Modeling relationships among active components in black raspberry (Rubus occidentalis L.) fruit extracts using high-resolution (1)H nuclear magnetic resonance (NMR) spectroscopy and multivariate statistical analysis

NMR Metabolite Profiling and Antioxidant Properties of Spartan, Jewels, Misty, and Camelia Blueberries

The health-promoting properties of blueberries are widely recognized and are mainly attributed to anthocyanins. However, fruit's chemical composition includes also other components and strongly depends on varieties and climatic conditions. Here, 1H NMR metabolite profiling and biological activity of four blueberry cultivars (Spartan, Jewels, Misty, Camelia) grown in Central Italy over two years were reported. Untargeted and targeted NMR analyses allowed the quantification of sugars, organic acids, amino acids, anthocyanins, lipids, and other compounds. Spectrophotometric assays evaluated total phenolic and flavonoid content, antioxidant activity, and enzyme inhibitory activity toward cholinesterase, α-amylase, α-glucosidase, and tyrosinase. Statistical analysis showed a correlation between chemical composition and biological activity, revealing markers specific to blueberry cultivars (quinic acid, quercitrin, myo-inositol, myrtillin, and petunidin-3-O-glucoside). Almost all antioxidant assays were correlated with the chlorogenic acid levels. A strong effect of harvesting on chemical composition and biological activities was observed, with Misty cultivar having the highest antioxidant activity.

Rubus urticifolius Compounds with Antioxidant Activity, and Inhibition Potential against Tyrosinase, Melanin, Hyaluronidase, Elastase, and Collagenase

In our study, using chromatographic techniques, we isolated three bioactive compounds, which were structurally elucidated as (E)-2-(3-(3,4-dimethoxyphenyl)acrylamido)-N-methylbenzamide (1), 4-Hydroxyquinoline-2-carboxylic acid (2), and (E)-2-Cyano-3-(4-hydroxyphenyl)acrylic acid (3), using spectroscopic methods. The anti-melanogenic, anti-inflammatory, antioxidant, and anti-aging properties were evaluated in vitro by measuring the activity of pharmacological targets including tyrosinase, melanin, NF-κB, hyaluronidase, elastase, collagenase, and Nrf2. Our results show that compound 1 is the most active with IC50 values of 14.19 μM (tyrosinase inhibition), 22.24 μM (melanin inhibition), 9.82-12.72 μM (NF-κB inhibition), 79.71 μM (hyaluronidase inhibition), 80.13 μM (elastase inhibition), 76.59 μM (collagenase inhibition), and 116-385 nM (Nrf2 activation) in the THP-1, HEK001, WS1, and HMCB cells. These findings underscore the promising profiles of the aqueous extract of R. urticifolius at safe cytotoxic concentrations. Additionally, we report, for the first time, the isolation and characterisation of these nitrogenous compounds in the R. urticifolius species. Finally, compound 1, isolated from R. urticifolius, is a promising candidate for the development of more effective and safer compounds for diseases related to skin pigmentation, protection against inflammation, and oxidative stress.

Advances in the Chemistry, Analysis and Adulteration of Anthocyanin Rich-Berries and Fruits: 2000-2022

Anthocyanins are reported to exhibit a wide variety of remedial qualities against many human disorders, including antioxidative stress, anti-inflammatory activity, amelioration of cardiovascular diseases, improvement of cognitive decline, and are touted to protect against neurodegenerative disorders. Anthocyanins are water soluble naturally occurring polyphenols containing sugar moiety and are found abundantly in colored fruits/berries. Various chromatographic (HPLC/HPTLC) and spectroscopic (IR, NMR) techniques as standalone or in hyphenated forms such as LC-MS/LC-NMR are routinely used to gauge the chemical composition and ensure the overall quality of anthocyanins in berries, fruits, and finished products. The major emphasis of the current review is to compile and disseminate various analytical methodologies on characterization, quantification, and chemical profiling of the whole array of anthocyanins in berries, and fruits within the last two decades. In addition, the factors affecting the stability of anthocyanins, including pH, light exposure, solvents, metal ions, and the presence of other substances, such as enzymes and proteins, were addressed. Several sources of anthocyanins, including berries and fruit with their botanical identity and respective yields of anthocyanins, were covered. In addition to chemical characterization, economically motivated adulteration of anthocyanin-rich fruits and berries due to increasing consumer demand will also be the subject of discussion. Finally, the health benefits and the medicinal utilities of anthocyanins were briefly discussed. A literature search was performed using electronic databases from PubMed, Science Direct, SciFinder, and Google Scholar, and the search was conducted covering the period from January 2000 to November 2022.

