A Sensitive LC-MS Method for Anthocyanins and Comparison of Byproducts and Equivalent Wine Content

Study of UV-Vis molar absorptivity variation and quantitation of anthocyanins using molar relative response factor

The effects of anthocyanin's substitution groups on the UV-Vis molar absorptivity were examined by analyzing a group of 31 anthocyanidin/anthocyanin reference standards with ultra-high performance liquid chromatography-diode array detector (UHPLC-DAD). The substitution groups on aglycones were found to associate with molar absorptivity variations, often neglected in anthocyanin quantitation, resulting in significant analytical errors. A simple yet comprehensive strategy based on the molar relative response factors (MRRFs) and a single master reference calibration (i.e., cyanidin-3-glucoside) was proposed to quantify anthocyanins in red cabbage, blueberry, and strawberry samples with improved analytical accuracy. The results indicate this approach provides an effective, inexpensive, and accurate analytical method for anthocyanins in food materials without using individual reference standards. MRRFs of 617 anthocyanins/anthocyanidins were calculated, and the information is freely available at https://BotanicalDC.online/anthocyanin/. This study could be critical to developing new reference methods for anthocyanin analysis and harmonizing results and data from various sources.

Ultrasound-Assisted Anthocyanins Extraction from Pigmented Corn: Optimization Using Response Surface Methodology

This study aimed to determine the optimal UAE conditions for extracting anthocyanins from pigmented corn using the Box-Behnken design (BBD). Six anthocyanins were identified in the samples and were used as response variables to evaluate the effects of the following working variables: extraction solvent pH (2-7), temperature (10-70 °C), solvent composition (0-50% methanol in water), and ultrasound power (20-80%). The extraction time (5-25 min) was evaluated for complete recovery. Response surface methodology suggested optimal conditions, specifically 36% methanol in water with pH 7 at 70 °C using 73% ultrasound power for 10 min. The method was validated with a high level of accuracy (>90% of recovery) and high precision (CV < 5% for both repeatability and intermediate precision). Finally, the proposed analytical extraction method was successfully applied to determine anthocyanins that covered a wide concentration range (36.47-551.92 mg kg-1) in several pigmented corn samples revealing potential varieties providing more health benefits.

The (Poly)phenolic Profile of Separate Winery By-Products Reveals Potential Antioxidant Synergies

The by-products of grapes (Vitis vinifera L.) in the winemaking process present a diverse phytochemical profile of (poly)phenols, essentially represented by phenolic acids, flavonoids, and stilbenes, which have health benefits. In winemaking, solid (grape stems and pomace) and semisolid (wine lees) by-products are generated, negatively impacting the sustainability of the agro-food activity and the local environment. Although information on the phytochemical profile of grape stems and pomace has been reported, especially information concerning (poly)phenols, research on wine lees is necessary to take advantage of the compositional traits of this residue. So, in the present work, an updated, in-depth comparison of the (poly)phenolic profiles of these three resulting matrices in the agro-food industry has been carried out to provide new knowledge and interesting data on the action of yeast and lactic acid bacteria (LAB) metabolism in the diversification of phenolic composition; additionally, we extract complementarities for the possible joint application of the three residues. The phytochemical analysis of the extracts was carried out using HPLC-PDA-ESI-MSn. The (poly)phenolic profiles of the residues showed significant discrepancies. The results obtained showed that the greatest diversity of (poly)phenols was found in the stems of the grapes, followed closely by the lees. Through technological insights, it has been suggested that yeasts and LAB, responsible for the fermentation of must, might play a key role in the transformation of phenolic compounds. This would provide new molecules with specific bioavailability and bioactivity features, which might interact with different molecular targets and, consequently, improve the biological potential of these underexploited residues.

