Analysis and Antioxidant Capacity of Anthocyanin Pigments. Part IV: Extraction of Anthocyanins

The Structure, Functions and Potential Medicinal Effects of Chlorophylls Derived from Microalgae

Microalgae are considered to be natural producers of bioactive pigments, with the production of pigments from microalgae being a sustainable and economical strategy that promises to alleviate growing demand. Chlorophyll, as the main pigment of photosynthesis, has been widely studied, but its medicinal applications as an antioxidant, antibacterial, and antitumor reagent are still poorly understood. Chlorophyll is the most important pigment in plants and algae, which not only provides food for organisms throughout the biosphere, but also plays an important role in a variety of human and man-made applications. The biological activity of chlorophyll is closely related to its chemical structure; its specific structure offers the possibility for its medicinal applications. This paper reviews the structural and functional roles of microalgal chlorophylls, commonly used extraction methods, and recent advances in medicine, to provide a theoretical basis for the standardization and commercial production and application of chlorophylls.

Effect of different concentrations of stem juice of Oxalis tuberosa Mol. and juice of the fruit of Gaultheria glomerata (Cav.) Sleumer on the antioxidant activity of the heat-treated functional beverage

Functional beverages with added health benefits are popular among peoples and athletes because they help them recover faster from intense workouts and perform better overall. This research set out to determine how well heat-treated stem juice from Oxalis tuberosa Mol. "oca" and fruit juice from Gaultheria glomerata (Cav.) Sleumer "laqa-laqa" performed as an antioxidant in a functional drink. The "oca" stems and the "laqa-laqa" fruit were collected to obtain the juice. For this study, 30 semi-trained panellists used sensory evaluation to rate four treatments (Bo, B1, B2, and B3) with varying quantities of "oca" and "laqa-laqa" juice. The results concluded that the treatment B2, which included 300 ml of "oca" stem juice, 800 ml of "laqa-laqa" juice, 1000 ml of treated water, and 220 g of refined sugar, was given the highest score after a physicochemical evaluation of its colour, smell, taste, and overall appearance. Similarly, the results showed that the protein content increased by 1.38%, the fat content by 1.08%, the moisture percentage by 99.5%, the ash content by 1.82%, and the carbohydrate content by 6.22% after B2 treatment. Similarly, results revealed significant enhancement in antioxidant profiling such as total polyphenols: 1825 mg of gallic acid/100 g and antioxidant Activity: 89.56% μmol of trolox /100 g. In conclusion, due to its high energy content and antioxidant activity, it may be a viable nutritional option for athletes who engage in rigorous, frequent physical exertion.

Effect of different extraction methods on antioxidant properties and encapsulation efficiency of anthocyanin of pomegranate peel

This study aimed to measure the efficiency, total anthocyanin content (TAC), and total phenol content (TPC) of pomegranate peel powder (PPP) extract from different extractions. Also, the characteristics of the nanoencapsulated extracts with maltodextrin (MD)/Lepidium perfoliatum (Qodume Shahri) seed gum were investigated. The highest and lowest extraction efficiency was related to solvent ethanol-water extraction (SEWE) (76.35%) and solvent ethanol extraction (SEE) (25.73%), respectively. Extracts obtained from microwave extraction (ME) and ultrasound extraction (UE) methods had the highest and lowest values of TAC (4.00-0.35) (mg C3G/g PPP) and TPC (702.13-232.58) (mg GAE/100 g sample), respectively. Peak 3213 in FT-IR indicates the O-H bond, which showed the highest content of phenolic compounds in the extract obtained from ME compared with SEE, SEWE, and UE. The nanoencapsulated extracts from SEE, SEE, and UE had the lowest particle size of peak 1, particle distribution in peak 1, and average particle size distribution compared with other extractions, respectively. The highest encapsulation efficiency of anthocyanin (EEA) and encapsulation efficiency of phenol (EEP) were related to UE (96.15%) and SEWE (86.57%), respectively. The EEP and EEA of SEE were not significantly different from ME and SEWE, respectively. On the other hand, the type and amount of extractive compounds in the extract have a great impact on the efficiency of nanoencapsulation and the average size distribution of nanoencapsulated particles. As a result, PPP extract is rich in antioxidant compounds, which can be determined by carefully examining the appropriate method of extraction and preservation of the extracted compounds.

