Salicortin

Variable lignin structure revealed in Populus leaves.[Pubmed:37416906]

RSC Adv. 2023 Jul 5;13(29):20187-20197.

Lignin has long been a trait of interest, especially in bioenergy feedstocks such as Populus. While the stem lignin of Populus is well studied, foliar lignin has received significantly less consideration. To this end, leaves from 11 field grown, natural variant Populus trichocarpa genotypes were investigated by NMR, FTIR, and GC-MS. Five of these genotypes were sufficiently irrigated, and the other six genotypes were irrigated at a reduced rate (59% of the potential evapotranspiration for the site) to induce drought treatment. Analysis by HSQC NMR revealed highly variable lignin structure among the samples, especially for the syringyl/guaiacyl (S/G) ratio, which ranged from 0.52-11.9. Appreciable levels of a condensed syringyl lignin structure were observed in most samples. The same genotype subjected to different treatments exhibited similar levels of condensed syringyl lignin, suggesting this was not a response to stress. A cross peak of delta(C)/delta(H) 74.6/5.03, consistent with the erythro form of the beta-O-4 linkage, was observed in genotypes where significant syringyl units were present. Principle component analysis revealed that FTIR absorbances associated with syringyl units (830 cm(-1), 1317 cm(-1)) greatly contributed to variability between samples. Additionally, the ratio of 830/1230 cm(-1) peak intensities were reasonably correlated (p-value < 0.05) with the S/G ratio determined by NMR. Analysis by GC-MS revealed significant variability of secondary metabolites such as tremuloidin, trichocarpin, and Salicortin. Additionally, salicin derivatives were found to be well correlated with NMR results, which has been previously hypothesized. These results highlight previously unexplored nuance and variability associated with foliage tissue of poplar.

Reductive Conversion Leads to Detoxification of Salicortin-like Chemical Defenses (Salicortinoids) in Lepidopteran Specialist Herbivores (Notodontidae).[Pubmed:37191771]

J Chem Ecol. 2023 Jun;49(5-6):251-261.

Lepidopteran specialist herbivores of the Notodontidae family have adapted to thrive on poplar and willow species (Salicaceae). Previous research showed that Cerura vinula, a member of the Notodontidae family occurring throughout Europe and Asia, uses a unique mechanism to transform Salicortinoids, the host plant's defense compounds, into quinic acid-salicylate conjugates. However, how the production of this conjugates relates to the detoxification of Salicortinoids and how this transformation proceeds mechanistically have remained unknown. To find the mechanisms, we conducted gut homogenate incubation experiments with C. vinula and re-examined its metabolism by analyzing the constituents of its frass. To estimate the contribution of spontaneous degradation, we examined the chemical stability of Salicortinoids and found that Salicortinoids were degraded very quickly by midgut homogenates and that spontaneous degradation plays only a marginal role in the metabolism. We learned how Salicortinoids are transformed into salicylate after we discovered reductively transformed derivatives, which were revealed to play key roles in the metabolism. Unless they have undergone the process of reduction, Salicortinoids produce toxic catechol. We also studied constituents in the frass of the Notodontidae species Cerura erminea, Clostera anachoreta, Furcula furcula, Notodonta ziczac, and Pheosia tremula, and found the same metabolites as those described for C. vinula. We conclude that the process whereby Salicortinoids are reductively transformed represents an important adaption of the Notodontidae to their Salicaceae host species.

Rapid screening of secondary aromatic metabolites in Populus trichocarpa leaves.[Pubmed:36899393]

Biotechnol Biofuels Bioprod. 2023 Mar 10;16(1):41.