Optimization of Supercritical Carbon Dioxide Extraction of Polyphenols from Black Rosehip and Their Bioaccessibility Using an In Vitro Digestion/Caco-2 Cell Model

The fruits of Rosa pimpinellifolia are rich sources of (poly)phenols, however they are underutilized due to the limited information available. The influence of the pressure, temperature, and co-solvent concentration (aqueous ethanol) of the supercritical carbon dioxide extraction (SCO₂-aqEtOH) on the extraction yield, total phenolic-, total anthocyanin-, catechin-, cyanidin-3-O-glucoside contents, and total antioxidant activity of black rosehip was investigated simultaneously. The maximum obtained total phenolic and total anthocyanin contents under the optimized extraction conditions (280 bar, 60 °C and 25% ethanol, v/v) were 76.58 ± 4.25 mg gallic acid equivalent and 10.89 ± 1.56 mg cyanidin-3-O-glucoside equivalent per g of the dry fruits, respectively. The optimal extract obtained by SCO₂-aqEtOH was compared to two other extraction procedures: ultrasonication using ethanol as solvent (UA-EtOH) and pressurized hot water extraction (PH-H₂O). The bioaccessibility and cellular metabolism of the phenolic compounds in the different black rosehip extracts were assessed using an in vitro digestion coupled with a human intestinal Caco-2 cell model. The in vitro digestive stability and cellular uptake of the phenolic compounds had no significant difference among the different extraction methods. The results of this study confirm the efficiency of SCO₂-aqEtOH extraction for phenolic compounds and, in particular, for anthocyanins, and could be used to produce new functional food ingredients from black rosehip with high antioxidant power containing both hydrophilic and lipophilic compounds.

An Optimized HPLC-DAD Methodology for the Determination of Anthocyanins in Grape Skins of Red Greek Winegrape Cultivars (Vitis vinifera L.)

A rapid and simple HPLC-DAD analytical method was developed and optimized for the determination of anthocynanins in three red Greek winegrape varieties (Kotsifali, Limnio, and Vradiano). The critical parameters, such as the acidifying solvent and the extraction temperature, which affect the extraction of anthocyanins from the grapes, were studied to find the optimum values. The developed methodology was validated in terms of selectivity, linearity, accuracy, and precision and presented satisfactory results. The limits of quantification (LOQs) ranged between 0.20 mg/kg to 0.60 mg/kg, and the limits of detection (LODs) ranged between 0.06 mg/kg and 0.12 mg/kg. The RSD% of the within-day and between-day assays were lower than 6.2% and 8.5%, respectively, showing adequate precision. The accuracy ranged between 91.6 and 119% for within-day assay and between 89.9 and 123% for between-day assay. Sixteen samples from the main regions of each variety as well as from the official ampelographic collections of Greece were collected during the 2020 growing season and were further analyzed by HPLC-DAD. Notable differences in the anthocyanin content were detected among the cultivars using hierarchical cluster analysis (HCA).

Extracts of Fruits and Plants Cultivated In Vitro of Aristotelia chilensis (Mol.) Stuntz Show Inhibitory Activity of Aldose Reductase and Pancreatic Alpha-Amylase Enzymes

Aristotelia chilensis is a plant whose fruit is considered a powerful natural antioxidant. During the last years, some investigations of the fruit have been carried out, finding antioxidant properties in the juice or the phenolic fraction. The antioxidant properties of the plant are useful in the inhibition of enzymes related to diabetes such as pancreatic aldose reductase and alpha-amylase. Because many synthetic drugs used today have limitations and potentially harmful side effects, the use of naturally occurring compounds, such as flavonoids, is clinically attractive. In this study, the characterization of aqueous extracts of fruits and in vitro plants of A. chilensis was carried out based on their content of anthocyanins and total phenols, the antioxidant capacity by the antiradical activity 2,2-diphenyl-1-picrilhydrazil (DPPH), and the profile of anthocyanins and other phenolic compounds by liquid chromatography coupled to mass spectrometry (LC-MS/MS). Subsequently, the effect of these extracts on the inhibition of bovine aldose reductase and pancreatic alpha-amylase enzymes was determined. According to our results, extracts of fruits and in vitro plants of A. chilensis achieved inhibition of the bovine aldose reductase enzyme of 85.54 ± 1.86% and 75.67 ± 1.21%, respectively. Likewise, the percentage of inhibition of the pancreatic alpha-amylase enzyme for fruit extracts was 29.64 ± 0.63%, while for in vitro plant extracts it was 47.66 ± 0.66%. The antioxidant and enzymatic inhibition activity of the extracts were related to the content of anthocyanins, such as delphinidin and cyanidin glycosides as well as the phenols derived from quercetin, myricetin, and kaempferol. The results obtained allow us to suggest that the in vitro culture of plants of A. chilensis represents a viable biotechnological alternative to obtain phenolic compounds for the inhibition of aldose reductase and pancreatic alpha-amylase enzymes.

