Author:
Publication: The Alchemist
Date: January 29, 2004
URL: http://www.chemweb.com/alchem/articles/1066208903226.html
Curcumin, the main active ingredient
in the curry spice turmeric, has been used in India as a household anti-inflammatory
remedy for centuries. In recent years, scientists have discovered many
other possible medicinal applications, especially against some kinds of
cancers, writes Kelly Galin - Runner-up of the International Young Chemistry
Writer of the Year Competition 2003.
This popular curry spice may someday
migrate from spice racks to medicine cabinets, offering cancer patients
an alternative treatment with no side effects.
"For cancer patients, a natural
and harmless cure could drastically change the way we treat the disease."
For the past decade there has been
a rapidly growing interest in curcumin's ability to fight cancer because
it is safe and can be taken orally. For cancer patients, a natural and
harmless cure could drastically change the way we treat the disease - and
offer even more incentive to spice up your next meal. Recently, biochemists
in South Korea determined for the first time how curcumin helps combat
cancer. Researchers have known that curcumin slows cancer growth for some
time, but until now, little has been known about how this actually works.
The molecule curcumin.
Ho Jeong Kwon, professor of Bioscience
and Biotechnology at Sejong University, Seoul, and his research team screened
3000 compounds from natural products in an attempt to find inhibitors of
aminopeptidase N (APN), an enzyme that plays a key role in tumour invasion
and angiogenesis. Curcumin was among those compounds screened, and was
identified as an irreversible inhibitor of APN.
The Spice of Life
The leafy plant, Curcuma Longa.
Reprinted with permission from David Skinner. ©1999-2004. David Skinner,
GingersRus.com.
What exactly is curcumin? Curcumin
is a phenolic natural product isolated from the rhizome - or underground
stem that sends out roots - of the leafy plant Curcuma longa (turmeric).
Closely related to the ginger family, turmeric is a spice used in curries,
and can be found all over India and other parts of Asia. India is the primary
exporter of turmeric, providing almost 80% of the world's supply. In India,
curry does not come as a powder - as in many western countries - but rather
as a subtle mixture of spices like turmeric, cardamom, ginger, coriander,
nutmeg, black pepper, red pepper, and poppy seed. British colonists in
India developed curry powder, a mixture of many spices, so they could easily
transport the spices to make Indian dishes in England.
Curcumin, the yellow colouring ingredient
in turmeric, not only gives your favorite curry powder its colour, but
also has cancer-fighting abilities that have been proven by its newly discovered
ability to inhibit APN, a membrane-bound, zinc-dependent metalloproteinase.
APN breaks apart proteins at the cell's surface, offering cancer cells
help invading nearby cells. Researchers believe this ectoenzyme is important
in metastatic tumour cell invasion. In other words, this enzyme may be
one of the main contributors to the spread of cancer. APN also plays a
significant role in angiogenesis. Angiogenesis, the formation of new blood
vessels, is essential for tumor growth and the transmission of cancerous
cells from the original site to new ones. Past studies have shown that
curcumin can arrest angiogenesis, leading researchers to enter the chemopreventitive
agent into Phase I clinical trials for cancer chemoprevention by the National
Cancer Institute.
Scurry for Curry
Once curcumin was identified as
an inhibitor of APN, Kwon and his team began searching for more answers.
To demonstrate the direct interaction between curcumin and APN, the group
confirmed both in vivo and in vitro by surface plasmon resonance analysis
and an antibody competition assay. Several derivatives of curcumin were
also tested, and bestatin, a known APN inhibitor, demonstrated the most
potent inhibitory activity. In the future, it may be possible to develop
potent derivatives of curcumin to fight APN and its effects.
So curcumin inhibits APN, but how
does this actually work? Well, there is still much work to be done. Scientists
are continuing to search for the way curcumin binds to APN, although Kwon
does suggest a possible mode of binding. Studies suggest curcumin's ?,?-unsaturated
ketones are critical for binding to the target proteins. Kwon believes
these ketones may be covalently linked to nucleophilic amino acid residues
in APN's active site.
"For some time, researchers have
been studying the health benefits of curry."
For some time, researchers have
been studying the health benefits of curry. Turmeric has been used traditionally
in Ayurvedic Indian medicine to improve overall health by naturally treating
arthritis, inflammation - and it has even believed to aid in digestion.
There is little doubt that this curry spice has healing powers, but the
discovery of curcumin's anticancer properties opens new doors for future
research. Curcumin is believed to help combat breast cancer, colon cancer,
stomach cancer, and even blood cancer. Currently, curcumin can be purchased
in pill form as a dietary supplement in health stores. There is also evidence
turmeric may aid in treatment of many other diseases and ailments including
alzheimer's, multiple sclerosis, and even radiation burns.
People in some countries with diets
rich in curry may have been reaping tumeric's health benefits for years.
Various studies conducted in recent years show people living in countries
such as India and Pakistan, where they consume large amounts of curry,
have a lower incidence of certain kinds of cancers. Many believe India's
low rate of alzheimer's disease can be attributed to their large consumption
of turmeric.
Surprisingly, turmeric and aspirin
have many similarities. Not only are they both used as anti-inflammatory
drugs, there is also mounting evidence pointing to their ability to inhibit
certain cancer causing enzymes. In a recent study, a group at the University
of California San Diego demonstrated curcumin's ability to inhibit cyclooxygenase-2
(COX-2), an enzyme known to be present in colon tumours. Curcumin could
eventually be favoured over aspirin as an inhibitor because it has virtually
no side effects, even with prolonged use.
Perhaps the ultimate cure for cancer
lies on our dinner plates. Curcumin may become a safe and viable alternative
to other cancer treatments in the near future. Researchers have taken a
great interest in substances that occur naturally in normal diets because
they may inhibit cancers with minimal toxicity. Studies show that certain
diets play an important role in minimizing the cancer death rate - even
as much as 90%. Cancer prevention may be as simple and tasty as a large
helping of curry chicken.
References
R. Pasqualini, E. Koivunen, R. Kain,
J. Lahdenranta, M. Sakamoto, A. Stryhn, R. Ashmun, L. Shapiro, W. Arap
& E. Ruoslahti. Aminopeptidase N Is a receptor for tumor-homing peptides
and a target for inhibiting agniogenesis. Cancer Res 2000, 60:722-727.
A. Goel, C. Boland & D. Chauhan.
Specific inhibition of cylclooxygenase-2 (COX-2) expression by dietary
curcumin in HT-29 human colon cancer cells. Cancer Letters 2001, 172:111-118.
Jo Shim, Jin Hee Kim, Hyun Young
Cho, Young Na Yum, Seung Hee Kim, Hyun-Ju Park, Bum Sang Shim, Seung Hoon
Choi & Ho Jeong Kwon. Irreversible inhibition of CD13/aminopeptidase
N by the antiangiogenic agent curcumin. Chemistry and Biology 2003, 10(8):695-704.
Biography
Kelly Galin: earned a Bachelor of
Science in chemistry and an english minor from the University of South
Carolina in December 2003. In the future, she hopes to pursue a career
in both chemistry and science writing. When not writing, she enjoys travelling
and reading. She lives in Columbia, South Carolina.
