Fruit Juices Reveal Promise in Blocking COVID-19 Replication, Study Finds

Researchers at St. Petersburg State University have identified several fruit juices that demonstrate the ability to suppress the activity of a key enzyme responsible for SARS-CoV-2 replication, offering potential avenues for both preventative measures and the development of modern COVID-19 treatments. The findings, published in Viruses in February 2026, highlight a novel, cost-effective method for screening potential antiviral compounds.

The Importance of Targeting the Main Protease

The SARS-CoV-2 main protease is crucial for the virus’s ability to multiply and spread. It’s considered a promising target for antiviral drug development because it differs significantly from similar enzymes found in human cells, potentially minimizing side effects in future medications.

A Novel Screening Method

Traditional methods for identifying inhibitors of this protease often require expensive equipment or high-biosecurity laboratories, limiting widespread application. Scientists at St. Petersburg State University, collaborating with the All-Russian Research Institute for Agricultural Microbiology and the All-Russian Institute of Plant Protection, developed a new “live detector” system. This system utilizes genetically modified bacteria that change color in the presence of inhibitors.

The system is designed with safety in mind, containing only the viral enzyme and lacking infectious activity. It allows for rapid and affordable preliminary screening of candidate compounds before more extensive testing in mammalian cell cultures and clinical trials.

Fruit Juice Analysis Reveals Inhibitory Effects

The researchers tested pomegranate, rhubarb, guelder-rose, grape, red currant, and black currant juices. Their analysis revealed varying degrees of inhibitory activity:

• Pomegranate juice demonstrated a significant intensification of the blue color, indicating strong suppression of protease activity.
• Guelder-rose juice showed minimal effect on the enzyme.
• Rhubarb and black currant exhibited a noticeable inhibitory effect.
• Grape and red currant juices did not produce the desired result.

Implications for Prevention and Treatment

These findings suggest that dietary adjustments, incorporating juices with identified inhibitory properties, could potentially play a role in reducing the risk of coronavirus infection or mitigating its early stages. The researchers emphasize that this method is a preliminary screening tool and does not replace rigorous biochemical assays or antiviral activity tests. Yet, it offers a valuable starting point for identifying promising candidates for further investigation.

“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,” said Issa Shaza, a postgraduate student at the Department of Genetics and Biotechnology, St Petersburg University.

Future Research and Applications

The researchers believe this platform could be adapted for the development of diagnostic systems for other viruses, extending its utility beyond COVID-19. Further research is needed to isolate the specific phytochemicals responsible for the observed inhibitory effects and to evaluate their efficacy and safety in clinical settings.

Source: 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