DoMYB5 and DobHLH24, Transcription Factors Involved in Regulating Anthocyanin Accumulation in Dendrobium officinale

As a kind of orchid plant with both medicinal and ornamental value, Dendrobium officinale has garnered increasing research attention in recent years. The MYB and bHLH transcription factors play important roles in the synthesis and accumulation of anthocyanin. However, how MYB and bHLH transcription factors work in the synthesis and accumulation of anthocyanin in D. officinale is still unclear. In this study, we cloned and characterized one MYB and one bHLH transcription factor, namely, D. officinale MYB5 (DoMYB5) and D. officinaleb bHLH24 (DobHLH24), respectively. Their expression levels were positively correlated with the anthocyanin content in the flowers, stems, and leaves of D. officinale varieties with different colors. The transient expression of DoMYB5 and DobHLH24 in D. officinale leaf and their stable expression in tobacco significantly promoted the accumulation of anthocyanin. Both DoMYB5 and DobHLH24 could directly bind to the promoters of D. officinale CHS (DoCHS) and D. officinale DFR (DoDFR) and regulate DoCHS and DoDFR expression. The co-transformation of the two transcription factors significantly enhanced the expression levels of DoCHS and DoDFR. DoMYB5 and DobHLH24 may enhance the regulatory effect by forming heterodimers. Drawing on the results of our experiments, we propose that DobHLH24 may function as a regulatory partner by interacting directly with DoMYB5 to stimulate anthocyanin accumulation in D. officinale.

Phytochemical Composition of the Fruit of Large Cranberry (Vaccinium macrocarpon Aiton) Cultivars Grown in the Collection of the National Botanic Garden of Latvia

In this study, we conducted a qualitative and quantitative analysis of anthocyanins, proanthocyanidins, flavonols and triterpenoids in samples of introduced and bred large cranberry fruits from the collection of the National Botanic Garden of Latvia. The highest total anthocyanin levels (8638-9316 µg/g) were detected in the fruit samples of the cranberry cultivars 'Black Veil', 'Franclin' and 'Early Black'. The highest total proanthocyanidin levels (2775-3389 µg/g) were found in cranberries of cultivars 'Kalnciema Agrā', 'Kalnciema Tumšā', 'Searles', 'Howes', and 'Kalnciema Ražīgā'. The highest levels of flavonol compounds (1373-1402 µg/g) were detected in cranberries of cultivars 'Howes', 'Black Veil' and 'Salaspils Melnās'. The highest levels of triterpenoids (5292-5792 µg/g) were determined in cranberries of cultivars 'Kalnciema Agrā', 'Septembra', 'Džbrūklene' and 'Early Black'. The results of our study allow for the estimation of differences in the content of secondary metabolites in the fruit samples of the studied cranberry cultivars and for the selection of promising cultivars for further introduction and cultivation in the climatic conditions of the Baltic countries. These results are also important for the selection of the most promising cranberry cultivars for the preparation of cranberry raw material, and the high-quality composition of plant material ensures the effectiveness of cranberry supplements and other cranberry preparations.

