Influence of Degree-of-Polymerization and Linkage on the Quantification of Proanthocyanidins using 4-Dimethylaminocinnamaldehyde (DMAC) Assay

Genotypic Variation and Potential Mechanisms of Resistance against Multiple Insect Herbivores in Cranberries

Plant genotypes often exhibit varying resistance levels to herbivores. However, the impact of this genotypic variation on resistance against multiple herbivores remains poorly understood, especially in crops undergoing recent process of domestication. To address this gap, we studied the magnitude and mechanism of resistance in 12 cranberry (Vaccinium macrocarpon) genotypes to three leaf-chewing herbivores - Sparganothis fruitworm (Sparganothis sulfureana), spotted fireworm (Choristoneura parallela), and spongy moth (Lymantria dispar) - along a domestication gradient (native 'wild' genotypes, 'early hybrid' genotypes, and 'modern hybrid' genotypes). Like cranberries, S. sulfureana and C. parallela are native to the United Sates, while L. dispar is an invasive pest. We measured the survival and growth of larvae on each genotype, as well as variation in plant performance (height and biomass) and leaf defensive chemical traits (C/N ratio, total phenolics, total proanthocyanidins, and flavonols levels) in these genotypes to elucidate potential resistance mechanisms. We found differences in C. parallela and L. dispar larval performance across genotypes, with larvae performing better on the modern hybrid genotypes, while S. sulfureana showed no differences. Morphological and chemical traits varied among genotypes, with total phenolics being the only trait correlated with C. parallela and L. dispar larval performance. Notably, the wild genotypes 'McFarlin' and 'Potter' had higher total phenolics and were more resistant to both herbivores than the modern hybrids 'Demoranville' and 'Mullica Queen.' This research contributes to a comprehensive understanding of the impact of crop domestication on multiple insect herbivores, offering insights for future breeding efforts to enhance host-plant resistance against agricultural pests.

Boosting the Antioxidant Potential of Polymeric Proanthocyanidins in Litchi (Litchi chinensis Sonn.) Pericarp via Biotransformation of Utilizing Lactobacillus Plantarum

In order to enhance the efficient utilization of polymeric proanthocyanidins from litchi pericarp, a process for transforming litchis' polymeric proanthocyanidins (LPPCs) by using Lactobacilli has been established for products with highly antioxidative properties. Lactobacillus plantarum was selected to enhance the transformation effect. The transformation rate of LPPCs reached 78.36%. The content of litchis' oligomeric proanthocyanidins (LOPCs) in the products achieved 302.84 μg grape seed proanthocyanidins (GPS)/mg DW, while that of total phenols was 1077.93 gallic acid equivalents (GAE) μg/mg DW. Seven kinds of substances have been identified in the products by using the HPLC-QTOF-MS/MS method, among which 4-hydroxycinnamic acid, 3,4-dihydroxy-cinnamic acid, and proanthocyanidin A2 were major components. The in vitro antioxidative activity of the products after transformation was significantly (p < 0.05) higher than those of LOPCs and LPPCs. The scavenging activity of the transformed products for DPPH free radicals was 1.71 times that of LOPCs. The rate of inhibiting conjugated diene hydroperoxides (CD-POV) was 2.0 times that of LPPCs. The scavenging activity of the products for ABTS free radicals was 11.5 times that of LPPCs. The ORAC value of the products was 4.13 times that of LPPCs. In general, this study realizes the transformation of polymeric proanthocyanidins into high-activity small-molecule substances.

Fluorogenic properties of 4-dimethylaminocinnamaldehyde (DMACA) enable high resolution imaging of cell-wall-bound proanthocyanidins in plant root tissues

Proanthocyanidins (PAs) are polymeric phenolic compounds found in plants and used in many industrial applications. Despite strong evidence of herbivore and pathogen resistance-related properties of PAs, their in planta function is not fully understood. Determining the location and dynamics of PAs in plant tissues and cellular compartments is crucial to understand their mode of action. Such an approach requires microscopic localization with fluorescent dyes that specifically bind to PAs. Such dyes have hitherto been lacking. Here, we show that 4-dimethylaminocinnamaldehyde (DMACA) can be used as a PA-specific fluorescent dye that allows localization of PAs at high resolution in cell walls and inside cells using confocal microscopy, revealing features of previously unreported wall-bound PAs. We demonstrate several novel usages of DMACA as a fluorophore by taking advantage of its double staining compatibility with other fluorescent dyes. We illustrate the use of the dye alone and its co-localization with cell wall polymers in different Populus root tissues. The easy-to-use fluorescent staining method, together with its high photostability and compatibility with other fluorogenic dyes, makes DMACA a valuable tool for uncovering the biological function of PAs at a cellular level in plant tissues. DMACA can also be used in other plant tissues than roots, however care needs to be taken when tissues contain compounds that autofluoresce in the red spectral region which can be confounded with the PA-specific DMACA signal.