BACKGROUND: High-throughput metabolomics analytical methodology is needed for population-scale studies of bioenergy-relevant feedstocks such as poplar (Populus sp.). Here, the authors report the relative abundance of extractable aromatic metabolites in Populus trichocarpa leaves rapidly estimated using pyrolysis-molecular beam mass spectrometry (py-MBMS). Poplar leaves were analyzed in conjunction with and validated by GC/MS analysis of extracts to determine key spectral features used to build PLS models to predict the relative composition of extractable aromatic metabolites in whole poplar leaves. RESULTS: The Pearson correlation coefficient for the relative abundance of extractable aromatic metabolites based on ranking between GC/MS analysis and py-MBMS analysis of the Boardman leaf set was 0.86 with R(2) = 0.76 using a simplified prediction approach from select ions in MBMS spectra. Metabolites most influential to py-MBMS spectral features in the Clatskanie set included the following compounds: catechol, Salicortin, salicyloyl-coumaroyl-glucoside conjugates, alpha-salicyloylsalicin, tremulacin, as well as other salicylates, trichocarpin, salicylic acid, and various tremuloidin conjugates. Ions in py-MBMS spectra with the highest correlation to the abundance of extractable aromatic metabolites as determined by GC/MS analysis of extracts, included m/z 68, 71, 77, 91, 94, 105, 107, 108, and 122, and were used to develop the simplified prediction approach without PLS models or a priori measurements. CONCLUSIONS: The simplified py-MBMS method is capable of rapidly screening leaf tissue for relative abundance of extractable aromatic secondary metabolites to enable prioritization of samples in large populations requiring comprehensive metabolomics that will ultimately inform plant systems biology models and advance the development of optimized biomass feedstocks for renewable fuels and chemicals.

Anti-Adipogenic Effects of Salicortin from the Twigs of Weeping Willow (Salix pseudolasiogyne) in 3T3-L1 Cells.[Pubmed:36296558]

Molecules. 2022 Oct 17;27(20):6954.

Salix pseudolasiogyne (Salicaceae), the "weeping willow," has been used in traditional Korean medicine to treat pain and fever due to its high concentrations of salicylic acid and salicin. The present study investigated bioactive compounds from S. pseudolasiogyne twigs to discover bioactive natural products. Phytochemical investigation of the ethanol (EtOH) extract of S. pseudolasiogyne twigs followed by liquid chromatography-mass spectrometry (LC/MS)-based analysis led to the isolation of two salicin derivatives, Salicortinol and Salicortin, the structures of which were determined by interpretation of their NMR spectra and data from the LC/MS analysis. To the best of our knowledge, this is the first report of Salicortinol isolated from S. pseudolasiogyne. The isolated compounds were evaluated for their anti-adipogenic effects in 3T3-L1 cells. Both Salicortinol and Salicortin were found to significantly inhibit adipocyte differentiation in 3T3-L1 cells. In particular, Salicortin exhibited a strong inhibitory effect on lipid accumulation. Furthermore, Salicortin inhibited the expression of lipogenic and adipogenic transcription factors, including FASN, FABP4, C/EBPalpha, C/EBPbeta, and PPARgamma, without inducing cytotoxicity. These results suggest that Salicortin could be a potential therapeutic compound for the prevention or treatment of metabolic disorders such as obesity.

Extracts of Waste from Poplar Wood Processing Alleviate Experimental Dextran Sulfate-Induced Colitis by Ameliorating Oxidative Stress, Inhibiting the Th1/Th17 Response and Inducing Apoptosis in Inflammatory Lymphocytes.[Pubmed:34829556]

Antioxidants (Basel). 2021 Oct 26;10(11):1684.