Black raspberry (Rubus occidentalis) attenuates inflammatory markers and vascular endothelial dysfunction in Wistar rats fed a high-fat diet with fructose solution

A continuous high-fat/high-fructose diet induces inflammation and lowers vascular endothelial function in the body. This research examined the effects of black raspberry (BR) powder consumption on the inflammatory response and endothelial dysfunction in rats fed with a high-fat diet and fructose solution. Wistar rats were randomly divided into two groups as control (AIN-93G diet + distilled water) and HFF (high-fat diet + 20% fructose solution) groups, for 16 weeks. At 8 weeks, the HFF was further divided into three subgroups: HFF, HFFBR2.5 (2.5% BR in high-fat diet), and HFFBR5 (5% BR in high-fat diet). The BR-fed groups showed significantly higher high-density lipoprotein-cholesterol and lower triglycerides than the HFF group. Rats supplemented with BR showed decreased mRNA and protein expressions of inflammatory cytokines and adhesion molecules in the liver and aorta tissues. Furthermore, the aortic protein expression of endothelial nitroxide synthase was significantly greater in the HFFBR2.5 and HFFBR5 than HFF. PRACTICAL APPLICATIONS: Black raspberry (BR: Rubus occidentalis) is abundant in flavonoids and anthocyanins. BR displays various biological activities and has been used to alleviate inflammatory conditions. In our study, BR supplementation showed promising effects against high-fat/high-fructose diet-induced inflammation and endothelial dysfunction in rats by decreasing markers of inflammation and improving vascular endothelial function. These findings suggest that BR consumption could have beneficial effects on the risk factors of cardiovascular disease.

Amino Acid Profile of Fruits as Potential Fingerprints of Varietal Origin

This study aims to assess the capability of the ¹H-NMR profiling of fruits from different genera in combination with multivariate data analysis to provide feasible information for fruit juices’ authenticity in terms of botanical origin. Nine fruit varieties from four genera were selected for the experimental plan. The juice obtained from the fruits was characterized using the ¹H-NMR technique, selecting the obtained amino acid profile of fruits as a potential specific fingerprint. Due to the complex information provided by the NMR spectra, a chemometric approach of the data was further applied to enable the differentiation of the fruit samples, highlighting thus its suitability as a discrimination tool for the varietal origin. The advantage of this analytical approach is given by the relatively simple working procedure, which consists of an easy, fast, and accessible preparation stage while providing complex information on fruit composition.

Enhanced Glucose Uptake in Human Liver Cells and Inhibition of Carbohydrate Hydrolyzing Enzymes by Nordic Berry Extracts

