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Heavy metals in soil and water resources pose a grave threat to all forms of life, especially due to their bio-accumulative nature. Out of various low-cost adsorbents that have been applied for the removal of heavy metals from contaminated systems, sawdust is a comparatively unexploited and readily available adsorbent. In this study, we have tested the efficacy of sawdust obtained from the wood of mango tree (Mangifera indica)for the quantitative removal of heavy metal ions like Ni(II), As(V), Cr(III) and Pb(II) from their aqueous solutions. Mango tree sawdust proved to be an efficient adsorbent for removing lead, nickel, chromium and arsenic ions from their respective aqueous solutions. Further, to validate the efficacy of sawdust for heavy metal ion removal from natural ecosystems, soil samples were collected from the Yamuna river floodplains in Delhi and Indian mustard (Brassica juncea), known to be a hyper-accumulator of metal ions, was grown in these metal-laden soils. Using atomic absorption spectroscopy (AAS), the amount of heavy metals have been determined in the dried and digested Indian mustard plants grown on soil treated with sawdust and the other without it, to draw a comparison and assess its efficacy for removing heavy metals from soil. Present results indicate that plants grown on soil mixed with sawdust have significantly lower heavy metal content. Thus, sawdust, a natural waste product from wood industry, proves to be a sustainable and low-cost solution for scaling down heavy metal ion pollution in soil and irrigation water, and subsequent toxicity in crops.

An increase in citrus fruit peel and pulp waste across the world poses severe waste management issues and an approach to reuse these industrial and domestic wastes can resolve many environmental and waste management problems. Here, we report the extraction of essential oils from waste Mosambi (Citrus limetta) fruit rinds and its potential use as a larvicidal, insecticidal and antimicrobial agent. The novelty of the study is the use of a household pressure cooker and the extraction has been facilitated outside of a laboratory, using the rinds of waste Mosambi (Citrus limetta), a raw material that has been seldom used for extraction purposes. We have adopted the steam distillation technique followed by solvent extraction using n-hexane. The reported method of extraction produces zero waste, is energy efficient and gives a good yield. The extracted essential oil was found to have larvicidal and insecticidal properties. It also possesses antibacterial activity against non-pathogenic strains Bacillus subtilisand Rhodococcus equi. Fungal strains, Aspergillus flavusand Alternaria carthamiwere also inhibited by the oil, indicating its antifungal nature.

Peptide deformylase (PDF) has emerged as an important antibacterial drug target. Considerable effort is being directed toward developing peptidic and non-peptidic inhibitors for this metalloprotein. In this work, the known peptidic inhibitor BB-3497 and its various ionization and tautomeric states are evaluated for their inhibition efficiency against PDF using a molecular mechanics (MM) approach as well as a mixed quantum mechanics/molecular mechanics (QM/MM) approach, with an aim to understand the interactions in the binding site. The evaluated Gibbs energies of binding with the mixed QM/MM approach are shown to have the best predictive power. The experimental pose is found to have the most negative Gibbs energy of binding, and also the smallest strain energy. A quantum mechanical evaluation of the active site reveals the requirement of strong chelation by the ligand with the metal ion. The investigated ligand chelates the metal ion through the two oxygens of its reverse hydroxamate moiety, particularly the N-O- oxygen, forming strong covalent bonds with the metal ion, which is penta-coordinated. In the uninhibited state, the metal ion is tetrahedrally coordinated, and hence chelation with the inhibitor is associated with an increase of the metal ion coordination. Thus, the strong binding of the ligand at the binding site is accounted for.

The interaction between neutrophils and endothelial cells is critical for the pathogenesis of vascular inflammation. However, the regulation of neutrophil adhesive function remains not fully understood. Intravital microscopy demonstrates that neutrophil DREAM promotes neutrophil recruitment to sites of inflammation induced by TNF-α but not MIP-2 or fMLP. We observe that neutrophil DREAM represses expression of A20, a negative regulator of NF-κB activity, and enhances expression of pro-inflammatory molecules and phosphorylation of IκB kinase (IKK) after TNF-α stimulation. Studies using genetic and pharmacologic approaches reveal that DREAM deficiency and IKKβ inhibition significantly diminish the ligand-binding activity of β2 integrins in TNF-α–stimulated neutrophils or neutrophil-like HL-60 cells. Neutrophil DREAM promotes degranulation through IKKβ-mediated SNAP-23 phosphorylation. Using sickle cell disease mice lacking DREAM, we show that hematopoietic DREAM promotes vaso-occlusive events in microvessels following TNF-α challenge. Our study provides evidence that targeting DREAM might be a novel therapeutic strategy to reduce excessive neutrophil recruitment in inflammatory diseases.

