantly inhibited in spider medium and in vivo assay with zebrafish embryo. Inhibition of C. albicans biofilm by protein isolates was well compared with COMSTAT and XTT assay. The conformational changes in the proteins of investigated samples were determined by fluorescence after denaturation with 8 M urea and showed slight differences in comparison with the natural product. This is the first study to envisage the use of amaranth protein isolates to immunocompromised patients in their diet plan that can prevent C. albicans infections and help them in recovery. These isolates can be used as natural polymers in biomedical applications and edible films for health benefits.

An in vitro and in silico identification of antibiofilm small molecules from seawater metaclone SWMC166 against Vibrio cholerae O1.

This study aimed to determine the antibiofilm activity of seawater microbes against Vibrio cholerae (VCO1) through functional metagenomics approach. A metagenomic library was constructed from Palk Bay seawater and the library was screened to identify the biofilm inhibitory metaclone. Metaclone SWMC166 (harbouring ∼30 kb metagenomic insert) was found to exhibit antibiofilm activity against VCO1. The biofilm inhibitory potential of partially purified ethyl acetate extract of SWMC166 (EA166) was further evaluated through microscopic studies and biochemical assays. Further, EA166 treated VCO1 divulged up-regulation of genes involved in high cell density-mediated quorum sensing (QS) pathway which was analysed by real-time PCR. In order to identify the genes of interest (within ∼30 kb insert), subcloning was performed through shotgun approach. Small molecules from positive subclones SC5 and SC8 were identified through HRLC-MS analysis. Resulted small molecules were docked against QS receptors of V. cholerae to identify the bioactive metabolites. Docking studies revealed that totally seven metabolites were able to interact with QS receptors that can possibly trigger the QS cascade and sequentially inhibit the biofilm formation and virulence factors of VCO1.

Cholinesterase inhibitory, anti-amyloidogenic and neuroprotective effect of the medicinal plant Grewia tiliaefolia - An in vitro and in silico study.

CONTEXT: Grewia tiliaefolia Vahl. (Tiliaceae) is a sub-tropical plant used as an indigenous medicine in India. However, its efficacy has not been evaluated against Alzheimer's disease. OBJECTIVES: The objective of this study is to evaluate cholinesterase inhibitory, anti-aggregation and neuroprotective activity of G. tiliaefolia. MATERIALS AND METHOD: Grewia tiliaefolia leaves were collected from Eastern Ghats region, India, and subjected to successive extraction (petroleum ether, chloroform, ethyl acetate, methanol and water). The extracts were subjected to in vitro antioxidant, anticholinesterase and anti-aggregation assays. The active methanol extract (MEGT) was separated using column chromatography. LC-MS analysis was done and the obtained compounds were docked against acetylcholinesterase (AChE) enzyme to identify the active component. RESULTS: Antioxidant assays demonstrated that the MEGT showed significant free radical scavenging activity at the IC50 value of 71.5 ± 1.12 µg/mL. MEGT also exhibited significant dual cholinesterase inhibition with IC50 value of 64.26 ± 2.56 and 54 ± 0.7 µg/mL for acetyl and butyrylcholinesterase (BChE), respectively. Also, MEGT showed significant anti-aggregation activity by preventing the oligomerization of Aß25-35. Further, MEGT increased the viability of Neuro2a cells up to 95% against Aß25-35 neurotoxicity. LC-MS analysis revealed the presence of 16 compounds including vitexin, ellagic acid, isovitexin, etc. In silico analysis revealed that vitexin binds effectively with AChE through strong hydrogen bonding. These results were further confirmed by evaluating the activity of vitexin in vitro, which showed dual cholinesterase inhibition with IC50 value of 15.21 ± 0.41 and 19.75 ± 0.16 µM for acetyl and butyrlcholinesterase, respectively. DISCUSSION AND CONCLUSION: Grewia tiliaefolia can be considered as a promising therapeutic agent for the treatment of AD.

An in silico, in vitro and in vivo investigation of indole-3-carboxaldehyde identified from the seawater bacterium Marinomonas sp. as an anti-biofilm agent against Vibrio cholerae O1.

Biofilm formation is a major contributing factor in the pathogenesis of Vibrio cholerae O1 (VCO1) and therefore preventing biofilm formation could be an effective alternative strategy for controlling cholera. The present study was designed to explore seawater bacteria as a source of anti-biofilm agents against VCO1. Indole-3-carboxaldehyde (I3C) was identified as an active principle component in Marinomonas sp., which efficiently inhibited biofilm formation by VCO1 without any selection pressure. Furthermore, I3C applications also resulted in considerable collapsing of preformed pellicles. Real-time PCR studies revealed the down-regulation of virulence gene expression by modulation of the quorum-sensing pathway and enhancement of protease production, which was further confirmed by phenotypic assays. Furthermore, I3C increased the survival rate of Caenorhabditis elegans when infected with VCO1 by significantly reducing in vivo biofilm formation, which was corroborated by a survivability assay. Thus, this study revealed, for the first time, the potential of I3C as an anti-biofilm agent against VCO1.