A Western lifestyle with low physical activity and a diet rich in sugar, fat and processed food contribute to higher incidences of diabetes and obesity. Enhanced glucose uptake in human liver cells was observed after treatment with phenolic extracts from different Nordic berries. All berry extracts showed higher inhibition against α-amylase and α-glucosidase than the anti-diabetic agent acarbose. Total phenolic content and phenolic profiles in addition to antioxidant activities, were also investigated. The berries were extracted with 80% methanol on an accelerated solvent extraction system (ASE) and then purified by C-18 solid phase extraction (SPE). Among the ASE methanol extracts, black chokeberry, crowberry and elderberry extracts showed high stimulation of glucose uptake in HepG2 cells and also considerable inhibitory effect towards carbohydrate hydrolyzing enzymes. SPE extracts with higher concentrations of phenolics, resulted in increased glucose uptake and enhanced inhibition of α-amylase and α-glucosidase compared to the ASE extracts. Crowberry and cloudberry were the most potent 15-lipoxygenase inhibitors, while bog whortleberry and lingonberry were the most active xanthine oxidase inhibitors. These results increase the value of these berries as a component of a healthy Nordic diet and have a potential benefit against diabetes.

2D-NMR investigation and in vitro evaluation of antioxidant, antigenotoxic and estrogenic/antiestrogenic activities of strawberry grape

Strawberry grape is considered beneficial due to its extensive phytochemical properties. To expand the knowledge about the chemical constituents and the biological activities of the whole plant, 2D-NMR investigation has been carried out on pulp, peel, seeds, stalks and leaves. Catechin and epicatechin were identified as the main constituents of the seed extract, quercetin and ferulic acid were detected in the leaves and malvidin and cyanidin glucopyranoside in the peels. The leaf, stalk and seed extracts were found to be very rich in phytochemicals and were tested for their ability to reduce the mutagenicity and genotoxicity of standard agents via Salmonella mutagenicity assay and SOS chromotest, respectively. Moreover, the estrogen/antiestrogen-like activity was evaluated on the MCF-7 estrogen-responsive cells. Seed and stalk extracts had an elevated antimutagenic/antigenotoxic activity. Stalk extracts highly reduced the proliferative effect of natural estrogen, 17β-estradiol.

(1)H NMR Metabolic Fingerprinting to Probe Temporal Postharvest Changes on Qualitative Attributes and Phytochemical Profile of Sweet Cherry Fruit

Sweet cherry fruits (Prunus avium cvs. 'Canada Giant', 'Ferrovia') were harvested at commercial maturity stage and analyzed at harvest and after maintenance at room temperature (storage at ∼20°C, shelf life) for 1, 2, 4, 6, and 8 days, respectively. Fruit were initially analyzed for respiration rate, qualitative attributes and textural properties: 'Canada Giant' fruit were characterized by higher weight losses and stem browning index, being more intense over the late stages of shelf life period; meanwhile 'Ferrovia' possessed appreciably better performance even after extended shelf life period. A gradual decrease of respiration rate was monitored in both cultivars, culminated after 8 days at 20°C. The sweet cherry fruit nutraceutical profile was monitored using an array of instrumental techniques (spectrophotometric assays, HPLC, (1)H-NMR). Fruit antioxidant capacity was enhanced with the progress of shelf life period, concomitant with the increased levels of total anthocyanin and of phenolic compounds. 'Ferrovia' fruit presented higher contents of neochlorogenic acid and p-coumaroylquinic acid throughout the shelf life period. We further developed an (1)H-NMR method that allows the study of primary and secondary metabolites in a single running, without previous separation and isolation procedures. Diagnostic peaks were located in the aliphatic region for sugars and organic acids, in the aromatic region for phenolic compounds and at 8.2-8.6 ppm for anthocyanins. This NMR-based methodology provides a unifying tool for quantitative and qualitative characterization of metabolite changes of sweet cherry fruits; it is also expected to be further exploited for monitoring temporal changes in other fleshy fruits.

