Beneficial Phytochemicals with Anti-Tumor Potential Revealed through Metabolic Profiling of New Red Pigmented Lettuces (Lactuca sativa L.).
ABSTRACT: The present study aimed to compare polyphenols among red lettuce cultivars and identify suitable cultivars for the development and utilization of healthy vegetables. Polyphenols, mineral elements, and antioxidant activity were analyzed in the leaves of six red pigmented lettuce (Lactuca sativa L.) cultivars; thereafter, we assessed the anti-tumor effects of cultivar B-2, which displayed the highest antioxidant activity. Quadrupole-Orbitrap mass spectrometry analysis revealed four classes of polyphenols in these cultivars. The composition and contents of these metabolites varied significantly among cultivars and primarily depended on leaf color. The B-2 cultivar had the highest antioxidant potential than others because it contained the highest levels of polyphenols, especially anthocyanin, flavone, and phenolic acid; furthermore, this cultivar displayed anti-tumor effects against the human lung adenocarcinoma cell line A549, human hepatoma cell line Bel7402, human cancer colorectal adenoma cell line HCT-8, and HT-29 human colon cancer cell line. Hence, the new red-leaf lettuce cultivar B-2 has a distinct metabolite profile, with high potential for development and utilization of natural phytochemical and mineral resources in lettuces and can be used as a nutrient-dense food product.
Project description:Rising life expectancy and the demanding modern lifestyle drive the growing appeal of healthy and balanced diets centered on vegetable and fruit consumption. Functional, phytonutrient-packed and principally raw food is in high demand. Microgreens constitute such a novel functional food that combines a high sensory and bioactive value, which invites comparison to their mature-leaf counterparts. For this purpose, a controlled environment chamber experiment was carried out to compare the mineral, phytochemical and antioxidant capacity attributes of two-pigmented Lactuca sativa L. var. capitata cultivars (green and red Salanova®) harvested at the microgreens and the mature-leaf stage. Macronutrients were assessed through ion chromatography, while carotenoids and polyphenols were assessed and quantified through HPLC-DAD and UHPLC-Q-Orbitrap HRMS, respectively. Calcium and magnesium were higher in microgreens irrespective of the cultivar; conversely, phosphorous, potassium and nitrate where higher in mature leaves. All pigments including chlorophyll, lutein and ?-carotene augmented at advanced maturity stage and were more concentrated in the red pigmented cultivar at both stages. Total polyphenols accumulated more densely in red Salanova, particularly in the microgreens stage; whereas, in green Salanova, the accumulation was significant but less pronounced in the mcirogreens stage. Chlorogenic acid, quercetin malonyl glucoside, rutin and coumaroyl quinic acid were the most concentrated phenolic acids in microgreens, while feruloyl tartaric acid was predominant in mature leaves. Finally, when a high carotenoids content is sought, mature lettuce leaves should be the prime culinary choice, whereas high polyphenolic content is dictated by both the cultivar and the harvest stage, with red Salanova microgreens being the most nutrient-packed choice.
Project description:BACKGROUND:Chicory (Cichorium intybus L.) is a traditional European crop that is highly appreciated for its contents of bioactive compounds, especially phenolics, which have high antioxidant activities. Among other factors, agricultural practice might affect the contents of these bioactive compounds, which are also important from a nutritional point of view, and affect the shelf-life. RESULTS:The antioxidant potential (AOP) of chicory plants treated with different fertilisers was investigated in vitro using DPPH radical scavenging and in vivo using the yeast Saccharomyces cerevisiae. Additionally, total phenolics content (TPC) was evaluated using Folin-Ciocalteu reagent, and total flavonoids content (TFC) using the aluminium chloride method. Four different chicory cultivars were included: 'Treviso', 'Verona' and 'Anivip' as red cultivars; and 'Castelfranco' as a red-spotted cultivar. These were grown in pots under controlled glasshouse conditions using organic and/or mineral fertilisers. The combination of organic and mineral fertilisers during red chicory growth resulted in significantly higher in-vitro and in-vivo AOPs compared to the control. For the red-spotted cultivar 'Castelfranco', this combined organic and mineral fertilisation decreased AOPs in vitro and increased AOPs in vivo. Among the cultivars examined, 'Castelfranco' treated with combined organic plus mineral fertilisers showed the highest AOP in vivo, accompanied by the lowest TPC and TFC. CONCLUSIONS:These data show that application of different fertilisers has different impacts on red and red-spotted chicory cultivars in terms of TFC and TPC, which for red-spotted chicory resulted in different AOPs in vitro and in vivo. The in-vitro AOP is well reflected in the in-vivo AOP for the red chicory cultivars, but less so for the red-spotted cultivar 'Castelfranco'. Based on the in-vivo AOPs for these chicory cultivars analysed, the combined organic plus mineral fertiliser treatment is recommended.
