Nutritional Value, Chemical Composition and Cytotoxic Properties of Common Purslane (Portulaca oleracea L.) in Relation to Harvesting Stage and Plant Part

Abstract

Purslane (Portulaca oleraceae L.) is a widespread weed, which is highly appreciated for its high nutritional value with particular reference to the content in omega-3 fatty acids. In the present study, the nutritional value and chemical composition of purslane plants in relation to plant part and harvesting stage were evaluated. Plants were harvested at three growth stages (29, 43 and 52 days after sowing (DAS)), while the edible aerial parts were separated into stems and leaves. Leaves contained higher amounts of macronutrients than stems, especially at 52 DAS. α-tocopherol was the main isoform, which increased at 52 DAS, as well total tocopherols (values were in the ranges of 197–327 μg/100 g fresh weight (fw) and 302–481 μg/100 g fw, for α-tocopherol and total tocopherols, respectively). Glucose and fructose were the main free sugars in stems and leaves, respectively, whereas stems contained higher amounts of total sugars (values were ranged between 0.83 g and 1.28 g/100 g fw). Oxalic and total organic acid content was higher in leaves, especially at the last harvesting stage (52 DAS; 8.6 g and 30.3 g/100 g fw for oxalic acid and total organic acids, respectively). Regarding the fatty acid content, stems contained mainly palmitic (20.2–21.8%) and linoleic acid (23.02–27.11%), while leaves were abundant in α-linolenic acid (35.4–54.92%). Oleracein A and C were the major oleracein derivatives in leaves, regardless of the harvesting stage (values were in the ranges of 8.2–103.0 mg and 21.2–143 mg/100 g dried weight (dw) for oleraceins A and C, respectively). Cytotoxicity assays showed no hepatotoxicity, with GI50 values being higher than 400 μg/mL for all the harvesting stages and plant parts. In conclusion, early harvesting and the separation of plant parts could increase the nutritional value of the final product through increasing the content of valuable compounds, such as omega-3 fatty acids, phenolic compounds and oleracein derivatives, while at the same time, the contents of anti-nutritional compounds such as oxalic acid are reduced.

Wild and Cultivated Centaurea raphanina subsp. mixta: A Valuable Source of Bioactive Compounds

“…In contrast to our study, Nemzer et al [59] reported a higher total and individual organic acids content in cultivated purslane plants compared to wild ones, although different genotypes were tested in both cases which may partially justify this difference [60]. According to the literature, organic acids composition shows a great variability among wild edible species, depending on the edible part and the growing conditions [20,[60][61][62][63]. Special focus is given on oxalic acid content which is undesirable when consumed in high amounts (daily consumption higher than 5 g for adults; [31]), since it reduces Ca availability and induces the formation of kidney stones [64,65].…”

“…Despite the higher oxalic acid content of cultivated C. raphanina spp. mixta plants observed in our study, the detected amounts are lower than those reported on a fresh weight basis in other wild (e.g., Chenopodium album [69], Sonchus oleraceus [61,70], Amaranthus viridis [71], Silybum marianum and Beta maritima [61], and purslane [60,62]) or cultivated species (e.g., spinach [72]) which are considered as rich sources of this anti-nutritional factor. Therefore, based on the set safe limit high amounts of C. raphanina spp.…”

“…The most abundant fatty acids in both wild and cultivated plants were α-linolenic (38.2% and 29.5% in wild and cultivated plants, respectively), linoleic (25.5% and 28.2% in wild and cultivated plants, respectively) and palmitic acid (22.2% and 28.4% in wild and cultivated plants, respectively), while other fatty acids such as behenic, oleic and stearic acid were detected in lower amounts. The same fatty acids were also detected in other wild edible greens such as Cichorium spinosum [10,18,19,82], Portulaca oleracea [60,62,83] and other species [84,85]. Recently, Nemzer et al [59] suggested significant differences in the fatty acids profile of wild and cultivated Portulaca oleracea plants, although the genotype was not the same in both cases to make safe conclusions regarding the effect of growing system.…”

Chemical Composition and Plant Growth of Centaurea raphanina subsp. mixta Plants Cultivated under Saline Conditions

“…Moreover, the broader Mediterranean region is characterized by small-scale farming which is the back-bone of the farming sector and of rural economies and is under increasing pressure due to land allocation for non-agricultural uses and to the ongoing climate change [2][3][4]. The ability of wild species to resist or tolerate stressful conditions suggests they could be used as alternative farming options in soils and climates where conventional species are difficult or impractical to be grown; for the same reason, these species can become an option for small-scale farming allowing the farmers to be competitive within the rapidly changing global market and market needs for novel foods [5][6][7][8][9][10]. Until recently, many reports have highlighted the importance of growing conditions and cultivation practices for producing wild edible greens, focusing on the domestication of these species, their incorporation in sustainable cultivation systems and the rational use of natural resources [2,[11][12][13][14][15].…”

Antioxidants Properties of Natural Products: A Themed Issue in Honor of Professor Isabel C.F.R. Ferreira

“…In addition, the phenolic profile of the plant in each stage was also described by the authors. Petropoulos et al [9] performed the nutritional and chemical composition evaluation of different parts of Portulaca oleracea L., namely stems and leaves, harvested in three growth stages. Additionally, the cytotoxicity of these samples was also assessed.…”