As a fast-growing tree, poplar is widely planted and typically used for wood processing in China. During poplar wood processing, a large amount of poplar sawdust (PS) and poplar leaves (PL) are produced and abandoned. To make full use of poplar resources and clarify the use of poplar as a feed additive, the active ingredients in PS and PL were extracted and isolated, and the anti-inflammatory effects of the extracts on mice with dextran sulfate sodium (DSS)-induced colitis were investigated. In vitro anti-inflammatory experiments showed that the ethyl acetate extract of PS and PL (PSE and PLE, respectively) could significantly inhibit the proliferation of concanavalin A (Con A)-activated lymphocytes. Salicortin, tremulacin and salireposide were identified in both PSE and PLE. Oral administration of PSE and PLE rescued DSS-induced colonic shortening, repaired tissue damage, and decreased the disease activity index (DAI). The antioxidant capacity, including the increased activities of glutathione peroxidase (GSH-Px), total superoxide dismutase (T-SOD and catalase (CAT) and decreased activity of myeloperoxidase (MPO), in the colons of mice with colitis was enhanced through the activation of ERK after treatment with PSE and PLE. The ratio of Th1 to Th17 cells, which can lead to inflammation in the spleen, was significantly decreased by the administration of PSE and PLE, while the phosphorylation of related transcription factors (p65, STAT1, and STAT3) was inhibited. Furthermore, PSE and PLE could induce apoptosis in Con A-activated lymphocytes, which may be associated with the increase in p-TBK1, as the molecular docking results also indicated that salireposide in PSE and PLE could interact with the TBK1 protein. Overall, our study provides a promising feed additive for improving intestinal inflammation in animals and a method for the full utilization of poplar resources.

Studies on the Polyphenolic Composition and the Antioxidant Properties of the Leaves of Poplar (Populus spp.) Various Species and Hybrids.[Pubmed:34138528]

Chem Biodivers. 2021 Jun 17.

The chemical composition in terms of flavonoid and salicylic compounds of leaves from 6 species and 3 hybrids of poplars (Populus) was identified with the use of TLC and HPLC-DAD/ESI-MS methods. Chromatographic analyses were carried out with 21 standard compounds including salicylic compounds (2), phenolic acids (3) and flavonoids (16). Moreover, on the basis of the obtained chromatographic data from the HPLC-DAD/ESI-MS and TLC separations, the presence of Salicortin, tremulacin and chlorogenic acid was confirmed, depending on the analyzed poplar species or hybrid. The content of salicylic compounds was determined by HPLC-UV method and expressed on salicin as free and total fraction. Total flavonoid content was determined by spectroscopic method as quercetin equivalent. Significant qualitative and quantitative differences in the chemical composition of the analyzed leaves were demonstrated. The highest concentration of flavonoids (8.02 mg/g) was found in the leaves of Populus nigra, while the highest content of salicylic compounds (47.14 mg/g) was found in the leaves of P.xberolinensis. The antioxidant and xanthine oxidase inhibition properties of extracts from poplar leaves were investigated by TLC bioautography. It has been shown that the richest set of compounds with antioxidant properties are present in the leaves of P. alba, P.xcandicans and P. nigra.

Antioxidant Activity and Chemical Characteristics of Supercritical CO(2) and Water Extracts from Willow and Poplar.[Pubmed:33494378]

Molecules. 2021 Jan 21;26(3):545.

