Citrullus lanatus (Thunb.) Mansf (Cucurbitaceae)

Synonyms

Citrullus lanatus (Thunb.) Matsum. & Nakai. subsp. lanatus var. citroides (L.H. Bailey) Mansf., Citrullus lanatus (Thunb.) Matsum. & Nakai var. citroides (L.H. Bailey) Mansf., Citrullus vulgaris Schrad. var. citroides L.H. Bailey., Colocynthis citrullus Linn. O. Ktze., Citrullus citrullus (L.) Karst., Cucubertia citrullus L., Momordica lanata Thunb. [1][2][3]

Vernacular Names:

Malaysia: Tembikai
English: Watermelon
India: Karingda
Chinese: Da Zi Gua Zi Xi Gua.

General Information

Description

A trailing annual herb or climber, broad-leaved with yellow flowers which grow in sandy gravelly soil, loam or clay on plains, river banks, centres of dry lakes, drainage areas or disturbed areas.  It can grow up to 10m, lying or creeping on the ground.

Leaves. Alternate, spiral, simple, petiolate, petiole 18-100(-120)mm long. Leaf blade 40-65(-200)mm long, 28-85(-150)mm wide, dissected (deeply), palmately lobed (3-5 lobed, central lobe longest), base tapering or cordate or hastate or auriculate or truncate, margins entire or crenate or dentate, apex acuminate or acute or mucronate or apiculate or retuse or emarginate. Blade with indumentum; indumentum hairy (upper surface sparsely villous; lower surface densely villous or occasionally papillose-hispid), hairs simple.

Flowers. Solitary, axillary; predominantly yellow, regular, slenderly pedicellate, pedicel 1.5-15(-80)mm long, perianth 2 -whorled. Calyx 3-8mm long, 5 sepals, all sepals joined. Corolla 4-17(-19)mm long, 5 petals, all petals joined. Stamens 3 (or 3 staminodes in female flowers), adnate to the perianth, all alternating with the corolla parts, free of each other. Anthers dehiscing via longitudinal slits. Ovary syncarpous, inferior, 1-celled. Ovules 20-50 per cell. Styles 1, simple (with 3-lobed stigma).

Fruit. Indehiscent, a berry (a pepo), fleshy, green or yellow (mottled green stripes, becoming yellow), 97-250mm long, 61-160mm wide.[4]  Fruit of wild plants 1.5-20cm in diameter, subglobose, greenish, mottled with darker green; of cultivated plants up to 30x60cm, subglobose or ellipsoid, green or yellowish, evenly coloured or variously mottled or striped. The fruits of the wild Kalahari form are small and round, the cultivated forms are large oblong fruits. In addition, they vary from pale yellow or light green (wild form) to dark green (cultivars), and with or without stripes; the pulp varies from yellow or green (wild forms) to dark red (cultivars). [5]

Plant Part Used

Fruit, seed kernel, kernel oil, rind. [2][9][11][13]

Chemical Constituents

A total of 177 yellow-fleshed C. lanatus  samples were tested for total carotenoids by the puree absorbance method using a diode array xenon flash spectrophotometer. The total carotenoid content ranged from 0 to 7μg/g fresh weight. The earlier research showed that Early Moonbeam, a canary yellow-fleshed C. lanatus , contained trace amounts of carotenoids which resulted from the presence of a nonfunctioning phytoene synthase gene which caused the accumulation of very low levels of carotenoids in these fruits, similar to that seen in tomatoes. The two major types of yellow-fleshed C. lanatus, are present, canary yellow and salmon yellow (tangerine type) C. lanatus.  The latter contains small amounts of prolycopene whereas the former contains multiple carotenoids (in low or trace amounts), lutein and β-carotene.  The high quantities of lycopene, a red pigmented carotenoid with powerful antioxidant properties was found in redfleshed C. Lanatus while orange-fleshed C. lanatus contain high amounts of prolycopene, and in some varieties, β-carotene and ζ-carotene. [6]

C. lanatus is a natural source of lycopene with an average content of 48.7μg/g fresh weight, about 60% higher than those of fresh tomatoes (average lycopene value of 32.2μg/g fresh weight ). [7]  The lycopene content varies among C. lanatus cultivars where some cultivars have a mean lycopene content of greater than 65μg/g fresh weight.  The higher amounts of lycopene (>50μg/g fresh weight) were found in seedless types. [7] The bryonolic acid (3 beta-hydroxy-D:C-friedoolean-8-en-29-oic acid) is an acidic, pentacyclic triterpene found exclusively in the roots of C. lanatus. [8] 

