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Oleandrin a possible treatment for COVID-19
.
Scientists warn
that the botanical natural product is unproven and could have lethal side
effects
by Bethany Halford
So what is
oleandrin and what do we know about it?
Oleandrin is a
sugar-containing compound found in Nerium oleander, a shrub that’s
popular for landscaping in the southern US and elsewhere.
The plant is
poisonous, causing nausea, vomiting, irregular heartbeat, and in some cases
death when consumed.
“Most people
who have grown up around this plant have been told since childhood, ‘Don’t eat
this plant. It will kill you,’” says Cassandra L. Quave, a medical ethnobotanist at
Emory University.
Oleandrin
accounts for much of N. oleander’s toxicity, and it’s in every part
of the plant from root to flower.
Reports of
poisonings resulting from the use of twigs from the plants to roast food date
back to the 1800s, although more recent tales about deadly feasts of hot dogs
roasted on oleander twigs have been debunked.
A case report
from 2006 details how two people suffered oleandrin poisoning after dining on
homemade snail stew (J. Anal. Toxicol. 2006, DOI: 10.1093/jat/30.9.683).
The snails had
been found near N. oleander plants in their garden and
analysis of the frozen leftover snails revealed they contained oleandrin, which
the snails probably took in when their slime mingled with the plant’s juices.
Sodium and
potassium pumps also control the water balance in cells, which is why people
with oleandrin poisoning experience nausea and diarrhea, adds Justin Brower, a
forensic toxicologist who writes the Nature’s
Poisons blog about toxic natural products and is working on a
book by the same name.
Quave and
Brower point out that oleandrin is structurally similar to digoxin, a cardiac glycoside used to treat
various cardiac conditions.
But they note
that digoxin has a narrow therapeutic window — the dose required for it to be
an effective treatment is close to the dose that makes it toxic.
Oleandrin
and N. oleander extracts have been studied as potential
treatments for cancer and as antivirals.
In July, a
preprint published on bioRxiv claimed that oleandrin can stop SARS-CoV-2, the
virus that causes COVID-19, from replicating in cells in a test tube (2020,
DOI: 10.1101/2020.07.15.203489).
The paper has
not yet been vetted by other scientists.
Robert Harrod,
a virologist at Southern Methodist University, has studied oleandrin’s ability
to block human T-cell leukemia virus, type 1, a retrovirus that causes a fatal
blood cancer, from spreading to other cells in test tubes (J. Antivir.
Antiretrovir. 2019, DOI: 10.35248/1948-5964.19.11.184).
He says
oleandrin probably does this by blocking cells from binding to the virus’s glycoprotein
spike — a process he says could be general for envelope viruses, including
SARS-CoV-2.
He notes that
there’s a lot more research needed to go from the preprint to giving oleandrin
to people, including tests in human cells, animal models, and early clinical
trials.
“Even if it
does make it into treatment of coronavirus as a therapeutic, this is going to
have to be monitored very closely by doctors,” Harrod says.
“It is a very
dangerous compound.”
Even so, he’s
not willing to dismiss the idea.
“We should wait
and look at the data before making a decision,” he says.
Because of the
recent hype around oleandrin, Emory’s Quave worries that people might try to
self-treat with N. oleander.
“Don’t consume
or smoke this plant or consume any oleandrin,” she warns.
Bethany
Halford,
Senior Correspondent
Bethany
Halford
Phone:
202-579-4133
E-Mail:
b_halford@acs.org
Twitter:
@beth_halford
Areas
of coverage: Chemistry in general, particularly organic chemistry, medicinal
chemistry, nanotechnology, and materials science. Also, as Newscripts editor,
loves a quirky science story.
Once
upon a time Bethany was a synthetic organic chemist, churning out new
molecules. She used to tell people she was a sculptor on a very small scale.
Now she sculpts stories. She works in her office and various coffee shops in
the Boston area.
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