Spatial and temporal control over DNA cleavage by photoactivated enediynes can be complemented by additional factors such as the release of internal strain, chelation, pH changes, intramolecular H-bonds, and substituent effects. This review presents design and reactivity of photoactivated enediynes/enynes and analyses the chemical, biological, and photophysical challenges in their applications.

As newer variants of SARS-CoV-2 continue to pose major threats to global human health and economy, identifying novel druggable antiviral targets is the key towards sustenance. Here, we identify an evolutionary conserved “E-L-L” motif present within the HR2 domain of all human and non-human coronavirus spike (S) proteins that play a crucial role in stabilizing its post-fusion six-helix bundle (6-HB) structure and thus, fusion-mediated viral entry. Mutations within this motif reduces the fusogenicity of the S protein without affecting its stability or membrane localization. We found that posaconazole, an FDA-approved drug, binds to this “E-L-L” motif and impedes the formation of 6-HB, thus effectively inhibiting SARS-CoV-2 infection in cells. While posaconazole exhibits high efficacy in blocking S protein-mediated viral entry, mutations within the “E-L-L” motif rendered the protein completely resistant to the drug, establishing its specificity towards this motif. Our data demonstrate that posaconazole restricts early stages of infection through specific inhibition of membrane fusion and viral genome release into the host cell and is equally effective towards all major variants of concerns of SARS-CoV-2 including beta, kappa, delta, and omicron. Together, we show that this conserved essential “E-L-L” motif is an ideal target for the development of prophylactic and therapeutic interventions against SARS-CoV-2.

This work describes the synthesis of azidonaphthalimide carboxylic acids which act as fluorescent templates with a built-in photoreactive group and a linker thus simplifying the design of protein labeling agents. These were separately connected to selectivity hands like a sulfonamide and ampicillin for successful labeling/detection of HCAII and PBPs, respectively.

A simple strategy for the synthesis of 6H-benzo[c]chromenes and 5,6-dihydrophenanthridines through a judicious use of Garratt-Braverman (GB) cyclization and Buchwald-Hartwig (BH) coupling in moderate to good yield, has been reported. The uniqueness of the GB reaction is exemplified in providing the required biaryl intermediate which could be successfully converted to the target skeleton via functional group transformations followed by BH coupling. The presence of a dihydro-isofuran moiety assisted in inducing a helical motif in these molecules, which is also confirmed by single crystal X-ray structural analysis. The crystallographic data gives valuable insight into the role of the non-bonding interaction in regulating the helicity.Scheme 2 Possible synthetic alternatives.Scheme 3 Mechanistic route for the two alternate GB cyclization pathways.This journal is