title: Determination of citrulline in watermelon rind.
abstract: Watermelon (Citrullus vulgaris Schrad.) is a natural and rich source of the non-essential amino acid citrulline. Citrulline is used in the nitric oxide system in humans and has potential antioxidant and vasodilatation roles. A method using gas chromatography-mass spectrometry (GC-MS) was developed to separate citrulline from glutamic acid, which co-elute when analyzed by high performance liquid chromatography. Watermelons were analyzed by GC-MS to determine the citrulline content among varieties, types, flesh colors, and tissues. Citrulline content ranged from 3.9 to 28.5 mg/g dry weight (dwt) and was similar between seeded and seedless types (16.6 and 20.3 mg/g dwt, respectively). Red flesh watermelons had slightly less citrulline than the yellow or orange flesh watermelons (7.4, 28.5 and 14.2 mg/g dwt, respectively). Rind contained more citrulline than flesh on a dry weight basis (24.7 and 16.7 mg/g dwt, respectively) but a little less on a fresh weight (fwt) basis (1.3 and 1.9 mg/g fwt, respectively). These results indicate that watermelon rind, an underutilized agricultural waste, offers a source of natural citrulline.
authors: Natural Products Utilization Research Unit, ARS, US Department of Agriculture, P.O. Box 8048, University, MS 38677, USA. arimando@ars.usda.gov
authors: Agnes M
authors: AM
authors: Rimando
authors: Penelope M
authors: PM
authors: Perkins-Veazie
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002956:Citrulline / Q000032:analysis* / Q000302:isolation & purification; D029773:Citrullus / Q000737:chemistry*; D005638:Fruit / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry
chemical_list: D002956:Citrulline