Antioxidants in Italian Head Lettuce (Lactuca sativa var. capitata  L.) Grown in Organic and Conventional Systems under Greenhouse Conditions

Abstract

Lettuce belongs to the Asteraceae family and it is native of the Mediterranean region. In our research, the effect of cultivation practices (organic versus conventional) on antioxidants in Italian head lettuce (Lactuca sativa var. capitata L.) grown in greenhouse was investigated. Bioactive molecule levels, antioxidant properties and the cytotoxicity of polyphenolic extracts from the edible part of head lettuce in Caco-2 cells were determined. FRAP values are 5.33 Ϯ 0.35 and 6.35 Ϯ0.08 mmol/kg in organic products and 4.83 Ϯ 0.16 and 1.80 Ϯ 0.04 mmol/kg in conventional products. FRAP values differ significantly (P < 0.001) between organic and conventional lettuces harvested in September. Significant differences are found between organic and conventional extracts in some target compounds such as quercetin, rutin, lutein, b-carotene and vitamin C. No difference in biological effect is observed between organic and conventional products harvested in July and in September, whereas a major cytotoxicity is found for polyphenol extracts derived from organic and conventional lettuces harvested in September. PRACTICAL APPLICATIONSNowadays, a new image of agriculture is emerging: agricultural production systems are closely related to the needs of consumers and to the search of products that meet food quality and safety. The results of this investigation highlighted the importance of factors such as cultivar, agronomic practices, climatic conditions, degree of ripeness, time of harvest and storage conditions. The variation of these elements represents, in fact, a key tool to obtain healthful and more nutritious food crops by increasing and maximizing the levels of bioactive molecules in foods. Our results suggest a potential to increase the commercial production of the selected specialty leafy greens. bs_bs_banner Journal of Food Biochemistry ISSN 1745-4514 56 Journal of Food Biochemistry 38 (2014) 56-61 © 2013 Wiley Periodicals, Inc. † Values are expressed as mean values Ϯ SD. Means in row for each compound followed by different letters differed significantly (P < 0.05). ‡ By column, levels of significance are represented by NS (not significant), * P < 0.05 and ** P < 0.01. ANTIOXIDANTS IN ITALIAN HEAD LETTUCEA. DURAZZO ET AL.

Effect of abiotic elicitation on the quality and antioxidant potential of lettuce and endive during storage

“…The content of phytochemicals and the biological properties of vegetables may be affected by several factors, including the genotype, growing conditions, as well as agronomical manipulation and elicitation (Baenas, García‐Viguera, & Moreno, ; Durazzo et al, ). Besides induction of production of many phytochemicals, elicitation also results in an increase in plant resistance to pathogens (Złotek & Wójcik, ).…”

Anti-inflammatory and antioxidant activity of polyphenolic extracts fromLactuca sativa(var.Maravilla de Verano) under different farming methods

“…The levels of phenolic acids and flavonols were significantly higher in the unfertilised treatment (A) compared to the three fertilised treatments (C, E, G), with significant differences respect to the lowest value found in plants subjected to mineral fetilisation (treatment K). The high content of phenolics in the minerally fertilised treatment (K) could be associated to the presence of more stressful conditions, in terms of plant and/or soil mineral deficits . Despite the lower levels of phenolic acids and flavonoids, plants under mineral fertilisation (K) showed levels of quercetin significantly higher than all other treatments (Fig.…”

“…The high content of phenolics in the minerally fertilised treatment (K) could be associated to the presence of more stressful conditions, in terms of plant and/or soil mineral deficits. 13,14 Despite the lower levels of phenolic acids and flavonoids, plants under mineral fertilisation (K) showed levels of quercetin significantly higher than all other treatments (Fig. 1A).…”

“…As they act as free radical scavengers, both these classes of secondary plant metabolites are used to counter oxidative stress caused by the environmental adversities and agronomic conditions experienced by plants . The polyphenolic content of lettuce can be influenced by environmental factors such as excessive light and UV, extreme temperature, water deficit, soil mineral composition, diseases, and climatic conditions, as well as agronomical practices, such as fertilisation plans, soil management, and cultivation techniques can cause quantitative and qualitative changes in phenolic compounds . Various studies have investigated the effects of the polyphenolic compounds present in green lettuce, in reducing oxidative and anti‐inflammatory stresses .…”

Polyphenols: A concise overview on the chemistry, occurrence, and human health

“…Flavonols are reported to be present in onions, apples, persimmon, saffron, berries, broccoli, lettuce, tea, and red wine (Bataglion, da Silva, Eberlin, & Koolen, 2015;Durazzo et al, 2014;Hoffmann-Ribani, Huber, & Rodriguez-Amaya, 2009;Sultana & Anwar, 2008;Valavanidis, Vlachogianni, Psomas, Zovoili, & Siatis, 2009). A meta-analysis of epidemiologic studies has shown that the intake of flavonols may reduce the risk of type-2 diabetes (Rienks, Barbaresko, Oluwagbemigun, Schmid, & Nöthlings, 2018).…”