Photodynamic Inactivation of Human Coronaviruses

Photodynamic inactivation (PDI) employs a photosensitizer, light, and oxygen to create a local burst of reactive oxygen species (ROS) that can inactivate microorganisms. The botanical extract PhytoQuinTM is a powerful photosensitizer with antimicrobial properties. We previously demonstrated that photoactivated PhytoQuin also has antiviral properties against herpes simplex viruses and adenoviruses in a dose-dependent manner across a broad range of sub-cytotoxic concentrations. Here, we report that human coronaviruses (HCoVs) are also susceptible to photodynamic inactivation. Photoactivated-PhytoQuin inhibited the replication of the alphacoronavirus HCoV-229E and the betacoronavirus HCoV-OC43 in cultured cells across a range of sub-cytotoxic doses. This antiviral effect was light-dependent, as we observed minimal antiviral effect of PhytoQuin in the absence of photoactivation. Using RNase protection assays, we observed that PDI disrupted HCoV particle integrity allowing for the digestion of viral RNA by exogenous ribonucleases. Using lentiviruses pseudotyped with the SARS-CoV-2 Spike (S) protein, we once again observed a strong, light-dependent antiviral effect of PhytoQuin, which prevented S-mediated entry into human cells. We also observed that PhytoQuin PDI altered S protein electrophoretic mobility. The PhytoQuin constituent emodin displayed equivalent light-dependent antiviral activity to PhytoQuin in matched-dose experiments, indicating that it plays a central role in PhytoQuin PDI against CoVs. Together, these findings demonstrate that HCoV lipid envelopes and proteins are damaged by PhytoQuin PDI and expands the list of susceptible viruses.

A look at photodynamic inactivation as a tool for pests and vector-borne diseases control

The control of pests and vector-borne diseases (VDBs) are considered public health issues Worldwide. Among the control techniques and pesticides used so far, photodynamic inactivation (PDI) has been shown as an eco-friendly, low cost, and efficient approach to eliminate pests and VDBs. PDI is characterized using a photosensitizing molecule, light and molecular oxygen (O2) resulting in production of reactive oxidative species which can promote the oxidation of biomolecules on pests and vectors. Herein, we review the past 51 years (1970–2021) regarding the use of photo pesticides, reporting the most important parameters for the protocol applied, the results obtained, and limitations. Moreover, we described the mechanism of action of the PDI, main classes of photopesticides used so far as well as the cell death mechanism resulting from the photodynamic action.