Comparing pH differential and methanol-based methods for anthocyanin assessments of strawberries

Anthocyanins are a group of water-soluble polyphenolic pigments found primarily in flowers, vegetables, and fruits. These pigments play critical roles in plant and human health. Spectrophotometric methods are a simple and inexpensive way to quantify anthocyanins in plant tissues. Two main spectrophotometric methods have been developed, organic solvent-based, and pH differential methods. Both of these methods are subject to interference from light-absorbing impurities and need to be optimized for different matrixes of different plant materials. Eight methods have been tested in this experiment to quantify anthocyanins in strawberry fruits. Six organic solvent-based methods tested methanol, chloroform-methanol, and MgO in different ratios. The other two methods were pH differential method and a combination of organic solvent-based and pH differential method. Two methods used organic solvents (methanol and chloroform-methanol) were the best in extracting anthocyanin from strawberry fruits. Adding MgO increased the pH of the extract and was less efficient in anthocyanin extraction. All other methods had lower anthocyanin yield compared with methanol and chloroform-methanol methods and are not recommended for strawberry fruit anthocyanin extraction.

Chemometric and sensometric techniques in enological data analysis

Enological evaluations capture the chemical and sensory space of wine using different techniques; many sensory methods as well as a variety of analytical chemistry techniques contribute to the amount of information generated. Data fusion, especially integrating data sets, is important when working with complex systems. The success reported when trying to integrate different modalities is generally low and has been attributed to the lack of statistically considerate strategies focusing on the data handling process. Multiple stages of data handling must be carefully considered when dealing with multi-modal data. In this review, the different stages in the data analysis process were examined. The study revealed misconceptions surrounding the process and elucidated rules for purpose-driven approaches by examining the complexities of each stage and the impact the decisions made at each stage have on the resulting models. The two major modeling approaches are either supervised (discrimination, classification, prediction) or unsupervised (exploration). Supervised approaches were emphatic on the pre-processing steps and prioritized increasing performance. Unsupervised approaches were mostly used for preliminary steps. The review found aspects often neglected when it came to the data collection and capturing which in the end contributed to the low success in combining sensory and chemistry data.

Total Anthocyanin Content of Strawberry and the Profile Changes by Extraction Methods and Sample Processing

Anthocyanins are the primarily pigments in many flowers, vegetables, and fruits and play a critical role in human and plant health. They are polyphenolic pigments that are soluble in water and usually quantified by spectrophotometric methods. The two main methods that quantify anthocyanins are pH differential and organic solvent-based methods. Our hypothesis was that these methods extract different anthocyanin profiles. Therefore, this experiment was designed to identify anthocyanin profiles that are extracted by pH differential and organic solvent-based methods and observe their total anthocyanin content from strawberries. Six methods were tested in this experiment to quantify and profile anthocyanins in strawberry fruits by spectrophotometry and Ultra High Performance Liquid Chromatography (UHPLC) respectively. Four methods used organic solvents (methanol, and chloroform-methanol) in different combinations. The next two methods were pH differential and a combination of organic solvent and the pH differential method. The results suggest that acidified chloroform-methanol extracted the highest anthocyanin content compared to water-based solvents. Methanol-water based solvents also performed better than methanol alone, because both methanol and water may extract different profiles of anthocyanins. Water-based extracts had the greatest absorbance at a lower wavelength (498 nm), followed by methanol (508 nm), and chloroform (530 nm). Chloroform-methanol solvent with higher pH (3.0) extracted pelargonidin as the main anthocyanin, while methanol and water-based solvents (with lower pH 1.0-2.0) extracted delphinidin as their main anthocyanin as identified by UHPLC. Therefore, chloroform-methanol and methanol-water solvents were the best solvents for extracting anthocyanins from strawberries. Also, freeze-dried strawberries had higher anthocyanin contents compared to fresh or frozen samples.

