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This study was conducted to investigate the effects of the extracts of green romaine lettuce (GRE) on sleep enhancement. GRE contains 1071.7 and 199.2 µg/g of extracts of lactucin and lactucopicrin, respectively, known as sleep enhancement substances. When 100 mg/kg of GRE was administered orally, sleep latency and duration time were significantly increased compared to controls (p < 0.05). Rapid eye movement (REM) sleep decreased with 100 mg/kg of GRE administration and non-REM (NREM) sleep also increased. There was no significant difference between REM and NREM among the oral GRE administration groups receiving 100, 120, and 160 mg/kg GRE. In the caffeine-induced insomnia model, total sleep time was significantly increased by 100 mg/kg GRE administration compared to the caffeine-treated group (p < 0.05). In addition, GRE inhibited the binding of [3H]-flumazenil in a concentration-dependent manner, and affinity of both lactucin and lactucopicrin to gamma-aminobutyric acid (GABA)A-benzodiazepine (BDZ) receptor was 80.7% and 55.9%, respectively. Finally, in the pentobarbital-induced sleep mouse model, the sleep enhancement effect of GRE was inhibited by flumazenil, an antagonist of BDZ. Thus, these results demonstrate that GRE acts via a GABAergic mechanism to promote sleep in a rodent model.

Background 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. Results 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. Conclusions Lettuce at the bolting stage accumulate relatively high amount of sesquiterpene lactones (SLs), quercetin malonylglucoside (QMG), methylkaempferol glucuronide (MKGR), kaempferol malonylglucoside (KMG), and 3-O-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. Electronic supplementary material The online version of this article (10.1186/s13065-019-0570-2) contains supplementary material, which is available to authorized users.

Free and glycosylated sesquiterpene lactones (SLs), which are abundant in leafy vegetables including Brussels/witloof chicory, possess health-promoting effects in vivo. However, the pharmacokinetics of dietary source of SLs remain largely unknown. In this open-label and single-dose trial, sixteen healthy volunteers consumed 150 g of Brussels/witloof chicory juice containing 48.77 &mu, mol SLs in 5 min. Blood, urine, and fecal samples were collected before and after chicory consumption in 24 h. No SLs were detected in the serum, urine, and fecal samples before chicory consumption in all of the participants. Chicory consumption increased lactucin, 11&beta, 13-dihydrolactucin, and their glucuronide/sulfate conjugates, rather than lactucopicrin and 11&beta, 13-dihydrolactucopicrin, as well as glycosylated SLs in biological samples. The peak concentration of total SLs in serum reached 284.46 nmol/L at 1 h, while, in urine, this peak was 220.3 nmol between 2 and 6 h. The recovery of total SLs in blood, urine, and feces was 7.03%, 1.13%, and 43.76% of the ingested dose, respectively. Human fecal suspensions with intestinal microbiota degraded glycosylated SLs in chicory, and converted lactucopicrin and 11&beta, 13-dihydrolactucopicrin to lactucin and 11&beta, 13-dihydrolactucin, respectively. Collectively, Brussels/witloof chicory SLs are poorly bioavailable and they undergo partial gut microbial and phase II metabolism in humans.

Scope Gut microbiota converts dietary phytochemicals into metabolites and modulates their health effects. The microbial metabolism of dietary terpenoids, as the sesquiterpene lactones of leafy vegetables, is unknown. Methods and results In vitro fermentation of lactucopicrin, lactucin, and romaine lettuce with gut microbiota from independent donors, show their extensive metabolism through untargeted metabolomics of the fecal incubations. Dehydroxylations and double bond hydrogenations are the main catabolic reactions. Isomers of dihydrolactucopicrin, tetrahydrolactucopicrin, and deoxylactucin, are observed after lactucopicrin metabolism. Tetrahydrolactucin and hexahydrolactucin are also found after lactucin metabolism. Lettuce fermentation shows similar metabolic conversions. Phase II conjugates of most of these metabolites are detected in the urine of healthy volunteers after escarole salad intake. Glucuronides, and sulfates, of dihydrolactucopicrin, tetrahydrolactucopicrin, dihydrolactucin, and deoxylactucin, are detected in the urine although with large inter-subject variability. Conclusion This is the first report on the gut microbiota metabolism of sesquiterpene lactones in humans, and one of the first reports to describe that dietary terpenoids of widely consumed leafy vegetables are extensively catabolized by human gut microbiota. A large inter-subject variation in the metabolism of sesquiterpene lactones also reflects differences in gut microbiota composition. It suggests that inter-individual differences in their health effects should be expected.