The seeds contain 25-46% fat and 30-35% protein. [9][10] The seeds protein is a good quality with predominant amounts of arginine, glumatic acid, aspartic acid and leucine. The protein yield from de-oiled melon seed meal varied from 75.49% to 86.08%. [11]  The fatty acid composition of the seed oil were, for saturated acids: C16, 11%; C18, 6.6%; for unsaturated acids: C18:1, 24.8% and C18:2, 57.6%. [10]  The seeds contain a high proportion of A5-sterols, with codisterol present as a trace component. [12]  The other sterols present as percentage of total A5-sterols were, 25(27)-dehydroporiferasterol, 28.7%; clerosterol, 31.2%; isofucosterol, 7.8%, stigmasterol, 13.9%; campesterol, 2.9% and sitosterol, 15.5%.

The compositions of melon seeds and kernel which were obtained from mature fruits [9], and presented on a moisture-free basis were as follows:  The crude fat content of the seed and kernel were 28.28 ± 0.85 and 49.95 ± 0.50%, respectively.  The crude protein content of the seed and kernel ranged from 23 to 27% and 38 to 40 %, respectively. [9][11]  The crude fibre content of the seed and kernel were 32.99 ± 1.78 and 1.79 ± 0.06%, respectively while the carbohydrate content of the seed and kernel were 12.76 ± 1.76 5.53 ± 0.17, respectively.  The ash content of the seed and kernel were 2.84 ± 0.19 and 2.71 ± 0.02 (9). The melon oil is pale yellow in colour (colour value of 16.0) with a refractive index of 1.482 and a specific gravity of 0.908.  The iodine value (a measure of its degree of unsaturation) was 145.7. [9]

The Reichert–Meissl number, a measure of the amount of water-soluble volatile fatty acids present in the oil, was 0.28 while the Polenske number, a measure of water-insoluble volatile fatty acids, was 0.51.  A higher Polenske number indicated the presence of more water-insoluble volatile fatty acids than the water-soluble volatile fatty acids in melon.  The saponification number for melon seed was 198.4, with a high amount (1.80%) of unsaponifiable matter in the oil.  The unsaturated fatty acid content of melon seed oil was 78.4%, this was comprised of 11.1% oleic acid and 67.3% linoleic acid. The saturated fatty acid content was 21.3% which consisted of 10.7% palmitic acid and 10.6% stearic acid. [9]

The raw seed kernels contain phytic acid, 5±0.1mg/g; oxalate, 12±0.4%; total phenols, 2±0.3mg catechin/g; hydrocyanic acid, 15±0.2mg/100 g; saponin, 4±0.1% while the kernel/seed ratio was 0.6±0.1g.  None of the vales were altered when the kernels were toasted to 100 or 125oC, except for the saponin level which was significantly raised at 125oC. The boiling significantly reduced the total oxalates and the hydrocyanic acid content of the kernels. [2]

Traditional Use:

The flesh of the ripe fruit is eaten or used as animal feed while the seed is roasted for use as roasted or salted foods. The kernel is used as a garnish or condiment in traditional Indian cooking.  The immature fruits are consumed as vegetables while the seed oil is used as cooking oil in some countries in Africa and the Middle East. [9]  The rind is used to make pickles and preserves and is extracted for pectin [11] and is traditionally used for making jam. The melon kernel is generally used as a soup thickener in Nigeria while the kernels are eaten as snacks. [2]

The seeds were used as a demulcent, pectoral, tonic, vermifuge, diuretic and to treat bed wetting. The seeds also have hypotensive effect.  The ripe fruit was used as a febrifuge, a diuretic and in the treatment of dropsy and renal stones.  The fruit rind was used in alcoholic poisoning and diabetes.  The root was used as a purgative while large doses were emetic. [13]

