Watermelon lycopene and allied Health Claims

Classification and nutritional profile 

Watermelon (Citrullus lanatus) has association with cucumber, pumpkin, squash and gourds; belonging to family Cucurbitaceae (Edwards et al., 2003[37]). 

Fruit of this plant is major consumed portion and variations in growth characteristics determine its end use quality (Maynard, 2001[79]; 

Oms-Oliu et al., 2009[93]). Considering the nutritional profile, consumption of 100 g watermelon provides 30 kcal.

 It contains almost 92 % water and 7.55 % of carbohydrates out of which 6.2 % are sugars and 0.4 % dietary fiber. It is enriched with carotenoid, vitamin C, citrulline, carotenoids and flavonoids and fat and cholesterol free, thus considered as low caloric fruit (Leskovar et al., 2004[69]; Bruton et al., 2009[17]).

 Additionally, watermelon is rich source of ß-carotene acts as an antioxidant and precursor of vitamin A.

Besides the presence of lycopene, it is a source of B vitamins, especially B₁ and B₆, as well as minerals such as potassium and magnesium (Huh et al., 2008[50]. 

Watermelon contains phenolics quite comparable with that of other fruits (Kaur and Kapoor, 2001[63]; Jaskani et al., 2005[55]).

 It is an inexpensive and nutritious source that is readily available to all socio-economic groups of 

Pakistan throughout the summer season. Its consumption depends on number of factors e.g. availability, income, age, gender, racial and ethnic norms. In this context, per capita consumption in Asian communities is almost 3 times greater as compared to other part of globe (Dermesonlouoglou et al., 2007[33](Fig. 1)).

Presently, functional foods and nutraceuticals are gaining immense importance in the prevention of various maladies through dietary regimen module. 

Consumption of fruits and vegetables based diet has pursuit a range of bioactive components, especially phytochemicals targeting life threatening ailments. In this context,

 lycopene is an extensively studied antioxidant potentially present in watermelon, tomato, pink guava etc. 

Watermelon is one of the unique sources having readily available cis-isomeric lycopene. The distinctive aroma of watermelon is imparted by medium- and short-chain fatty acids along with geranial, ß-ionone and neral. Its consumption has been escalated owing to rich nutritional profile and allied health benefits. 

It is effective in reducing the extent of cancer insurgence, cardiovascular disorders, diabetes and macular diseases. 

The structural characteristics, physiochemical properties and therapeutic effects of lycopene are the limelight of the manuscript. However, further research investigations are still needed to address the health enhancing potential of watermelon lycopene.

Watermelon: a potential source of lycopene

Earlier, only tomato and its products were considered as potential sources of lycopene but now there are proven facts that watermelon also contains appreciable amount of cis-configured lycopene.

 Thus consumer is gradually shifting towards 

watermelon and its allied products for their health concerns.

 Nevertheless, the quantity of lycopene varies depending upon the variety and growing conditions (Fish and Davis, 2003[41]). Overall, 

lycopene ranges from 2.30-7.20 mg/100 g fresh weight bases, present in crystalline form in cell (Huh et al., 2008[50]; Chaoensiri et al., 2009[25]

; Artes-Henandez et al., 2010[9]).

 More interestingly, lycopene contents of red fleshed watermelon are almost 40 % higher than tomato i.e. 4.81 and 3.03 mg/100 g, respectively.

 However, yellow orange and yellow colored fleshed have relatively less lycopene content i.e. 3.68 and 2.51 mg/100 g, respectively (Jaskani, 2005[55];

 Choudhary et al., 2009[28]). In tomato, lycopene is available in relatively higher quantity after heat treatment due to break down of protein-carotenoid complex. In contrast, lycopene from watermelon is available directly to the human body just after consumption (Edwards et al., 2003[37]; Perkins-Veaize and Collins, 2004[94]; Jaskani et al., 2006[56]; Saftner et al., 2007[103]).

Storage conditions are also cardinal that significantly affect the concentrations of lycopene, phenolics and vitamin C contents. The higher ratio of lycopene to carotene in watermelon i.e. 1:12 yields remarkable antioxidant capacity (Mort et al., 2008[85]). Owing to this specific characteristic, foods high in lycopene contents are referred as functional foods (Shi and Maguer, 2000[107]; Collins et al., 2005[30]; Jiang and Lin, 2007[59]; Davis et al., 2008[32]).

Lycopene health claims

Lycopene has potential to prevent various chronic ailments like dyslipidemia, diabetes, oncogenesis, neurodegenerative diseases, osteoporosis etc. 

The protective aspects are ascribed to the singlet oxygen scavenging ability. Numerous metabolic syndromes arise due to high free radicals formation reacting with macromolecules thus oxidizing proteins, lipids and DNA. 

Lycopene protects humans from various pathogenic attacks responsible for an array of diseases (Ilic and Misso, 2012[52]; Sesso et al., 2005[106]).

 Several authors have reported that lycopene holds nutraceutical potential and being antioxidant provides protection against free radicals and oxidative damage (Krinsky, 1998[66]; Rao and Agarwal, 1999[97]; Choksi and Joshi, 2007[27]). Free radicals are produced in the body during oxidation reduction reaction however, excessive production deteriorates body defense mechanism, cell membrane and organelles. These degenerative processes resulted in life threatening ailments (Humberto, 2000[51]; Heber and Lu, 2002[47];

 Perkins-Veazie and Collins, 2006[95]). The presence of large number of double bonds is responsible for its fairly high free radical scavenging or singlet oxygen quenching ability even better than α- and ß-carotene,

 lutein and α-tocopherol (Rivero et al., 2001;[101] Perkins-Veazie and Collins, 2004[96]). 

Lycopene provides protection against degenerative disorders via mechanisms like gap-junction communication, gene function regulation, phase II drug-metabolizing pathways and carcinogenic metabolism (Arab and Steck, 2000[8]; Collins et al., 2004[29]). It has been established through epidemiological studies that lycopene plays a role in maintaining normal cellular differentiation and division (Giovannucci et al., 2002[46];

 Choudhary et al., 2009[28]). Lycopene scavenges free radicals at cellular level due to its attachment in cell membrane thereby may prevent hypercholesterolemia and hyperglycemia along with allied dysfunctions (Marinova et al., 2005[77]; Fisher and Frazee, 2006[43]).

Ref

EXCLI J. 2014 Jun 3;13:650–660.

Watermelon lycopene and allied health claims

Ambreen Naz 1,*, Masood Sadiq Butt 2, Muhammad Tauseef Sultan 3, Mir Muhammad Nasir Qayyum 4, Rai Shahid Niaz 5