Lactuca L. species belong to the Asteraceae family and these plants are traditionally used for therapeutic purposes around the world. The dried milky latex of L. serriola is known as &ldquo, lettuce oil&rdquo, and is used as a sedative in Turkey. This study aimed to evaluate the sedative effects and analyze the chemical compositions of latexes obtained from some Lactuca species growing in Turkey. The sedative effects were evaluated through various behavioral tests on mice. For this purpose, latexes were obtained from L. glareosa Boiss., L. viminea (L.) J. Presl and C. P, L. mulgedioides (Vis and Panćić) Boiss. and Kotschy ex. Boiss., L. saligna L., and L. serriola L. The latex from L. saligna showed the highest sedative effects, whilst L. serriola and L. viminea latexes also displayed significant sedative effects compared to the control group at a dose of 100 mg/kg. However, the latexes from L. glareosa and L. mulqedioides did not exhibit any sedative effects on mice. Characteristic sesquiterpene lactones (lactucin, lactucopicrin, 11,13&beta, dihydrolactucin, and 11,13&beta, dihydrolactucopicrin) were determined qualitatively and quantitatively by high-performance liquid chromatography (HPLC). Lactucin was identified as the main component.

Cichorium intybus L. has recently gained major attention due to large quantities of health-promoting compounds in its roots, such as inulin and sesquiterpene lactones (SLs). Chicory is the main dietary source of SLs, which have underexplored bioactive potential. In this study, we assessed the capacity of SLs to permeate the intestinal barrier to become physiologically available, using in silico predictions and in vitro studies with the well-established cell model of the human intestinal mucosa (differentiated Caco-2 cells). The potential of SLs to modulate inflammatory responses through modulation of the nuclear factor of activated T-cells (NFAT) pathway was also evaluated, using a yeast reporter system. Lactucopicrin was revealed as the most permeable chicory SL in the intestinal barrier model, but it had low anti-inflammatory potential. The SL with the highest anti-inflammatory potential was 11&beta, 13-dihydrolactucin, which inhibited up to 54% of Calcineurin-responsive zinc finger (Crz1) activation, concomitantly with the impairment of the nuclear accumulation of Crz1, the yeast orthologue of human NFAT.

Lettuce is an important annual leafy vegetable and bitterness is its potent flavor character. Lettuce germplasm differ their phenotypic characters and sesquiterpene lactones (SLs) contents which are important for consumer’s acceptance. This study was carried out to evaluate the phenotypic characters and SLs contents in one hundred lettuce germplasm in Jeonju, Korea. Twenty-three agro-morphological (16 qualitative and 7 quantitative) traits and two SLs (lactucin and lactucopicrin) contents were studied in these germplasm. Germplasm exhibited the variation in qualitative and quantitative characters. Average plant weight was 423.9 g with a range from 116.0 to 905.0 g. Lactucin content was varied from 19.7 (IT 294226) to 194.4 ㎍/g (IT 294298) with an average concentration of 84.7 ㎍/g. Lactucopicrin ranged from 82.5 (IT 300134) to 2228.6 ㎍/g (IT 294210) with an average concentration of 586.3 ㎍/g. Total SLs content was ranged from 120.1 (IT 300134) to 2286.6 (IT 294210) ㎍/g with the average concentration of 671.0 ㎍/g. Significant (p≤0.05) differences were found between crisp head and butter head germplasm for lactucin, lactucopicrin and total SLs content. Crisp head germplasm revealed the highest average lactucin (112.9 ㎍/g), lactucopicrin (734.8 ㎍/g) and total SLs content (847.7 ㎍/g). Crisp head and leafy type germplasm exhibited more total SLs content (847.7 and 744.7 ㎍/g, respectively) than cos (524.9 ㎍/g) and butter head type (519.4 ㎍/g). Principal component analyses of the quantitative traits indicated that the first principal component axis accounted more than 91% of the total variation. This study revealed the ample genetic variation in the agro-morphological traits and SLs contents to support the selection for improved lettuce varieties.

Chicory (Cichorium intybus L.var. sativum L., Asteraceae) is a multipurpose plant cultivated as vegetable and coffee substitute in Europe and North America, also as folk medicine in China. The extracts from chicory roots showed significant effect on inhibition against α-glucosidase. By a bioassay-guided approach, the chemical fraction with high α-glucosidase inhibition was found and its chemical profile was tentatively described by UPLC-Q-TOF/MS to include 28 compounds. Further chemical isolation yielded six compounds, their chemical structures were elucidated as 11β-13-dihydrolactucin (1), lactucin (2), 8-deoxylactucin (3), jacquinelin (4), 11β,13-dihydrolactucopicrin (5) and lactucopicrin (6), and among them, the compound 4 showed the strongest inhibitory activity against yeast α-glucosidase with IC50 value of 4.180 μM. The present results suggest that chicory roots can eventually exhibit anti-diabetic effect and the sesquiterpenes may be responsible for the activity.

