Geneticists find fruit juices can help fight COVID-19
Researchers from St Petersburg University and other scientific organizations have developed a method to identify inhibitors of the enzyme responsible for coronavirus replication. While investigating this mechanism, the specialists discovered that certain fruit juices suppress the enzyme's activity. The findings suggest that other natural plant-based substances could eventually form the basis for COVID-19 medications.
The main protease of SARS-CoV-2 is an enzyme that plays a key role in viral replication, enabling the virus to multiply and spread. It is considered a promising target for developing antiviral drugs against COVID-19 because it recognizes and cleaves a specific amino acid sequence not targeted by functionally similar enzymes in human cells. As the researchers note, this characteristic could help minimize the risk of side effects from future medications.
Inhibitors can slow down or completely halt biochemical processes, making them promising candidates for antiviral drug development. However, effective use of inhibitors requires fundamentally new screening tools that are accessible, high-throughput, inexpensive, and easy to interpret. Currently available methods either require costly specialized equipment or must be conducted in high-biosecurity laboratories, limiting their widespread application.
Scientists from St Petersburg University, in collaboration with colleagues from the All-Russian Research Institute for Agricultural Microbiology and the All-Russian Institute of Plant Protection, have developed a novel approach to address this challenge. The method created by the experts functions as a "live detector" that changes color depending on the presence of inhibitors.
"In genetic engineering, we often use genes whose products produce a color reaction — we took one such gene as our foundation. Normally, its product causes bacteria growing on a medium with a specific substrate to turn blue. We modified this gene by inserting a segment encoding the amino acid sequence recognized by the main coronavirus protease. Then we introduced the protease gene itself into the same bacterium. As a result, the protease 'cut' the protein responsible for the cells turning blue," explained Tatiana Matveeva, Professor at the Department of Genetics and Biotechnology, St Petersburg University.
As the geneticists emphasize, the system they created contains only the viral enzyme, which lacks infectious activity, making it completely safe for living organisms. Another advantage of the method is the ability to conduct rapid, cost-effective primary screening of candidate compounds, which can later be tested on mammalian cell cultures and in clinical trials.
Plants served as the source of potential inhibitors: pomegranate, rhubarb, guelder-rose, grape, red currant, and black currant juices were selected for analysis. Using biochemical and computational methods, the scientists determined that certain phytochemicals can suppress the activity of the main coronavirus protease.
Experiments with pomegranate juice showed a significant intensification of the blue color as its concentration increased, indicating successful suppression of protease activity in bacterial cells. Guelder-rose juice, conversely, contained few substances affecting the enzyme. Rhubarb and black currant demonstrated a noticeable inhibitory effect, while grape and red currant juices did not produce the desired result. According to the researchers, these findings could be useful both for preventive measures and for developing new medications against COVID-19.
"We have obtained important information about how diet could be adjusted when there is a risk of coronavirus infection, as well as about possibilities for suppressing the virus in the early stages of the disease. Our method could become one of the tools in the search for medications not only for COVID-19 but also for future infections. Diagnostic systems for other viruses could also be developed using this same platform," said Issa Shaza, a postgraduate student at the Department of Genetics and Biotechnology, St Petersburg University.
The researchers emphasize that the proposed method does not replace high-precision biochemical assays or antiviral activity tests. Its purpose is to serve as a preliminary screening tool, helping to prioritize candidates in the search for inhibitors of the main SARS-CoV-2 protease.
More information:
Shaza S. Issa et al, Targeting SARS-CoV-2 Main Protease: A Bacteria-Based Colorimetric Assay for Screening Natural Antiviral Inhibitors, Viruses (2026). DOI: 10.3390/v18020178
Provided by St. Petersburg State University
