Citrulline and Arginine Content of Taxa of Cucurbitaceae

Abstract

Watermelon is the most significant, natural plant source of L-citrulline, a non-proteinaceous amino acid that benefits cardiovascular health and increases vasodilation in many tissues of the body. Watermelon is a member of the Cucurbitaceae, which includes squash, melon, pumpkin, and cucumber. It is possible that other cucurbits could be good sources of citrulline or of arginine, its direct precursor. Twenty-one cultigens were evaluated in triplicate at two locations in North Carolina to estimate citrulline and arginine amounts and variation due to cultigen, replication, and environment. Cultigens containing the highest amount of citrulline (based on LS means) in g/kg fresh weight were ’Crimson Sweet’ watermelon (2.85), ’Dixielee’ watermelon (2.43), casaba-type melon (0.86), mouse melon (0.64), and horned melon rind (0.45). Additionally, mouse melon, horned melon, and bitter gourd (arils) may be interesting sources of arginine-family amino acids, perhaps because of their large seed and aril content relative to mesocarp.

Multivariate Analysis of Amino Acids and Health Beneficial Properties of Cantaloupe Varieties Grown in Six Locations in the United States

“…They observed significant variation in the Cit and Arg levels within Cucumis melo cultivars. The Cit content ranged from 163 to 863 µg/g fresh weight and Arg ranged from 94 to 180 µg/g fresh weight [ 47 ]. These findings showed that amino acids contents are strongly influenced by growing locations and cultivars.…”

Fruit Morphology, Citrulline, and Arginine Levels in Diverse Watermelon (Citrullus lanatus) Germplasm Collections

“…Watermelon fruit is 93% water with small amounts of protein, fat, minerals, and vitamins, and with main nutritional components including, carbohydrates, vitamin A, lycopene, and β-carotene [ 2 , 3 ]. The contents of the metabolites in watermelon fruit varies with cultivar, ploidy, genotype, flesh color, and fruit anatomy [ 4 , 5 , 6 , 7 , 8 , 9 ]. The flesh of watermelon fruits is consumed in many parts of the world and is proven to be beneficial for disease prevention partly due to the presence of vitamins, lycopene, and amino acids such as citrulline and arginine.…”

“…Several reports indicate that both exhibit beneficial effects on plant metabolism and human health [ 3 , 10 ]. Citrulline is unusually abundant in watermelon, more than any other plant taxon recorded to date [ 5 , 8 ]. It is also available in most cucurbits, including bitter melon, cucumber, muskmelon, pumpkin, bottle gourd, dishrag gourd, and wax gourd [ 8 , 11 ].…”

“…Citrulline is unusually abundant in watermelon, more than any other plant taxon recorded to date [ 5 , 8 ]. It is also available in most cucurbits, including bitter melon, cucumber, muskmelon, pumpkin, bottle gourd, dishrag gourd, and wax gourd [ 8 , 11 ]. Drought-tolerant watermelon accumulates high levels of citrulline in response to oxidative stress caused by drought conditions [ 10 ].…”

“…In rats, watermelon extract and arginine were shown to improve cardiovascular disease risk factors [ 16 ]. Since oral administration of free arginine could result in side effects such as nausea, gastrointestinal discomfort, and diarrhea in humans [ 17 , 18 ], citrulline can be more efficient in diseases related to arginine deficiencies due to its increased bioavailability, better absorption into the bloodstream, and reduced side-effects [ 8 ]. Citrulline efficiently scavenges the hydroxyl radical and effectively protects DNA and an enzyme from oxidative injuries [ 10 ], and can also exert a positive effect on vasodilation [ 5 ].…”