In recent years we initiated extensive studies on the characterization of the population structure of wild Lactuca relatives (WLRs) originating from their center of origin and diversity in Southwest Asia. A comparative phytochemical study of nine sesquiterpene lactones in natural populations of the wild lettuce L. altaica Fisch. & C.A. Mey. (Asteraceae) was performed, based on 22 plants, representing seven original individual seed samples derived from three localities representing three regions in Armenia. The compounds were profiled and quantified in leaves and roots of the plants, grown in a controlled glasshouse. The contents of major sesquiterpene lactones, that including the following eight guaianolides: cichorioside B, lactucin, 11β,13-dihydrolactucin, crepidiaside B, 8-deoxylactucin, jacquinelin, lactucopicrin/11β,13-dihydrolactucopicrin, as well as the germacranolide glucoside – lactuside A, were estimated by HPLC/PDA. The L. altaica plants could be characterized by the occurrence of lactuside A in their roots, and the mixture of lactucopicrin/11β,13-dihydrolactucopicrin in both their roots and leaves by relatively high amounts, similarly to results obtained for three commercial cultivars of L. sativa. The total content of sesquiterpene lactones in the roots was significantly higher than that in the leaves. This study is likely the first report of detailed screening of L. altaica natural populations and individuals, even by low sample size, for any trait. Species within the primary lettuce gene pool, should be considered as an attractive source of germplasm in further research and improvement of cultivated lettuce, Lactuca sativa L. While using interspecific hybridization in order to elevate the sesquiterpene levels in cultivated lettuces, the lactones quality (profile) and quantity, as well as the cross-ability level of the wild Lactuca spp. with the crop and fertility of the obtained offspring should be considered.

Chicory (Cichorium intybus L.) is a medicinal and industrial plant from the Asteraceae family that produces a variety of sesquiterpene lactones (STLs), most importantly bitter guaianolides: lactucin, lactucopicrin and 8-deoxylactucin as well as their modified forms such as oxalates. These compounds have medicinal properties; however, they also hamper the extraction of inulin – a very important food industry product from chicory roots. The first step in guaianolide biosynthesis is catalyzed by germacrene A synthase (GAS) which in chicory exists in two isoforms – GAS long (encoded by CiGASlo) and GAS short (encoded by CiGASsh). AmiRNA silencing was used to obtain plants with reduced GAS gene expression and level of downstream metabolites, guaianolide-15-oxalates, as the major STLs in chicory. This approach could be beneficial for engineering new chicory varieties with varying STL content, and especially varieties with reduced bitter compounds more suitable for inulin production.

Sesquiterpene lactones (SLs) are the main determinants of radicchio bitterness and the control of their concentrations is a key point for the market value of this product. An innovative analytical approach based on two complementary mass spectrometers, Orbitrap-HRMS and MS/MS, was used for quantitative analysis of SLs in aerial part of four different varieties of chicory. Data highlighted the presence of eight SLs: 11β,13-dihydrolactucin, lactucin, 8-deoxy-lactucin, dihydro-8-deoxylactucin, dihydrolactucopicrin, lactucopicrin, lactuside C (jaquinellin glucoside) and dihydro-lactucopicrin oxalate. Significant varietal differences were found. The highest amount of SLs was found in the radicchio “Treviso Precoce” variety (189.71 μg/g), the lowest amount in “Treviso Tardivo” variety (45.78 μg/g). Lactucopicrin was the most abundant compound with concentration ranged between 99.36 in “Treviso Precoce” and 13.50 μg/g in “Treviso Tardivo” while dihydro-lactucopicrin oxalate was the less abundant in all analyzed varieties with an average concentration of about 1% on the total amount of SLs.

The anthelmintic activity of chicory (Cichorium intybus L.) herbage has been attributed to sesquiterpene lactones. Chicory leaves contain significant amounts of lactucin (LAC), 8-deoxylactucin (DOL), and lactucopicrin (LPIC), but the proportions of these three sesquiterpene lactones vary among forage chicory cultivars. To determine whether the individual compounds differ in anthelmintic activity, we prepared sesquiterpene lactone-enriched extracts from leaves of two forage chicory cultivars, 'Grasslands Puna' (Puna) and 'Forage Feast', and tested their effects on the hatching of a predominantly Haemonchus contortus egg population. The dominant constituents in the Puna and Forage Feast extracts were DOL and LAC, respectively; LPIC concentrations in the two extracts were similar. Extracts from both cultivars inhibited egg hatching at all concentrations tested (P