Photochemistry, Functional Properties, Food Applications, and Health Prospective of Black Rice

This review investigates black rice’s photochemistry, functional properties, food applications, and health prospects. There are different varieties of black rice available in the world. The origins of this product can be traced back to Asian countries. This rice is also known as prohibited rice, emperor’s rice, and royal’s rice. Black rice is composed of different nutrients including fiber, protein, carbohydrates, potassium, and vitamin B complex. It contains an antioxidant called anthocyanin and tocopherols. Antioxidants are found mostly in foods that are black or dark purple. Due to its nutritious density, high fiber level, and high antioxidant content, black rice is a good alternative to white and brown rice. Utilizing black rice in various foods can enhance the nutritional value of food and be transformed into functional food items. Many noncommunicable diseases (NCDs) can be prevented by eating black rice daily, including cancer cells, atherosclerosis, hypertension, diabetes, osteoporosis, asthma, digestive health, and stroke risk. This review aim was to discuss the role of nutritional and functional properties of black rice in the formation of functional food against different noncommunicable diseases.

Onion anthocyanins: Extraction, stability, bioavailability, dietary effect, and health implications

Anthocyanins are high-value compounds, and their use as functional foods and their natural colorant have potential health benefits. Anthocyanins seem to possess antioxidant properties, which help prevent neuronal diseases and thereby exhibit anti-inflammatory, chemotherapeutic, cardioprotective, hepatoprotective, and neuroprotective activities. They also show different therapeutic effects against various chronic diseases. Anthocyanins are present in high concentrations in onion. In recent years, although both conventional and improved methods have been used for extraction of anthocyanins, nowadays, improved methods are of great importance because of their higher yield and stability of anthocyanins. In this review, we compile anthocyanins and their derivatives found in onion and the factors affecting their stability. We also analyze different extraction techniques of anthocyanins. From this point of view, it is very important to be precisely aware of the impact that each parameter has on the stability and subsequently potentiate its bioavailability or beneficial health effects. We present up-to-date information on bioavailability, dietary effects, and health implications of anthocyanins such as antioxidant, antidiabetic, anticancerous, antiobesity, cardioprotective, and hepatoprotective activities.

Up-To-Date Analysis of the Extraction Methods for Anthocyanins: Principles of the Techniques, Optimization, Technical Progress, and Industrial Application

Nowadays, food industries are concerned about satisfying legal requirements related to waste policy and environmental protection. In addition, they take steps to ensure food safety and quality products that have high nutritional properties. Anthocyanins are considered high added-value compounds due to their sensory qualities, colors, and nutritional properties; they are considered bioactive ingredients. They are found in high concentrations in many by-products across the food industry. Thus, the non-conventional extraction techniques presented here are useful in satisfying the current food industry requirements. However, selecting more convenient extraction techniques is not easy. Multiple factors are implicated in the decision. In this review, we compile the most recent applications (since 2015) used to extract anthocyanins from different natural matrices, via conventional and non-conventional extraction techniques. We analyze the main advantages and disadvantages of anthocyanin extraction techniques from different natural matrices and discuss the selection criteria for sustainability of the processes. We present an up-to-date analysis of the principles of the techniques and an optimization of the extraction conditions, technical progress, and industrial applications. Finally, we provide a critical comparison between these techniques and some recommendations, to select and optimize the techniques for industrial applications.

Alternative Extraction and Downstream Purification Processes for Anthocyanins

Anthocyanins are natural pigments displaying different attractive colors ranging from red, violet, to blue. These pigments present health benefits that increased their use in food, nutraceuticals, and the cosmetic industry. However, anthocyanins are mainly extracted through conventional methods that are time-consuming and involve the use of organic solvents. Moreover, the chemical diversity of the obtained complex extracts make the downstream purification step challenging. Therefore, the growing demand of these high-value pigments has stimulated the interest in designing new, safe, cost-effective, and tunable strategies for their extraction and purification. The current review focuses on the potential application of compressed fluid-based (such as subcritical and supercritical fluid extraction and pressurized liquid extraction) and deep eutectic solvents-based extraction methods for the recovery of anthocyanins. In addition, an updated review of the application of counter-current chromatography for anthocyanins purification is provided as a faster and cost-effective alternative to preparative-scale HPLC.