Pre-Clinical Data

Pharmacology

Antioxidant activity

The molecular mechanisms of drought/oxidative stress-tolerance in wild C. lanatus was elucidated by subjecting plants that were grown in a growth chamber with a light intensity of 700μmol photons/m2/s, 16 hours daily light period, day/night temperatures of 35/25oC and a relative humidity of 50/60% to water deprivation. [14]  A mRNA differential display technique was used to follow changes in the gene expression patterns in the leaves. The up-regulated genes (designated ‘‘wadi’’ for C. lanatus drought-induced genes) were cloned into plasmid vectors and the sequences compared with those in public databases.  The cDNAs that were identified encoded a broad spectrum of proteins, some of which were induced by abiotic stresses in other plants.  One of the isolated genes exhibited significant homology to plant type-2 metallothionein.  This gene was shown by Northern blotting to be induced in wild C. lanatus leaves under drought/high light stress conditions.  The metallothionein has established roles in Cd-detoxification and Cu/Zn-homeostasis and protected fungal and vertebrate cells from oxidative injuries.  The protein product of this gene was named CLMT2 (C. lanatus metallothionein type-2).  The CLMT2 protein (10-40μM) dose-dependently suppressed the reaction between salicylate (200μM) and hydroxyl radicals, thus was a potent scavenger of hydroxyl radicals.  In contrast, an order higher concentration of citrulline (a compatible solute in wild C. lanatus ) was required for effective competition with salicylate for the radicals.  The rate constant for CLMT2 was estimated to be 1.2 x 1011 /M/s, which was one- or two orders higher than those reported for antioxidants  such as ascorbate and glutathione (7.2 and 8.8 x 109/M/s, respectively) or citrulline (3.9x109 /M/s).  The degradation of DNA by hydroxyl radicals generated by the iron/H2O2 system was dose-dependently suppressed by CLMT2 with almost complete suppression elicited by 12 μM CLMT2. [14]

The wild C. lanatus plants that grow in the Kalahari desert, Botswana, exhibit exceedingly high drought tolerance.  Their leaves showed massive accumulation of the free amino acid citrulline.  To determine whether citrulline has hydroxyl radical scavenging property, its reactivity in vitro against hydroxyl radicals was determined.  The citrulline competed with salicylate for hydroxyl radicals produced by iron/H2O2 in a concentration-dependent manner with an ID50 of 6.6 ±1.2mM and a rate constant of (3.9 ± 0.82)x109/M/s.  The citrulline (50-200mM) also effectively protected DNA from attacks by reactive oxygen species.  The citrulline (200 or 400mM) protected pyruvate kinase from oxidative damage without much effect on other metabolic enzymes. [15]

The lycopene is a red pigment that occurs naturally in C. lanatus.  It is a highly effective antioxidant with free radical scavenging activity and has the highest singlet oxygen quenching rate of all carotenoids. [7][16]  The use of lycopene as a dietary supplement has shown potential in reducing the risk of coronary heart disease [17] and to decrease the susceptibility of low density lipoprotein (LDL) to oxidation [18] besides protection from other cellular oxidative damage.  Its other benefits include relief of oral leukoplakia [19] and prostate cancer [20] and the suppression of human papilloma virus (HPV). [21]  The treatment of rats with lycopene (10 or 50mg/kg per os for 2 weeks) resulted in the accumulation of lycopene in the liver, liver microsomes, and blood plasma and an increase in total plasma antioxidant activity.  The lipid peroxidation in the liver was inhibited while solubilization of lysosomal enzymes was reduced. [22] 

Antiallergy activity

The bryonolic acid or its derivatives, was active against at least three types of allergies. [8] The synthetic derivatives, in particular a potassium salt of its succinate ester has significantly greater activities than the natural compound. 

Toxicities

No documentation

Teratogenic effects

No documentation

Clinical Data

Clinical Trials

No documentation

Adverse Effects in Human:

C. lanatus allergy has been described, especially in patients with pollinosis. [23]

Use in Certain Conditions

Pregnancy / Breastfeeding

No documentation

Age Limitations

Neonates / Adolescents

No documentation

Geriatrics

No documentation


Chronic Disease Conditions

No documentation

Interactions

Interactions with drugs

No documentation

Interactions with Other Herbs / Herbal Constituents

No documentation

Contraindications

Contraindications

No documentation

Case Reports

A series of case reports of patients with ragweed (Ambrosia artemisiifolia) allergy who also experienced oral symptoms after eating various members of the Cucurbitaceae family (C. lanatus , cantaloupe, honeydew melon, zucchini, and cucumber) was described. The fifty percent of the patients with ragweed allergy also had IgE directed against these fruits while crossreactivity between watermelon (C. lanatus) and ragweed pollen was shown in enzyme-linked immunosorbent assay (ELISA)-based IgE inhibition experiments.  The mellon allergy mostly occurred in patients with pollinosis.  The melon allergens were identified by IgE immunoblotting experiments using sera from patients who displayed oral allergy symptoms following melon ingestion.  The melon profilin, a 13-kDa component was identified as a major allergen.  It is stable in human saliva, probably due to the lack digestive proteases such as pepsin in saliva, but it is digested within a few seconds by simulated gastric fluid.  This lead to the speculation that melon profiling may be responsible for the local oral symptoms of melon allergy.  The ten percent of patients with melon allergy may display severe anaphylactic reactions. [23]