Naturally occurring cationic antimicrobial peptides (AMPs) mostly adopt α-helical structures in bacterial membrane mimetic environments. To explore the design of novel β-sheet AMPs, we identified two short cationic amphipathic β-strand segments from the crystal structure of the innate immune protein, MyD88. Interestingly, of these, the 10-residue arginine–valine-rich synthetic MyD88-segment, KRCRRMVVVV (M3), exhibited β-sheet structure when bound to the outer membrane Gram-negative bacterial component, LPS. Isothermal titration calorimetric data showed that M3 bound to LPS with high affinity, and the interaction was hydrophobic in nature. Supporting these observations, computational studies indicated strong interactions of multiple and consecutive valine residues of M3 with the acyl chain of LPS. Moreover, M3 adopted nanosheet and nanofibrillar structure in 25% acetonitrile/water and isopropanol, respectively. M3 showed substantial antibacterial activities against both Gram-positive and Gram-negative bacteria which it appreciably retained in the presence of human serum and physiological salts. M3 was non-hemolytic against human red blood cells and non-cytotoxic to 3T3 cells up to 200 μM and to mice in vivo at a dose of 40 mg/kg. Furthermore, M3 neutralized LPS-induced pro-inflammatory responses in THP-1 cells and rat bone marrow-derived macrophages. Consequently, M3 attenuated LPS-mediated lung inflammation in mice and rescued them (80% survival at 10 mg/kg dose) against a lethal dose of LPS. The results demonstrate the identification of a 10-mer LPS-interacting, β-sheet peptide from MyD88 with the ability to form nanostructures and in vivo activity against LPS challenge in mice. The identified M3-template provides scope for designing novel bioactive peptides with β-sheet structures and self-assembling properties.

The interaction between neutrophils and endothelial cells (ECs) is critical for the pathogenesis of vascular inflammation. Neutrophil recruitment to inflamed tissues is initiated by rolling on activated ECs through the interactions between P-/E-selectins and their ligands. Subsequently, activated integrins (mainly αLβ2 and αMβ2) and chemokine receptors bind to their ligands on ECs and mediate slow-rolling, adhesion, crawling, and transmigration of neutrophils. Although many neutrophil adhesion receptors have been identified, the regulation of their ligand-binding function remains not fully understood. Using real-time intravital microscopy with mice lacking downstream regulatory element antagonist modulator (DREAM) and their bone marrow chimeric mice, we demonstrated that hematopoietic cell DREAM contributes to neutrophil recruitment to sites of vascular inflammation induced by TNF-α- but not a G protein-coupled receptor ligand, MIP-2 or fMLP. Our studies using adoptive neutrophil transfers and flow chamber assays revealed that neutrophil DREAM positively regulates the neutrophil recruitment processes under TNF-α-induced inflammatory conditions. Using RNA-seq and biochemical and cell biological studies, we found that neutrophil DREAM upregulates numerous pro-inflammatory molecules and down-regulates anti-inflammatory molecules after TNF-α treatment. In particular, neutrophil DREAM repressed expression of A20, a negative regulator of NF-κB signaling, and enhanced phosphorylation of IκB kinase (IKK) in response to TNF-α, suggesting the role of neutrophil DREAM in NF-κB activity. Furthermore, we observed that DREAM deletion and IKK inhibition significantly diminishes the ligand-binding activity of β2 integrins in neutrophils after short-term treatment with TNF-α and that deletion of neutrophil DREAM does not affect the expression of other neutrophil adhesion receptors, such as PSGL-1, L-selectin, CD44, CXCR2, and CXCR4. As assessed by flow cytometry using conformation-specific reporter antibodies, knockdown of DREAM in neutrophil-like HL-60 cells decreased TNF-α-induced activation of β2 integrins. Neutrophil DREAM promoted degranulation through IKK-mediated SNAP-23 phosphorylation after short-term treatment with TNF-α, implying the role of neutrophil DREAM-IKK signaling in NF-κB-independent signaling. Using intravital microscopy with Berkeley mice (a mouse model of sickle cell disease) deficient in hematopoietic or nonhematopoietic DREAM, we demonstrated that hematopoietic cell DREAM is crucial for inducing intravascular cell-cell aggregation and vaso-occlusive events in microvessels following the TNF-α challenge. Furthermore, infusion of DREAM KO neutrophils, compared with WT neutrophils, significantly reduced neutrophil recruitment and vaso-occlusive events in TNF-α-challenged SCD mice. These results demonstrate that neutrophil DREAM positively regulates β2 integrin function and promotes neutrophil recruitment during sterile inflammation via NF-κB-dependent and independent mechanisms. Our study provides evidence that targeting DREAM might be a novel therapeutic strategy to reduce excessive neutrophil recruitment in inflammatory diseases.

No relevant conflicts of interest to declare.