Nuclear Magnetic Resonance-Based Metabolic Comparative Analysis of Two Apple Varieties with Different Resistances to Apple Scab Attacks

Apple scab, caused by the fungus Venturia inaequalis, is the most serious disease of the apple worldwide. Two cultivars (Malus domestica), having different degrees of resistance against fungi attacks, were analyzed by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy. Aqueous and organic extracts of both apple flesh and skin were studied, and over 30 metabolites, classified as organic acids, amino acids, carbohydrates, phenolic compounds, lipids, sterols, and other metabolites, were quantified by means of one-dimensional (1D) and two-dimensional (2D) NMR experiments. The metabolic profiles of the two apple cultivars were compared, and the differences were correlated with the different degrees of resistance to apple scab by means of univariate analysis. Levels of metabolites with known antifungal activity were observed not only to be higher in the Almagold cultivar but also to show different correlation patterns in comparison to Golden Delicious, implying a difference in the metabolic network involved in their biosynthesis.

Metabolomic Analysis Reveals Cyanidins in Black Raspberry as Candidates for Suppression of Lipopolysaccharide-Induced Inflammation in Murine Macrophages

The extracts produced by multisolvent extraction and subfractionation with preparative liquid chromatography of black raspberry (Rubus coreanus Miquel) cultivated in Gochang, South Korea, were tested for their anti-inflammatory effects. The metabolomic profiling and analysis by orthogonal partial least-squares discriminant analysis (OLPS-DA) suggested that cyanidin, cyanidin-3-glucoside (C3G), and cyanidin-3-rutinoside (C3R) were key components for the anti-inflammatory responses in the most active fraction BF3-1, where they were present at 0.44, 1.26, and 0.56 μg/mg of BF3-1, respectively. Both BF3-1 and mixture of these cyanidins at the same ratio reduced lipopolysaccharide (LPS)-induced protein level of iNOS expression and suppressed mRNA and protein expressions of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β through inhibiting the phosphorylation of mitogen-activated protein kinases (MAPKs) and STAT3 in murine macrophage RAW264.7 cells. Overall, the results suggested that co-administration of cyanidin, C3G, and C3R is more effective than that of cyanidin alone and that the coexistence of these anthocyanin components in black raspberry plays a vital role in regulating LPS-induced inflammation even at submicromolar concentrations, making it possible to explain the health beneficial activity of its extracts.

Untargeted NMR-based methodology in the study of fruit metabolites

In this review, fundamental aspects of the untargeted NMR-based methodology applied to fruit characterization are described. The strategy to perform the structure elucidation of fruit metabolites is discussed with some examples of spectral assignments by 2D experiments. Primary ubiquitous metabolites as well as secondary species-specific metabolites, identified in different fruits using an untargeted ¹H-NMR approach, are summarized in a comprehensive way. Crucial aspects regarding the quantitative elaboration of spectral data are also discussed. The usefulness of the NMR-based metabolic profiling was highlighted using some results regarding quality, adulteration, varieties and geographical origin of fruits and fruit-derived products such as juices.

NMR methodologies in the analysis of blueberries

An NMR analytical protocol based on complementary high and low field measurements is proposed for blueberry characterization. Untargeted NMR metabolite profiling of blueberries aqueous and organic extracts as well as targeted NMR analysis focused on anthocyanins and other phenols are reported. Bligh-Dyer and microwave-assisted extractions were carried out and compared showing a better recovery of lipidic fraction in the case of microwave procedure. Water-soluble metabolites belonging to different classes such as sugars, amino acids, organic acids, and phenolic compounds, as well as metabolites soluble in organic solvent such as triglycerides, sterols, and fatty acids, were identified. Five anthocyanins (malvidin-3-glucoside, malvidin-3-galactoside, delphinidin-3-glucoside, delphinidin-3-galactoside, and petunidin-3-glucoside) and 3-O-α-l-rhamnopyranosyl quercetin were identified in solid phase extract. The water status of fresh and withered blueberries was monitored by portable NMR and fast-field cycling NMR. (1) H depth profiles, T2 transverse relaxation times and dispersion profiles were found to be sensitive to the withering.

