A targeted metabolomics approach to understand differences in flavonoid biosynthesis in red and yellow raspberries

High-throughput color determination of red raspberry puree and correlation of color parameters with total anthocyanins

BACKGROUND

Red raspberry fruit color is a key driver of consumer preference and a major target of breeding programs worldwide. Screening for fruit color typically involves the determination of anthocyanin content and/or the assessment of color through a colorimeter. However, both procedures are time-consuming when the analyses involve hundreds or thousands of samples. The objectives of this study were to develop a high-throughput method for red raspberry puree color measurement and to test the correlations between color parameters and total anthocyanin content. Color coordinates were collected with a colorimeter on 126 puree samples contained in Petri dishes and with the Tomato Analyzer Color Test (TACT) module to assess the same samples prepared in Petri dishes and in 96-well plates. An additional 425 samples were analyzed using only 96-well plates. Total anthocyanins were extracted from all 551 samples.

RESULTS

Regression models for L*, a*, b* measured with the colorimeter and TACT using Petri dishes were all significant (p < 0.001), but very consistent only for L* (R2 = 0.94). Significant (p < 0.001) and very consistent regressions (R2 = 0.94 for L* and b*, R2 = 0.93 for a*) were obtained for color parameters measured with TACT using Petri dishes and TACT using plates. Of the color parameters measured with the colorimeter, only L*, a*/b*, and hue significantly correlated with total anthocyanins (p < 0.05), but, except for L* (R = - 0.79), the correlations were weak (R = - 0.23 for a*/b* and R = 0.22 for hue). Conversely, all correlations with total anthocyanins and color parameters measured with TACT were significant (p < 0.001) and moderately strong (e.g., R = - 0.69 for L* and R = 0.55 for a*/b*). These values were indicative of darker colors as total anthocyanin content increased.

CONCLUSIONS

While the colorimeter and TACT-based methods were not fully interchangeable, TACT better captured color differences among raspberry genotypes than the colorimeter. The correlations between color parameters measured with TACT and total anthocyanins were not strong enough to develop prediction models, yet the use of TACT with 96-well plates instead of Petri dishes would enable the high-throughput measurement of red raspberry puree color.

Chromosome-scale genome, together with transcriptome and metabolome, provides insights into the evolution and anthocyanin biosynthesis of Rubus rosaefolius Sm. (Rosaceae)

Rubus rosaefolius is a kind of red raspberry possessing high nutritional and pharmaceutical value. Here we present a chromosome-level draft genome of R. rosaefolius. Of the total 131 assembled scaffolds, 70 with a total size of 219.02 Mb, accounting for 99.33% of the estimated genome size, were anchored to seven pseudochromosomes. We traced a whole-genome duplication (WGD) event shared among members of the Rosaceae family, from which were derived 5090 currently detectable duplicated gene pairs (dgps). Of the WGD-dgps 75.09% underwent purifying selection, and approximately three-quarters of informative WGD-dgps expressed their two paralogs with significant differences. We detected a wide variety of anthocyanins in the berries of R. rosaefolius, and their total concentration remained relatively stable during berry development but increased rapidly during the ripening stage, mainly because of the contributions of pelargonidin-3-O-glucoside and pelargonidin-3-O-(6″-O-malonyl)glucoside. We identified many structural genes that encode enzymes, such as RrDFR, RrF3H, RrANS, and RrBZ1, and play key roles in anthocyanin biosynthesis. The expression of some of these genes significantly increased or decreased with the accumulation of pelargonidin-3-O-glucoside and pelargonidin-3-O-(6″-O-malonyl)glucoside. We also identified some transcription factors and specific methylase-encoding genes that may play a role in regulating anthocyanin biosynthesis by targeting structural genes. In conclusion, our findings provide deeper insights into the genomic evolution and molecular mechanisms underlying anthocyanin biosynthesis in berries of R. rosaefolius. This knowledge may significantly contribute to the targeted domestication and breeding of Rubus species.

Quantitative trait loci mapping of polyphenol metabolites from a 'Latham' x 'Glen Moy' red raspberry (Rubus idaeus L) cross

OBJECTIVE

The objective of this study was to investigate the genetic control of polyphenol accumulation in red raspberry (Rubus idaeus L).

METHODS

The levels of total anthocyanins and 37 individual polyphenol metabolites were measured over three years in a raspberry biparental mapping population. Quantitative trait loci (QTLs) for these traits were mapped onto a high-density SNP linkage map.

