Bioactive Compounds from Norway Spruce Bark: Comparison Among Sustainable Extraction Techniques for Potential Food Applications

A new and highly efficient source of t-resveratrol: Cephalaria Syriaca (L.) Roem. & Schult

Recently, interest in bioactive plant compounds has increased due to their properties in preventing and treating diseases like cancer and neurodegenerative disorders. In this study, caffeic acid and t-resveratrol were extracted from Cephalaria syriaca seeds using ultrasonic assisted extraction (UAE) and supercritical carbon dioxide (Sc-CO2) extraction methods. Independent variables were temperature (40, 60, 80 °C), pressure (130, 215, and 300 bar), and co-solvent ratio (ethanol v/v (3.0, 6.5, 10.0%)) were selected. While extraction process conditions were optimized using response surface methodology, polyphenols were determined by an HPLC system. As a result of the Sc-CO2 experimental studies, maximum caffeic acid (88.75 ± 1.71 μg/g dw) was obtained at 80 °C, 130 bar, and 10% ethanol conditions and maximum t-resveratrol (2949.45 ± 51.78 μg/g dw) was obtained at 60 °C, 130 bar, and 6.5% ethanol conditions. The results of the UAE method were found to be 76.21 ± 2.40 μg/g dw caffeic acid and 4629 ± 123.2 μg/g dw t-resveratrol.

Digested galactoglucomannan mitigates oxidative stress in human cells, restores gut bacterial diversity, and provides chemopreventive protection against colon cancer in rats

Galactoglucomannan (GGM) is the predominant hemicellulose in coniferous trees, such as Norway spruce, and has been used as a multipurpose emulsifier in the food industry. In vitro digestion with a cellular antioxidant activity assay was performed to determine the bioaccessibility and antioxidant activity of phenolic compounds, and the behaviour of GGM on in vivo experimental assay against induced colon cancer. The results showed that digestion decreased the bioaccessibility and antioxidant capacity of phenolic compounds. Cellular analysis did not support these findings once an antioxidant effect was observed in human cell lines. GGM attenuated the initiation and progression of colon cancer, by reducing the foci of aberrant crypts in rats, and modified the intestinal bacterial microbiota (disrupting the balance between Firmicutes and Bacteroidetes phyla). Thus, GGM provided chemopreventive protection against the development of colon cancer and acted as an intracellular antioxidant agent.

Phytochemicals from Bark Extracts and Their Applicability in the Synthesis of Thermosetting Polymers: An Overview

This review focuses on recent research on the phytochemicals found in bark from different trees and their potential to be used as substrates for the synthesis of thermosetting resins. Recent studies about the influence of each bark harvesting step on the extracted phytochemicals, from debarking to extraction, are investigated. A comparison of bark extracts in terms of the correlation between extraction conditions and efficiency (based on the total phenolic content (TPC) and extraction yield) is presented for six groups of trees (Norway spruce, pine species, other conifers, oak species, other deciduous trees of the north temperate zone, tropical and subtropical trees) and evaluated. The evaluation revealed that there is an interesting relationship between the extraction time and the type of solvent for some types of tree bark. It was found that a relatively short extraction time and a solvent temperature close to the boiling point are favourable. The latest research on the application of bark extracts in different types of thermosetting resins is described. This review discusses the attractiveness of bark extracts in terms of functional groups and the possibilities arising from extractable phytochemicals. In addition, different approaches (selective versus holistic) and methods of application are presented and compared.

Extraction of Bioactive Compounds from Prestonia mollis Leaves and Their Impregnation into Polylactic Acid Using High-Pressure Technologies: Potential for Biomedical Application

