Syringaresinol Attenuates α-Melanocyte-Stimulating Hormone-Induced Reactive Oxygen Species Generation and Melanogenesis.

Ginseng has been utilized for centuries in both the medicinal and cosmetic realms. Recent studies have actively investigated the biological activity of ginseng berry and its constituents. (+)-Syringaresinol [(+)-SYR], an active component of ginseng berry, has been demonstrated to have beneficial effects on the skin, but its potential impact on skin pigmentation has not been fully explored. Here, the antioxidant and anti-pigmentary activity of (+)-SYR were evaluated in B16F10 murine melanoma cells and in an artificial human pigmented skin model, Melanoderm™. A real-time PCR, Western blotting, immunofluorescence staining, and histochemistry staining were conducted to confirm the effects of (+)-SYR on pigmentation. (+)-SYR reduced melanogenesis and dendrite elongation in α-melanocyte-stimulating hormone (α-MSH)-primed B16F10 cells with low cytotoxicity. (+)-SYR suppressed the expression of melanogenic genes, namely tyrosinase (TYR), tyrosinase-related protein 1 (TRP-1), and tyrosinase-related protein 2 (TRP-2). Notably, (+)-SYR attenuated α-MSH-induced cytosolic and mitochondrial reactive oxygen species (ROS) generation, which was attributable at least in part to the suppression of NADPH oxidase-4 (NOX 4) expression. Finally, the brightening activities of (+)-SYR were verified using Melanoderm™, underscoring the potential of ginseng berry and (+)-SYR as functional ingredients in skin-brightening cosmetics.

Syringaresinol attenuates Tau phosphorylation and ameliorates cognitive dysfunction induced by sevoflurane in aged rats.

Cognitive dysfunction following anesthesia with agents such as sevoflurane is a significant clinical problem, particularly in elderly patients. This study aimed to explore the protective effects of the phytochemical syringaresinol (SYR) against sevoflurane-induced cognitive deficits in aged Sprague-Dawley rats and to determine the underlying mechanisms involved. We assessed the impact of SYR on sevoflurane-induced cognitive impairment, glial activation, and neuronal apoptosis through behavioral tests (Morris water maze), immunofluorescence, Western blotting for key proteins involved in apoptosis and inflammation, and enzyme-linked immunosorbent assays for interleukin-1ß, tumor necrosis factor-α, and interleukin-6. SYR treatment mitigated sevoflurane-induced cognitive decline, reduced microglial and astrocyte activation (decreased Iba-1 and GFAP expression), and countered neuronal apoptosis (reduced Bax, cleaved-caspase3, and cleaved-PARP expression). SYR also enhanced Sirtuin-1 (SIRT1) expression and reduced p-Tau phosphorylation; these effects were reversed by the SIRT1 inhibitor EX527. SYR exerts neuroprotective effects on sevoflurane-induced cognitive dysfunction by modulating glial activity, apoptotic signaling, and Tau phosphorylation through the SIRT1 pathway. These findings could inform clinical strategies to safeguard cognitive function in patients undergoing anesthesia.

(-)-Syringaresinol attenuates ulcerative colitis by improving intestinal epithelial barrier function and inhibiting inflammatory responses.

BACKGROUND: (-)-Syringaresinol (SYR), a natural lignan with significant antioxidant and anti-inflammatory activities, possesses various pharmacological benefits including cardio-protective, antibacterial, anticancer, and anti-aging effects. It was shown that the effectiveness of (+)-syringaresinol diglucoside on the ulcerative colitis (UC) was attributed to the active metabolite (+)-syringaresinol (the enantiomor of SYR). However, the efficacy of SYR against UC remains unclear, and the associated molecular mechanism has not been revealed yet PURPOSE: This study aimed to assess the protective effect of SYR in UC and its underlying mechanism STUDY DESIGN AND METHODS: We examined SYR's protective impact on the intestinal epithelial barrier and its ability to inhibit inflammatory responses in both a lipopolysaccharide (LPS)-induced Caco-2 cell model and a dextran sodium sulfate (DSS)-induced UC mouse model. We also explored the potential signaling pathways regulated by SYR using transcriptome analysis and western blot assay RESULTS: In Caco-2 cells, SYR significantly increased trans-epithelial electrical resistance, reduced tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interferon-γ (IFN-γ), and cyclooxygenase-2 (COX-2) levels, and enhanced cellular tight junction protein expression and distribution. In mice with UC, oral treatment with SYR (10, 20, 40 mg·kg-1) dose-dependently increased body weight, colon length, and expression of tight junction proteins, decreased disease activity index score, spleen coefficient, cytokine serum levels, bacterial translocation, and intestinal damage, and also preserved the ultrastructure of colonic mucosal cells. Transcriptomics indicated that the anti-UC effect of SYR is mediated via the PI3K-Akt/MAPK/Wnt signaling pathway. CONCLUSION: In summary, SYR effectively mitigated the development of UC by enhancing the intestinal epithelial barrier function and attenuating the inflammatory response. The plant-derived product SYR might be a potentially effective therapeutical agent against UC.