Read More

  1) Botanical Info

References

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  2. Badifu G. I. O.  Effect of processing on proximate composition, antinutritional and toxic contents of kernels from Cucurbitaceae species grown in Nigeria.  Journal of Food Composition and Analysis, 14: 153-161, 2001.
  3. USDA Natural Resources Conservation Service.  http://plants.usda.gov/java/profile?symbol=CILAL
  4. Florabase. Flora of Western Australia. Plant description by Amanda Spooner, James Carpenter, Gillian Smith and Kim Spence, 2007.  http://florabase.calm.wa.gov.au/browse/profile/7370
  5. CIAT-FAO. http://www.fao.org/ag/AGP/AGPC/doc/GBASE/Safricadata/citlan.htm
  6. Davis A. R, Collins J, Fish W. W, Tadmor Y, Webber III C. L, Perkins-Veazie P.  Rapid method for total carotenoid detection in canary yellow-fleshedwatermelon.  Journal of Food Science, 72(5): S319- S323, 2007.7
  7. Perkins-Veazie P, Collins JK, Pair SD, Roberts W.  Lycopene content differs among red-fleshed watermelon cultivars.  Journal of Science and Food Agriculture, 81: 983-987, 2001.
  8. Tabata M; Tanaka S; Cho H. J; Uno C; Shimakura J; Ito M; Kamisako W; Honda C.  Production of an anti-allergic triterpene bryonolic acid, by plant cell cultures.  Journal of Natural Products, Feb; 56 (2): 165-74, 1993.
  9. Das M, Das S. K, Suthar S. H.  Composition of seed and characteristics of oil from karingda [Citrullus lanatus (Thumb) Mansf].  International Journal of Food Science and Technology, 37: 893–896, 2002.
  10. Girgis P and Turner T. D.  Lesser known Nigerian edible oils and fats.  III. Fatty acid compositions as determined by Gas-Liquid Chromatography.  J. Sci. Fd Agric., 23: 259-262, 1972.
  11. Wani A. A, Sogi D. S, Grover L, Saxena D. C.  Effect of temperature, alkali concentration, mixing time and meal/solvent ratio on the extraction of watermelon seed proteins-a response surface approach.  Biosystems Engineering, 94(1): 67–73, 2006.
  12. Garg V. K and Nes W. R.  Occurrence of A5-sterols in plants producing predominantly A7-sterols: studies on the sterol compositions of six Cucurbitaceae seeds. Phytochemistry, 25(II): 2591-2597, 1986.
  13. Plants For A Future. http://www.pfaf.org/database/plants.php?Citrullus+lanatus
  14. Akashi K, Nishimura N, Ishida Y, Yokota A.  Potent hydroxyl radical-scavenging activity of drought-induced type-2 metallothionein in wild watermelon.  Biochemical and Biophysical Research Communications, 323: 72-78, 2004.
  15. Akashi K, Miyake C, Yokota A.  Citrulline, a novel compatible solute in drought-tolerant wild watermelon leaves, is an e¤cient hydroxyl radical scavenger.  FEBS Letters, 508: 438-442, 2001.
  16. Xu Y, Leo M. A, Lieber C. S.  Lycopene attenuates arachidonic acid toxicity in HepG2 cells overexpressing CYP2E1.  Biochem Biophys Res Commun., 11: 303(3):745-50, 2003.
  17. Sesso H. D, Liu S, Gaziano J. M, Buring J. E.  Dietary lycopene, tomato-based food products and cardiovascular disease in women.  J Nutr., 133(7):2336-41, 2003.
  18. Chopra M, O'Neill M. E, Keogh N, Wortley G, Southon S, Thurnham DI.  Influence of increased fruit and vegetable intake on plasma and lipoprotein carotenoids and LDL oxidation in smokers and nonsmokers.  Clin Chem.,46(11):1818-29, 2000.
  19. Singh M, Krishanappa R , Bagewadi A, Keluskar V. Efficacy of oral lycopene in the treatment of oral leukoplakia. Oral Oncology, 40(6): 591-596, 2004.
  20. Clinton S. K, Emenhiser C, Schwartz S. J, Bostwick D. G, Williams A. W, Moore BJ, Erdman J. W Jr.  cis-trans Lycopene isomers, carotenoids, and retinol in the human prostate.  Cancer Epidemiol Biomarkers Prev., 5(10): 823-33, 1996.
  21. Sedjo R. L, Roe D. J, Abrahamsen M, Harris R. B, Craft N, Baldwin S, Giuliano AR.  Vitamin A, carotenoids, and risk of persistent oncogenic human papillomavirus infection. Cancer Epidemiol Biomarkers Prev., 11(9): 876-84, 2002.
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  23. Egger M, Mutschlechner S, Wopfner N.  Review.  Pollen-food syndromes associated with weed pollinosis: an update from the molecular point of view.  Allergy, 61: 461-476, 2006.