A dangerous fungal pathogen has proven no match for what may be one of the most useful plants in nature.
Scientists studying the chemical properties of cannabis have found it kills one of the most dangerous fungal pathogens in the world – in a laboratory setting, at least.
Cryptococcus neoformans, a species of fungus behind cryptococcosis and cryptococcal meningitis, appears to be vulnerable to topical treatment with cannabidiol and cannabidivarin, compounds found in the plant Cannabis sativa.
“When Cryptococcus neoformans gets to your central nervous system, it causes life-threatening meningitis,” explains biologist Hue Dinh of Macquarie University in Australia. “The mortality rate is very high, and it’s really hard to treat.”
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Fungal pathogens pose a pretty significant threat to human health, with around 300 species known to cause diseases in humans, with varying levels of severity. Because pathogens such as fungi and bacteria continually develop resistances to drugs, new treatment options are continually needed to keep them at bay.
One strategy is to look at medications that have already been approved for human use for other ailments. Dinh and her colleagues turned their research to cannabis, isolating five compounds to test on C. neoformans and a range of other pathogens.
They isolated the fungal species in a lab, and applied the compounds. Cannabidiol (CBD), which is non-psychoactive, and cannabidivarin (CBDV), which is psychoactive, both killed C. neoformans adroitly, acting even faster than current antifungal treatments. They were also effective at eradicating the fungal pathogens responsible for such conditions as jock itch and athlete’s foot.
“Proteomics analysis revealed that the antifungal activity of CBD and CBDV was linked to destabilization of the membrane, alterations in ergosterol biosynthesis, disruption of metabolic pathways, as well as selective involvement of mitochondrial-associated proteins,” the researchers wrote in their paper.
It’s one thing to kill a fungus in a petri dish, but quite another to observe the treatment working in a living system. To test their findings further, the researchers turned to Galleria mellonella, the greater wax moth.
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The larvae of this moth possess an innate immune response that is similar to that of mammals. They are also inexpensive to obtain, have short lifespans, and require no special equipment to keep, making them an excellent model for large-scale studies of infectious pathogens and the treatments thereof.
Moth larvae were given small burn wounds, and then divided into groups. One group was left alone with just the burn wounds as a control; the remainder were infected with C. neoformans, and treated with different medicaments.
One group was treated with CBD dissolved in dimethyl sulfide. Another group was treated with dimethyl sulfide without the CBD. Finally, the last group was treated using Amphotericin B, a medication used to treat serious fungal infections in humans.
The results were striking. The survival rate of the larvae treated with CBD was significantly higher than the survival rate of the larvae treated with the dimethyl sulfide alone, and also higher than the survival rate of the Amphotericin B group.
In fact, it was nearly as high as the survival rate of the control group – the larvae that had not been infected with the fungus at all.
Although the treatment of infections that reach the lungs and brain is a bit more complicated, the result suggests that, at the very least, the topical application of cannabidiol might be effective at treating a range of fungal skin infections.
“If we can demonstrate that these ones work well for common infections,” Dinh says, “you could actually just get some CBD oil and then rub it on your skin to treat it.”
The research has been published in PLOS Neglected Tropical Diseases.