Syringaresinol promotes the recovery of spinal cord injury by inhibiting neuron apoptosis via activating the ubiquitination factor E4B/AKT Serine/Threonine kinase signal pathway.

Spinal cord injury (SCI) is a serious traumatic disease with no effective treatment. This study aimed to explore the therapeutic effect of syringaresinol on SCI. First, the potential targets and associated signaling pathways of syringaresinol were predicted by bioinformatics analysis and molecular docking. Second, MTT was employed to evaluate cell proliferation rate, Western blot was performed to detect protein expression, RT-qPCR was conducted to detect mRNA expression levels, flow cytometry and 5-ethynyl-2'-deoxyuridine (EDU) staining were used to determine cell apoptosis, and immunofluorescence and immunohistochemistry were used to estimate the expression of RNA binding fox-1 homolog 3 and clipped caspase 3. Basso-Beattie-Bresnahan scores and inclined plate tests were conducted to analyze hindlimb locomotor function. Results showed that syringaresinol could inhibit the apoptosis of glutamate-treated SHSY5Y cells by upregulating the expression of ubiquitination factor E4B (UBE4B) and activating the AKT serine/threonine kinase (AKT) signaling pathway. This effect can be rescued by UBE4B knockdown or AKT pathway inhibition. Syringaresinol remarkably improved locomotor function and increased neuronal survival in SCI rats. Our results suggested that syringaresinol could promote locomotor functional recovery by reducing neuronal apoptosis by activating the UBE4B/AKT signaling pathway.

Determination of the Contents of Three Lignans in Dendrobium fimbriatum Hook / 广州中医药大学学报

Objective To establish the method for content determination of three lignans of Dendrobium Fimbriatum Hook..Methods The lignans in Dendrobium tasselii were identified by high-performance liquid chromatography/multi-stage mass spectrometry(HPLC-ESI/MSn)coupled with ultraviolet absorption spectrometry(UV)coupled with retention time localization of high-performance liquid chromatography(HPLC).The separation was carried out on a Kromasil 100-5 C18 column(4.6 mm×250 mm,5 μm)using a gradient elution of acetonitrile-0.1%formic acid solution as the mobile phase,the volume flow rate was 0.8 mL·min-1 and the column temperature was 35℃,and the mass spectrometry was performed using an ESI ion source with the data collected in the negative ion mode.The HPLC content was determined on the same column as that of MS analysis,with the mobile phase methanol + acetonitrile(V/V=1∶1)-0.01 mol/L ammonium acetate solution,gradient elution,flow rate of 0.8 mL·min-1,column temperature of 40℃,and detection wavelength of 215 nm.Results Syringaresinol di-O-glucoside and(-)-Syringaresinol 4-O-β-D-glucopyranoside and DL-Syringaresinol were identified from Dendrobium fimbriatum Hook.,and the results of content determination showed that the linear ranges of above three components were respectively 0.1701-3.4020,0.1020-2.0400,0.0403-0.8060 μg(r≥0.9995),the average recoveries were in the range of 97.71%-101.67%,and the relative standard deviations(RSDs)were all less than 3.0%.The contents of Syringaresinol di-O-glucoside and(-)-Syringaresinol 4-O-β-D-glucopyranoside and DL-Syringaresinol in the 10 batches of samples were 0.7779-1.3852,0.0734-0.1966,0.0295-0.1882 mg·g-1.Conclusion This research method can provide a reference basis for the quality evaluation method of Dendrobium fimbriatum Hook..