RESULTS

At least one QTL was detected for each trait, with good consistency among the years. On four linkage groups (LG), there were major QTLs affecting several metabolites. On LG1, a QTL had large effects on anthocyanins and flavonols containing a rutinoside or rhamnose group. On LG4, a QTL had large effects on several flavonols and on LG5 and LG6 QTLs had large effects on ellagic acid derivatives. Smaller QTLs were found on LG2 and LG3.

CONCLUSION

The identification of robust QTLs for key polyphenols in raspberry provides great potential for marker-assisted breeding for improved levels of potentially health beneficial components.

Biochemical Characterization of Black and Green Mutant Elderberry during Fruit Ripening

The content of sugars, organic acids, phenolic compounds and selected enzyme activities in the anthocyanin pathway were analyzed in NIGRA (Sambucus nigra var. nigra-black fruits) and VIRIDIS (S. nigra var. viridis-green fruits) fruits over four stages of ripening. The share of glucose and fructose in green fruits was higher than in colored fruits, and the sugar content increased significantly until the third developmental stage. Ripe NIGRA berries had 47% flavonol glycosides, 34% anthocyanins, 3% hydroxycinnamic acids and 14% flavanols, whereas the major phenolic group in the VIRIDIS fruits, making up 88% of the total analyzed polyphenols, was flavonols. NIGRA fruits were rich in anthocyanins (6020 µg g-1 FW), showing strong activation of the late anthocyanin pathway (dihydroflavonol 4-reductase, anthocyanidin synthase). In both color types, phenylalanine ammonia lyase and chalcone synthase/chalcone isomerase activities were highest in the first stage and decreased during ripening. In VIRIDIS fruit, no anthocyanins and only one flavanol (procyanidin dimer) were found. This was most likely caused by a lack of induction of the late anthocyanin pathway in the last period of fruit ripening. The VIRIDIS genotype may be useful in studying the regulatory structures of anthocyanin biosynthesis and the contribution of distinct flavonoid classes to the health benefits of elderberries.

Phenolic profiles and their responses to pre- and post-harvest factors in small fruits: a review

The consumption of small fruits has increased in recent years. Besides their appealing flavor, the commercial success of small fruits has been partially attributed to their high contents of phenolic compounds with multiple health benefits. The phenolic profiles and contents in small fruits vary based on the genetic background, climate, growing conditions, and post-harvest handling techniques. In this review, we critically compare the profiles and contents of phenolics such as anthocyanins, flavonols, flavan-3-ols, and phenolic acids that have been reported in bilberries, blackberries, blueberries, cranberries, black and red currants, raspberries, and strawberries during fruit development and post-harvest storage. This review offers researchers and breeders a general guideline for the improvement of phenolic composition in small fruits while considering the critical factors that affect berry phenolics from cultivation to harvest and to final consumption.

Liquid Chromatographic Quadrupole Time-of-Flight Mass Spectrometric Untargeted Profiling of (Poly)phenolic Compounds in Rubus idaeus L. and Rubus occidentalis L. Fruits and Their Comparative Evaluation

This study provided a detailed profiling of the antioxidant and bioactive compounds occurring in three varieties of Rubus idaeus L. fruits (“Fall Gold”, “Glen Ample” and “Tulameen”) compared to Rubus occidentalis L. black raspberry (“Jewel” cultivar), adopting a comprehensive untargeted metabolomics approach developed with UHPLC analysis coupled with quadrupole/time-of-flight high resolution mass spectrometry, using the SWATH^® acquisition protocol. The feature selection and annotation workflow, applied to the analysis of raspberry extracts in both polarities, allowed identifying 68 bioactive compounds mainly belonging to the classes of (poly)phenolic compounds. Interestingly, some of these identifications (e.g., ferulic acid glycosides and the ellagitannin-like nobotanin/malabathrin) represent the first report in raspberry fruits. Principal component analysis made possible highlighting the features more related to the expression of a genotype effect within the R. idaeus species or between the two raspberry species herein investigated. Overall, flavanols were the most discriminating features for the Fall Gold variety, whereas ellagitannins and flavonol glycosides represent more distinctive metabolic traits in Glen Ample and Tulameen fruits. Moreover, R. occidentalis Jewel variety was strongly characterized by the occurrence of anthocyanins, such as cyanidin, pelargonidin and delphinidin glycosides.

