Beyond pickles—medicine from watermelon rind? - Science Update - medicinal applications of citrulline - Brief Article

Agricultural Research, Sept, 2003 by Agnes M. Rimando

Scientists interested in determining the relative amounts of an important amino acid called citrulline that's present in different watermelon varieties were recently surprised to find it concentrated in the melons' rind. Citrulline plays an important role in the body's urea cycle, which removes nitrogen from the blood and helps convert it to urea that is excreted in the urine. Disorders in the urea cycle can lead to a lethal buildup of proteins, such as ammonia, in the bloodstream. That's where citrulline helps create arginine--an amino acid involved in the urea cycle--which some people produce too little of.

Arginine or citrulline is often recommended to address those, and other, disorders. Arginine boosts nitric oxide, which relaxes blood vessels and thus may help treat angina and other cardiovascular problems. It may also play a role in blood-circulation problems associated with sickle-cell anemia and has been credited with boosting muscle growth, stimulating the immune system, improving wound healing, curing impotence, and more.

Researchers' next step will be to see whether the citrulline-arginine relationship can be exploited to develop rind-based extract or dietary-supplement products that address arginine- or sickle-cell deficiencies.

Agnes M. Rimando, USDA-ARS Natural Products Utilization Research Unit, Oxford, Mississippi; phone (662) 915-1037, e-mail arimando@ars.usda.gov. Penelope Perkins-Veazie, USDA-ARS South Central Agricultural Research Laboratory, Lane, Oklahoma; phone (580) 889-7395, e-mail pperkins-usda@lane-ag.org.