The research comes as the HIV-1 virus, and its subsequent development into AIDS – acquired immunodeficiency syndrome – has continued to spread worldwide in epidemic-like proportions.
Currently about 40 million people around the world are infected with the HIV virus. At least 70% of this number live in Africa.
The research utilized the HeLa cell line. This is a human cell line that has been used for decades in countless other human cell studies, including polio research, cancer research and AIDS research.
Multiple cultures of the cells were either bathed in dilutions of Silymarin or not, at varying concentrations, using triplicate parallel testing. The cell dilutions were then incubated with two different strains of the HIV-1 virus.
After different incubation periods, including 48-hours, two-days, and up to two weeks, the cell cultures were analyzed and cross-analyzed for HIV-1 infection and growth rates. The multiple assays were conducted using two independent analysis groups, and then the test results were compared.
HIV-1 replication studies were also done using PBMC (immune) cells to test HIV’s replication within the immune system. Here again cells were tested with and without the Silymarin extract solution. T-cell proliferation and cytokine production were also tested.
At higher doses the Silymarin complex inhibited the two strains of HIV-1 viruses by 97% and 80%. The 97% inhibition took place with the earliest and most found form of HIV-1, the LAI strain. Silymarin also suppressed the replication of LAI HIV-1 as tested with immune cells. Silymarin also blocked the LAI and BAL HIV-1 strains from further infecting cells during the incubation period.
Silymarin’s inhibition of the LAI HIV-1 infection among PBMC immune cells lasted for over two weeks in the cell cultures.
The Milk thistle extract also inhibited the production of T-cells and B-cells, unrelated to any cell death or toxicity.
In their discussion, the researchers stated:
“This study shows for the first time that a mixture of two compounds derived from silymarin and formulated for intravenous dosing inhibited HIV-1 infection in multiple cell types including human PBMCs, CEM cells, and TZM-bl cells. SIL’s anti-HIV effects were seen against four viruses.”
Their Silimarin solution was produced using two key compounds, silybin A and silybin B. These were converted to disodium disuccinyl silybin A and disodium disuccinyl silybin B to aid their dilution into the solutions. The body performs a similar process as it ‘chelates’ compounds to allow for their absorption into the body.
Because Silymarin is not water-soluble, it is relatively difficult to fully absorb, and infusions of the Milk thistle herb – tea, in other words – provide little if any medicinal compound absorption.
The researchers also noted that due to Silymarin’s ability to slow the production of T-cells, this could also help prevent the depletion of immune function – which typically occurs at least partially because HIV infection will deplete the body’s T-cells.
The researchers, in fact, saw multiple mechanisms of action among Silymarin with respect to inhibiting, slowing and preventing HIV infections. They stated: “Cumulatively, the data presented in this report suggest that SIL inhibited viruses by multiple inhibitory mechanisms that target the cell and reduce the activation status/potential.”
They also noted that Silymarin’s ability to slow liver inflammation associated with the Hepatitis-C virus – which is thought to infect nearly a third of those in Western countries infected with HIV – may also offer a therapeutic route for those who are co-infected with HIV and HCV.
The groundbreaking research was led by Stephen J. Polyak, Ph.D., a professor in the University of Washington’s Department of Laboratory Medicine and Department of Microbiology. He was the recipient of the American Liver Foundation’s Liver Scholar Award, and his research has been suppored by the National Institutes of Health.
Written by Case Adams
McClure J, Lovelace ES, Elahi S, Maurice NJ, Wagoner J, Dragavon J, Mittler JE, Kraft Z, Stamatatos L, Horton H, De Rosa SC, Coombs RW, Polyak SJ. Silibinin Inhibits HIV-1 Infection by Reducing Cellular Activation and Proliferation. PLoS One. 2012;7(7):e41832.