Syringaresinol alleviates IgG immune complex induced acute lung injury via activating PPARγ and suppressing pyroptosis.

Acute lung injury (ALI) is a life-threatening condition characterized by severe lung inflammation and tissue damage. In this study, we investigate the potential therapeutic efficacy of (+)-Syringaresinol (SYG), a natural compound known for its antioxidant and anti-inflammatory properties, in alleviating ALI induced by IgG immune complexes (IgG-IC). Using MH-S cells as a model, we explore SYG's ability to target peroxisome proliferator-activated receptor gamma (PPARγ) and its anti-inflammatory properties. Our comprehensive investigation aims to elucidate the specific molecular mechanisms underlying SYG's effects against pyroptosis, as revealed through transcriptomic analysis. Validation in C57BL/6 mice provides in vivo support. Our findings indicate that SYG effectively mitigates IgG-IC-induced lung damage, as evidenced by a significant reduction in lung inflammation and tissue injury. SYG treatment notably decreases pro-inflammatory cytokine levels (TNF-α, IL-6, IL-1ß) in both lung tissue and cells. Molecular docking analysis reveals SYG's robust binding to PPARγ, leading to the inhibition of IgG-IC-induced inflammatory signaling pathways. Additionally, transcriptomic analysis unveils SYG's potential in suppressing macrophage pyroptosis, potentially through the downregulation of key inflammatory mediators (NLRP3, GSDMD, Caspase-1). In summary, our study presents compelling evidence supporting SYG as an effective therapeutic agent for ALI. SYG's activation of PPARγ contributes to the suppression of NF-κB and C/EBPs expression, thereby mitigating inflammation. Moreover, SYG demonstrates the ability to inhibit macrophage pyroptosis by targeting the NLRP3/GSDMD/caspase-1 axis.

Skin wound healing effects of (+)-syringaresinol from ginseng berry.

Background: Ginseng has been used as a traditional medicine and functional cosmetic ingredients for many years. Recent studies have focused on the potential biological effects of the ginseng berry and its ingredients. (+)-Syringaresinol (SYR) is enriched in ginseng berry and its beneficial effects on the skin have been recently reported. However, little is known about the its effects on the wound healing process of skin. Methods: Here, we evaluated the skin wound healing effect of (+)-SYR using the human fibroblast Hs68 cell and ex vivo pig and human skin tissue model. Scratch wound test and hydrogen peroxide (HPO) induce chemical wound model were employed. Results: (+)-SYR promoted the migration and proliferation of Hs68 cells without significant cytotoxicity at the tested concentrations. Especially, in ex vivo pig and human skin tissue, HPO-induced chemical wound was recovered almost completely by (+)-SYR. In line with the finding in Hs68, the protein expression levels of TGF-ß and PCNA, a proliferation marker were increased, demonstrating the beneficial effects of (+)-SYR on skin wound repair. Conclusion: Collectively, we demonstrated that (+)-SYR from ginseng berry, can enhance the wound healing effect by accelerating cell proliferation and skin regeneration, suggesting the potential utility of (+)-SYR for skin wound repair.

Syringaresinol attenuates osteoarthritis via regulating the NF-κB pathway.

Osteoarthritis (OA) is a now regarded as a worldwide whole joint disease with synovial inflammation, cartilage degeneration, and subchondral sclerosis. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used drugs for OA treatment which only relieve the symptoms and restrain the progression of OA. However, various severe adverse effects often occur in patients with long-term NSAIDs use, which heavily burdens the healthcare system and impacts the quality of life. Therefore, it is much imperative to identify alternative drugs with increased efficacy. Syringaresinol (Syr), a naturally occurring phytochemical which belonging to the lignan group of polyphenols, shows anti-tumor and anti-oxidant activities, which to benefit human health. Studies has shown Syr can regulate the inflammatory response by modulating the secretion and expression level of cytokines IL-6, IL-8, and tumor necrosis factor (TNF)-α. it also shows the inhibitory effect on NF-κB pathway in mouse cells. In the present study, we aimed to demonstrate the anti-inflammatory effects of Syr in OA. In vitro Syr treatment in IL-1ß-activated mouse chondrocytes significantly restrained the expression of NO, PGE2, IL-6, TNF-α, INOS, COX-2 and MMP-13. Moreover, it considerably ameliorated the degradation of aggrecan and collagen II. Furthermore, the phosphorylation of the NF-kB signaling pathway was significantly suppressed by Syr. Moreover, in vivo, the cartilage degeneration was attenuated and the increased Osteoarthritis Research Society International (OARSI) scores were reversed in the DMM + Syr group, comprared to those in the DMM group. In sum, our study demonstrated that Syr can attenuate the inflammation in vitro and further verified its effect on OA in vivo. Thus, Syr might be a potent therapeautic alternative for OA treatment.