Project description:Reduction of nitrogen application in crop production is desirable for ecological and health-related reasons. Interestingly, nitrogen deficiency can lead to enhanced concentrations of polyphenols in plants. The reason for this is still under discussion. The plants' response to low nitrogen concentration can interact with other factors, for example radiation intensity. We cultivated red and green leaf lettuce hydroponically in a Mediterranean greenhouse, supplying three different levels of nitrogen (12 mM, 3 mM, 0.75 mM), either in full or reduced (-50%) radiation intensity. In both red and green lettuce, we found clear effects of the nitrogen treatments on growth characteristics, phenolic and photosynthetic compounds, nitrogen, nitrate and carbon concentration of the plants. Interestingly, the concentrations of all main flavonoid glycosides, caffeic acid derivatives, and sucrose increased with decreasing nitrogen concentration, whereas those of chlorophylls, ?-carotene, neoxanthin, lactucaxanthin, all trans- and cis-violaxanthin decreased. The constitutive concentrations of polyphenols were lower in the green cultivar, but their relative increase was more pronounced than in the red cultivar. The constitutive concentrations of chlorophylls, ?-carotene, neoxanthin, all trans- and cis-violaxanthin were similar in red and green lettuce and with decreasing nitrogen concentration they declined to a similar extent in both cultivars. We only detected little influence of the radiation treatments, e.g. on anthocyanin concentration, and hardly any interaction between radiation and nitrogen concentration. Our results imply a greater physiological plasticity of green compared to the red lettuce regarding its phenolic compounds. They support the photoprotection theory regarding anthocyanins as well as the theory that the deamination activity of phenylalanine ammonia-lyase drives phenylpropanoid synthesis.
Project description:Space farming for fresh food production is essential for sustaining long-duration space missions and supporting human life in space colonies. However, several obstacles need to be overcome including abnormal light conditions and energy limitations in maintaining Bioregenerative Life Support Systems (BLSSs). The aim of the present study was to evaluate six lettuce cultivars (baby Romaine, green Salanova, Lollo verde, Lollo rossa, red oak leaf and red Salanova) of different types and pigmentations under optimal and suboptimal light intensity and to identify the most promising candidates for BLSSs. Baby Romaine performed better than the rest of the tested cultivars under suboptimal light intensity, demonstrating a more efficient light-harvesting mechanism. Stomatal resistance increased under suboptimal light conditions, especially in the case of Lollo verde and red oak leaf cultivars, indicating stress conditions, whereas intrinsic water-use efficiency was the highest in baby Romaine and red oak leaf cultivars regardless of light regime. Nitrate content increased under suboptimal light intensity, especially in the cultivars green Salanova and Lollo verde, while P and Ca accumulation trends were also observed in baby Romaine and Lollo verde cultivars, respectively. Chicoric acid was the major detected phenolic acid in the hydroxycinnamic derivatives sub-class, followed by chlorogenic, caffeoyl-tartaric and caffeoyl-meso-tartaric acids. Chicoric and total hydroxycinnamic acids were not affected by light intensity, whereas the rest of the detected phenolic compounds showed a varied response to light intensity. Regarding cultivar response, red oak leaf exhibited the highest content in chicoric acid and total hydroxycinnamic acids content under suboptimal light intensity, whereas red Salanova exhibited the highest hydroxycinnamic derivatives profile under optimal light conditions. The main detected carotenoids were ?-cryptoxanthin and violaxanthin+neoxanthin, followed by lutein and ?-carotene. All the target carotenoids decreased significantly under low light intensity, while red Salanova maintained a distinct carotenoids profile. Overall, cultivation of assorted lettuce cultivars is the optimal scenario for space farming, where baby Romaine could provide adequate amounts of fresh biomass owing to its high light-use efficiency while red oak leaf and red Salanova could contribute to the daily dietary requirements for health-promoting bioactive compounds such as polyphenols and carotenoids.