The isolation of water-soluble natural products - challenges, strategies and perspectives

Covering period: up to 2019Water-soluble natural products constitute a relevant group of secondary metabolites notably known for presenting potent biological activities. Examples are aminoglycosides, β-lactam antibiotics, saponins of both terrestrial and marine origin, and marine toxins. Although extensively investigated in the past, particularly during the golden age of antibiotics, hydrophilic fractions have been less scrutinized during the last few decades. This review addresses the possible reasons on why water-soluble metabolites are now under investigated and describes approaches and strategies for the isolation of these natural compounds. It presents examples of several classes of hydrosoluble natural products and how they have been isolated. Novel stationary phases and chromatography techniques are also reviewed, providing a perspective towards a renaissance in the investigation of water-soluble natural products.

Development of comprehensive liquid chromatography with diode array and mass spectrometric detection for the characterization of (poly-)phenolic and flavonoid compounds and application to asparagus

The main objective of the present work was to develop a method for the simultaneous and comprehensive analysis of (poly-)phenolic and flavonoid compounds with liquid chromatography with diode array and mass spectrometric detection and its application to green asparagus samples. To this end, a representative set of polyphenols was used to develop the method. A through method validation was carried out with these. The method was applied to asparagus samples known as a healthy vegetable being rich in bioactive compounds. Polyphenol contents of asparagus samples were determined by carrying out quantitative and qualitative analyses by LC-DAD-ESI/MS. In this context asparagus sample extracts were obtained using solvents of different polarity. The results were evaluated statistically and showed that rutin is the major phenolic compound in asparagus. This demonstrates the versatility of this rapid and sensitive method for the simultaneous analysis of (poly-)phenolic and flavonoid compounds which was successfully applied to asparagus samples.

State of the Art of Anthocyanins: Antioxidant Activity, Sources, Bioavailability, and Therapeutic Effect in Human Health

The antioxidant activity of anthocyanins in food is well known. Numerous antioxidant assays have been proposed to measure the capacity of anthocyanins to prevent the oxidation process that naturally occurs. Different solvents, temperatures, and pH levels are applied in each assay, and these factors should be taken into account in order to obtain useful and reproducible results. The concentration and the structure of these compounds are directly related to their antioxidant capacity and their environment. However, the effectiveness of the anthocyanin ingestion against diseases is also influenced by its bioavailability. Novel methodologies that simulate the digestion process have been developed in order to facilitate the current knowledge of anthocyanins bioavailability. Studies highlight the potential synergy effect between parent compounds and their derivatives (metabolites, conjugated products, and microbe-generated metabolites). The aim of this review is to provide an overview of advantages and disadvantages of the most common methods to determine the antioxidant activity of anthocyanins, chemical structure, and concentration of these compounds in different edible fruits, vegetables, and plants; their bioavailability after intake; as well as the main therapeutic effect described in the scientific literature.

Research Advances of Purple Sweet Potato Anthocyanins: Extraction, Identification, Stability, Bioactivity, Application, and Biotransformation

Purple sweet potato anthocyanins are kinds of natural anthocyanin red pigments extracted from the root or stem of purple sweet potato. They are stable and have the functions of anti-oxidation, anti-mutation, anti-tumor, liver protection, hypoglycemia, and anti-inflammation, which confer them a good application prospect. Nevertheless, there is not a comprehensive review of purple sweet potato anthocyanins so far. The extraction, structural characterization, stability, functional activity, application in the food, cosmetics, medicine, and other industries of anthocyanins from purple sweet potato, together with their biotransformation in vitro or by gut microorganism are reviewed in this paper, which provides a reference for further development and utilization of anthocyanins.