Syringaresinol protects against diabetic nephropathy by inhibiting pyroptosis via NRF2-mediated antioxidant pathway.

Diabetic nephropathy (DN) is one of the serious complications of diabetes that has limited treatment options. As a lytic inflammatory cell death, pyroptosis plays an important role in the pathogenesis of DN. Syringaresinol (SYR) possesses anti-inflammatory and antioxidant properties. However, the therapeutic effects and the underlying mechanism of SYR in DN remain unclear. Herein, we showed that SYR treatment ameliorated renal hypertrophy, fibrosis, mesangial expansion, glomerular basement membrane thickening, and podocyte foot process effacement in streptozotocin (STZ)-induced diabetic mice. Mechanistically, SYR prevented the abundance of pyroptosis-related proteins such as NOD-like receptor family pyrin domain containing 3 (NLRP3), cysteinyl aspartate-specific proteinase 1 (Caspase-1), and gasdermin D (GSDMD), and the biosynthesis of inflammatory cytokines interleukin 1ß (IL-1ß) and interleukin 18 (IL-18). In addition, SYR promoted the nuclear translocation of nuclear factor E2-related factor 2 (NRF2) and enhanced the downstream antioxidant enzymes heme oxygenase 1 (HO-1) and manganese superoxide dismutase (MnSOD), thereby effectively decreasing excess reactive oxygen species (ROS). Most importantly, knockout of NRF2 abolished SYR-mediated renoprotection and anti-pyroptotic activities in NRF2-KO diabetic mice. Collectively, SYR inhibited the NLRP3/Caspase-1/GSDMD pyroptosis pathway by upregulating NRF2 signaling in DN. These findings suggested that SYR may be promising a therapeutic option for DN.

Molecular docking and biochemical validation of (-)-syringaresinol-4-O-ß-D-apiofuranosyl-(1→2)-ß-D-glucopyranoside binding to an allosteric site in monoamine transporters.

Albizia julibrissin Durazz is one of the most common herbs used for depression and anxiety treatment, but its mechanism of action as an antidepressant or anxiolytic drug have not been fully understood. We previously isolated and identified one lignan glycoside compound from Albizia Julibrissin Durazz, (-)-syringaresinol-4-O-ß-D-apiofuranosyl-(1→2)-ß-D-glucopyranoside (SAG), that inhibited all three monoamine transporters with a mechanism of action different from that of the conventional antidepressants. In this study, we generated homology models for human dopamine transporter and human norepinephrine transporter, based on the X-ray structure of Drosophila dopamine transporter, and conducted the molecular docking of SAG to all three human monoamine transporters. Our computational results indicated that SAG binds to an allosteric site (S2) that has been demonstrated to be formed by an aromatic pocket positioned in the scaffold domain in the extracellular vestibule connected to the central site (S1) in these monoamine transporters. In addition, we demonstrated that SAG stabilizes a conformation of serotonin transporter with both the extracellular and cytoplasmic pathways closed. Furthermore, we performed mutagenesis of the residues in both the allosteric and orthosteric sites to biochemically validate SAG binding in all three monoamine transporters. Our results are consistent with the molecular docking calculation and support the association of SAG with the allosteric site. We expect that this herbal molecule could become a lead compound for the development of new therapeutic agents with a novel mechanism of action.

Syringaresinol derived from Panax ginseng berry attenuates oxidative stress-induced skin aging via autophagy.