Disaccharide Type Affected Phenolic and Volatile Compounds of Citrus Fiber-Blackberry Cream Fillings

The food industry is continuously developing ingredients, processing methods and packaging materials to improve the quality of fruit products. The aim of this work was to study the possibility of using citrus fiber in the preparation of blackberry cream fillings in combination with disaccharides (sucrose, maltose and trehalose). Evaluations of the phenolics, proanthocyanidins, antioxidant activity, color and volatiles of blackberry cream fillings were conducted after preparation and after three months of storage. Blackberry cream fillings were prepared from citrus fiber (5%), blackberry juice and disaccharides (50%). Disaccharide type had an effect on all investigated parameters. The highest phenol content was in fillings with trehalose (4.977 g/100 g) and the lowest was in fillings prepared with sucrose (4.249 g/100 g). The same tendency was observed after storage. Fillings with maltose had the highest proanthocyanidins content (473.05 mg/100 g) while fillings with sucrose had the lowest amount (299.03 mg/100 g) of these compounds. Regarding volatile compounds, terpenes and aldehydes and ketones were evaluated in the highest concentration. Terpenes were determined in the highest concentration in fillings with trehalose (358.05 µg/kg), while aldehydes and ketones were highest in fillings with sucrose (250.87 µg/kg). After storage, concentration of volatiles decreased. These results indicate that the selection of adequate disaccharides is very important since it can influence the final quality of the product.

Formulation and Stability of Cellulose-Based Delivery Systems of Raspberry Phenolics

Encapsulation of bioactives is a tool to prepare their suitable delivery systems and ensure their stability. For this purpose, cellulose was selected as carrier of raspberry juice phenolics and freeze-dried cellulose/raspberry encapsulates (C/R_Es) were formulated. Influence of cellulose amount (2.5%, 5%, 7.5% and 10%) and time (15 or 60 min) on the complexation of cellulose and raspberry juice was investigated. Obtained C/R_Es were evaluated for total phenolics, anthocyanins, antioxidant activity, inhibition of α-amylase and color. Additionally, encapsulation was confirmed by FTIR. Stability of C/R_Es was examined after 12 months of storage at room temperature. Increasing the amount of cellulose during formulation of C/R_E from 2.5% to 10%, resulted in the decrease of content of total phenolics and anthocyanins. Additionally, encapsulates formulated by 15 min of complexation had a higher amount of investigated compounds. This tendency was retained after storage. The highest antioxidant activities were determined for C/R_E with 2.5% of cellulose and the lowest for those with 10% of cellulose, regardless of the methods used for its evaluation. After storage of 12 months, antioxidant activity slightly increased. Encapsulates with 2.5% of cellulose had the highest and those with 10% of cellulose the lowest capability for inhibition of α-amylase. The amount of cellulose also had an impact on color of C/R_Es. Results of this study suggest that cellulose could be a good encapsulation polymer for delivering raspberry bioactives, especially when cellulose was used in lower percentages for formulation of encapsulates.

Screening of Phenolic Compounds in Australian Grown Berries by LC-ESI-QTOF-MS/MS and Determination of Their Antioxidant Potential

Berries are grown worldwide with the most consumed berries being blackberries (Rubus spp.), blueberries (Vaccinium corymbosum), red raspberries (Rubus idaeus) and strawberries (Fragaria spp.). Berries are either consumed fresh, frozen, or processed into wines, juices, and jams. In recent times, researchers have focused their attention on berries due to their abundance in phenolic compounds. The current study aimed to evaluate the phenolic content and their antioxidant potential followed by characterization and quantification using LC-ESI-QTOF-MS/MS and HPLC-PDA. Blueberries were highest in TPC (2.93 ± 0.07 mg GAE/gf.w.) and TFC (70.31 ± 1.21 µg QE/gf.w.), whereas the blackberries had the highest content in TTC (11.32 ± 0.13 mg CE/gf.w.). Blueberries had the highest radical scavenging capacities for the DPPH (1.69 ± 0.09 mg AAE/gf.w.), FRAP (367.43 ± 3.09 µg AAE/gf.w.), TAC (1.47 ± 0.20 mg AAE/gf.w.) and ABTS was highest in strawberries (3.67 ± 0.14 mg AAE/gf.w.). LC-ESI-QTOF-MS/MS study identified a total of 65 compounds including 42 compounds in strawberries, 30 compounds in raspberries, 28 compounds in blueberries and 21 compounds in blackberries. The HPLC-PDA quantification observed phenolic acid (p-hydroxybenzoic) and flavonoid (quercetin-3-rhamnoside) higher in blueberries compared to other berries. Our study showed the presence of phenolic acids and provides information to be utilized as an ingredient in food, pharmaceutical and nutraceutical industries.

