A Catalog of Natural Products Occurring in Watermelon-Citrullus lanatus.

Sweet dessert watermelon (Citrullus lanatus) is one of the most important vegetable crops consumed throughout the world. The chemical composition of watermelon provides both high nutritional value and various health benefits. The present manuscript introduces a catalog of 1,679 small molecules occurring in the watermelon and their cheminformatics analysis for diverse features. In this catalog, the phytochemicals are associated with the literature describing their presence in the watermelon plant, and when possible, concentration values in various plant parts (flesh, seeds, leaves, roots, rind). Also cataloged are the chemical classes, molecular weight and formula, chemical structure, and certain physical and chemical properties for each phytochemical. In our view, knowing precisely what is in what we eat, as this catalog does for watermelon, supports both the rationale for certain controlled feeding studies in the field of precision nutrition, and plant breeding efforts for the development of new varieties with enhanced concentrations of specific phytochemicals. Additionally, improved and comprehensive collections of natural products accessible to the public will be especially useful to researchers in nutrition, cheminformatics, bioinformatics, and drug development, among other disciplines.

Effects of watermelon supplementation on aortic blood pressure and wave reflection in individuals with prehypertension: a pilot study.

BACKGROUND: Oral L-citrulline is efficiently converted to L-arginine, the precursor for endothelial nitric oxide (NO) synthesis. Oral L-arginine supplementation reduces brachial blood pressure (BP). We evaluated the effects of watermelon supplementation on aortic BP and arterial function in individuals with prehypertension. METHODS: Heart rate (HR), brachial systolic BP (bSBP), brachial pulse pressure (bPP), aortic SBP (aSBP), aortic PP (aPP), augmentation index (AIx), AIx adjusted for HR of 75 beats/min (AIx@75), amplitude of the first (P1) and second (P2) systolic peaks, reflection time (Tr), and carotid-femoral pulse wave velocity (PWV) were evaluated in the supine position in nine subjects (four men/five women, age 54 ± 3 years) with prehypertension (134/77 ± 5/3 mm Hg). Subjects were randomly assigned to 6 weeks of watermelon supplementation (L-citrulline/L arginine, 2.7 g/1.3 g/day) or placebo followed by a 4-week washout period and then crossover. RESULTS: There was a significant treatment effect (change in the value of watermelon minus placebo from baseline to 6 weeks) on bPP (-8 ± 3 mm Hg, P < 0.05), aSBP (-7 ± 2 mm Hg, P < 0.05), aPP (-6 ± 2 mm Hg, P < 0.01), AIx (-6 ± 3%, P < 0.05), AIx@75 (-4 ± 2%, P < 0.05), and P2 (-2 ± 1 mm Hg, P < 0.05). There was no significant treatment effect (P > 0.05) on bSBP, brachial diastolic BP (DBP), aortic DBP, Tr, P1, HR, and carotid-femoral PWV. CONCLUSIONS: This pilot study shows that watermelon supplementation improves aortic hemodynamics through a decrease in the amplitude of the reflected wave in individuals with prehypertension.

Consumer acceptability of low-sugar watermelon sweetened with non-calorie sweetener by a Native American community.

Watermelons are a good source of lycopene, a carotenoid that exhibits antioxidant activity and may protect against some cancers. However, intake of watermelon may be restricted for individuals who have diabetes or those who limit carbohydrate intake. A low-sugar watermelon was developed at Lane, Oklahoma using traditional plant breeding techniques. The objective of this study was to determine whether the artificially sweetened low-sugar watermelon was acceptable with Native Americans, a group with a high incidence of diabetes. The red flesh from a low-sugar watermelon and a commercial variety of watermelon was removed and cut into cubes. Low and high levels of artificial sweetener were added to the low-sugar watermelon. Students at a Native American school (Grades 1-12) and adults at a Native American Feeding Center were asked to rate how much they liked or disliked the watermelon using a seven-point hedonic scale. Sugar composition, pH, lycopene and other carotenoids were analyzed from samples using established methods. The pH, lycopene, beta-carotene and total carotenoid levels were similar among fruit. Artificially sweetened fruit were rated slightly more acceptable in taste than the commercial control watermelons by both age groups. The low-sugar watermelons were lower in sugar composition but were comparable with conventional melons in all other quality factors and were found acceptable in taste by a broad age group of Native American consumers.

Determination of citrulline in watermelon rind.

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.