Tackling the Future Pandemics: Broad-Spectrum Antiviral Agents (BSAAs) Based on A-Type Proanthocyanidins

A-type proanthocyanidins (PAC-As) are plant-derived natural polyphenols that occur as oligomers or polymers of flavan-3-ol monomers, such as (+)-catechin and (-)-epicatechin, connected through an unusual double A linkage. PAC-As are present in leaves, seeds, flowers, bark, and fruits of many plants, and are thought to exert protective natural roles against microbial pathogens, insects, and herbivores. Consequently, when tested in isolation, PAC-As have shown several biological effects, through antioxidant, antibacterial, immunomodulatory, and antiviral activities. PAC-As have been observed in fact to inhibit replication of many different human viruses, and both enveloped and non-enveloped DNA and RNA viruses proved sensible to their inhibitory effect. Mechanistic studies revealed that PAC-As cause reduction of infectivity of viral particles they come in contact with, as a result of their propensity to interact with virion surface capsid proteins or envelope glycoproteins essential for viral attachment and entry. As viral infections and new virus outbreaks are a major public health concern, development of effective Broad-Spectrum Antiviral Agents (BSAAs) that can be rapidly deployable even against future emerging viruses is an urgent priority. This review summarizes the antiviral activities and mechanism of action of PAC-As, and their potential to be deployed as BSAAs against present and future viral infections.

Membrane-based Operations for the Fractionation of Polyphenols and Polysaccharides From Winery Sludges

The present work investigated the impact of ultrafiltration (UF) and nanofiltration (NF) membranes on the recovery and fractionation of polyphenolic compounds and polysaccharides from Sangiovese and Cabernet Sauvignon wine lees. A laboratory-made flat-sheet membrane in cellulose acetate (CA400-38) was used in the UF treatment of Sangiovese wine lees; three laboratory-made flat-sheet membranes in cellulose acetate (CA316, CA316-70, CA400-22) and a polyamide commercial membrane (NF90) were used in the NF treatment of Cabernet Sauvignon wine lees. All membranes were characterized in terms of hydraulic permeability and rejection toward references solutes; the performances of the membranes were measured in terms of productivity, fouling index, cleaning efficiency and retention toward target compounds.

Experimental results indicated that all UF and NF membranes were effective in separating target compounds rejecting more than 92% of polysaccharides with polyphenols preferentially permeating through the membrane. The UF membrane rejected more than 40% of total polyphenols; rejections toward non-flavonoids and flavonoids were less than 25% and 12.5%, respectively.

The laboratory-made NF membranes exhibited higher permeate flux values (of the order of 11–12 L/m2h) in comparison with the commercial NF membrane, despite the observed differences in the retention of specific solutes. Among the prepared membranes the CA316 showed a total rejection toward most part of non-flavonoids and flavonoids.

The experimental results support the use of UF and NF processes in a sequential design to fractionate and refine phenolic compounds from winery sludge for the production of concentrated fractions with high antioxidant activities.

Condensed Tannins, a Viable Solution To Meet the Need for Sustainable and Effective Multifunctionality in Food Packaging: Structure, Sources, and Properties

Condensed tannins (CT) have been the focus of increasing interest in the last years as a result of their potent biological properties, which have prompted their use in the food and feed sector as functional ingredients. The possible exploitation of these compounds as multifunctional additives for the implementation of active food packaging has also been recently appreciated. In this perspective, an overview of the structural features, accessible sources, methods of analysis, and functional properties of CT is provided, with the aim of critically emphasizing the opportunities offered by this widespread class of natural phenolic compounds for the rational design of multifunctional and sustainable food packaging materials.

Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols

Phenolic compounds such as phenolic acids, flavonoids, and stilbenes comprise an enormous family of bioactive molecules with a range of positive properties, including antioxidant, antimicrobial, or anti-inflammatory effects. As a result, plant extracts are often purified to recover phenolic compound-enriched fractions to be used to develop nutraceutical products or dietary supplements. In this article, we review the properties of some remarkable plant-based nutraceuticals in which the active molecules are mainly polyphenols and related compounds. Methods for the characterization of these extracts, the chemical determination of the bioactivities of key molecules, and the principal applications of the resulting products are discussed in detail.