Production of pyranoanthocyanins using Escherichia coli co-cultures

Hydroxyphenyl-pyranoanthocyanins are one of the pyranoanthocyanins found in red wines and some fruit juices. Since they have a fourth ring (pyran or ring D) which provides higher color intensity and exceptional stability toward pH variations in comparison to their anthocyanin precursors, these molecules are one of the most important candidates as natural colorants especially for low- and medium-acidic food and beverages. However, their isolation and characterization are difficult due to their very low concentration. In this study, we co-cultured recombinant E. coli strains to synthesize pyranoanthocyanins with improved titers and yields. To accomplish this task, firstly we engineered 4-vinylphenol and 4-vinylcatechol producer modules then we co-cultured each one of these strains with cyanidin-3-O-glucoside producer recombinant cells to obtain pyranocyanidin-3-O-glucoside-phenol (cyanidin-3-O-glucoside with vinylphenol adduct) and pyranocyanidin-3-O-glucoside-catechol (cyanidin-3-O-glucoside with vinylcatechol adduct). By optimizing the co-culture conditions, we were able to significantly increase final titers and yields, allowing our co-culture approach to easily outperform production of pyranoanthocyanins from red wine. Finally, we demonstrate that the produced pyranoanthocyanins are far more stable than the starting plant-produced cyanidin 3-O-glucoside.

Recovery of Anthocyanins Using Membrane Technologies: A Review

Anthocyanins are naturally occurring polyphenolic compounds and give many flowers, fruits and vegetable their orange, red, purple and blue colors. Besides their color attributes, anthocyanins have received much attention in recent years due to the growing evidence of their antioxidant capacity and health benefits on humans. However, these compounds usually occur in low concentrations in mixtures of complex matrices, and therefore large-scale harvesting is needed to obtain sufficient amounts for their practical usage. Effective fractionation or separation technologies are therefore essential for the screening and production of these bioactive compounds. In this context, membrane technologies have become popular due to their operational simplicity, the capacity to achieve good simultaneous separation/pre-concentration and matrix reduction with lower temperature and lower operating cost in comparison to other sample preparation methods. Membrane fractionation is based on the molecular or particle sizes (pressure-driven processes), on their charge (electrically driven processes) or are dependent on both size and charge. Other non-pressure-driven membrane processes (osmotic pressure and vapor pressure-driven) have been developed in recent years and employed as alternatives for the separation or fractionation of bioactive compounds at ambient conditions without product deterioration. These technologies are applied either individually or in combination as an integrated membrane system to meet the different requirements for the separation of bioactive compounds. The first section of this review examines the basic principles of membrane processes, including the different types of membranes, their structure, morphology and geometry. The most frequently used techniques are also discussed. Last, the specific application of these technologies for the separation, purification and concentration of phenolic compounds, with special emphasis on anthocyanins, are also provided.

Spectrophotometric Analysis of Phenolic Compounds in Grapes and Wines

Phenolic compounds are of crucial importance for red wine color and mouthfeel attributes. A large number of enzymatic and chemical reactions involving phenolic compounds take place during winemaking and aging. Despite the large number of published analytical methods for phenolic analyses, the values obtained may vary considerably. In addition, the existing scientific knowledge needs to be updated, but also critically evaluated and simplified for newcomers and wine industry partners. The most used and widely cited spectrophotometric methods for grape and wine phenolic analysis were identified through a bibliometric search using the Science Citation Index-Expanded (SCIE) database accessed through the Web of Science (WOS) platform from Thompson Reuters. The selection of spectrophotometry was based on its ease of use as a routine analytical technique. On the basis of the number of citations, as well as the advantages and disadvantages reported, the modified Somers assay appears as a multistep, simple, and robust procedure that provides a good estimation of the state of the anthocyanins equilibria. Precipitation methods for total tannin levels have also been identified as preferred protocols for these types of compounds. Good reported correlations between methods (methylcellulose precipitable vs bovine serum albumin) and between these and perceived red wine astringency, in combination with the adaptation to high-throughput format, make them suitable for routine analysis. The bovine serum albumin tannin assay also allows for the estimation of the anthocyanins content with the measurement of small and large polymeric pigments. Finally, the measurement of wine color using the CIELab space approach is also suggested as the protocol of choice as it provides good insight into the wine's color properties.