Chondroprotection of fruit peels in a monosodium iodoacetate-induced osteoarthritis rat model via downregulation of Col1A1

The potential of the fruit peels of mango, orange, cantaloupe, and pomegranate in the treatment of osteoarthritis (OA) was evaluated in a rat model. Their metabolic profiles were characterized using ultrahigh-performance liquid chromatography (UPLC)-electrospray ionization-mass spectroscopy and 66 albino rats were intra-articularly injected with monosodium iodoacetate in the knee joints. The extracts were orally administered at doses of 200 and 400 mg/kg for 28 days. Serum levels of IL-6 and tissue levels of cyclooxygenase-2 (COX-2), peroxisome proliferator-activated receptor-gamma (PPARγ), and alpha-smooth muscle actin (α-SMA) were measured using ELISA. COL1A1 expression was measured by quantitative polymerase chain reaction. Histopathological changes in the joints were examined. In the extracts, 85 metabolites were annotated, and the levels of interleukin (IL)-6, COX-2, α-SMA, malondialdehyde, and nitric oxide were significantly reduced, while PPARγ and glutathione levels were significantly raised in all treated groups compared to the OA group. All extracts downregulated the cartilage mRNA expressions for COL1A1 dose-dependently. Mango peel extract exhibited the best chondroprotective effect. The in silico study showed the link between mango extract metabolites and COX-2.

Antioxidant Activity, α-Glucosidase Inhibition and UHPLC-ESI-MS/MS Profile of Shmar (Arbutus pavarii Pamp)

The genus Arbutus (Ericaceae) has been traditionally used in folk medicine due to its phytomedicinal properties, especially Arbutus pavarii Pamp. However, this plant has not been evaluated for its efficacy, quality, and consistency to support the traditional uses, potentially in treating diabetes. Despite previous studies that revealed the biological activities of A. pavarii as antioxidant and α-glucosidase inhibitory agents, scientific reports on the bioactive compounds that contribute to its health benefits are still scarce. Therefore, this research focused on the evaluation of antioxidant and α-glucosidase inhibitory activities of the methanol crude extracts and various fractions of the leaf and stem bark, as well as on metabolite profiling of the methanol crude extracts. The extracts and fractions were evaluated for total phenolic (TPC) and total flavonoid (TFC) contents, as well as the DPPH free radical scavenging, ferric reducing antioxidant power (FRAP), and α-glucosidase inhibitory activities. Methanol crude extracts of the leaf and stem bark were then subjected to UHPLC-ESI-MS/MS. To the best of our knowledge, the comparative evaluation of the antioxidant and α-glucosidase inhibitory activities of the leaf and stem bark of A. pavarii, as well as of the respective solvent fractions, is reported herein for the first time. Out of these extracts, the methanolic crude extracts and polar fractions (ethyl acetate and butanol fractions) showed significant bioactivities. The DPPH free radical and α-glucosidase inhibitions was highest in the leaf ethyl acetate fraction, with IC₅₀ of 6.39 and 4.93 µg/mL, respectively, while the leaf methanol crude extract and butanol fraction exhibited the highest FRAP with 82.95 and 82.17 mmol Fe (II)/g extract. The UHPLC-ESI-MS/MS analysis resulted in the putative identification of a total of 76 compounds from the leaf and stem bark, comprising a large proportion of plant phenolics (flavonoids and phenolic acids), terpenoids, and fatty acid derivatives. Results from the present study showed that the different parts of A. pavarii had potent antioxidant and α-glucosidase inhibitory activities, which could potentially prevent oxidative damage or diabetes-related problems. These findings may strengthen the traditional claim on the medicinal value of A. pavarii.