Renewable feedstock from perennial industrial crops, including those cultivated on marginal land in a short-rotation coppice system, could be an important contribution to the bioeconomy. The majority of data available on the topic are limited to the production of bioenergy from this type of biomass. According to the concept of bioeconomy, biomass-based bioproducts have priority over energy production. This paper characterizes the chemical composition and antioxidant activity of extracts from bark (b), wood (w) or a mixture of bark and wood (b + w) from Salix purpurea, Salix viminalis and Populus nigra obtained using supercritical carbon dioxide (scCO(2)), scCO(2) and water (1%, w/w) or only water. Generally, a high concentration of polyphenols was obtained after extraction with scCO(2) and water, while the lowest concentration was found in extracts obtained with scCO(2). The highest concentration of polyphenols (p < 0.05) was obtained in an extract from P. nigra (b) (502.62 +/- 9.86 mg GAE/g dry matter (d.m.)) after extraction with scCO(2) and water, whereas the lowest polyphenol concentration was observed in an scCO(2) extract from S. purpurea (b) (6.02 +/- 0.13 mg GAE/g d.m.). The flavonoids were effectively separated by extraction with scCO(2) (0.88-18.37 mg QE/g d.m.). A positive linear relationship between the antioxidant activity determined by DPPH and ABTS assays and the concentration of polyphenols was demonstrated, R(2) = 0.8377 and R(2) = 0.9568, respectively. It is most probable that the concentration of flavonoids, rather than the concentration of polyphenols, determines the chelating activity of Fe(2+). The Fe(2+)-chelating activity of scCO(2) extracts ranged from 75.11% (EC(50) = 5.41 mg/cm(3), S. purpurea, b + w) to 99.43% (EC(50) = 0.85 mg/cm(3), P. nigra, b + w). The lowest chelating activity was demonstrated by the extracts obtained with scCO(2) and water (maximum 26.36%, S. purpurea, b + w). In extracts obtained with scCO(2) and water, p-hydroxybenzoic acid (210-428 microg/g), p-coumaric acid (56-281 microg/g), saligenin (142-300 microg/g) and Salicortin (16-164 microg/g) were the dominant polyphenols. All of these chemical compounds occurred mainly in the free form. The S. purpurea, S. viminalis and P. nigra biomass proved to be an attractive source of biologically active compounds for various possible applications in food, drugs or cosmetics. These compounds could be extracted using an environmentally friendly method with scCO(2) and water as a co-solvent.

A willow UDP-glycosyltransferase involved in salicinoid biosynthesis.[Pubmed:33249501]

J Exp Bot. 2021 Feb 27;72(5):1634-1648.

The salicinoids are phenolic glycosides that are characteristic secondary metabolites of the Salicaceae, particularly willows and poplars. Despite the well-known pharmacology of salicin, that led to the development of aspirin >100 years ago, the biosynthetic pathways leading to salicinoids have yet to be defined. Here, we describe the identification, cloning, and biochemical characterization of SpUGT71L2 and SpUGT71L3-isozymic glycosyltransferases from Salix purpurea-that function in the glucosylation of ortho-substituted phenols. The best substrate in vitro was salicyl-7-benzoate. Its product, salicyl-7-benzoate glucoside, was shown to be endogenous in poplar and willow. Together they are inferred to be early intermediates in the biosynthesis of Salicortin and related metabolites in planta. The role of this UDP-glycosyltransferase was confirmed via the metabolomic analysis of transgenic plants produced by RNAi knockdown of the poplar orthologue (UGT71L1) in the hybrid clone Populus tremulaxP. alba, INRA 717-1B4.

Miyabeacin: A new cyclodimer presents a potential role for willow in cancer therapy.[Pubmed:32296088]

Sci Rep. 2020 Apr 15;10(1):6477.

Willow (Salix spp.) is well known as a source of medicinal compounds, the most famous being salicin, the progenitor of aspirin. Here we describe the isolation, structure determination, and anti-cancer activity of a cyclodimeric salicinoid (miyabeacin) from S. miyabeana and S. dasyclados. We also show that the capability to produce such dimers is a heritable trait and how variation in structures of natural miyabeacin analogues is derived via cross-over Diels-Alder reactions from pools of ortho-quinol precursors. These transient ortho-quinols have a role in the, as yet uncharacterised, biosynthetic pathways around Salicortin, the major salicinoid of many willow genotypes.

Polyphenols from Salix tetrasperma Impair Virulence and Inhibit Quorum Sensing of Pseudomonas aeruginosa.[Pubmed:32187997]

Molecules. 2020 Mar 16;25(6):1341.