NPid: an Automatic Approach to Rapid Identification of Known Natural Products in the Crude Extract of Crabapple Based on 2D 1H-13C Heteronuclear Correlation Spectra of the Extract Mixture

An automatic approach to identification of natural products (NPid) in complex extracts by exploring pure shift HSQC (psHSQC) and H2BC spectra of the mixture is developed, which integrated information on chemical shifts (CS), adjacent relationships (AR) and peak intensities (PI) of ¹H-¹³C groups for identification of candidate natural product in a customized NMR database. A weighted comprehensive score is calculated for each candidate from the values of CS, AR and PI to rate the likelihood of its existence in the complex mixture. Using the crude extract of crabapple (Malus fusca) as an example, a customized NMR database of natural products from plants of the genus Malus was constructed. The performance of NPid was first evaluated using simulated data in four scenarios, that is, for identification of structurally similar natural products, identification of natural products with part of peaks missing in psHSQC due to low concentration, without available adjacent relationship information, or without useful peak intensity information. The false positive and false negative rates of the natural products identified by NPid were estimated by Monte Carlo simulation. It shows that AR and PI can effectively reduce the false positive rate of identification. Proof of concept of the proposed method was elucidated on a model mixture consisting of 10 known natural products. Application of this method was then demonstrated on an authentic sample of crude extract of crabapple and 19 known natural products were successfully identified and confirmed by standard spiking.

Abnormal expression of bHLH3 disrupts a flavonoid homeostasis network, causing differences in pigment composition among mulberry fruits

Mulberry fruits with high concentrations of anthocyanins are favored by consumers because of their good taste, bright color, and high nutritional value. However, neither the regulatory mechanism controlling flavonoid biosynthesis in mulberry nor the molecular basis of different mulberry fruit colors is fully understood. Here, we report that a flavonoid homeostasis network comprising activation and feedback regulation mechanisms determines mulberry fruit color. In vitro and in vivo assays showed that MYBA-bHLH3-TTG1 regulates the biosynthesis of anthocyanins, while TT2L1 and TT2L2 work with bHLH3 or GL3 and form a MYB-bHLH-WD40 (MBW) complex with TTG1 to regulate proanthocyanidin (PA) synthesis. Functional and expression analyses showed that bHLH3 is a key regulator of the regulatory network controlling mulberry fruit coloration and that MYB4 is activated by MBW complexes and participates in negative feedback control of the regulatory network to balance the accumulation of anthocyanins and proanthocyanidins. Our research demonstrates that the interaction between bHLH3 and MYB4 in the homeostasis regulatory network ensures that the fruits accumulate desirable flavonoids and that this network is stable in pigment-rich mulberry fruits. However, the abnormal expression of bHLH3 disrupts the balance of the network and redirects flavonoid metabolic flux in pale-colored fruits, resulting in differences in the levels and proportions of anthocyanins, flavones, and flavonols among differently colored mulberry fruits (red, yellow, and white). The results of our study reveal the molecular basis of the diversity of mulberry fruit colors.

Fresh red raspberry phytochemicals suppress the growth of hepatocellular carcinoma cells by PTEN/AKT pathway

The red raspberry (Rubus idaeus L.) is a common fruit worldwide and its extract has been found to inhibit the growth of many types of tumors, mainly because it is rich in bioactive phytochemicals. However, the mechanism underlying its anticancer activity in hepatocellular carcinoma (HCC) is not well understood. Herein, the aim of this study was to determine the effects of red raspberry phytochemicals on the proliferation of hepatocellular carcinoma cells and to elucidate its biochemical and molecular targets. CCK8 and colony formation, as well as flow cytometry assays, were employed to determine the effects of red raspberry extract (RRE) on cell proliferation and cell cycle distribution in HCC cells. Our results showed that RRE significantly inhibited cell proliferation and arrested cell cycle progression at the S phase in HCC cells. RRE increased the expression of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) by reducing the methylation status of the PTEN gene promoter and inhibiting DNMT1 expression and regulated AKT signaling pathway. These findings show that red raspberry phytochemicals inhibit the proliferation of HCC cells by regulating PTEN/AKT signaling pathway, providing evidence that RRE may be used as a potential auxiliary therapy for patients with HCC.

