Bioactive Phenolic Compounds, Metabolism and Properties: a Review on Valuable Chemical Compounds in Scots Pine and Norway Spruce
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Phytochem Rev https://doi.org/10.1007/s11101-019-09630-2 (0123456789().,-volV)( 0123456789().,-volV) Bioactive phenolic compounds, metabolism and properties: a review on valuable chemical compounds in Scots pine and Norway spruce Sari Metsa¨muuronen . Heli Sire´n Received: 30 January 2019 / Accepted: 5 July 2019 Ó The Author(s) 2019 Abstract Phenolics and extracted phenolic com- effects between aglycones and their glycosides have pounds of Scots pine (Pinus sylvestris) and Norway been observed. Minimum inhibition concentrations of spruce (Picea abies) show antibacterial activity below 10 mg L-1 against bacteria have been reported against several bacteria. The majority of phenolic for gallic acid, apigenin, and several methylated and compounds are stilbenes, flavonoids, proanthocyani- acylated flavonols present in these industrially impor- dins, phenolic acids, and lignans that are biosynthe- tant trees. In general, the phenolic compounds are sized in the wood through the phenylpropanoid more active against Gram-positive bacteria, but api- pathway. In Scots pine (P. sylvestris), the most genin is reported to exhibit strong activity against abundant phenolic and antibacterial compounds are Gram-negative bacteria. The present review lists some pinosylvin-type stilbenes and flavonol- and dihy- of the biosynthesis pathways for the antibacterial droflavonol-type flavonoids, such as kaempferol, phenolic metabolites found in Scots pine (P. sylves- quercetin, and taxifolin and their derivatives. In tris) and Norway spruce (P. abies). The antimicrobial Norway spruce (P. abies) on the other hand, the main activity of the compounds is collected and compared stilbene is resveratrol and the major flavonoids are to gather information about the most effective sec- quercetin and myricetin. In general, when the results ondary metabolites. from the literature regarding the activities of flavonoid glycosides and their aglycones against a total of Keywords Antibacterial compounds Á Metabolic twenty-one microorganisms are summarized, it was pathway Á Plant enzymes Á Norway spruce Á Scots pine Á found that phenolic glycosides are less active than the Wood Á Phenols corresponding aglycones, although a number of exceptions are also known. The aglycones in plants Abbreviations respond to various kinds of biotic stress. Synergistic ASE Accelerated solvent extractor ANS Anthocyanidin synthase S. Metsa¨muuronen CHS Chalcone synthase Department of Chemical Technology, Lappeenranta CoA Coenzyme A University of Technology, P.O. Box 20, DFR Dihydroflavonol 4-reductase 53851 Lappeenranta, Finland DNA Deoxyribonucleic acid H. Sire´n(&) dPCD Developmentally programmed cell death Department of Chemistry, University of Helsinki, dw Dry weight P.O. Box 55, 00014 Helsinki, Finland FSI Flavone synthase e-mail: heli.m.siren@helsinki.fi 123 Phytochem Rev FLS Flavonol synthase age of wood, the harvesting time, the genetic origin, LAR Leucoanthocyanidin reductase the growing period and district all influence the LDL Low density lipoproteins concentrations of the isolated bio compounds (Routa MBC Minimum or minimal bactericidal et al. 2017). The concentrations are also affected by concentration the wood parts (needles, knots i.e. the branch bases MRSA Methicillin resistant Staphylococcus aureus inside tree stems, roots, barks, heartwood, and MIC Minimum or minimal inhibitory phloems) and the sampling positions (height, depth). concentration In addition, the most commonly used sample pretreat- PMT 1,2 pinosylvin O-methyltransferase genes 1 ment techniques have an enormous influence on the and 2 content of extractives. Extraction systems (hot water PKS Polyketide synthase enzymes and supercritical fluid extractions, ultrasonication, SSF Solid state fermentation autoclave handling, microwaving), enzyme and STS Stilbene synthase microbe treatments with reactions, and organic sol- VRE Vancomycin-resistant enterococci vents, acids or bases need to be standardized, since w/w Weight per weight they have effects on the yields of bioactive compounds and their concentrations. Thus, the phenolic com- pounds of low molecular weights may originate from hydrolysis of the wood due to degradation of the Background material and are not in fact the extractives from the wood. Another determinant is the analysis method Utilization of wood-based compounds, extracts, and used to identify and characterize the wood com- biomass has increased enormously (Rauha et al. 2000; pounds. When sample manipulation, such as deriva- Jansson et al. 2013; Boden et al. 2014; Ganthaler et al. tization, is used to improve the sensitivity to reach the 2017). Structural components of wood (cellulose, methodological levels of