Effect of fermentation and sterilization on anthocyanins in blueberry

BACKGROUND

Blueberry products have various health benefits due to their high content of dietary anthocyanins. The aim of this study was to investigate the impact of fermentation and sterilization on total anthocyanin content, composition and some quality attributes of blueberry puree. The blueberry puree used here was fermented for 40 h at 37 °C by Lactobacillus after sterilization. The method of ultra-performance liquid chromatography-mass spectrometry was optimized for the rapid analysis of anthocyanins. Quality attributes including pH, color, total soluble solids and viscosity were measured.

RESULTS

A total of 21 anthocyanins and five anthocyanidins were quantified by ultra-performance liquid chromatography. Fermented blueberry had reduced total anthocyanin content (29%) and levels of individual anthocyanins compared with fresh blueberry. Total anthocyanin content was decreased 46% by sterilization, and different degradation behavior of individual anthocyanin was appeared between fermented and sterilized-fermented blueberry puree. Fermentation and sterilization decreased the total soluble solids and pH and changed color parameters, while minimally influencing viscosity.

CONCLUSIONS

The loss of total anthocyanin content by fermentation was related to the unstable structure of blueberry anthocyanins. Anthocyanins are sensitive to temperature (>80 °C), and degradation of anthocyanins by sterilization in blueberry should be considered in the fermentation procedure. © 2016 Society of Chemical Industry.

Application of natural deep eutectic solvents to the extraction of anthocyanins from Catharanthus roseus with high extractability and stability replacing conventional organic solvents

Natural deep eutectic solvents (NADES) have attracted a great deal of attention in recent times as promising green media. They are generally composed of neutral, acidic or basic compounds that form liquids of high viscosity when mixed in certain molar ratio. Despite their potential, viscosity and acid or basic nature of some ingredients may affect the extraction capacity and stabilizing ability of the target compounds. To investigate these effects, extraction with a series of NADES was employed for the analysis of anthocyanins in flower petals of Catharanthus roseus in combination with HPLC-DAD-based metabolic profiling. Along with the extraction yields of anthocyanins their stability in NADES was also studied. Multivariate data analysis indicates that the lactic acid-glucose (LGH), and 1,2-propanediol-choline chloride (PCH) NADES present a similar extraction power for anthocyanins as conventional organic solvents. Furthermore, among the NADES employed, LGH exhibits an at least three times higher stabilizing capacity for cyanidins than acidified ethanol, which facilitates their extraction and analysis process. Comparing NADES to the conventional organic solvents, in addition to their reduced environmental impact, they proved to provide higher stability for anthocyanins, and therefore have a great potential as possible alternatives to those organic solvents in health related areas such as food, pharmaceuticals and cosmetics.

Development and validation of a liquid chromatography method for anthocyanins in strawberry (Fragaria spp.) and complementary studies on stability, kinetics and antioxidant power

A RPLC-DAD method for the analysis of eight anthocyanins was developed, validated and applied to strawberry extracts. The chromatographic method was conducted under gradient elution in acidulated water-methanol mobile phase and octadecyl-silica columns. An ultrasound extraction procedure was optimized by a 3(2) factorial design (%HCl in methanol, temperature, and time) and response surface methodology. Method validation was performed according to the following parameters: linearity (R(2)>0.99, p-value<10(-4), F>725), LOD (3-7 μmol L(-1)) and LOQ (9-22 μmol L(-1)), selectivity/specificity (baseline separation of all analytes and peak purity), instrumental precision (<6.4%CV), repeatability (<6.3%CV) and intermediate precision (<9.9%CV), recovery (83-99%), robustness (mobile phase pH, column temperature and flow rate) and stability (high temperatures and storage; 1st order kinetics). The antioxidant power of anthocyanins was measured on-line (ABTS(+) reaction; Trolox as reference). Ten strawberry extracts were quantified (average values: 24.2 μg/g for cyanidin-3-glucoside and 49.1 μg/g for pelargonidin-3-glucoside).