Dietary Red Raspberry Reduces Colorectal Inflammation and Carcinogenic Risk in Mice with Dextran Sulfate Sodium-Induced Colitis

BACKGROUND

Ulcerative colitis causes recurring intestinal mucosal injury and sustained inflammation, increasing the likelihood of colorectal cancer (CRC) development. Dietary red raspberry (RB) is a rich source of phytonutrients known to have anti-inflammatory activity; however, the role of RB on CRC prevention in chronic colitis has not been examined.

OBJECTIVE

This study examined the effects of dietary RB supplementation on inflammation, epithelium repair, and oncogenic signaling in dextran sulfate sodium (DSS)-induced chronic colitis in mice.

METHODS

Six-week-old male C57BL/6J mice were fed a control or RB (5% of dry feed weight; n = 12/group) diet for 10 wk. Starting from the fourth week, mice were administered 2 repeated cycles of 1% DSS (7-d DSS treatment plus 14-d recovery) and were monitored daily for disease activity index (DAI) score. Colonic tissues were collected at the end of the study for histochemical, immunohistochemical, and biochemical analysis of inflammation, differentiation and proliferation markers.

RESULTS

RB supplementation reduced the DAI score and histologic damage (by 38.9%; P ≤ 0.01), expression of inflammatory mediators (by 20-70%; P ≤ 0.01), infiltration of CD4 T cells (by 50%; P ≤ 0.05), and α4β7 integrin and related adhesion molecules (by 33.3%; P ≤ 0.01). Furthermore, RB supplementation facilitated epithelium repair, as evidenced by enhanced goblet cell density, expression of transcription factors including Kruppel-like factor 4 (Klf4) and Hairy and enhancer of split 1 (Hes1), terminal differentiation markers, mucin 2 (Muc2), and intestinal alkaline phosphatase (by 20-200%; P ≤ 0.01). Conversely, proliferating cell nuclear antigen (by 70%; P ≤ 0.01), β-catenin, and signal transducer and activator of transcription 3 (STAT3) signaling (by 19-33%; P ≤ 0.05) were reduced by RB supplementation. In addition, RB supplementation enhanced p53 stability (by 53%) and reduced oncogenic gene expression (by 50-60%).

CONCLUSION

RB supplementation reduced DAI score and the risk of CRC development during recurring colitis in mice, suggesting that RB is a possible dietary supplement for patients with ulcerative colitis and related gut inflammatory diseases.

Raspberry promotes brown and beige adipocyte development in mice fed high-fat diet through activation of AMP-activated protein kinase (AMPK) α1

Development of brown and beige/brite adipocytes increases thermogenesis and helps to reduce obesity and metabolic syndrome. Our previous study suggests that dietary raspberry can ameliorate metabolic syndromes in diet-induced obese mice. Here, we further evaluated the effects of raspberry on energy expenditure and adaptive thermogenesis and determined whether these effects were mediated by AMP-activated protein kinase (AMPK). Mice deficient in the catalytic subunit of AMPKα1 and wild-type (WT) mice were fed a high-fat diet (HFD) or HFD supplemented with 5% raspberry (RAS) for 10 weeks. The thermogenic program and related regulatory factors in adipose tissue were assessed. RAS improved the insulin sensitivity and reduced fat mass in WT mice but not in AMPKα1^-/- mice. In the absence of AMPKα1, RAS failed to increase oxygen consumption and heat production. Consistent with this, the thermogenic gene expression in brown adipose tissue and brown-like adipocyte formation in subcutaneous adipose tissue were not induced by RAS in AMPKα1^-/- mice. In conclusion, AMPKα1 is indispensable for the effects of RAS on brown and beige/brite adipocyte development, and prevention of obesity and metabolic dysfunction.