the instruments, the origi- hemicelluloses, and lignin) and other organic sub- nality of the sample matrix is lost. stances which are integrated to biomass conversion processes, are the basic materials of biorefineries. Wood contains high molecular weight compounds, but Background for primary and secondary also a wide variety of low molecular mass compounds metabolites known as extractives. The small compounds can be separated from the high molecular and water-insoluble Scots pine (Pinus sylvestris) and Norway spruce wood constituents through using various kinds of (Picea abies) have been chosen for the discussion of extraction techniques. Thus, the industrial use of wood the review, since they are the most common trees in components has increased and even extracts are now Northern Europe. In addition, bio refinery industry used as starting fluids and mixtures in health products with related industry focus interest to isolate new and industrial chemicals including botulin, furfural chemicals for replacing polymers with bio-compounds derivatives, stilbens, tannins, flavonoids, tall oil, and and investigate for reusing wastes. Extractives of pulp resin (Roitto et al. 2008; Royer et al. 2012; Long et al. and paper industry contain mostly wood species of 2013). Valuable bio-based compounds can be Scots pine (P. sylvestris) and Norway spruce (P. abies) obtained directly from different parts of standing trees for new bio-based materials, energy, and bio fuel. (Roitto et al. 2008; Royer et al. 2012; Long et al. 2013; Nowadays, the place of renewable energy is increas- Sire´n et al. 2015; Metsa¨muuronen and Sire´n 2014; ingly important. Biomass is the primary source of Janusz et al. 2017;Bo¨ke et al. 2015), artificially renewable energy, and therefore the ‘‘valuable com- cultivated and fermentated mixtures (Martins et al. pounds’’ are isolated to use only the rest material in 2011), or isolated by-products of forest industries energy production (Ge´rardin 2016). (Mantau et al. 2010). A number of chemical compounds can be isolated The compositions and concentrations of wood from or produced in Scots pine (P. sylvestris) and extracts from different wood types vary a lot. The Norway spruce (P. abies). When native in the wood, they can be classified as primary and secondary 123 Phytochem Rev metabolites. Primary metabolites have essential meta- collected for energy production. However, usually bolic roles in the plant. Primary metabolites are wood residues are left in the forest after the harvesting usually described as substances that are essential of tree trunks. There is little research in literature chemical units of living plant cells. These fundamental describing what compounds in wood parts are bene- substances are cellulose, hemicelluloses, polysaccha- ficial for production and for energy industry, and in ride, and lignin. Plants synthesize a vast number of what concentrations they exist. Removal techniques small molecules that are secondary metabolites. In for advantageous chemicals from stumps and thick contrast to primary metabolites, they are not necessary roots can be used to extract commercially valuable for tissue growth. Secondary metabolites are formed biochemicals (Berg 2014; Hakkila 2012), like pheno- by evolution to defend plants against harmful attacks lics, stilbenes, flavonoids, flavanones, flavonols, fla- by herbivores, pathogens, insects, plant-eating ani- van-3-ols, anthocyanidins, and proanthocyanidins. mals, and UV radiation (Wink 2003). Therefore, their The oily tar from the Scots pine (P. sylvestris) tree composition is plant-specific and genetically con- has traditionally been prepared from terpenes and trolled. Secondary metabolites are classified as terpenoids and for thousands of years, utilized as a aliphatic compounds (terpenes and terpenoids, resin preservative for timber (Holmbom 2011). Further- acids, sterols, fats, waxes, fatty acids), phenolic more, oleoresin, terpene, and lipid components of compounds (flavonoids, simple phenols, tannins, stil- Scots pine (P. sylvestris) and Norway spruce (P. abies) benes), and other secondary metabolites (sugars, have been extracted as by-products in wood pulping alkaloids). Phenolic compounds comprise a struc- processes. They have been further refined to turpentine turally and functionally diverse group of aromatic and tall-oil and, more recently, also used for the hydrocarbon rings, and usually at least one hydroxyl production of biofuel (Holmbom 2011). Phenolic group. In general, secondary metabolites from wood compounds are involved in resistance mechanisms as species from temperate regions have fungicidal, precursors to defense-related compounds or synthesis fungistatic, or bactericidal properties (Routa et al. of polymers. They are supposed to modulate the 2017; Schultz and Nicola 2000; Treutter 2006; Gan- activity of other phytochemicals (Schultz