Bioassay directed isolation and biological evaluation of compounds isolated from Rubus fairholmianus Gard

The in vitro and in silico analysis of Rubus fairholmianus acetone extract for antioxidant, antiproliferative, and anti-inflammatory activity led to the isolation of six compounds. Amongst all the six isolated compounds tested, 1-(2-hydroxyphenyl)-4-methylpentan-1-one (compound 1) and 2-[(3-methylbutoxy) carbonyl] benzoic acid (compound 2) were found to be more active in inhibiting BRCA and COX target proteins, which also showed the better results for DPPH and ABTS radical scavenging assays. The promising results of this investigation emphasize the importance of using R. fairholmianus in the treatment of radical generated disorders mainly cancer and other inflammatory diseases.

NMR-based metabolomic investigation of bioactivity of chemical constituents in black raspberry (Rubus occidentalis L.) fruit extracts

Black raspberry (Rubus occidentalis L.) (BR) fruit extracts with differing compound profiles have shown variable antiproliferative activities against HT-29 colon cancer cell lines. This study used partial least-squares (PLS) regression analysis to develop a high-resolution (1)H NMR-based multivariate statistical model for discerning the biological activity of BR constituents. This model identified specific bioactive compounds and ascertained their relative contribution against cancer cell proliferation. Cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside were the predominant contributors to the extract bioactivity, but salicylic acid derivatives (e.g., salicylic acid glucosyl ester), quercetin 3-glucoside, quercetin 3-rutinoside, p-coumaric acid, epicatechin, methyl ellagic acid derivatives (e.g., methyl ellagic acetyl pentose), and citric acid derivatives also contributed significantly to the antiproliferative activity of the berry extracts. This approach enabled the identification of new bioactive components in BR fruits and demonstrates the utility of the method for assessing chemopreventive compounds in foods and food products.

Nonanthocyanin secondary metabolites of black raspberry (Rubus occidentalis L.) fruits: identification by HPLC-DAD, NMR, HPLC-ESI-MS, and ESI-MS/MS analyses

Nonanthocyanin secondary metabolites potentially contributing to the antiproliferative bioactivity of black raspberry ( Rubus occidentalis L.) fruits were extracted in ethyl acetate and isolated by semipreparative and analytical HPLC and analyzed by NMR, HPLC-ESI-MS, and ESI-MS/MS techniques. Here we present complete and partial structures of a variety of the chemical entities such as quercetin 3-glucoside, quercetin 3-rutinoside, myricetin glucoside, dihydrokaempferol glucoside, benzoic acid β-d-glucopyranosyl ester, 3,4-dihydroxybenzoic acid, epicatechin, caffeic acid, p-coumaric acid, p-coumaryl glucoside, p-coumaryl sugar ester, ellagic acid, methyl ellagic acid acetylpentose, methyl ellagic acid valerylpentose, trans-piceid, phloretin glucoside (phloridzin), dihydrosinapic acid, salicylic acid β-d-glucopyranosyl ester, a salicylic acid derivative without attached sugar, p-alkylphenyl glucoside, and a citric acid derivative. To our knowledge, 15 of these compounds were not previously reported in black raspberry fruits.

Effect of black raspberry ( Rubus occidentalis L.) extract variation conditioned by cultivar, production site, and fruit maturity stage on colon cancer cell proliferation

Black raspberries have been shown to inhibit multiple stages of oral, esophageal, and colon cancer. The objective of this study was to evaluate how black raspberry extract variability conditioned by horticultural factors affected the antiproliferative activity of 75 black raspberry extracts using an in vitro colon cancer cell model. HT-29 cells grown in 96-well plates were treated with freeze-dried extracts at 0.6 and 1.2 mg of extract/mL of medium. Percent cell growth inhibition for each concentration of the extracts was determined using the sulforhodamine B assay. All extracts significantly inhibited the growth of HT-29 colon cancer cells in a dose-dependent manner. Cell proliferation was significantly influenced by cultivar, production site, and stage of maturity. The lack of correlation between growth inhibition and extract total phenolic and total monomeric anthocyanin assays suggested horticultural parameters influence bioactivity in a complex manner.