Enhanced solvent extraction (ESE) and pressurized liquid extraction (PLE) have been used for the first time to obtain antioxidant compounds from Prestonia mollis leaves. The effects of pressure (100-250 bar), temperature (55-75 °C) and the composition of the extraction solvent (ethanol, water and hydroalcoholic mixtures) were evaluated according to multilevel factorial designs. PLE provided the largest extraction yields compared to ESE, as well as a greater impact of the operating conditions studied. The highest total phenolic content was obtained when using a hydroalcoholic mixture (CO2/ethanol/water 50/25/25) through ESE at 100 bar and 75 °C. The antioxidant capacity of this extract is related to higher concentration levels of the identified flavonoids: Quercetin 3-O-xylosyl-rutinoside, Kaempferol 3-(2G-apiosylrobinobioside) and Kaempferol 4'-glucoside 7-rhamnoside. This extract was tested for the supercritical impregnation of polylactic acid (PLA), which is a polymer widely used in the biomedical industry. The influence of pressure (100-400 bar), temperature (35-55 °C), amount of extract (3-6 mL) and impregnation time (1-2 h) have been evaluated. The best results were obtained by impregnating 3 mL of extract at 100 bar and 55 °C for 2 h, achieving 10% inhibition with DPPH methods. The extract presented a potentially suitable impregnation of PLA for biomedical applications.

Antioxidant and Wound Healing Bioactive Potential of Extracts Obtained from Bark and Needles of Softwood Species

Interest in the extraction of phytochemical bioactive compounds, especially polyphenols from biomass, has recently increased due to their valuable biological potential as natural sources of antioxidants, which could be used in a wide range of applications, from foods and pharmaceuticals to green polymers and bio-based materials. The present research study aimed to provide a comprehensive chemical characterization of the phytochemical composition of forest biomass (bark and needles) of softwood species (Picea abies L., H. Karst., and Abies alba Mill.) and to investigate their in vitro antioxidant and antimicrobial activities to assess their potential in treating and healing infected chronic wounds. The DPPH radical-scavenging method and P-LD were used for a mechanistic explanation of the biomolecular effects of the investigated bioactive compounds. (+)-Catechin, epicatechin, rutin, myricetin, 4 hydroxybenzoic and p-cumaric acids, kaempherol, and apigenin were the main quantified polyphenols in coniferous biomass (in quantities around 100 µg/g). Also, numerous phenolic acids, flavonoids, stilbenes, terpenes, lignans, secoiridoids, and indanes with antioxidant, antimicrobial, anti-inflammatory, antihemolytic, and anti-carcinogenic potential were identified. The Abies alba needle extract was more toxic to microbial strains than the eukaryotic cells that provide its active wound healing principles. In this context, developing industrial upscaling strategies is imperative for the long-term success of biorefineries and incorporating them as part of a circular bio-economy.

The Potential Value of Debarking Water as a Source of Polyphenolic Compounds for the Specialty Chemicals Sector

Forest-based industries produce huge quantities of bark during their primary processing activities. In Nordic pulp and paper industries, where a wet debarking process is used for bark removal, toxic debarking water and bark press water are produced as a by-product. However, polyphenols represent an important fraction of the debarking water and bark press water. These polyphenolic compounds are of commercial interest in chemical specialty sectors since polyphenols have been proven to have diverse health benefits, and after collecting them from waste sources, they can act as alternatives to oil-based chemicals. Determining the economic potential of polyphenolic compounds, identifying their molecular structure, and determining the antioxidant capacity of these compounds present in debarking water and bark can support the identification of their potential applications. The results show that water extractions from bark have a lower efficiency than (partial) alcoholic extractions. Nevertheless, a considerable amount of low-molecular polyphenolic compounds, which are of interest for high-end applications, was found in all extracts. Bark press water has a highly versatile range of polyphenolic compounds and showed some antioxidant activity, making it a great source for the collection of polyphenolic compounds, in contrast to debarking water, which had a much lower polyphenolic content and low antioxidant activity.