Project description:Consumer interest toward natural ingredients is creating a growing trend in the food industry and research for the development of natural products such as colorants, antimicrobials and antioxidants. Semi-processed frozen prickly pear (Opuntia ficus-indica (L.) Mill.) juices (PPJs), obtained from three cultivars with white, red and yellow pulp, with different harvest times ("Agostani" and "Bastardoni"), were characterized for betalains, total phenolics, flavonoids, carotenoids, antioxidant capacity (by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH)) and antimicrobial potential against foodborne pathogenic bacteria. Through chemical assays, PPJs showed high contents of total polyphenols, flavonoids and betalains and marked antioxidant capacity. PPJs from the first harvest ("Agostani") revealed the significantly highest amount of polyphenols in white cultivar and of betacyanin and betaxanthin in yellow and red cultivars; antioxidant capacity was significantly higher in "Agostani" PPJs than in "Bastardoni" ones. Regarding antimicrobial potential, all PPJs revealed good antibacterial activity, particularly against Salmonella enterica as evidenced by the widest inhibition haloes. These results encourage the suitability of the first flowering prickly pear fruits, with low market value as fresh fruit but with high nutritional features, to be processed as semi-finished product. In particular, its use as ingredient in foods with high risk of Salmonella contamination may act as a natural preservative.
Project description:The effect of elicitation in butterhead lettuce on carotenoid and polyphenol metabolism was evaluated. Different concentrations of arachidonic acid (AA), salicylic acid (SA), methyl jasmonate (MJ) (15, 45, and 90 ?M) and Harpin protein (HP) (30, 60, and 120 mg/L) were applied on red and green butterhead lettuces. Total phenolic and flavonoid content were incremented by MJ (90 ?M) in green and red lettuce. Carotenoids were increased in red lettuce (AA; 45 ?M). Green lettuce modifies their phenolic acid profile after elicitation with AA and MJ; meanwhile, red lettuce incremented mainly in hydroxycinnamic acids and flavonols, MJ being the elicitor with the highest effect. There was an impact on secondary metabolite enzyme gene transcript concentration. Phenylalanine ammonia-lyase (PAL) and lycopene beta cyclase (LBC) increased in both varieties after elicitation. A relationship between phytochemical increase and the activation of the metabolic pathways after elicitation in butterhead lettuce was observed.
Project description:Lettuce is an important leafy vegetable that represents a significant dietary source of antioxidants and bioactive compounds. However, the levels of metabolites in different lettuce cultivars are poorly characterized. In this study, we used combined GC?×?GC-TOF/MS and UPLC-IMS-QTOF/MS to detect and relatively quantify metabolites in 30 lettuce cultivars representing large genetic diversity. Comparison with online databases, the published literature, standards as well using collision cross-section values enabled putative identification of 171 metabolites. Sixteen of these 171 metabolites (including phenolic acid derivatives, glycosylated flavonoids, and one iridoid) were present at significantly different levels in leaf and head type lettuces, which suggested the significant metabolomic variations between the leaf and head types of lettuce are related to secondary metabolism. A combination of the results and metabolic network analysis techniques suggested that leaf and head type lettuces contain not only different levels of metabolites but also have significant variations in the corresponding associated metabolic networks. The novel lettuce metabolite library and novel non-targeted metabolomics strategy devised in this study could be used to further characterize metabolic variations between lettuce cultivars or other plants. Moreover, the findings of this study provide important insight into metabolic adaptations due to natural and human selection, which could stimulate further research to potentially improve lettuce quality, yield, and nutritional value.
