Multifunctional Antibacterial Nanonets Attenuate Inflammatory Responses through Selective Trapping of Endotoxins and Pro-Inflammatory Cytokines.

Extracellular lipopolysaccharide (LPS) released from bacteria cells can enter the bloodstream and cause septic complications with excessive host inflammatory responses. Target-specific strategies to inactivate inflammation mediators have largely failed to improve the prognosis of septic patients in clinical trials. By utilizing their high density of positive charges, de novo designed peptide nanonets are shown to selectively entrap the negatively charged LPS and pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). This in turn enables the nanonets to suppress LPS-induced cytokine production by murine macrophage cell line and rescue the antimicrobial activity of the last-resort antibiotic, colistin, from LPS binding. Using an acute lung injury model in mice, it is demonstrated that intratracheal administration of the fibrillating peptides is effective at lowering local release of TNF-α and IL-6. Together with previously shown ability to simultaneously trap and kill pathogenic bacteria, the peptide nanonets display remarkable potential as a holistic, multifunctional anti-infective, and anti-septic biomaterial.

Discovery and development of labdane-oxindole hybrids as small-molecule inhibitors against chikungunya virus infection.

Chikungunya virus (CHIKV) infection, a febrile illness caused by a mosquito-transmitted alphavirus, has afflicted millions of people worldwide. There is currently no approved effective antiviral treatment for CHIKV infection. In this study, we report a new class of small-molecule CHIKV inhibitors, the oxindole-labdanes, that potently block the replication of CHIKV with good selectivity. Andrographolide, a previously reported inhibitor of CHIKV infection, was used as the lead compound for our initial structure-activity relationship (SAR) study. From a focused library of 72 andrographolide analogues, we identified the lead compound (E)-2 with improved antiviral activities. Further optimization of (E)-2 led to the discovery of the normal-labdane 7-chloro-oxindole (E)-42 as potent inhibitor against two low-passage CHIKV isolates from human patients with an EC50 of 1.55 µM against CHIKV-122508 and 0.14 µM against CHIKV-6708. Compound (E)-42 displayed minimal cytotoxic liability (CC50 > 100 µM), thus furnishing good selectivity relative to the host cells. Mechanistically, (E)-42 does not inactivate the viral particles but rather acts on the host cells to interfere with the viral replication, demonstrating both prophylactic and therapeutic effects. Our findings open a new avenue for the development of oxindole-labdane compounds as promising antiviral drugs against CHIKV infection.