Reactivity of flavanols: Their fate in physical food processing and recent advances in their analysis by depolymerization

Flavanols, a subgroup of polyphenols, are secondary metabolites with antioxidant properties naturally produced in various plants (e.g., green tea, cocoa, grapes, and apples); they are a major polyphenol class in human foods and beverages, and have recognized effect on maintaining human health. Therefore, it is necessary to evaluate their changes (i.e., oxidation, polymerization, degradation, and epimerization) during various physical processing (i.e., heating, drying, mechanical shearing, high-pressure, ultrasound, and radiation) to improve the nutritional value of food products. However, the roles of flavanols, in particular for their polymerized forms, are often underestimated, for a large part because of analytical challenges: they are difficult to extract quantitatively, and their quantification demands chemical reactions. This review examines the existing data on the effects of different physical processing techniques on the content of flavanols and highlights the changes in epimerization and degree of polymerization, as well as some of the latest acidolysis methods for proanthocyanidin characterization and quantification. More and more evidence show that physical processing can affect content but also modify the structure of flavanols by promoting a series of internal reactions. The most important reactivity of flavanols in processing includes oxidative coupling and rearrangements, chain cleavage, structural rearrangements (e.g., polymerization, degradation, and epimerization), and addition to other macromolecules, that is, proteins and polysaccharides. Some acidolysis methods for the analysis of polymeric proanthocyanidins have been updated, which has contributed to complete analysis of proanthocyanidin structures in particular regarding their proportion of A-type proanthocyanidins and their degree of polymerization in various plants. However, future research is also needed to better extract and characterize high-polymer proanthocyanidins, whether in their native or modified forms.

Liquid Chromatographic Fingerprints for the Characterization of Flavanol-Rich Nutraceuticals Based on 4-Dimethylaminocinnamaldehyde Precolumn Derivatization

Flavanols consist of a great family of bioactive molecules displaying a wide range of health-promoting attributes for humans, including antioxidant, antimicrobial or anti-inflammatory effects. As a result, botanical species rich in this type of compound are often used to develop nutraceutical products or dietary supplements with recognized healthy attributes. This paper aims at characterizing nutraceutical products using liquid chromatographic fingerprints related to flavanol composition. Catechins and their oligomers were exploited to characterize and authenticate various commercial products prepared with extracts of red berries and medicinal plants. These compounds resulted in interesting descriptors of some fruits and vegetables, thus providing an additional perspective for the study of nutraceuticals. For such a purpose, a new method based on liquid chromatography with UV/Vis detection (HPLC–UV/Vis) with precolumn derivatization with 4-dimethylaminocinnamaldehyde was developed. Results indicated that the separation of flavanols was very complex due to the degradation of procyanidin derivatives. The resulting data sets were analyzed using chemometric methods such as principal component analysis and partial least square–discriminant analysis. Despite the complexity of chromatographic fingerprints, nutraceutical samples could be discriminated according to their main ingredients. In general, catechin and epicatechin were the most abundant compounds in the different samples, and procyanidin A2 was highly specific to cranberry.

Identification of an anti-plant-virus molecule in Alpinia zerumbet

In plants, viral diseases are second only to fungal diseases in terms of occurrence, and cause substantial damage to agricultural crops. The aqueous extracts of shell ginger, Alpinia zerumbet exhibit inhibitory effects against virus infections in belonging to the Solanaceae family. In this study, we isolated an anti-plant-virus molecule from the extracts using a conventional method involving a combination of reversed phase column chromatography, dialysis, and lyophilization. The anti-plant-virus molecule was identified as proanthocyanidin, which mostly consisted of epicatechin and exhibited more than 40 degrees of polymerization.

Recovery of Phenolic Compounds from Red Grape Pomace Extract through Nanofiltration Membranes

The winemaking process generates a large amount of residues such as vine shots, stalks, grape pomace, and wine lees, which were only recently considered for exploitation of their valuable compounds. The purpose of this work was to investigate the performance of nanofiltration for the recovery of phenolic compounds, with bioactive capacity like antioxidant, from red grape pomace extract. Four membranes were compared in this study-three cellulose acetate (CA series: lab-prepared by phase inversion) and one commercial (NF90). All membranes were characterized for their hydraulic permeability and rejection coefficients to reference solutes like saccharose, glucose, raffinose, polyethylene glycol, sodium chloride, and sodium sulfate. Permeation flowrates and rejection coefficients towards total phenolics content, antioxidant activity, proanthocyanidins, glucose and fructose were measured in the nanofiltration of grape pomace extract using selected operating conditions. Among the investigated membranes, the CA400-22 exhibited the highest permeate flux (50.58 L/m² h at 20 bar and 25 °C), low fouling index (of about 23%), the lowest rejection coefficients towards the reference solutes and the best performance in terms of separation between sugars and phenolic compounds. Indeed, the observed rejections for glucose and fructose were 19% and 12%, respectively. On the other hand, total phenolics content and proanthocyanidins were rejected for 73% and 92%, respectively.