Volatile Compounds in Norway Spruce (Picea abies) Significantly Vary with Season

Norway spruce (Picea abies) is one of the most important commercial conifer species naturally distributed in Europe. In this paper, the composition and abundance of essential oil and hydrosol from the needles and branches of P. abies were investigated with an additional evaluation of changes related to different times of the year, annual shoots and branches, and differences in composition under different microenvironments. Essential oils and hydrosols obtained via hydrodistillation were analyzed using gas chromatography-mass spectrometry (GC-MS), where 246 compounds in essential oil and 53 in hydrosols were identified. The relative amounts of monoterpenes, sesquiterpenes, and diterpenes in essential oil changed significantly during the year, with the highest peak of monoterpenes observed in April (72%), the highest abundance of sesquiterpenes observed in August (21%), and the highest abundance of diterpenes observed in June (27%). The individual compound with the highest variation was manool, with variation from 1.5% (April) to 18.7% (June). Our results also indicate that the essential oil with the lowest allergenic potential (lowest quantity of limonene and linalool) was obtained in late spring or summer. Location had no significant influence on composition, while the method of collection for distillation (whole branch or annual shoots) had a minor influence on the composition. All nine main compounds identified in the hydrosol samples were oxygenated monoterpenes. The composition of P. abies hydrosol was also significantly affected by season. The method of preparing the branches for distillation did not affect the composition of P. abies hydrosol, while the location had a minor effect on composition.

Fundamental Insights on the Physical and Chemical Properties of Organosolv Lignin from Norway Spruce Bark

The interest in the bark and the attempt to add value to its utilization have increased over the last decade. By applying an integrated bark biorefinery approach, it is possible to investigate the recovery of compounds that can be used to develop green and sustainable alternatives to fossil-based materials. In this work, the focus is on extracting Norway spruce (Picea abies) bark lignin via organosolv extraction. Following the removal of the extractives and the subcritical water extraction to remove the polysaccharides, a novel cyclic organosolv extraction procedure was applied, which enabled the recovery of lignin with high quality and preserved structure. Main indicators for low degradation and preservation of the lignin structure were a high β-O-4' content and low amounts of condensed structures. Furthermore, high purity and low polydispersity of the lignin were observed. Thus, the obtained lignin exhibits high potential for use in the direct development of polymer precursors and other bio-based materials. During the extraction sequence, around 70% of the bark was extracted. Besides the lignin, the extractives as well as pectic polysaccharides and hemicelluloses were recovered with only minor degradation, which could potentially be used for the production of biofuel or other high-value products such as emulsifiers or adhesives.

From the forest to the plate - Hemicelluloses, galactoglucomannan, glucuronoxylan, and phenolic-rich extracts from unconventional sources as functional food ingredients

This study aimed to characterise pressurised hot water (PHW) extracts from nonconventional sources of functional carbohydrates and phenolic compounds in terms of antioxidant capacity, antiviral activity, toxicity, and human erythrocytes' protection antidiabetic potential. PHW extracts of Norway spruce bark (E1 + E2) and Birch sawdust (E3 + E4) contained mostly galactoglucomannan and glucuronoxylan. In contrast, samples E5 to E9 PHW extracted from Norway spruce, and Scots pine bark are rich sources of phenolic compounds. Overall, phenolic-rich extracts presented the highest inhibition of α-amylase and α-glucosidase and protection against stable non-enveloped enteroviruses. Additionally, all extracts protected human erythrocytes from hemolysis. Cell-based experiments using human cell lines (IMR90 and A549) showed extracts' non-toxicin vitroprofile. Considering the relative toxicological safety of extracts from these unconventional sources, functional carbohydrates and polyphenol-rich extracts can be obtained and further used in food models.

Underutilized Northern plant sources and technological aspects for recovering their polyphenols

Consumers worldwide are increasingly interested in the authenticity and naturalness of products. At the same time, the food, agricultural and forest industries generate large quantities of sidestreams that are not effectively utilized. However, these raw materials are rich and inexpensive sources of bioactive compounds such as polyphenols. The exploitation of these raw materials increases income for producers and processors, while reducing transportation and waste management costs. Many Northern sidestreams and other underutilized raw materials are good sources of polyphenols. These include berry, apple, vegetable, softwood, and rapeseed sidestreams, as well as underutilized algae species. Berry sidestreams are especially good sources of various phenolic compounds. This chapter presents the properties of these raw materials, providing an overview of the techniques for refining these materials into functional polyphenol-rich ingredients. The focus is on economically and environmentally sound technologies suitable for the pre-treatment of the raw materials, the modification and recovery of the polyphenols, as well as the formulation and stabilization of the ingredients. For example, sprouting, fermentation, and enzyme technologies, as well as various traditional and novel extraction methods are discussed. Regarding the extraction technologies, this chapter focuses on safe and green technologies that do not use organic solvents. In addition, formulation and stabilization that aim to protect isolated polyphenols during storage and extend shelflife are reviewed. The formulated polyphenol-rich ingredients produced from underutilized renewable resources could be used as sustainable, active ingredients--for example, in food and nutraceutical industries.