Project description:<h4>Background</h4>Identification and screening of cultivars rich in bioactive phytoconstituents can be potentially useful to make nutrient-dense dishes and in medicinal formulations. In this study, we have identified, characterized and quantified caffeoylquinic acids, dicaffeoylquinic acid, dicaffeoyltartaric acid, kaempferol conjugates, quercetin malonylglucoside, sesquiterpene lactones, and cyanidin in 22 lettuce cultivars at mature and bolting stages using UPLC-PDA-Q-TOF-HDMS, UPLC, and HPLC.<h4>Results</h4>The composition and contents of the studied metabolites and antioxidant activity varied significantly and depend on leaf color, cultivar type and stage of maturity. The main phenolic acid components of lettuce were quinic and tartaric acid derivatives, whereas kaempferol derivatives were the dominant flavonoids. The sum of the content of phenolic acids ranged from 18.3 to 54.6 mg/100 g DW and 15.5 to 54.6 mg/100 g DW, whereas the sum of the contents of flavonoids ranged from 9.2 to 25.9 mg/100 g DW and 14.9 to 83.0 mg/100 g DW in mature and bolting stage cultivars, respectively. The content of cyanidin, lactucin, lactucopicrin, and ABTS radical antioxidant activity were in the range of 0.3 to 9.7 (mature stage) and 0.5 to 10.2 mg/g DW (bolting stage), 1.8 to 41.9 (mature stage) and 9.7 to 213.0 (bolting stage) µg/g DW, 9.9 to 344.8 (mature stage) and 169.2 to 3888.2 (bolting stage) µg/g DW, and 12.1 to 29.0 (mature stage) and 15.7 to 30.3 (bolting stage) mg TE/g DW, respectively. The principal component analysis (PCA) showed that the green and red pigmented lettuce cultivars were grouped to the negative and positive sides of PC1, respectively, while the green/red pigmented cultivars were distributed throughout the four quadrants of the PCA plots with no prominent grouping. The loading plot showed that phenolic acids, flavonoids, and cyanidin are the most potent contributors to the radical scavenging activity of lettuce extracts.<h4>Conclusions</h4>Lettuce at the bolting stage accumulate relatively high amount of sesquiterpene lactones (SLs), quercetin malonylglucoside (QMG), methylkaempferol glucuronide (MKGR), kaempferol malonylglucoside (KMG), and 3-<i>O</i>-caffeoylquinic acid (3-CQA) compared to the mature stage. Higher amount of phytoconstituents were found to be accumulated in the red pigmented lettuce leaves compared to the green lettuce leaves. In addition, the contents of most of the metabolites in lettuce seem to increase with age of the leaves. The presence of the two bitter SLs, lactucin and lactucopicrin, in significantly high amount in lettuce leaves at bolting stage could diminish consumer acceptance. However, alternatively, these leaves could be utilized by nutraceutical companies working to recover these compounds.
Project description:Considering that functional components of plant foods are mainly secondary-metabolism products, we investigated the shaping of health-promoting compounds in hydroponically grown butterhead lettuce (Lactuca sativa L. var. capitata) as a function of the strength of the nutrient solution utilized. To this aim, untargeted metabolomics profiling, in vitro antioxidant capacity (total phenolics, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), cupric reducing antioxidant capacity (CUPRAC), and ferric reducing antioxidant power (FRAP) assays), and the inhibition of selected enzyme activities were investigated in two butterhead lettuce cultivars with different pigmentation, i.e., green and red Salanova. Full-strength nutrition, together with half- and quarter-strength solutions of macronutrients, was tested. Our results indicate that by reducing the nutrients strength, we could elicit a distinctive shaping of the phenolic profile of lettuce. It is noteworthy that only specific classes of phenolics (namely, lignans and phenolic acids, followed by flavones and anthocyanins) were modulated by the induction of nutritional eustress (fold-change values in the range between -5 and +11). This indicates that specific responses, rather than a generalized induction of phenolic compounds, could be observed. Nonetheless, a genotype-dependent response could be observed, with the red cultivar being much more responsive to nutritional deprivation than the green Salanova lettuce. Indeed, analysis of variance (ANOVA) confirmed a genotype x nutrition interaction in red Salanova (p < 0.001). As a consequence of the changes in phenolic composition, also the antioxidant capacity (p < 0.001) and amylase inhibition (p < 0.001) properties were affected by the growing conditions. However, the effect on cholinesterase and tyrosinase inhibition was poorly affected by the nutritional strength. Provided that yields are not compromised, the application of a controlled nutritional eustress in hydroponically cultivated lettuce may represent a valuable strategy to produce food with tailored functional features in a sustainable manner.
Project description:The false fruits of apple (<i>Malus domestica</i>) and pear (<i>Pyrus communis</i>) are consumed all over the world, contributing to the dietary intake of health-promoting antioxidant phytochemicals. For example, polyphenols confer many beneficial effects (according to their chemical structure, bioavailability, and absorption efficiency in the gut) and the consumption of polyphenol-rich apple and pear fruits may therefore reduce the risk of some diseases. However, the content of such molecules is highly dependent on the specific fruit cultivar. To examine this metabolic diversity in detail, we used metabolomic analysis (NMR and HPLC-DAD/MS) to profile the metabolome of six apple and five pear cultivars. We also determined the antioxidant capacity of the extracts (FRAP assay) and correlated this with the metabolomic composition and abundance of specific metabolites. We observed the cultivar-specific accumulation of sugars, amino acids, malic acid, and various polyphenols, which was also related to the growing season for some cultivars. We found that the ancient Italian apple Pom Prussian was enriched for chlorogenic acid as well as more characteristic polyphenols (phloretin derivatives), the pear cultivar Abate Fetel was low in sucrose, and both cultivars displayed high in vitro antioxidant activity. These cultivars may, therefore, be particularly attractive to health-conscious consumers.