Palatability and anthelmintic activity of chicory (Cichorium intybus L.) forage are influenced by the sesquiterpene lactones lactucin (LAC), 8-deoxylactucin (DOL) and lactucopicrin. Therefore, the objective of this study was to determine how sesquiterpene lactone concentration and composition vary during the growing season. Three forage chicory cultivars (Puna, Forage Feast and Lacerta) grown in West Virginia and Pennsylvania (USA) were managed during two consecutive years to maintain plants in the vegetative stage, and sesquiterpene lactones in leaves were quantified after each growth interval. Cultivars differed in the total concentration of sesquiterpene lactones and in the proportions of LAC and DOL. Total sesquiterpene lactone concentration generally decreased or remained constant during the season, but the specific response depended on the cultivar. Differences in seasonal patterns between years corresponded with unusual climatic conditions. The three cultivars had similar concentrations of DOL in the spring. Forage Feast provided a dramatically lower concentration of DOL during the summer. Uniformly high concentrations of DOL across the growing season in Puna and Lacerta make these cultivars attractive for use in bioactive pastures for control of Haemonchus contortus. Changes in both sesquiterpene lactone concentration and composition during the season result in large variations in forage bitterness.

Concentration of bitter sesquiterpene lactones (SL), lactucin, lactucopicrin, and 8-deoxylactucin, has been associated with low soil P fertility and reduced livestock preference for forage chicory (Cichorium intybus L.). We evaluated the effect of cultivar and available soil phosphorus (ASP) on meat goat (Capra hircus L.) preferences for 'Grasslands Puna (Puna)' 'Forage Feast,' and 'INIA le Lacerta (Lacerta)'chicory grown under varying P fertility. Soil Bray-P was used to designate ASP as low (LP, mean 8.6 mg kg -1 ), medium (MP, 21.7 mg kg -1 ), and high (HP, 40.1 mg kg -1 ) for the preference test. In September, clipped fresh forage was offered to confined Boer-cross goat kids using a replicated 3 by 3 Latin square design with an extra period. Preferences were measured using dry matter intake for cultivar effects and multidimensional scaling (MDS) for ASP effects. Across cultivars, soil Bray-P was positively related to leaf P and Mg concentrations. Soil Bray-P did not affect lactucopicrin or 8-deoxylactucin, and was positively associated with lactucin, in contrast to the hypothesis. Goats exhibited no preferences among cultivars despite up to fourfold differences in individual SL. Within cultivars, goats preferred Puna with less lactucin and total SL, Lacerta with less lactucopicrin and leaf Mg, and Forage Feast with more cell wall. Goats were able to detect relatively small differences in SL within cultivars, but this had little practical effect on intake of the forage because they ate it even when bitter. Therefore, P fertilization for fall-grown chicory is unlikely to improve forage intake in goats.

Two new sesquiterpene lactones, namely 8-O-methylsenecioylaustricin (1) and epi-8 alpha-angeloyloxy-cichoralexin (2), as well as a new triterpene glycoside (taraxasterol 3-O-beta-D-glucoside, 3), together with the three known sesquiterpene lactones lactucin (4), lactucopicrin (5), and 11 beta,13-dihydrolactucin (6), were isolated from the stems of Cichorium glandulosum BOISS. FT HUET. The chemical structures were elucidated on the basis of spectroscopic methods.

The principal bitter sesquiterpene lactones (BSLs; latucin, 8-deoxylactucin, and lactucopicrin) in six red and four green-pigmented leaf lettuce (Lactuca sativa L. var. crispa L.) cultivars were identified and quantified using high-performance liquid chromatography, proton nuclear magnetic resonance, and liquid chromatography–mass spectrometry and the contribution of each to the overall bitterness was determined. The concentration of each BSL and the total varied significantly among cultivars and there were significant differences resulting from leaf color (green versus red) and morphology (cut versus curled leaves) with red and curled leaf cultivars having higher BSL concentrations. The concentrations of lactucin, 8-deoxylactucin, and lactucopicrin ranged from 2.9 to 17.2, 2.8 to 17.1, and 8.8 to 36.1 μg·g−1 dry weight, respectively, with the total concentration ranging from 14.6 to 67.7 μg·g−1. Bitterness of the cultivars was assessed using a bitter activity value calculated using the concentration and bitterness threshold value for each BSL. Lactucopicrin was the primary contributor to bitterness as a result of its concentration and lower bitterness threshold; its relative proportion of the total bitterness activity value across all cultivars was over 72%. The concentration of individual BSLs differed with leaf location on the plant (i.e., basal, midstalk, and flower stalk). The concentrations in lactucin, 8-deoxylactucin, and lactucopicrin in flower stalk leaves were significantly higher (i.e., 2.9, 12.4, and 5.4 times, respectively) than in basal leaves, with the concentrations increasing acropetally. Genetic differences among cultivars and with leaf location on the plant contribute to the wide range in bitterness in lettuce.