HPLC-ESI/MS profiling, phytoconstituent isolation and evaluation of renal function, oxidative stress and inflammation in gentamicin-induced nephrotoxicity in rats of Ficus spragueana Mildbr. & Burret

Ficus spragueana Mildbr. & Burret (family Moraceae) was reported to have various biological activities. However, its activity in treatment of renal injury has not been investigated yet. The current study aimed to evaluate the effects of F. spragueana leaf extract on nephrotoxicity caused by gentamicin. Gentamicin is an important broad-spectrum antibiotic; nevertheless, it exhibits serious nephrotoxic adverse effects. HPLC-ESI/MS spectrometric analysis of the extract revealed the presence of 37 phenolic compounds. Moreover, five compounds were isolated from the leaf extract, and identified on the basis of spectroscopic analysis. The isolated compounds were syringic acid (1), p-coumaric acid (2), 3',5' O-dicaffeoylquinic acid (3), luteolin-8-C-β-D glucopyranoside (orientin) (4) and 8-methoxy kaempferol-3-O-[α-L-rhamnopyranosyl (1→2) β-D-glucopyranoside] (5). The gentamicin-induced nephrotoxicity model was used to evaluate the protective effect of F. spragueana on renal toxicity biomarkers throughout the development of acute kidney injury. Administration of extract led to improvement in kidney function through inhibition of kidney injury molecule-1, creatinine, blood urea nitrogen and total bilirubin, as well as decreasing the inflammatory markers interlukin1-beta and myeloperoxidase. Furthermore, it reduced the oxidative stress by increasing reduced glutathione and total antioxidant capacity levels while decreasing malondialdehyde and nitric oxide content, and improved renal histopathological injuries.

Biological Management of Banana Fusarium Wilt Caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 Using Antagonistic Fungal Isolate CSR-T-3 (Trichoderma reesei)

Fusarium wilt in bananas is one of the most devastating diseases that poses a serious threat to the banana industry globally. With no effective control measures available to date, biological control has been explored to restrict the spread and manage the outbreak. We studied the effective biological control potential of different Trichoderma spp. in the management of Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4). Expression of the defense related genes and metabolites in banana plants inoculated with Foc TR4 and treated with effective Trichoderma sp interactions were also studied. The in vitro growth inhibition of Foc TR4 by Trichoderma reesei isolate CSR-T-3 was 85.19% indicating a higher antagonistic potential than other Trichoderma isolates used in the study. Further, in in vivo assays, the banana plants treated with the isolate CSR-T-3 T. reesei had a significant reduction in the disease severity index (0.75) and also had increased phenological indices with respect to Foc TR4 treated plants. Enhanced activity of defense enzymes, such as β-1, 3-glucanase, peroxidase, chitinase, polyphenol oxidase, and phenylalanine ammonia lyase with higher phenol contents were found in the Trichoderma isolate CSR-T-3 treated banana plants challenge-inoculated with Foc TR4. Fusarium toxins, such as fusaristatin A, fusarin C, chlamydosporal, and beauveric acid were identified by LC-MS in Foc TR4-infected banana plants while high intensity production of antifungal compounds, such as ß-caryophyllene, catechin-o-gallate, soyasapogenol rhamnosyl glucoronide, peptaibols, fenigycin, iturin C19, anthocyanin, and gallocatechin-o-gallate were detected in T. reesei isolate CSR-T-3 treated plants previously inoculated with Foc TR4. Gene expression analysis indicated the upregulation of TrCBH1/TrCBH2, TrXYL1, TrEGL1, TrTMK1, TrTGA1, and TrVEL1 genes in CSR-T-3 treatment. LC-MS and gene expression analysis could ascertain the upregulation of genes involved in mycoparasitism and the signal transduction pathway leading to secondary metabolite production under CSR-T-3 treatment. The plants in the field study showed a reduced disease severity index (1.14) with high phenological growth and yield indices when treated with T. reesei isolate CSR-T-3 formulation. We report here an effective biocontrol-based management technological transformation from lab to the field for successful control of Fusarium wilt disease caused by Foc TR4 in bananas.

