Exploring Important Medicinal Uses for
Watermelon Rinds By Luis Pons
Most people don't think much about watermelon rinds. Although
some use rinds to make pickled, candied and even fried dishes, most folks
discard them once they eat the melon's sweet fruit.
However, an Agricultural
Research Service study has found the rinds contain citrulline, an amino
acid that plays an important role in the human body's urea cycle, which removes
nitrogen from the blood and helps convert it to urine. That's where citrulline
helps create arginine, another amino acid--one in which some people are
Recent medical research by other scientists has examined whether
the citrulline-arginine relationship can be exploited to create treatments for
vascular tone problems associated with sickle-cell anemia.
Agnes Rimando, a research chemist at the ARS
Products Utilization Research Unit in Oxford, Miss., says the discovery may
lead to production of rind-based extract or dietary-supplement products that
address arginine- or sickle-cell-related deficiencies. She conducted the
research in collaboration with plant physiologist Penelope Perkins-Veazie of
ARS' South Central Agricultural Research
Laboratory in Lane, Okla.
In the urea cycle, citrulline combines with another acid to
create arginine. Also found within the watermelon's sweet and watery interior,
citrulline is a "nonessential" amino acid, meaning it need not be ingested
because the body produces it. Amino acids, the body's "building blocks," are
produced when digestion breaks down protein.
Arginine boosts nitric oxide, which relaxes blood vessels and
thus may help treat angina and other cardiovascular problems. This intrigues
scientists studying blood circulation problems associated with sickle-cell
anemia. Arginine has also been credited with boosting muscle growth, improving
wound healing, combating fatigue, stimulating the immune system, curing
impotence and fighting cancer.
Disorders in the urea cycle can lead to a lethal buildup of
proteins such as ammonia in the bloodstream. Arginine or citrulline are often
recommended to address these disorders.
Rimando says the discovery came early during a study, involving
her and Perkins-Veazie's labs, that was aimed at determining the citrulline
content of different watermelon varieties.
ARS is the chief scientific research agency of the
U.S. Department of Agriculture.