AsianScientist (Mar. 15, 2022) – Extract from the bark of a neem tree has shown antiviral effects against SARS-CoV-2, the virus that causes COVID-19, according to a recently published study in Virology. The India-US research team hopes that the findings can support the development of new medications to lower the risk of serious illness and curb the spread of coronavirus infections.
The neem tree (Azadirachta indica) is a big-leaf mahogany indigenous to India. The tree’s various components have been reported to have various medicinal properties against certain virus, bacteria and parasites. The extracts derived from the bark in particular have beneficial effects against malaria, stomach and intestinal ulcers, and skin disorders, laboratory studies have shown.
Given the bark extract’s history in addressing diseases, researchers from the Indian Institute of Science Education and Research Kolkata and the University of Colorado in the US investigated whether neem extracts would similarly help suppress COVID-19 infections. The team combined different methods to comprehensively examine the extract’s effects against coronaviruses.
Computer modeling done by the researchers revealed that the neem bark extract can target a wide range of viral proteins. Certain components can bind to various regions on the SARS-CoV-2 spike protein, which is responsible for enabling viral entry into human cells. The binding of neem compounds stabilizes the spike protein and effectively acts as a block on key regions that typically bind with the host cell. That prevents the spike proteins from fusing with the host cell.
Because the virus is no longer able to latch onto the host cells, it cannot access the host’s genetic machinery needed for its replication. The viral replication typically correlates with disease progression and severity, even allowing the virus to spread to other cells and organs in the body. Accordingly, cutting off this access point can prevent SARS-CoV-2 from severely damaging the body.
In the lab, the researchers introduced the bark extracts to samples of human lung cells infected with SARS-CoV-2. They found that the extracts inhibited viral infection and replication in the cells, primarily by reducing the expression of genes that code for the viral envelope. The envelope is an important outer layer that protects the virus’ genetic material and helps the virus move through the cell membrane to enter the cell.
By blocking entry and reducing viral replication, the extract also relieved other complications that COVID-19 causes, including inflammation in the brain and hepatitis in mice models.
Overall, the neem compounds showed potential as antiviral agents both for protecting against infection and mitigating disease severity after infection. Moreover, the researchers highlighted that the multi-targeted nature of its effects—particularly its capacity to bind to several spike regions—may make the extract effective against new variants that carry mutations in their spike protein.
Moving forward, the researchers aim to identify the specific compounds in the neem bark that are responsible for the antiviral effects. That could help guide the development of neem-based antiviral therapies and determining the dosage requirements for treating coronavirus infections.
“The antiviral properties of neem bark extract offer a new premise for restricting viral spread, replication and fusion. Our studies can guide new antiviral therapeutic efforts to combat the ongoing COVID-19 pandemic and hold promise for treating the future emergence of new coronavirus strains,” the authors wrote.
Source: Indian Institute of Science Education and Research Kolkata; Photo: Shutterstock.
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