The coronavirus infectious disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and has been spreading rapidly worldwide, creating a pandemic. This article describes the evaluation of the antiviral activity of nordihydroguaiaretic acid (NDGA), a molecule found in Creosote bush (Larrea tridentata) leaves, against SARS-CoV-2 in vitro. A 35 µM concentration of NDGA was not toxic to Vero cells and exhibited a remarkable inhibitory effect on the SARS-CoV-2 cytopathic effect, viral plaque formation, RNA replication, and expression of the SARS-CoV-2 spike glycoprotein. The 50% effective concentration for NDGA was as low as 16.97 µM. Our results show that NDGA could be a promising therapeutic candidate against SARS-CoV-2.

The discovery and design of antiviral agents have gained unprecedented significance due to the emergence of global health threats. The use of synthetic chemistry has enabled the modification of existing molecules and the creation of entirely novel compounds. In our laboratory, we have enzymatically synthesized a novel bioconjugate, lithocholic acid oleate (LO), derived from lithocholic acid (LCA), a bile acid that has been proven by researchers to exhibit antiviral activity in vitro. The study presented herein describes the preparative synthesis, formulation, and evaluation of LO both in vitro and in vivo for its antiviral activity against human herpes simplex virus 1 (HSV-1) as a model of viral infection. Evaluation of cytotoxicity using A549 cells indicated that a combination of LO (400 μM) and LCA (30 μM) exhibited a favorable safety profile while effectively inhibiting HSV-1 infection comparable to acyclovir treatment. Furthermore, in the in vivo assay, animals treated with an oily formulation containing 7% LO; 0.50% LCA; and 3% oleic acid (OA), 48 h prior to virus exposure, showed results even superior to a 5% acyclovir commercial formulation in terms of scar formation and wound recovery. These promising results enable the development of new preventive products against HSV-1 and probably other viruses.

Zika virus (ZIKV) is a mosquito-borne virus and Aedes agypti has been mentioned as the main vector of the disease. Other mosquito species in the Aedes and Culex genera have been suggested to have the potential for being competent vectors, based on experimental exposition of mosquitoes to an infectious blood meal containing ZIKV. Here, we report the isolation in cell culture of ZIKV from different body parts of wild-caught female mosquitoes ( Ae. aegypti , Ae. vexans, Culex quinquefasciatus , Cx. coronator , and Cx. tarsalis ) and whole male mosquitoes ( Ae. aegypti and Cx. quinquefasciatus ) in Mexico. Importantly, the virus was isolated from the salivary glands of all of these mosquitoes, strongly suggesting that these species are potential vectors for ZIKV.

SARS-CoV-2 has been reported as one of the deadliest viruses in history. Currently, few antiviral treatments are available to prevent SARS-CoV-2 progression to severe disease, especially in low-income countries. Natural products stand as a potential source of bioactive compounds. The antiviral activity against SARS-CoV-2 of Chlorella vulgaris has been demonstrated, however, the nature of its antiviral compounds remains unexplored. In this study, in vitro antiviral activity of extracts and fractions derived from C. vulgaris algae dry powder, was assessed. To determine the in vitro antiviral activity Vero cells were incubated with different concentrations of extracts and fractions against 100 TCID50/ml of SARS-CoV-2 variants. C. vulgaris ethanolic and diethyl ether extracts showed no cytopathic effect in 100% of the replicates. Fractions F11, F12, and F21, composed of high-weight polysaccharides and small proteins, partially protect against viral infection. These results suggest that polysaccharides, proteins, and pigments are related to antiviral activity.