Optimisation of extraction procedure and development of LC-DAD-MS methodology for anthocyanin analysis in anthocyanin-pigmented corn kernels

An ultra-high-performance liquid chromatography-diode array detector-mass spectrometry method was developed for characterisation and quantification of anthocyanin components in complex corn-kernel matrices. The anthocyanin profiles and total anthocyanin content (TAC) of mature seeds of five types of anthocyanin-pigmented corn were reported. Internal standard was used to validate the efficiency of extraction and optimise the liquid extraction procedure for anthocyanins. A total of eighteen anthocyanins were identified and quantified. Cyanidin-based glucosides were the major pigments of purple-pericarp sweetcorn (75.5% of TAC) and blue-aleurone maize (91.6%), while pelargonidin-based glucosides composed the main anthocyanins of reddish-purple-pericarp sweetcorn (61.1%) and cherry-aleurone maize (74.6%). Importantly, previous studies reported the presence of acetylated and succinylated anthocyanins in corn kernels; these compounds were found to be artefact pigments, generated during the extraction process. These crucial findings provide the correct anthocyanin profiles of pigmented corns, and emphasise the importance of using acidified solutions for the extraction of corn-based anthocyanins.

Anthocyanin composition and changes during kernel development in purple-pericarp supersweet sweetcorn

The current study reports the anthocyanin profile of purple 'supersweet' sweetcorn, recently developed from purple Peruvian maize, and the effect of kernel maturity on anthocyanin accumulation. Twenty anthocyanin compounds, consisting of cyanidin-, peonidin-, and pelargonidin-based glucosides, were identified and quantified in purple- and reddish-purple-pericarp sweetcorn accessions. For the first time, four isomers of cyanidin-3-malonylglucoside, four isomers of pelargonidin-3-malonylglucoside and two to three isomers each of cyanidin-3-dimalonylglucoside, peonidin-3-malonylglucoside and pelargonidin-3-dimalonylglucoside, were identified in the new pigmented sweetcorn. While cyanidin-based glucosides predominated in the purple-pericarp accession, pelargonidin-based glucosides predominated in the reddish-purple accession. Total anthocyanin concentration increased significantly (p < 0.05) during the optimum sweetcorn eating period (23 to 28 DAP) and continued to increase as the kernels further matured (>28 DAP). As kernels continued to mature, pigment coverage across the pericarp progressively increased from a small spot at the stigma end of the kernel, to gradually spreading over the entire kernel.

Extraction techniques and analysis of anthocyanins from food sources by mass spectrometry: An update

This article reviews recent developments in methods of sample preparation and analytical methodologies for the quantification of anthocyanins and their extraction from food sources. Various methods for sample extraction and purification are highlighted and evaluated. The use of UV-diode array, along with improved liquid chromatography (LC) and mass spectrometry (MS) and/or the combination of both methods have facilitated the identification of analytes. The use of one-dimensional and two-dimensional HPLC has significantly improved resolution with a shorter amount of time. Other LC × LC combinations to improve orthogonality are also discussed. The most efficient anthocyanin extraction method from food sources is pressurized liquid extraction. Moreover, electrospray ionization (ESI) and MS²/time-of-flight are currently the most popular instruments used for identification of anthocyanins; being positive mode of ESI the most widely used procedure for anthocyanin identification. Several databases for mass spectrometry polyphenol identification have been described for reference.

Trends in Microextraction Techniques for Sample Preparation

Although analytical scientists equivocally agree that “no sample preparation” would be the best approach, the fact is that all samples that are handled in any analytical laboratory need to undergo treatment to some extent prior to their introduction to the analytical instrument [...]