Bacterial resistance represents one of the emerging obstacles in plants, animals, and humans that impairs treatment with antibacterial agents. Targeting of the bacterial quorum sensing system is one of the strategies to overcome this problem. Recently, research has been focused on natural and food components which can function as quorum sensing inhibitors. In this study, a methanol extract from Salix tetrasperma stem bark was phytochemically profiled by LC-MS analysis. This resulted in the identification of 38 secondary metabolites with (epi)catechin-(epi)catechin, epicatechin, tremulacin, Salicortin, and trichocarposide as the major constituents. The extracts of both stem bark and the previously profiled flower of S. tetrasperma were tested for anti-quorum sensing activity in a common and widely distributed pathogen Pseudomonas aeruginosa. The natural products inhibited swimming and swarming motilities, as well as proteolytic and hemolytic activities in a dose-dependent manner. Molecular docking of the constituents from both extracts against the quorum sensing controlling systems Lasl/LasR, rhll/rhlR, and PQS/MvfR showed that epicatechin, (epi)catechin-(epi)catechin, p-hydroxy benzoyl galloyl glucose, p-hydroxy benzoyl protocatechuic acid glucose, and caffeoylmalic acid could be the main active components. This study supports the importance of secondary metabolites, especially polyphenols, as quorum sensing inhibitors.

To compete or defend: linking functional trait variation with life-history tradeoffs in a foundation tree species.[Pubmed:32060731]

Oecologia. 2020 Apr;192(4):893-907.

Although chemical deterrents to herbivory often exact costs in terms of plant growth, the manner in which those costs arise, and their physiological relationship to other functional traits, remain unclear. In the absence of appreciable herbivory, we examined interrelationships among chemical defense levels and other foliar functional traits (e.g., light-saturated photosynthesis, specific leaf area, nitrogen concentration) as co-determinants of tree growth and, by extension, competitive ability in high-density populations comprising 16 genotypes of Populus tremuloides. Across genotypes, concentrations of chemical defenses were not significantly related to other leaf functional traits, but levels of the salicinoid phenolic glycosides (SPGs) salicin, Salicortin and tremulacin were each negatively correlated with relative mass growth (RMG) of aboveground woody tissue (P

Salix alba (white willow) medicinal plant presents genotoxic effects in human cultured leukocytes.[Pubmed:31906808]

J Toxicol Environ Health A. 2019;82(23-24):1223-1234.

Salix alba (SA), commonly known as white willow, is a plant used in folk medicine for the treatment of chronic and acute inflammation, infection, pain, and fever. The phytochemical characterization of the bark extract of this plant indicated that its main component is salicin, a precursor of the anti-inflammatory agent acetylsalicylic acid. Considering the lack of studies evaluating the genetic toxicity and cytotoxic action of SA bark extract on human cells, as well as the chemical characterization of its major phenolic compounds, the present study was designed to (1) investigate the cytotoxic and genotoxic potential of SA bark extract on human peripheral leukocyte cells and human hepatoma cell line HepG2, and (2) characterize its major phenolic constituents. The phenolic compounds found were salicylic acid, salicin, salidroside, saligenin, tremulodin, salicoylsalicin, Salicortin, and tremulacin. The results using trypan blue staining test showed viability decreases (viability less than 70%) for concentrations of SA extract equal and higher to 200 microg/ml. Low genotoxic activity (comet assay) was exhibited for 50 and 100 microg/ml SA extract in human leukocytes. SA did not exert a marked clastogenic/aneugenic effect on leukocytes and HepG2 human cells. Data suggest that the genotoxic effects of SA bark extract occur when it is not metabolized by liver enzymes.

Discovery of salicyl benzoate UDP-glycosyltransferase, a central enzyme in poplar salicinoid phenolic glycoside biosynthesis.[Pubmed:31736216]

Plant J. 2020 Apr;102(1):99-115.