Lactucin (1) and its derivatives lactucopicrin (2) and 11β,13-dihydrolactucin (3), which are characteristic bitter sesquiterpene lactones of Lactuca virosa and Cichorium intybus, were evaluated for analgesic and sedative properties in mice. The compounds showed analgesic effects at doses of 15 and 30 mg/kg in the hot plate test similar to that of ibuprofen, used as a standard drug, at a dose of 30 mg/kg. The analgesic activities of the compounds at a dose of 30 mg/kg in the tail-flick test were comparable to that of ibuprofen given at a dose of 60 mg/kg. Lactucopicrin appeared to be the most potent analgetic of the three tested compounds. Lactucin and lactucopicrin, but not 11β,13-dihydrolactucin, also showed sedative properties in the spontaneous locomotor activity test.

The forage potential of chicory (Cichorium intybus L.) has not been realized in southern West Virginia (WV) because ruminants are reluctant to consume the herbage. Chicory contains bitter sesquiterpene lactones that can adversely impact palatability. This study was undertaken to determine whether sesquiterpene lactone concentrations in chicory grown in southern WV differ from those in chicory grown in central Pennsylvania (PA) where chicory is grazed readily. Herbage was collected in 1997 and 1998 from cultivars Grasslands Puna (Puna), INIA le Lacerta (Lacerta), and Forage Feast established at research sites near State College, PA, and Beckley, WV. The total concentration of sesquiterpene lactones in WV-grown cultivars was 0.58% (dry matter basis) in Puna, 0.59% in Lacerta, and 0.79% in Forage Feast in 1997 and ranged from 1.03 (Lacerta) to 1.52% (Forage Feast) in 1998. In PA-grown cultivars, sesquiterpene lactones represented 0.16 (Puna), 0.18 (Lacerta), and 0.27% (Forage Feast) of the forage dry matter in 1997 and ranged from 0.32 (Lacerta) to 0.55% (Forage Feast) in 1998. Concentrations of lactucin, lactucopicrin, and total sesquiterpene lactones in Forage Feast exceeded those in the other cultivars grown at the same site. The lowest concentrations of lactucopicrin and total sesquiterpene lactones observed among WV-grown cultivars were higher (2-fold or more) than the highest concentrations present in cultivars grown the same year in PA. Mineral analyses of soils from the two cultivation sites indicate that P availability may influence sesquiterpene lactone composition of chicory herbage. Results provide a foundation for future studies of environmental effects on sesquiterpene lactone composition and palatability of chicory herbage.

Lactuca sativa (lettuce) belongs to Asteraceae family important leafy vegetable known for its medicinal properties. The lettuce is a food that should not lack in our meals, we should keep in mind that its low fat and carbohydrate contents and its high contents of water, it provides caloric power of only 13 Kcal /100gm are very appropriate for weight loss diets. It is rich in minerals, especially potassium that is very necessary to maintain appropriate levels of liquids in the body, together with calcium and phosphorus makes it especially for the correct well being of the bones. It contains selenium, an antioxidant that has a medicinal property in prevention of certain type of cancers, colon, prostrate and lungs. It contains many necessary amino acids for the formation of the proteins, alanine, and necessary for the construction of muscular and nervous tissues, glycine for the correct operation of immunological system. The most of therapeutic properties of this plant is due to sesquiterpene lactones- lactucin, lactucopicrin the most bioactive compound of Lactuca sativa. This review mainly focuses on the pharmacological action of the Lettuce and active constituents for the wide spectrum biological properties, such as anti-oxidant, anti-inflammatory, anti-microbial, analgesic, neuroprotective and sedative properties etc. Since Lettuce has medicinal therapeutic potential its usage in dietary supplementation can be exploited. Lettuce has also acquired a folk reputation. More clinical studies are needed to further asses the efficiency and safety in therapeutic application

One of the quality parameters of chicory (Cichorium intybus L.) is its slightly bitter taste which is caused by sesquiterpene lactones. As the quality of chicons is highly dependent on the quality of the roots, the effects of the cultivation conditions of the roots on the levels of sesquiterpene lactones in chicons were investigated. Roots from a collection of 11 commercially available and 2 experimental chicory cultivars were grown at five different locations with two nitrogen manuring levels to evaluate the differences in sesquiterpene lactone levels as measured with enzyme-linked immunosorbent assays (ELISAs). There were significant differences (P