Dietary red raspberries attenuate dextran sulfate sodium-induced acute colitis

Persistent intestinal inflammation severely impairs intestinal integrity resulting in inflammatory bowel disease. Red raspberries (RB) are a rich source of bioactive compounds; their beneficial effect on the colitis protection was evaluated in the current study using a dextran sulfate sodium (DSS)-induced acute colitis mouse model. Six-week-old mice were fed a standard rodent research diet supplemented with RB (0 or 5% w/w, n=20 each group) for 6 weeks. At the 4th week of dietary treatment, approximately half of mice in each dietary group (n=12 each group) were subjected to 2.5% DSS induction for 6 days, followed by 6 days of recovery, to induce colitis. RB supplementation decreased body weight loss (P≤.01), disease activity index (P≤.01), and colon shortening (P≤.05) in DSS-treated mice. In addition, RB supplementation protected the colonic structure (P≤.01), associated with suppressed NF-κB signaling and reduced expression of inflammatory interleukin (IL)-1β, IL-6, IL-17, cyclooxegenase-2, and tumor necrosis factor-α in DSS-treated mice. RB supplementation reduced neutrophil infiltration, monocyte chemoattractant protein-1 mRNA expression, and xanthine oxidase content, but enhanced catalase content in DSS-treated mice. Consistently, RB supplementation reduced pore forming tight junction protein claudin-2, increased barrier strengthening claudin-3, zonula occluden-1 protein content and mucin (MUC)-2 mRNA level, and activated AMP-activated protein kinase (AMPK) in DSS-treated mice. In conclusion, dietary RB protected against inflammation and colitis symptoms induced by DSS, providing a promising dietary approach for the management of colitis.

Hyphenated MS-based targeted approaches in metabolomics

Review of targeted metabolomics, with a focus on the description of analytical methods.

Nonsense Mutation Inside Anthocyanidin Synthase Gene Controls Pigmentation in Yellow Raspberry (Rubus idaeus L.)

Yellow raspberry fruits have reduced anthocyanin contents and offer unique possibility to study the genetics of pigment biosynthesis in this important soft fruit. Anthocyanidin synthase (Ans) catalyzes the conversion of leucoanthocyanidin to anthocyanidin, a key committed step in biosynthesis of anthocyanins. Molecular analysis of the Ans gene enabled to identify an inactive ans allele in a yellow fruit raspberry ("Anne"). A 5 bp insertion in the coding region was identified and designated as ans⁺⁵. The insertion creates a premature stop codon resulting in a truncated protein of 264 amino acids, compared to 414 amino acids wild-type ANS protein. This mutation leads to loss of function of the encoded protein that might also result in transcriptional downregulation of Ans gene as a secondary effect, i.e., nonsense-mediated mRNA decay. Further, this mutation results in loss of visible and detectable anthocyanin pigments. Functional characterization of raspberry Ans/ans alleles via complementation experiments in the Arabidopsis thaliana ldox mutant supports the inactivity of encoded protein through ans⁺⁵ and explains the proposed block in the anthocyanin biosynthetic pathway in raspberry. Taken together, our data shows that the mutation inside Ans gene in raspberry is responsible for yellow fruit phenotypes.

Pathway Analysis and Metabolites Identification by Metabolomics of Etiolation Substrate from Fresh-Cut Chinese Water Chestnut (Eleocharis tuberosa)

Fresh-cut Chinese water chestnuts (CWC) turn yellow after being peeled, reducing their shelf life and commercial value. Metabolomics, the systematic study of the full complement of small molecular metabolites, was useful for clarifying the mechanism of fresh-cut CWC etiolation and developing methods to inhibit yellowing. In this study, metabolic alterations associated with etiolation at different growth stages (0 day, 2 days, 3 days, 4 days, 5 days) from fresh-cut CWC were investigated using LC–MS and analyzed by pattern recognition methods (principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA), and orthogonal projection to latent structures-discriminant analysis (OPLS-DA)). The metabolic pathways of the etiolation molecules were elucidated. The main metabolic pathway appears to be the conversion of phenylalanine to p-coumaroyl-CoA, followed by conversion to naringenin chalcone, to naringenin, and naringenin then following different pathways. Firstly, it can transform into apigenin and its derivatives; secondly, it can produce eriodictyol and its derivatives; and thirdly it can produce dihydrokaempferol, quercetin, and myricetin. The eriodictyol can be further transformed to luteolin, cyanidin, dihydroquercetin, dihydrotricetin, and others. This is the first reported use of metabolomics to study the metabolic pathways of the etiolation of fresh-cut CWC.

