Gary
POSNER
Malaria Cure
17-Apr-2007
Contact: Lisa De Nike
LDE@jhu.edu
443-287-9960
Johns Hopkins University
Malaria-Infected Mice Cured by
1 Dose of New Drug
Compound
based on plant-derived, ancient Chinese folk remedy

Gary Posner, Scowe Professor of
Chemistry at Johns Hopkins and leader of a team that has
developed a new series of malaria drugs.
Johns Hopkins University researchers have cured malaria-infected
mice with single shots of a new series of potent, long lasting
synthetic drugs modeled on an ancient Chinese herbal folk
remedy.
The team also has developed several other compounds which
defeated the febrile disease in rodents after three oral doses.
These peroxide compounds, containing a crucial oxygen-oxygen
unit, promise not only to be more effective than today's best
malaria remedies, but also potentially safer and more efficient,
said research team leader Gary Posner, Scowe Professor of
Chemistry in the Krieger School of Arts and Sciences at Johns
Hopkins.
An article about the team's work is slated to appear on the Web
on April 17 in the ASAP section of The Journal of Medicinal
Chemistry. Go here: http://tinyurl.com/3cwg3a
"We are disclosing, for the first time, the curative activity of
a new generation of compounds that are long-lasting and
therapeutic, even when used by themselves," Posner said. "Older
drugs in this family of peroxide antimalarials also are known to
be fast-acting, but they are unfortunately short-lived and not
curative when used by themselves."
Though they say their results are very promising, the
researchers caution that the new compounds must be thoroughly
tested for safety and for how they are absorbed, distributed and
metabolized in, and eliminated from, rodents' bodies before
human tests begin.
Malaria afflicts between 300 million and 500 million people a
year, killing between 1.5 million and 3 million, mostly children
and mostly in developing nations. The parasite that causes the
disease is spread by female mosquitoes feeding on human blood.
The most commonly fatal species of the malaria parasite now
shows strong resistance to most current treatments, making the
development of effective new drugs a worldwide priority.
Since 1992, Posner and his team, which includes collaborator
Theresa Shapiro, professor and chair of clinical pharmacology at
the Johns Hopkins School of Medicine, have been tackling that
challenge by designing a series of peroxide compounds, called
trioxanes.
"As a class, these compounds have proven to be unusually
valuable in several ways, from their brisk and potent
antimalarial activity to their lack of resistance and
cross-resistance with other antimalarial agents," Shapiro said.
The Johns Hopkins trioxanes mimic artemisinin, the active agent
in a Chinese herbal drug used to treat malaria and other fevers
for thousands of years. Artemisinin comes from the Artemisia
annua plant, an herb also known by a variety of names including
sweet wormwood.
The oxygen-oxygen unit in the peroxides causes malaria parasites
essentially to self-destruct. The parasites digest hemoglobin,
the oxygen-carrying pigment of red blood cells, and, in the
process, release a substance called heme, a deep-red
iron-containing blood pigment. When the heme encounters
peroxides, a powerful chemical reaction occurs, releasing
carbon-free radicals and oxidizing agents that eventually kill
the parasites.
But the first generation of trioxane drugs also had a number of
shortcomings, including a half-life of less than one hour. (A
drug's half-life is the amount of time it takes for half of it
to be metabolized.) Posner and team believe that their new
compounds address those disadvantages.
"Our semi-synthetic artemisinin-derived compounds successfully
overcome the disadvantages of their first-generation
predecessors," he said. "Most important is their curative
activity after a single, low dose, which is distinctly unusual.
But based on our intentional design, they may also have a longer
half-life in animals. We also designed them to be more
lipophilic, meaning they have an enhanced ability to dissolve in
fats and thus to arrive inside malaria-infected red blood
cells."
In addition, the new compounds are far less likely to break down
into toxic substances when they are metabolized in the test
animals' bodies, making them potentially safer than their
predecessors.
Although the substance is inexpensive by Western standards, the
widespread use of artemisinins in the developing world remains
limited, in part by availability and the cost of separating the
active ingredient from the Artemisia annua plant. Posner and his
team contend that the potency and curative activity of their
compounds provide "a substantially more efficient and economical
use of the price-setting natural product."
The team's research was supported by the National Institutes of
Health and the Johns Hopkins University Malaria Research
Institute.
Patents
WO2008127381
ARTEMISININ DERIVATIVES
Inventor: BRANDO LORRAINE V [US] ; POSNER GARY
2008-10-23
Abstract -- This disclosure
provides improved derivatives of artemisinin; pharamaceutical
compositions containing these compounds; methods for preparing
these compounds and compositions; methods of using these
compounds and compositions for preventing, controlling or
treating infectious diseases including but not limited to
parasitic infectious diseases such as T. gondii infection,
trypanosome parasite infection, plasmodia parasite infection,
and cryptosporidium parasite infection; methods for preventing,
controlling or treating toxoplasma infection; and methods for
treating psychiatric disorders associated with toxoplasma
infection including but not limited to schizophrenia using the
disclosed compounds and compositions alone or in combination
with one or more antipsychotic drugs.
HK1047047
Water-soluble trioxanes as potent
and safe antimalarial agents
Inventor: POSNER GARY H ; PARKER MICHAEL
2006-01-13
US7417156
Orally active, antimalarial,
anticancer, artemisinin-derived trioxane dimers with high
selectively, stability and efficacy
Inventor: POSNER GARY H [US] ; SHAPIRO THERESA
Also published as: // WO2004028476 // WO2004028476 //
AU2003277022 // AU2003277022
2006-06-29
Abstract -- In only two
steps and in 65% overall yield, natural trioxane artemisinin (I)
was converted on gram scale into C-10-carba trioxane dimer (3).
This new, very stable dimer was then transformed easily in one
additional step into four different dimers (4-7). Alcohol and
diol dimers (4 and 5) and ketone dimer (7) are 10 times more
antimalarially potent in vitro than artemisinin (1), and alcohol
and diol dimers (4 and 5) are strongly inhibitory but not
cytotoxic toward several human cancer cell lines. Water-soluble
carboxylic acid derivatives (8a-10c and 12) were easily prepared
from dimers (4-6); they are thermally stable even at 60 DEG C.
for 24 hours, are more orally efficacious as antimalarials than
either artelinic acid or sodium artesunate, and have potent and
selective anticancer activities.; Further derivitization of the
alcohol dimers (4 and 17), diol dimer (5) and ketone (7) has
produced a number of analogs also antimalarially active in vitro
at sub-nanomolar concentrations (most notably: pyridine N-oxides
(13, 15, 18, 23, 24 and 25), phosphoric acid triesters (26 and
27), sulfonamide (40) and cyclic carbonate (41)). In addition,
dimers (13 and 19) are more efficacious (when administered both
orally and i.v.) and less toxic (when administered
intraperitoneally to mice as a single dose) than clinically-used
sodium artesunate, thereby giving them a better antimalarial
therapeutic index than sodium artesunate.