Lettuce (Lactuca sativa), a leafy vegetal widely consumed worldwide, fresh cut or minimally processed, constitutes a major dietary source of natural antioxidants and bioactive compounds. In this study, reversed-phase ultra-high-performance liquid chromatography (RP-UHPLC) coupled to electrospray ionization-quadrupole-time-of-flight mass spectrometry (ESI-QTOF-MS) was applied for the comprehensive profiling of polar and semi-polar metabolites from three lettuce cultivars (baby, romaine, and iceberg). The UHPLC systems allowed the use of a small-particle-size C18 column (1.8 μm), with very fine resolution for the separation of up to seven isomers, and the QTOF mass analyzer enabled sensitive detection with high mass resolution and accuracy in full scan. Thus, a total of 171 compounds were tentatively identified by matching their accurate mass signals and suggested molecular formula with those previously reported in family Asteraceae. Afterwards, their structures were also corroborated by the MS/MS data provided by the QTOF analyzer. Well-known amino acids, organic acids, sesquiterpene lactones, phenolic acids and flavonoids were characterized, e.g. lactucin, lactucopicrin, caftaric acid, chlorogenic acid, caffeoylmalic acid, chicoric acid, isochlorogenic acid A, luteolin, and quercetin glycosides. For this plant species, this is the first available report of several isomeric forms of the latter polyphenols and other types of components such as nucleosides, peptides, and tryptophan-derived alkaloids. Remarkably, 10 novel structures formed by the conjugation of known amino acids and sesquiterpene lactones were also proposed. Thus, the methodology applied is a useful option to develop an exhaustive metabolic profiling of plants that helps to explain their potential biological activities and folk uses.

Monoclonal antibodies (MAbs) against lactucin and lactucopicrin (two of the bitter principles of chicory; Cichorium intybus L.) have been prepared. In competitive ELISA, the sera from mice immunized with keyhole limpet haemocyanin (KLH)‐lactucin and KLH‐ lactucopicrin have been screened for cross‐reactivity to various sesquiterpene lactones with a guaiane skeleton that are present in chicory, such as lactucin, 8‐deoxylactucin, and their 11β,13‐dihydro derivatives, and lactucopicrin. Mice showing low cross‐reactivity were used to produce hybridomas that were screened for cross‐reactivity in the same way. The screening resulted in a lactucopicrin‐specific hybridoma (no. 4H10) showing a low cross‐reactivity (≪1%)for lactucin, 8‐deoxylactucin and their 11β,13‐dihydro derivatives. From KLH‐lactucin immunized mice, hybridoma no. 9F12 showed the best characteristics, i.e. 25% cross‐reactivity to 8‐deoxylactucin and its 11β,13‐dihydro derivative, and a 10% cross‐reactivity to lactucopicrin. The affinity constants...

The bitter taste of chicory is caused by sesquiterpene lactones. The levels of lactucopicrin and lactucin-like sesquiterpene lactones, i.e. lactucin, 8-deoxylactucin and their 11β,13-dihydro derivatives, in chicons from four different chicory cultivars (Cichorium intybus L.) were determined by ELISA. Data were used to determine the sample size needed for the statistically reliable determination of the levels of sesquiterpene lactones in chicory. The sample size varied from 6 to 12 chicons. No relation between the weight of chicons and the sesquiterpene lactone levels was found. The distribution of sesquiterpene lactones in chicons from two cultivars, i.e. cv. Focus and cv. Monitor, was studied with ELISA. In both cultivars the central axis contained the major part of the sesquiterpene lactones as compared to the proximal and distal parts of the leaves. Storage at 2 °C and 10 °C for up to 13 days had no effect on the level of lactucin-like sesquiterpene lactones in the chicons. After 7 days of storage a slight increase of lactucopicrin content was observed as compared with chicons analysed after 1 and 13 days of storage.

Polyclonal antisera against lactucin and lactucopicrin, two bitter-tasting principles of chicory (Cichorium intybus L.), were obtained after immunization of rabbits with KLH−lactucin and KLH−lactucopicrin conjugates, respectively. In competitive ELISA, the sera from KLH−lactucopicrin-immunized rabbits showed a very low cross-reactivity with other sesquiterpene lactones containing a guaiane skeleton, 0.5% with lactucin, 1% with a mixture of lactucin and 11β,13-dihydrolactucin, and 5% with 8-deoxylactucin and 11β,13-dihydro-8-deoxylactucin. The sera from rabbits immunized with KLH−lactucin showed 50% cross-reaction with 8-deoxylactucin and its 11β,13-dihydro derivative and only 0.4% cross-reaction with lactucopicrin. In competitive ELISAs, chicory extracts spiked with free sesquiterpene lactones showed an expected increase in inhibition level. These ELISAs seem useful in the assessment of chicory bitterness. Keywords: Sesquiterpene lactones; chicory (Cichorium intybus); lactucin; lactucopicrin; bitter taste...