Background: In aged skin, reactive oxygen species (ROS) induces degradation of the extracellular matrix (ECM), leading to visible aging signs. Collagens in the ECM are cleaved by matrix metalloproteinases (MMPs). Syringaresinol (SYR), isolated from Panax ginseng berry, has various physiological activities, including anti-inflammatory action. However, the anti-aging effects of SYR via antioxidant and autophagy regulation have not been elucidated. Methods: The preventive effect of SYR on skin aging was investigated in human HaCaT keratinocytes in the presence of H2O2, and the keratinocyte cells were treated with SYR (0-200 µg/mL). mRNA and protein levels of MMP-2 and -9 were determined by real-time PCR and Western blotting, respectively. Radical scavenging activity was researched by 2,2 diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. LC3B level was assessed by Western blotting and confocal microscopy. Results: SYR significantly reduced gene expression and protein levels of MMP-9 and -2 in both H2O2-treated and untreated HaCaT cells. SYR did not show cytotoxicity to HaCaT cells. SYR exhibited DPPH and ABTS radical scavenging activities with an EC50 value of 10.77 and 10.35 µg/mL, respectively. SYR elevated total levels of endogenous and exogenous LC3B in H2O2-stimulated HaCaT cells. 3-Methyladenine (3-MA), an autophagy inhibitor, counteracted the inhibitory effect of SYR on MMP-2 expression. Conclusion: SYR showed antioxidant activity and up-regulated autophagy activity in H2O2-stimulated HaCaT cells, lowering the expression of MMP-2 and MMP-9 associated with skin aging. Our results suggest that SYR has potential value as a cosmetic additive for prevention of skin aging.

Syringaresinol Resisted Sepsis-Induced Acute Lung Injury by Suppressing Pyroptosis Via the Oestrogen Receptor-ß Signalling Pathway.

Acute lung injury (ALI) is a common lung disease characterized by severe acute inflammatory lung injury in patients with sepsis. Syringaresinol (SYR) has been reported to have anti-apoptotic and anti-inflammatory effects, but whether it could prevent pyroptosis to improve sepsis-induced ALI remains unclear. The purpose of this work was to examine the impact of SYR on sepsis-induced ALI and investigate the underlying mechanisms. The ALI model was induced by caecal ligation and puncture (CLP) in C57BL/6 mice, structural damage in the lung tissues was determined using haematoxylin and eosin (HE) staining, and the levels of related inflammatory cytokines and macrophage polarization were examined by enzyme-linked immunosorbent assays (ELISAs) and flow cytometry, respectively. The activation of the NLRP3 inflammasome and the protein levels of TLR4, NF-κB and MAPKs was measured by western blotting. The results demonstrated that SYR pretreatment significantly reduced lung tissue histological damage, inhibited the production of proinflammatory cytokines and albumin in bronchoalveolar lavage fluid (BALF), and decreased myeloperoxidase (MPO) levels, thereby alleviating lung tissue injury. Meanwhile, septic mice treated with SYR displayed a higher survival rate and lower percentage of M1 macrophages in the BALF and spleen than septic mice. In addition, lung tissues from the CLP + SYR group exhibited downregulated protein expression of NLRP3, ASC, GSDMD caspase-1 p20 and TLR4, along with decreased phosphorylated levels of NF-κB, ERK, JNK and P38, indicating that SYR administration effectively prevented CLP-induced pyroptosis in the lung. SYR also suppressed LPS-induced pyroptosis in RAW 264.7 cells by inhibiting the activation of the NLRP3 inflammasome, which was abolished by an oestrogen receptor-ß (ERß) antagonist (PHTPP). In conclusion, SYR exerted protective effects on CLP-induced ALI via the oestrogen receptor-ß signalling pathway.

Syringaresinol attenuates sepsis-induced cardiac dysfunction by inhibiting inflammation and pyroptosis in mice.

The mortality of sepsis-induced cardiac dysfunction (SICD) is very high due to the complex pathophysiological mechanism. Syringaresinol (SYR) is a natural abstract which possesses anti-inflammatory property. The present study aims was to identify the protective impact of SYR on sepsis-induced cardiac dysfunction and investigate the specific mechanisms. We found that SYR improved the cardiac function and alleviated myocardial injury in mice that subjected to cecal ligation and puncture, in addition, SIRT1 expression was significantly elevated after SYR treatment compared to sepsis group both in vivo and in vitro, along with suppression of NLRP3 activation and proinflammatory cytokines release. However, SIRT1 inhibitor EX427 abolished the impact of SYR on LPS-induced pyroptosis in cardiomyocytes. Furthermore, molecular docking analysis predicted that there is high affinity between SYR and estrogen receptor (ER), ER inhibitor ICI182780, the specific ERß inhibitor PHTP and the specific ERαinhibitor AZD9496 were used to examine the role of ER in the protective effect of SYR against SICD, and the results suggested that ER activation was essential for the cardioprotective function of SYR. In conclusion, SYR ameliorates SICD via the ER/SIRT1/NLRP3/GSDMD pathway.

