Synthesis and characterization of carbohydrate-based biosurfactant mimetics.

Glycolipid biosurfactants are of interest for various industry sectors. We report the synthesis and characterization of enantiopure poly-amido-saccharides (PASs) containing myristoyl (C14), palmitoyl (C16), or stearoyl (C18) terminal chain lengths as mimetics of glycolipid biosurfactants. These amphiphilic polymers are water soluble, adopt a helical secondary structure, decompose at temperatures greater than 240 °C, are non-cytotoxic, and self-assemble into nanostructures. Polymers containing the shorter hydrophilic chain lengths and the hydrophobic C14 chain exhibit the lowest surface tension among all polymers.

The in-vitro effect of famotidine on sars-cov-2 proteases and virus replication.

The lack of coronavirus-specific antiviral drugs has instigated multiple drug repurposing studies to redirect previously approved medicines for the treatment of SARS-CoV-2, the coronavirus behind the ongoing COVID-19 pandemic. A recent, large-scale, retrospective clinical study showed that famotidine, when administered at a high dose to hospitalized COVID-19 patients, reduced the rates of intubation and mortality. A separate, patient-reported study associated famotidine use with improvements in mild to moderate symptoms such as cough and shortness of breath. While a prospective, multi-center clinical study is ongoing, two parallel in silico studies have proposed one of the two SARS-CoV-2 proteases, 3CLpro or PLpro, as potential molecular targets of famotidine activity; however, this remains to be experimentally validated. In this report, we systematically analyzed the effect of famotidine on viral proteases and virus replication. Leveraging a series of biophysical and enzymatic assays, we show that famotidine neither binds with nor inhibits the functions of 3CLpro and PLpro. Similarly, no direct antiviral activity of famotidine was observed at concentrations of up to 200 µM, when tested against SARS-CoV-2 in two different cell lines, including a human cell line originating from lungs, a primary target of COVID-19. These results rule out famotidine as a direct-acting inhibitor of SARS-CoV-2 replication and warrant further investigation of its molecular mechanism of action in the context of COVID-19.