The salicinoids are anti-herbivore phenolic glycosides unique to the Salicaceae (Populus and Salix). They consist of a salicyl alcohol glucoside core, which is usually further acylated with benzoic, cinnamic or phenolic acids. While salicinoid structures are well known, their biosynthesis remains enigmatic. Recently, two enzymes from poplar, salicyl alcohol benzoyl transferase and benzyl alcohol benzoyl transferase, were shown to catalyze the production of salicyl benzoate, a predicted potential intermediate in salicinoid biosynthesis. Here, we used transcriptomics and co-expression analysis with these two genes to identify two UDP-glucose-dependent glycosyltransferases (UGT71L1 and UGT78M1) as candidate enzymes in this pathway. Both recombinant enzymes accepted only salicyl benzoate, salicylaldehyde and 2-hydroxycinnamic acid as glucose acceptors. Knocking out the UGT71L1 gene by CRISPR/Cas9 in poplar hairy root cultures led to the complete loss of Salicortin, tremulacin and tremuloidin, and a partial reduction of salicin content. This demonstrated that UGT71L1 is required for synthesis of the major salicinoids, and suggested that an additional route can lead to salicin. CRISPR/Cas9 knockouts for UGT78M1 were not successful, and its in vivo role thus remains to be determined. Although it has a similar substrate preference and predicted structure as UGT71L1, it appears not to contribute to the synthesis of Salicortin, tremulacin and tremuloidin, at least in roots. The demonstration of UGT71L1 as an enzyme of salicinoid biosynthesis will open up new avenues for the elucidation of this pathway.

Variability in the composition of phenolic compounds in winter-dormant Salix pyrolifolia in relation to plant part and age.[Pubmed:29906656]

Phytochemistry. 2018 Sep;153:102-110.

The phenolic phytochemicals of winter-dormant Salix pyrolifolia were determined from the vegetative buds, and the bark and wood of different-aged twigs by HPLC-DAD and UHPLC-QTOF-MS analyses. All the plant parts were composed of salicylate glucosides and the other Salix-specific, simple phenolic glucosides as well as of phenolic acids, flavonoids and the high molecular-weight condensed tannins. The flavonoid composition was most diverse in buds and they also contained a large amount of chlorogenic acid (5-caffeoylquinic acid IUPAC), while salicylate glucosides and simple phenolic glucosides predominated in bark. The wooden interior part of the twigs contained fewer components and the lowest concentrations of compounds. Salicortin was the main compound in winter-dormant S. pyrolifolia (over 10% of bark biomass), but the concentrations of picein, salireposide, isosalipurposide, catechin and condensed tannins were also high. The flavonoid composition was highly naringenin- and quercetin-biassed. The composition of phytochemicals was organ-specific and remained relatively similar between different-aged trees. However, there were compound-specific fluctuations in the concentrations of phytochemicals with the age of the trees and within plant parts. Generally, the one-year-old plants differed from the older trees in their high concentration of condensed tannins in all the plant parts studied and in the highest concentration of isosalipurposide in bark, while the total amounts of salicylate glucosides in plant parts, and of naringenin glucosides in buds, tended to be highest in 20 year-old-trees.

Large effect quantitative trait loci for salicinoid phenolic glycosides in Populus: Implications for gene discovery.[Pubmed:29686853]

Ecol Evol. 2018 Mar 8;8(7):3726-3737.

Genomic studies have been used to identify genes underlying many important plant secondary metabolic pathways. However, genes for salicinoid phenolic glycosides (SPGs)-ecologically important compounds with significant commercial, cultural, and medicinal applications-remain largely undescribed. We used a linkage map derived from a full-sib population of hybrid cottonwoods (Populus spp.) to search for quantitative trait loci (QTL) for the SPGs Salicortin and HCH-Salicortin. SSR markers and primer sequences were used to anchor the map to the V3.0 P. trichocarpa genome. We discovered 21 QTL for the two traits, including a major QTL for HCH-Salicortin (R(2) = .52) that colocated with a QTL for Salicortin on chr12. Using the V3.0 Populus genome sequence, we identified 2,983 annotated genes and 1,480 genes of unknown function within our QTL intervals. We note ten candidate genes of interest, including a BAHD-type acyltransferase that has been potentially linked to Populus SPGs. Our results complement other recent studies in Populus with implications for gene discovery and the evolution of defensive chemistry in a model genus. To our knowledge, this is the first study to use a full-sib mapping population to identify QTL intervals and gene lists associated with SPGs.