Quantification of cranberry proanthocyanidins by normal-phase high-performance liquid chromatography using relative response factors

INTRODUCTION

American cranberries (Vaccinium macrocarpon) contain primarily A-type proanthocyanidins (PACs), which have been shown to prevent urinary tract infection. Currently, the accurate quantification of cranberry PACs is still lacking.

OBJECTIVE

A normal-phase high-performance liquid chromatography (NP-HPLC) method using relative response factors was developed and validated to quantify cranberry PAC oligomers and polymers.

MATERIALS AND METHODS

PAC oligomers with degree of polymerisation (DP) 3-9 and total polymers were isolated from the cranberry juice concentrate. Characterisation of the isolated PAC oligomers was performed by ultra-performance liquid chromatography-high resolution mass spectrometry. The relative response factors of oligomers from DP 2-9 and total polymers were determined against procyanidin A2. Method validation was conducted to assess limit of detection, limit of quantification, the linearity and working range, precision and accuracy. In addition, quantifications of PACs by NP-HPLC using relative response factors and two other commonly used methods were conducted in three cranberry food products.

RESULTS

Cranberries PACs oligomers contained both A-type and B-type linkage, with epicatechin and epigallocatechin as basic units. Method validation results suggested this method is reliable and reproducible. Quantifications of PACs by NP-HPLC using relative response factors yielded higher values than that by the other two methods.

CONCLUSION

A NP-HPLC method using the relative response factors was developed and validated. This method provides a more accurate approach in determining cranberry PACs. It can be used to quantify individual oligomers from DP 2-9, total polymers and total PACs in cranberries and cranberry products.

Identification of a Proanthocyanidin from Litchi Chinensis Sonn. Root with Anti-Tyrosinase and Antioxidant Activity

This work follows an ethnobotanical study that took place in the island of Mayotte (France), which pointed out the potential properties of Litchi chinensis Sonn. roots when used to enhance skin health and appearance. Through in vitro testing of a crude methanolic extract, high anti-tyrosinase (skin whitening effect) and antioxidant activities (skin soothing effect) could be measured. HPLC successive bio-guided fractionation steps allowed the purification of one of the compounds responsible for the biological activities. The isolated compound was characterized by UV, IR, MS and 2D-NMR, revealing, for the first time in Litchi chinensis Sonn. roots, an A-type proanthocyanidin and thus revealing a consensus among the traditional use shown by the ethnobotanical study, in vitro biological activities and chemical characterization.

Multiscale Localization of Procyanidins in Ripe and Overripe Perry Pears by Light and Transmission Electron Microscopy

Histochemical staining with 4-dimethylaminocinnamaldehyde (DMACA), light microscopy, and transmission electron microscopy (TEM) were applied to characterize procyanidin localization at ripe and overripe stages in perry pear flesh (cv. 'De Cloche'). Pear flesh contained stone cell clusters surrounded by very large parenchyma cells. DMACA staining showed procyanidins mainly located in parenchyma cells from the fruit mesocarp. Under light microscopy and TEM, procyanidins appeared in the vacuole of parenchyma cells as uniformly stained granules, probably tannosomes. They were differently dispersed in ripe and overripe perry pears, as the granules remained free inside the vacuole in ripe pears and mostly attached to the tonoplast in overripe pears.