Metabolic engineering of Saccharomyces cerevisiae for de novo production of dihydrochalcones with known antioxidant, antidiabetic, and sweet tasting properties

Dihydrochalcones are plant secondary metabolites comprising molecules of significant commercial interest as antioxidants, antidiabetics, or sweeteners. To date, their heterologous biosynthesis in microorganisms has been achieved only by precursor feeding or as minor by-products in strains engineered for flavonoid production. Here, the native ScTSC13 was overexpressed in Saccharomyces cerevisiae to increase its side activity in reducing p-coumaroyl-CoA to p-dihydrocoumaroyl-CoA. De novo production of phloretin, the first committed dihydrochalcone, was achieved by co-expression of additional relevant pathway enzymes. Naringenin, a major by-product of the initial pathway, was practically eliminated by using a chalcone synthase from barley with unexpected substrate specificity. By further extension of the pathway from phloretin with decorating enzymes with known specificities for dihydrochalcones, and by exploiting substrate flexibility of enzymes involved in flavonoid biosynthesis, de novo production of the antioxidant molecule nothofagin, the antidiabetic molecule phlorizin, the sweet molecule naringin dihydrochalcone, and 3-hydroxyphloretin was achieved.

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De novo biosynthesis of phloretin in S. cerevisiae.

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De novo pathway extended to various dihydrochalcones of commercial interest.

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A barley CHS exhibits very high specificity for phloretin production.

Targeted and untargeted mass spectrometric approaches in discrimination between Myrtus communis cultivars from Sardinia region

In the present study, the discrimination of phytochemical content of Myrtus communis berries from different geographical origin and cultivars was explored by Liquid Chromatography-Electrospray Ionization-Fourier Transform-Mass Spectrometry (LC-ESI-FT-MS) metabolic profiling and quantitative analysis. Experiments were carried on myrtle plants grown in an experimental area of Sardinia region, obtained by the germination of seeds taken from berries collected in each part of the region. A preliminary untargeted approach on fruit's extracts was realized by collecting LC-ESI-FT-(Orbitrap)-MS data obtained by operating in negative ion mode and performing principal component analysis with the result of differentiation of samples. In a second step, targeted analysis with a reduced number of variables was realized. A data matrix was obtained by the data fusion of positive and negative ionization LC-ESI-MS results, by using as variables the peak areas of each known compounds. By the observation of principal component analysis, results found that anthocyanins, and mainly derivatives of cyanidin, are the principal marker compounds responsive for the discrimination of samples based on the geographical origin of the seeds. Based on this finding, finally, an LC-diode array detector method was developed, validated and applied for the quantitative analysis of berries' extracts based on 11 commercial standard compounds corresponding to the identified markers. Copyright © 2016 John Wiley & Sons, Ltd.

Sea Buckthorn (Hippophaë rhamnoides ssp. rhamnoides) Berries in Nordic Environment: Compositional Response to Latitude and Weather Conditions

Flavonol glycosides (FGs) in sea buckthorn (Hippophaë rhamnoides ssp. rhamnoides) berries of varieties 'Tytti' and 'Terhi', cultivated in northern Finland (68°02' N) for six years and southern Finland (60°23' N) for seven years, were investigated and compared by HPLC-DAD-ESI-MS/MS. The average total content of 23 identified glycosides of isorhamnetin and quercetin was 103 ± 23 and 110 ± 21 mg/100 g fresh berries in 'Terhi' and 'Tytti', respectively. The total contents of FGs, flavonol diglycosides, and triglycosides in both varieties were higher in the north than in the south, whereas total flavonol monoglycoside content behaved vice versa (p < 0.05). Among the 89 weather variables studied, the sum of the daily mean temperatures that are 5 °C or higher from the start of growth season until the day of harvest was the most important variable which associated negatively with the accumulation of FGs in berries. Such influence was much stronger in berries from the north than from the south.

White versus blue: Does the wild 'albino' bilberry (Vaccinium myrtillus L.) differ in fruit quality compared to the blue one?

