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. ...

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-Momordica charantia L. is a valuable food and medicinal plant of the gourd family (Cucurbitaceae) that is cultivated in tropical and subtropical regions of the world. Physicochemical properties of M. charantia based on cultivars, parts and growing stage were investigated. Crude protein contents of leaf were 27.5%, 26.9%, and 23.6% in native leaf (NL), cv. Erabu leaf (EL), and cv. Dragon leaf (DL), respectively. In particular, the crude protein content was the highest in leaves. The crude fat content was in the order of developmental stage 1 of cv. Erabu fruit (EF1) and developmental stage 1 of native fruit (NF1) with values of 4.0%, and 3.9%, respectively. There was also high amount of crude fiber in stem of all three cultivars. The crude ash content was in the order of cv. Erabu leaf, cv. Dragon leaf, and developmental stage 3 of native fruit (NF3) with values of 23.2%, 17.4%, and 13.6%, respectively. The major minerals found in M. charantia were K, Ca, and Mg. The potassium contents of developmental stage 3 of native fruit (NF3), developmental stage 3 of cv. Dragon fruit (DF3), cv. Dragon stem (DS), and developmental stage 2 of native fruit (NF2) were 498.37, 339.21, 314.30, and 307.34 ㎎ /100g, respectively, while the calcium contents were decreased of EL, DL, and NL with values of 513.45, 371.69, and 209.43 ㎎/100g, respectively. The calcium content was higher in leaves and stems than fruits. On the otherhand, the highest magnesium content was measured in EL (69.92 ㎎/100g). The highest contents of chlorophyll a, chlorophyll b, and total chlorophyll were found in NL (442.9 ㎎/100g dw), EL (759.6 ㎎/100g dw), and EL (1164.9 ㎎/100g dw), respectively. The vitamin C contents from developmental stage 2 of cv. Erabu fruit (EF2), NF3, developmental stage 3 of cv. Erabu on fruit (EF3), and NF2 were found with values of 2849.9, 2330.5, 1985.1, and 1844.5 ㎎/㎏, respectively, and found to be higher in Korean cultivar and Erabu fruit than in Dragon. The charantin contents of leaf were higher than the fruit found to be 547.71, 506.04 and 395.62 ㎍/g dw in DL, EL and EF2, respectively. According to the results, mineral contents, total chlorophyll and charantin contents of M. charantia were higher in the leaves (EL and DL) than the fruits. And, vitamin C content was the highest in the fruit (EF2 and EF3). Therefore, much more research needs to be undertaken to use of the leaves as well as fruits. The data showed that M. charantia can be considered a good source of nutrient for application in food system.

Different physiological and genetic studies show that the variations in the accumulation of pigment-stimulating metabolites result in color differences in soybean seed coats. The objective of this study was to analyze the nutrient contents and antioxidant potential in black, brown, and green seed-coated soybeans. Significant variations in protein (38.9–43.3%), oil (13.9–20.4%), total sugar (63.5–97.0 mg/g seed), total anthocyanin (3826.0–21,856.0 μg/g seed coat), total isoflavone (709.5–3394.3 μg/g seed), lutein (1.9–14.8 μg/g), total polyphenol (123.0–385.8 mg gallic acid/100 g seed), total flavonoid (22.1–208.5 mg catechin/100 g seed), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS; 275.0–818.8 mg Trolox/100 g seed), and 2,2-diphenyl-1-picrylhydrazyl (DPPH; 96.3–579.7 mg Trolox/100 g seed) were found among the soybean genotypes. Ilpumgeomjeong2 contained the lowest protein but the highest oil and total sugar. The lowest oil-containing Wonheug had the highest protein content. Socheong2 was rich in all four variables of antioxidants. Anthocyanins were detected only in black soybeans but not in brown and green soybeans. The variation in isoflavone content was up to 5-fold among the soybean genotypes. This study could be a valuable resource for the selection and improvement of soybean because an understanding of the nutrient content and antioxidant potentials is useful to develop effective strategies for improving the economic traits; for example, the major emphasis of soybean breeding for fatty acids is to enhance the oleic and linoleic acid contents and to decrease linolenic acid content.