‘Puna II’ forage chicory (Cichorium intybus L.) was bred from ‘Grasslands Puna’ chicory by selection for tolerance to the fungus Sclerotinia, cool‐season activity, greater uniformity, and higher levels of the sesquiterpene lactones, lactucin and lactucopicrin. It is intended for use as a pure sward on non‐milking farms, and as a component of mixed swards on all grazing farms. Breeding took place from 1992 to 1997, and involved two interdependent screening paths, for (1) tolerance to Sclerotinia and (2) vigour and uniformity, then high levels of lactucin and lactucopicrin. In most years, the seed harvested from each path was incorporated also into the alternate path for the following year. The two paths were combined in 1997 to provide a final single breeding population. ‘Puna II’ is more uniform than ‘Grasslands Puna’ in morphology and leaf shape. It is also more erect and much more winter‐active, and at least as persistent. It is much more persistent than a cultivar bred simultaneously for dairy...

Objective The four major active compositions, namely esculetin, lactucin, lactucopicrin and chlorogenic acid in seed, stem and root of the Cichorium glandulosum Boiss. et Huet that planted in Xinjiang have been quantified by HPLC. Method HPLC method was used, with Inertsil ODS-SP column (4.6 mm x 250 mm, 5 pm). The flow rate was 1.0 mL x min(-1). The column temperature was set at 32 degrees C. The mobile phase was methanol--0.2% formic acid, 0-40 min, methanol 30%--70% gradients. Injection volume was 5 microL. The detecting wavelength were 256, 350, 299 and 229 nm, respectively. Result The percentage recoveries were 98.2%, 99.57%, 100.50%, and 99.46% for chlorogenic acid, esculetin, lactucin, and lactucopicrin, respectively. The correlation coefficients (r) were 1.000, 0.9989, 0.9998, 1.000 and RSD were 1.6%, 1.5%, 0.77%, 2.0% for chlorogenic acid, esculetin, lactucin, and lactucopicrin, respectively. The contents of the chlorogenic acid, esculetin, lactucin and lactucopicrin were 0.0048, 0.0043, 0.6789, 0.7520 mg x g(-1), respectively in the root, and 0.0710, 0.1890, 0.2396 and 0.0520 mg x g(-1) in the seeds of C. glandulosum, respectively. Conclusion This method was sensitive, rapid and simple, with good linearity, recovery and reproducibility.

Five known and one new sesquiterpene lactones were isolated from fresh chicory roots (Cichorium intybus). The new compound 11(S),13-dihydrolactucopicrin was identified by UV, 1 H NMR, 13 C NMR, and mass spectroscopy. The extraction procedure and HPLC analysis of sesquiterpene lactones in chicory were improved. The bitterness detection thresholds of all compounds were individually determined by triangle testing

Samples of red-coloured lettuce and chicory were assessed for bitterness by sensory analysis and compared with conventional green-coloured varieties. The amounts of the sesquiterpene lactones lactucin, 8-deoxylactucin and lactucopicrin and their glycosides were determined using enzyme hydrolysis and high performance liquid chromatography. The level of each of these compounds was compared with the bitterness score found for each sample, and the resulting correlation data suggested that the increasing level of one of these compounds, lactucin glycoside, was closely related to the increase in bitterness.

Because of the skeletal complexity and similarity of the polarity, little research was reported on the isolation of sesquiterpene lactones by high-speed counter-current chromatography (HSCCC). Herein, three sesquiterpene lactones were successfully purified from the ethyl acetate extract of the roots of the traditional Uyghur medicinal plant Cichorium glandulosum Boiss. et Huet. by HSCCC. The separation was performed in two steps with two solvent systems: n-hexane-ethyl acetate-methanol-water (1.5:5:2.75:5, v/v/v/v) and ethyl acetate-methanol-water (20:1:20, v/v/v). From 166 mg of the ethyl acetate extract, 19 mg of lactucopicrin was isolated with the first solvent system and 10 mg of 11beta,13-dihydrolactucin and 16 mg of lactucin were obtained with the second solvent system. All purified compounds were over 94% purity as determined by HPLC analysis, and these chemical structures were confirmed by (1)H NMR and (13)C NMR.