Tri- and Tetrameric Proanthocyanidins with Dentin Bioactivities from Pinus massoniana

Guided by dentin biomechanical bioactivity, this phytochemical study led to the elucidation of an extended set of structurally demanding proanthocyanidins (PACs). Unambiguous structure determination involved detailed spectroscopic and chemical characterization of four A-type dimers (2 and 4-6), seven trimers (10-16), and six tetramers (17-22). New outcomes confirm the feasibility of determining the absolute configuration of the catechol monomers in oligomeric PACs by one-dimensional (1D) and two-dimensional (2D) NMR. Electronic circular dichroism as well as phloroglucinolysis followed by mass spectrometry and chiral phase high-performance liquid chromatography (HPLC) analysis generated the necessary chiral reference data. In the context of previously reported dentin-bioactive PACs, accurately and precisely assigned ¹³C NMR resonances enabled absolute stereochemical assignments of PAC monomers via (i) inclusion of the ¹³C NMR γ-gauche effect and (ii) determination of differential ¹³C chemical shift values (Δδ_C) in comparison with those of the terminal monomer (unit II) in the dimers 2 and 4-6. Among the 13 fully elucidated PACs, eight were identified as new, and one structure (11) was revised based on new knowledge gained regarding the subtle, stereospecific spectroscopic properties of PACs.

Quantitative analysis of proanthocyanidins in cocoa using cysteamine-induced thiolysis and reversed-phase UPLC

The thiolysis of B-type proanthocyanidins in cocoa by cysteamine was evaluated and optimized for its application in cocoa proanthocyanidin quantification. Four thiolysis products consisting of epicatechin, catechin, and their thioethers formed with cysteamine were separated and characterized by reversed-phase UPLC with photo diode array (PDA) detection and high-resolution mass spectrometry (HRMS). A thiolysis time of 20 min under 60 °C temperature was determined as the optimal condition for cocoa proanthocyanidin depolymerization. The optimized thiolysis condition was applied to four cocoa bean samples for proanthocyanidin quantification, using commercially available procyanidin B2 dimer as a reference standard. Satisfactory linearity and quantification and detection limits were achieved for the calibration curves, and proanthocyanidin contents determined by thiolysis were found to be higher than those determined by a published method based on normal-phase HPLC with fluorescence detection. Results in this study suggest promising application potential of cysteamine as an odorless thiolysis agent in routine quantitative analysis of B-type proanthocyanidins. Graphical abstract.

Composition of Anthocyanins and Proanthocyanidins in Three Tropical Vaccinium Species from Costa Rica

Total polyphenol content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC), and proanthocyanidin (PAC) content were determined in fruit from three tropical Vaccinium species (Vaccinium consanguineum, Vaccinium floribundum, and Vaccinium poasanum) from Costa Rica sampled at three stages of fruit development. Results show that TAC increased as the fruit developed, while TPC, TFC, and PAC content decreased. Anthocyanin profiles were evaluated using electrospray ionization tandem mass spectrometry. Cyanidin and delphinidin glycosides were the predominant anthocyanins for the three tropical Vaccinium species. Proanthocyanidins were characterized using attenuated total reflection Fourier transform infrared spectroscopy, nuclear magnetic resonance, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presence of procyanidin structures with B-type interflavan bonds were observed, but deconvolution of mass spectrometry isotope patterns indicated that PACs with one or more A-type interflavan bonds accounted for more than 74% of the oligomers at each degree of polymerization.

Comparison of Common Analytical Methods for the Quantification of Total Polyphenols and Flavanols in Fruit Juices and Ciders

Multiple analytical methods are used for quantification of total polyphenols and total flavanols in fruit juices and beverages. Four methods were evaluated in this study: Folin-Ciocalteu (F-C), Lowenthal permanganate (L-P), 4-dimethylaminocinnamaldehyde (DMAC), and the bovine serum albumin (BSA) precipitation method. Method validation parameters, including working range, limit of detection, limit of quantitation, precision (repeatability), accuracy, and specificity, were assessed and compared. The F-C method was not specific to polyphenols, and the L-P method had the widest working range but lacked accuracy. The DMAC method was the most specific to flavanols, and the BSA method was not suitable for quantification of smaller flavanols, such as catechin and epicatechin. Quantitative performance was evaluated using commercial fruit juice samples (n = 14), apple juice samples of different cultivars (n = 22), and commercial ciders (n = 17). In general, the L-P titration method and DMAC method resulted in higher quantitative values than the F-C method and BSA precipitation method, respectively. However, ratios of results obtained by the L-P and F-C method ranged from 1 to 28, and ratios of results obtained by the DMAC and BSA precipitation method ranged from <1 to 280. This tremendous variation is likely due to variation in polyphenol composition and sample matrix. This information provides perspective for comparison of results obtained through these different methods, and a basis for choosing the most appropriate analytical method for quantification of polyphenols to address a specific research question when working with commercial fruit juice, apple juice from different apple cultivars, and commercial ciders. PRACTICAL APPLICATION: This study compared results obtained when four common polyphenol quantification methods were applied to a diverse selection of fruit juices and beverages with distinct polyphenol composition and sample matrix. The matrix and polyphenol composition of the samples significantly influenced the results. Our findings can help manufacturers of fruit-based products choose the most appropriate analytical method for polyphenol quantification as part of a quality assurance program or to convey information on dietary polyphenol content to consumers. An assessment of analytical method validation parameters is provided for each of the four methods, which will help users of these methods to understand their limitations.