Wild albino and blue bilberry fruit were analyzed to compare different fruit characteristics linked to the composition of primary and secondary metabolites. Compounds were identified using HPLC-MS and standard quality parameters were determined. Albino berries were significantly smaller, accumulated less water and were characterized by 23% higher dry weight. Soluble solids content and pH value were higher in albino bilberry and their surface was lighter and characterized by a yellow hue. Both bilberry forms accumulated identical individual sugars and organic acids; however, the albino form had 33% higher content of total sugars and 9% higher content of total organic acids compared to the blue type. Fifteen anthocyanins were identified in both forms, but in albino bilberries, individual anthocyanins were only detected in traces. Blue bilberry contained 1.6-fold higher levels of flavanols, 2.1-fold higher levels of flavonols, 2.5-fold higher levels of hydroxycinnamic acid derivatives and consequently, 4.6-fold higher total phenolic content.

Medicinal Effect of Nutraceutical Fruits for the Cognition and Brain Health

The recent era is witnessing evaluation of medicinal and nutritional value of fruits and fruit juices for the management and prevention of brain diseases like headache stress, anxiety, hypertension, and Alzheimer's and Parkinson's diseases by the scientists and researchers worldwide. Fruits possess various chemicals such as antioxidants and polyphenols, which reduce and balance the effect of hormone in brain responsible for brain disease. Natural remedy is cheap, easily available, nontoxic, and easy to prepare and provides good mental health as compared to other remedies. The main objective of this review is to acknowledge medicinal benefits of fruits for the cognition and management of brain disease.

Discovery of A-type procyanidin dimers in yellow raspberries by untargeted metabolomics and correlation based data analysis

INTRODUCTION

Raspberries are becoming increasingly popular due to their reported health beneficial properties. Despite the presence of only trace amounts of anthocyanins, yellow varieties seems to show similar or better effects in comparison to conventional raspberries.

OBJECTIVES

The aim of this work is to characterize the metabolic differences between red and yellow berries, focussing on the compounds showing a higher concentration in yellow varieties.

METHODS

The metabolomic profile of 13 red and 12 yellow raspberries (of different varieties, locations and collection dates) was determined by UPLC-TOF-MS. A novel approach based on Pearson correlation on the extracted ion chromatograms was implemented to extract the pseudospectra of the most relevant biomarkers from high energy LC-MS runs. The raw data will be made publicly available on MetaboLights (MTBLS333).

RESULTS

Among the metabolites showing higher concentration in yellow raspberries it was possible to identify a series of compounds showing a pseudospectrum similar to that of A-type procyanidin polymers. The annotation of this group of compounds was confirmed by specific MS/MS experiments and performing standard injections.

CONCLUSIONS

In berries lacking anthocyanins the polyphenol metabolism might be shifted to the formation of a novel class of A-type procyanidin polymers.

Modern plant metabolomics: advanced natural product gene discoveries, improved technologies, and future prospects

Plant metabolomics has matured and modern plant metabolomics has accelerated gene discoveries and the elucidation of a variety of plant natural product biosynthetic pathways. This review covers the approximate period of 2000 to 2014, and highlights specific examples of the discovery and characterization of novel genes and enzymes associated with the biosynthesis of natural products such as flavonoids, glucosinolates, terpenoids, and alkaloids. Additional examples of the integration of metabolomics with genome-based functional characterizations of plant natural products that are important to modern pharmaceutical technology are also reviewed. This article also provides a substantial review of recent technical advances in mass spectrometry imaging, nuclear magnetic resonance imaging, integrated LC-MS-SPE-NMR for metabolite identifications, and X-ray crystallography of microgram quantities for structural determinations. The review closes with a discussion on the future prospects of metabolomics related to crop species and herbal medicine.

A high fat, high cholesterol diet leads to changes in metabolite patterns in pigs--a metabolomic study

Non-targeted metabolite profiling can identify biological markers of dietary exposure that lead to a better understanding of interactions between diet and health. In this study, pigs were used as an animal model to discover changes in metabolic profiles between regular basal and high fat/high cholesterol diets. Extracts of plasma, fecal and urine samples from pigs fed high fat or basal regular diets for 11 weeks were analysed using ultra-high performance liquid chromatography with high-resolution mass spectrometry (UHPLC-HRMS) and chemometric analysis. Cloud plots from XCMS online were used for class separation of the most discriminatory metabolites. The major metabolites contributing to the discrimination were identified as bile acids (BAs), lipid metabolites, fatty acids, amino acids and phosphatidic acid (PAs), phosphatidylglycerol (PGs), glycerophospholipids (PI), phosphatidylcholines (PCs) and tripeptides. These results suggest the developed approach can be used to identify biomarkers associated with specific feeding diets and possible metabolic disorders related to diet.