Lactuca saligna and Lactuca virosa are two wild lettuce species that show multiple virus resistance, and both have been successfully used in breeding programs for the introduction of virus resistance into commercial lettuce, Lactuca sativa. These two wild Lactuca species contained three major sesquiterpene lactones, i.e. lactucin, 8-deoxylactucin, and lactucopicrin, as measured by gradient RP-HPLC. L. saligna contained 103, 372, and 79 μg/g, respectively, and L. virosa contained 257, 173, and 1733 μg/g, respectively, of these three lactones that are present in both free and glycoside bound forms. The commercial lettuce varieties Montello (L. sativa) and Saladcrisp, derived from L. sativa×L. saligna, had very low levels of lactucin and lactucopicrin and were devoid of 8-deoxylactucin. Five breeding lines of lettuce, bred from the same interspecies cross as var. Saladcrisp, were also devoid of 8-deoxylactucin and contained between 0 and 60% as much lactucin or lactucopicrin as their parent strains. One lettuce breeding line, 93-426, contained only 18 μg/g of lactucin and was devoid of both lactucopicrin and 8-deoxylactucin, but this line is resistant to three viruses. This suggests that the level and types of these sesquiterpenene lactones present in lettuce have little effect on virus resistance. Nevertheless, lettuce breeders using wild Lactuca as resistant parents should be cognizant of their high levels of sesquiterpene lactones

Wounding leaves or stems of Lactuca species releases a milky latex onto the plant surface. We have examined the constituents of latex from Lactuca sativa (lettuce) cv. Diana. The major components were shown to be novel 15-oxalyl and 8-sulfate conjugates of the guaianolide sesquiterpene lactones, lactucin, deoxylactucin, and lactucopicrin. The oxalates were unstable, reverting to the parent sesquiterpene lactone on hydrolysis. Oxalyl derivatives have been reported rarely from natural sources. The sulfates were stable and are the first reported sesquiterpene sulfates from plants. Unusual tannins based on 4-hydroxyphenylacetyl conjugates of glucose were also identified. Significant qualitative and quantitative variation was found in sesquiterpene lactone profiles in different lettuce varieties and in other Lactuca spp. The proportions of each conjugate in latex also changed depending on the stage of plant development. A similar profile was found in chicory, in which oxalyl conjugates were identified, but the 8-sulfate conjugates were notably absent. The presence of the constitutive sesquiterpene lactones was not correlated with resistance to pathogens but may have a significant bearing on the molecular basis of the bitter taste of lettuce and related species. The induced sesquiterpene lactone phytoalexin, lettucenin A, was found in the Lactuca spp. but not in chicory.

The phytochemical investigation of the aerial parts of LACTUCA SALIGNA L. revealed the presence of lactucin, lactucopicrin, and a new guaianolide named 11beta,13-dihydrolactucopicrin. The structural configuration was established through spectral data.

The solubility of lactucin, 8-deoxylactucin and lactucopicrin, all sesquiterpene lactones of chicory roots, was determined as a function of pH (pH 1–10) in the presence and absence of polysaccharides. The stability of the sesquiterpene lactones, when dissolved in water, decreased under influence of daylight as a function of pH. Enzymatic hydrolysis of lactucopicrin by commercial enzyme preparations, used for liquefaction of chicory roots into lactucin and p-hydroxyphenylacetic acid, was not found.

Amounts of the sesquiterpene lactones and the major phenolics were determined in the chicory plant at different times during the growing season. The levels of the sesquiterpene lactones (lactucin, lactupicrin and 8-deoxylactucin) and the hydroxycoumarin cichoriin were found to be highest in the most actively growing regions of the plant. In two-choice and no-choice feeding experiments with borosilicate discs, 8-deoxylactucin, lactupicrin and cichoriin significantly reduced feeding of Schistocerca gregaria at levels comparable to those present in the plant. Cichoriin was still significantly antifeedant at 0.006% dry wt, while aesculin, aesculetin and the caffeic acid ester, chicoric acid were inactive. We conclude that the three sesquiterpene lactones secreted in the latex provide a significant barrier to herbivory in chicory, although the phenolics and notably cichoriin also protect the plant from insect feeding.

The release of lactucin, 8-deoxylactucin and lactucopicrin, all sesquiterpene lactones, which are bitter constituents of chicory, has been studied during enzymatic liquefaction of chicory roots with commercial pectolytic and cellulolytic enzymes at 40 °C for 24 h. After 5–8 h most of these bitter compounds are found in the liquid phase (supernatant) and not in the sediment (residue), except for lactucopicrin, which ist hardly soluble in aqueous solution.

8-Deoxylactucin, lactucin and lactupicrin were isolated from Cichorium intybus . 8-Deoxylactucin and jacquilenin were isolated from Leontodon autumnalis and were found in particular abundance in flowers of the latter species. Flowers of L. autumnalis do not produce pentacyclic triterpenoid diols. Thus this species is the first noted exception to the Zimmermann rule, which correlates the co-occurrence of triterpenoid diols and carotenoids in flowers of Compositae plants.