Evaluation of the Degree of Polymerization of the Proanthocyanidins in Cranberry by Molecular Sieving and Characterization of the Low Molecular Weight Fractions by UHPLC-Orbitrap Mass Spectrometry

4-dimethylammino-cinnamaldehyde (DMAC) assays quantify total proanthocyanidins (PACs) but do not provide qualitative PAC molecular weight distribution information and cannot discriminate between A- and B-type PACs. We developed an efficient method for assessing PAC molecular weight distributions. The PACs from three commercial cranberry extracts (A1-A3) were fractionated by molecular sieves with cut-offs of 3, 10, 30, 50, and 100 kDa, and each fraction was analyzed by DMAC assays. A1, A2, and A3 contained 27%, 33%, and 15% PACs, respectively. Approximately 28 PACs, 20 flavonols, and 15 phenolic acids were identified by UHPLC-DAD-Orbitrap MS in A1 and A3, while A2 contained only flavan-3-ols. Epicatechin was the main monomer in A1 and A3, and catechin was the main in A2. Procyanidin A2 was the main dimer in A1 and A3, representing more than 85% of the total dimers, while it constituted approximately only 24% of A2. A1 and A3 contained quercetin, isorhamnetin, myricetin, and their glycosides, which were totally absent in A2. In A1 and A3 the PACs were mainly distributed in the fractions 30-3 and <3 kDa, while in A2 more than 70% were present in the fraction less than 3 kDa. Overall, obtained data strongly suggests that A2 is not cranberry-derived, or is adulterated with another source of PACs.

Development of a Thiolysis HPLC Method for the Analysis of Procyanidins in Cranberry Products

The objective of this study was to develop a thiolysis HPLC method to quantify total procyanidins, the ratio of A-type linkages, and A-type procyanidin equivalents in cranberry products. Cysteamine was utilized as a low-odor substitute of toluene-α-thiol for thiolysis depolymerization. A reaction temperature of 70 °C and reaction time of 20 min, in 0.3 M of HCl, were determined to be optimum depolymerization conditions. Thiolytic products of cranberry procyanidins were separated by RP-HPLC and identified using high-resolution mass spectrometry. Standards curves of good linearity were obtained on thiolyzed procyanidin dimer A2 and B2 external standards. The detection and quantification limits, recovery, and precision of this method were validated. The new method was applied to quantitate total procyanidins, average degree of polymerization, ratio of A-type linkages, and A-type procyanidin equivalents in cranberry products. Results showed that the method was suitable for quantitative and qualitative analysis of procyanidins in cranberry products.

Black Currant (Ribes nigrum L.) and Bilberry (Vaccinium myrtillus L.) Fruit Juices Inhibit Adhesion of Asaia spp

The aim of the study was to evaluate the activity of high-polyphenolic black currant (Ribes nigrum L.) and bilberry (Vaccinium myrtillus L.) juices against bacterial strains Asaia lannensis and Asaia bogorensis isolated as spoilage of commercial soft drinks. The composition of fruit juices was evaluated using chromatographic techniques HPLC and LC-MS. The adhesion to glass, polystyrene, and polyethylene terephthalate in two different culture media was evaluated by luminometry and the plate count method. The major anthocyanins in the V. myrtillus were petunidin-3-glucoside, malvidin-3-glucoside, cyanidin-3-glucoside, and delphinidin-3-glucoside, while in R. nigrum delphinidin-3-rutinoside and cyanidin-3-rutinoside were detected. The LC-MS analysis showed presence of anthocyanins (delphinidin, cyanidin, petunidin, and malvidin derivatives), phenolic acids (chlorogenic and neochlorogenic acids), flavonols (quercetin-3-glucoside, quercetin-3-rutinoside), and flavanols (procyanidin B2 and procyanidin type A2). Additionally, in the bilberry juice A type procyanidin trimer was detected. The adhesion of Asaia spp. cells depended on the type of medium, carbon sources, and the type of abiotic surfaces. We noted that the adhesion was significantly stronger in minimal medium containing sucrose. The addition of bilberry and black currant juices notably reduced bacterial growth as well as cell adhesion to polyethylene terephthalate surfaces.