Chemical composition and bioactive compounds of Cucurbitaceae seeds: Potential sources for new trends of plant oils

Citrullus lanatus var. ‘Crimson’, and 82.78% for the Cucumis melo var. ‘Ananas’ seed oils. 
The Citrullus lanatus seed oil witnessed the highest linoleic acid content (68.07%) and the 
lowest oleic acid content (14.25%). Since all the examined seed oil samples were rich in both 
oleic and linoleic acids, they might be used as cooking or salad oils or might even be used for 
margarine manufacturing. The major saturated fatty acids in the seed oils of pumpkin, 
watermelon and melon were palmitic and stearic acids. The total saturated fatty acids content 
of Cucurbita pepo seed oil was higher (24.01%) than those of Cucumis melo and Citrullus 
lanatus (20.24% and 24.01%). These results are confirmed by the findings of Veronezi and 
Jorge (2015) for Cucurbita moschata and Cucurbita maxima seed oils, El-Adawy and Taha 
(2001) for Cucurbita pepo and Citrullus vulgaris seed oils, Nyam at al. (2009) for Citrullus 
lanatus seed oil, Górnás and Rudzińska (2016) for Citrullus lanatus (Thumb). Matsum. & 
Nakai and Cucumis melo L. seed oils, and Mallek-Ayadi et al. (2018) for Cucumis melo L. 
seed oil. 
3.4. Triacylgycerol (TAG) composition 
The determination of the fatty acid composition is undoubtedly decisive for evaluating 
both the stability and the nutritional quality of vegetable oils. However, the determination of 
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the type and the amounts of TAG species within the Cucurbitaceae seed oils is much more 
important for understanding their physical and functional properties.
The distribution of TAGs is illustrated in Table 4 and in the light of the corresponding 
results, the Cucurbita pepo var. ‘Essahli’ and the Cucumis melo var. ‘Ananas’ seed oils 
contained 13 TAGs. The Citrullus lanatus var. ‘Crimson’ seed oil, however, contained 12 
TAGs among which the glycerol-palmitate-linoleate-stearate was not detected. 
Table 4 demonstrates that the main TAGs in the Cucurbita pepo var. ‘Essahli’ seed oil 
were glycerol-oleate-dilinoleate (OLL), followed by glycerol trilinoleate (LLL), glycerol-
dioleate-linolenate (OOLn), glycerol-palmitate-linoleate-linolenate (PLLn), and glycerol-
palmitate-oleate-linoleate (POL). Note that the results of the triglyceride analysis are in 
perfect accordance with the previous studies for pumpkin seed oils. In fact, Arslan et al. 
(2017) reported that OLL was the dominant triglyceride in the cold pressed Cucurbita pepo L. 
var. ‘Celtik’ seed oils from the central Anatolia region of Turkey (Konya). The other 
triglycerides were LLL, POL, LnPO and OOL. Similarly, Neᵭeral et al. (2012) investigated 
both husked and naked seed oils produced by three processes differing in the degree of 
thermal treatment wherein the seeds were exposed (roasted pressed, pressed and unroasted, 
pressed with cooling). They found that OLL was the abundant triglyceride followed by LLL, 
PLL, LOO, and SLL + PLO isomers. 
The Citrullus lanatus and Cucumis melo seed oils presented similar triglyceride 
patterns as the LLL, LLnLn, OOLn, and OLL were the major triglyceride isomers. The 
Glycerol-linoleate-dilinolenate and glycerol trilinoleate were also the main TAGs in the 
Citrullus lanatus var. ‘Crimson’ (29.15%) and the Cucumis melo var. ‘Ananas’ (18.38%) seed 
oils, respectively.
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In this regard, previous studies revealed that TAG types such as OLL, OOL, POL, 
SOL, and POO increased the oils’ oxidative stability (Neff et al., 1993; Neff et al., 1994). The 
TAG composition of the Cucurbitaceae seed oil evinces an adequate oxidative stability of the 
seed oil, which might be favourable for food and industrial applications. 
3.5. Phytosterols 
The sterol composition of Cucurbita pepo var. ‘Essahli’, Citrullus lanatus var. 
‘Crimson’, and Cucumis melo var. ‘Ananas’ seed oils is illustrated in Table 3. Fifteen 
phytosterols were identified in all analysed Cucurbitaceae seed oils, namely cholesterol, 
brassicasterol, 24-methylenecholesterol, campesterol, campestanol, stigmasterol, Δ5-
avenasterol, Δ5,23-stigmastadienol, Δ 5,24- stigmastadienol, Δ 7- campesterol, Δ 7-
stigmastenol, Δ 7-avenasterol, clerosterol, sitosterol and sitostanol. The β-sitosterol, which 
accounted for 1923.51 mg/kg, 2298.83 mg/kg, and 3248.48 mg/kg for the Cucurbita pepo,