(-)-Syringaresinol suppressed LPS-induced microglia activation via downregulation of NF-κB p65 signaling and interaction with ERß.

Albiziae Cortex (AC) is a well-known traditional Chinese medicine with sedative-hypnotic effects and neuroprotective ability. However, the bioactive components of AC responsible for the neuro-protective actitivity remain unknown. Here, we investigated the anti-neuroinflammatory effects of (-)-syringaresinol (SYR) extracted from AC in microglia cells and wild-type mice. As a result, (-)-SYR significantly reduced lipopolysaccharide (LPS)-induced production of interleukin - 6 (IL-6), tumor necrosis factor α (TNF-α), interleukin -1 beta (IL-1ß), cycloxygenase-2 (COX-2), and nitric oxide (NO) in BV2 microglia cells. (-)-SYR also significantly reduced M1 marker CD40 expression and increased M2 marker CD206 expression. Moreover, we found that (-)-SYR inhibited LPS-induced NF-κB activation by suppressing the translocation of NF-κB p65 into the nucleus in a concentration-dependent manner. Meanwhile, estrogen receptor ß (ERß) was found to be implied in the anti-inflammatory activity of (-)-SYR in BV2 microglia. In vivo experiments revealed that administration of (-)-SYR in mice significantly reduced microglia/astrocytes activation and mRNA levels of proinflammatory mediators. Taken together, our data indicated that (-)-SYR exerted the anti-neuroinflammatory effects by inhibiting NF-κB activation and modulation of microglia polarization, and via interaction with ERß. The anti-neuroinflammatory activity of (-)-SYR may provide a new therapeutic avenue for the treatment of brain diseases associated with inflammation.

Syringaresinol as a novel androgen receptor antagonist against wild and mutant androgen receptors for the treatment of castration-resistant prostate cancer: molecular docking, in-vitro and molecular dynamics study.

Phytoestrogens are dietary estrogens having similar structure as of estrogen. Some of these phytoestrogens are androgen receptor (AR) antagonists and exhibit preventive role in the prostate cancer. However, in androgen-independent prostate cancer (AIPC) the ARs were mutated (T877A, W741L, F876L, etc.) and these mutant ARs convert the antagonist to agonist. Our aim in this study is to find phytoestrogens that could function as an antagonist with wild and mutant ARs. The phytoestrogens were analyzed for binding affinity with wild and mutant ARs in agonist and antagonist conformations. The point mutations were carried out using Chimera. The antagonist AR conformation was modeled using Modeller. We hypothesize that the compounds having binding affinity with agonist AR conformation could not function as a full or pure antagonist. Most of the phytoestrogens have binding affinity with agonist AR conformation contradicting previous results. For example, genistein which is a widely studied isoflavone has known AR antagonist property. However, in our study, it had good binding affinity with agonist AR conformation. Hence, to confirm our hypothesis, we tested genistein in LNCaP (T877A mutant AR) cells by qPCR studies. The genistein functioned as an antagonist only in the presence of an androgen indicting a partial agonist type of activity. The in-vitro results supported our docking hypothesis. We applied this principle and found syringaresinol could function as an antagonist with wild and mutated ARs. Further, we carried out molecular dynamics for the hit molecule to confirm its antagonist binding mode with mutant AR.Communicated by Ramaswamy H. Sarma.

Naphthalene Structures Derived from Lignins During Phenolation.

Phenolation is a commonly used method to improve the reactivity of lignin for various applications. In this study, resinol lignin models (syringaresinol and pinoresinol) and eucalyptus alkali lignin were treated under acid-catalyzed phenolation conditions to investigate the products derived from resinol (ß-ß) structures of lignins. The phenolation products were characterized by means of GC-MS and NMR spectroscopy following separation using flash chromatography and thin-layer chromatography. A series of new naphthalene products were identified from phenolation of syringaresinol, and the corresponding guaiacyl analogs were also identified by GC-MS. The C1-Cα bond of these resinol compounds was cleaved to release syringol or guaiacol during phenolation. In addition, diphenylmethane products formed from phenol or phenol and syringol/guaiacol were found in the phenolation products. Comparatively, more naphthalene products were obtained by phenolation from syringaresinol than those obtained from pinoresinol. HSQC NMR characterization of the phenolated alkali lignin revealed that naphthalene structures formed in the phenolated lignin.