Phytochemical Profile and Biological Effects of Spruce (Picea abies) Bark Subjected to Ultrasound Assisted and Microwave-Assisted Extractions

The bark of various tree species is a byproduct of the forestry industry that is not used at its full potential, considering the wide range of phytochemicals that are contained in these vegetal matrices and the health benefits that these compounds could provide for society. Our goal was to assess and compare the phytochemical composition of some hydroalcoholic spruce (Picea abies) bark extracts attained by ultrasound assisted extraction (UAE) and microwave-assisted extraction (MAE) and their antioxidant and antibacterial effects. The levels of total phenolics and tannins in the bark extracts were determined using methods based on the Folin-Ciocâlteu reagent, while specific phenolic and volatile compounds were identified and quantified using an UPLC-PDA method and a GC-FID method, respectively. After the chemical composition assessment, the antioxidant capacity (AC) was evaluated by measuring the scavenging ability against two free radicals (DPPH and ABTS). The minimum inhibitory concentration (MIC) was determined to assess the antibacterial activity of the extracts. The results indicated that the extracts produced by UAE had higher contents of polyphenols and tannins and also a higher content of the main phenolic compounds identified, catechin and epicatechin, compared to the MAE extracts. In contrast the highest content of volatile terpenoids (mainly α- and β-pinene) was found in the MAE extracts. All of the tested extracts exhibited relatively high antioxidant activities (especially the UAE extracts) and low MICs against Gram-positive bacteria but were mildly efficient against Gram-negative bacteria. These findings show that the spruce bark might be an important source of bioactive compounds that can be easily extracted from these industrial secondary products. Various uses of this vegetal material may emerge, due to its antioxidant and antibacterial effects.

Natural Antioxidants: Innovative Extraction and Application in Foods

Research has devoted great attention to the study of the biological properties of plants, animal products, microorganisms, marine species, and fungi, among others, often driven by the need to discover new medicines [...].

Investigation of Total Phenolic Content and Antioxidant Activities of Spruce Bark Extracts Isolated by Deep Eutectic Solvents

Extracts from spruce bark obtained using different deep eutectic solvents were screened for their total phenolic content (TPC) and antioxidant activities. Water containing choline chloride-based deep eutectic solvents (DESs) with lactic acid and 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol, with different molar ratios, were used as extractants. Basic characteristics of the DESs (density, viscosity, conductivity, and refractive index) were determined. All the DESs used behave as Newtonian liquids. The extractions were performed for 2 h at 60 °C under continuous stirring. TPC was determined spectrophotometrically, using the Folin-Ciocalteu reagent, and expressed as gallic acid equivalent (GAE). The antioxidant activity was determined spectrophotometrically by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The TPC varied from 233.6 to 596.2 mg GAE/100 g dry bark; radical scavenging activity (RSA) ranged between 81.4% and 95%. This study demonstrated that deep eutectic solvents are suitable solvents for extracting phenolic compounds from spruce bark.

Ultrasonic-assisted extraction of polyphenols and antioxidants from Picea abies bark

Spruce bark represents a reservoir of bioactive compounds. The aim of this study was to investigate the effect of independent variables (temperature, liquid to solid ratio, time and methanol content) and their interaction within the extraction process by the response surface methodology (RSM). The effect of conventional (solvent extraction; SE) and modern (ultrasound-assisted extraction; UAE) methods for the extraction of antioxidants (antioxidant capacity; AC) and polyphenols (total polyphenol content; TPC) was compared. Maximum yields of AC and TPC by SE and UAE were obtained at modified optimal conditions of 63 °C, methanol content of 53 % (v/v) and 38 mL of extraction solvent per gram of dry material. Two-step extraction process consisting of the fast washing and slow diffusion steps was suitable described by Peleg and Patricelli mathematic models. The HPLC fingerprints of both extracts did not show significant differences while the content of phenolic compounds extracted by UAE was 1.1- to 7.1-times higher than that obtained by SE, quantified by HPLC.