Syringaresinol Protects against Type 1 Diabetic Cardiomyopathy by Alleviating Inflammation Responses, Cardiac Fibrosis, and Oxidative Stress.

SCOPE: Syringaresinol (SYR) is a phenolic compound, which could be found in various cereals and medicinal plants. It exerts both anti-inflammatory and antioxidant pharmacological properties. However, little is known about the effect of SYR on modulating diabetic cardiomyopathy. The present study aimed to investigate the pharmacodynamic effect of SYR on diabetic cardiomyopathy and the underlying molecular mechanism. METHODS AND RESULTS: In STZ-induced type 1 diabetic mice, orally administration with SYR in every other day for 8 weeks significantly improves cardiac dysfunction and preventes cardiac hypertrophy and fibrosis. The macrophage infiltration and oxidative stress biomarkers are also suppressed by SYR without affecting hyperglycemia and body weight. In neonatal cardiomyocytes, high glucose-induced cell apoptosis and fibrosis are potently decreased by SYR, and the inflammatory response and oxidant stress are also alleviated by SYR incubation. Mechanistically, SYR may exert protective effects by restoring suppression of antioxidant kelch-like ECH-associated protein 1 (Keap1)/nuclear factor-E2-related factor 2 (Nrf2) system and abnormal activation of transforming growth factor-ß (TGF-ß)/mothers against decapentaplegic homolog (Smad) signaling pathway in vitro and in vivo. CONCLUSION: The results indicated that SYR could be a potential therapeutic agent for the treatment of diabetic cardiomyopathy by inhibiting inflammation, fibrosis, and oxidative stress. The signaling pathway of Keap1/Nrf2 and TGF-ß/Smad could be used as therapeutic targets for diabetic complications.

Small Molecule from Natural Phytochemical Mimics Dietary Restriction by Modulating FoxO3a and Metabolic Reprogramming.

Many studies utilizing animal models have revealed the genetic and pharmacogenetic modulators of the rate of organismal aging. However, finding routes for healthy aging during extended life remains one of the largest questions. With regards to an antiaging reagent, it has been shown that natural phytochemical syringaresinol (SYR) delays cellular senescence by activating sirtuin1 (SIRT1). Here, it is found that SYR treatment results in metabolic changes similar to those observed during dietary restriction (DR). The DR mimetic effects are mediated by FoxO3a-dependent SIRT1 activation and insulin/insuline growth factor-1 signaling modulation. The direct binding of SYR-FoxO3a is identified and this could partially explain the DR-like phenotype. The report gives a clue as to how the longevity gene involves the DR pathway and suggests that natural phytochemicals applied as a geroprotector mimics DR effects.

(-)-Syringaresinol-4-O-ß-D-glucopyranoside from Cortex Albizziae inhibits corticosterone-induced PC12 cell apoptosis and relieves the associated dysfunction.

The neuroprotective effects and potential mechanisms of (-)-Syringaresinol-4-O-ß-D-glucopyranoside (SRG), a natural lignan glycoside extracted from Cortex Albizziae, were investigated using corticosterone (CORT)-induced PC12 cells as an in vitro anxiety model. PC12 cells were treated with 100 µM CORT and 5, 10, or 20 µM SRG for 48 h. Cell viability and lactate dehydrogenase (LDH) leakage were measured. Apoptosis were detected using FITC-coupled Annexin V (AV) and propidium iodide (PI) staining flow cytometric analyses and TUNEL assays. Rhodamine 123 and Fluo-3-AM staining flow cytometric analyses were used to detect mitochondrial membrane potential (ΔΨm) and intracellular calcium concentration ([Ca2+]i), respectively. Western blot was used to detect brain-derived neurotrophic factor (BDNF), Bax, Bcl-2, cAMP-response element binding protein (CREB), cytosolic cytochrome c (Cyt c), caspase-3, and cleaved caspase-3. Experimental data showed that SRG promoted cell proliferation, reduced LDH release, inhibited apoptosis, improved ΔΨm values, decreased [Ca2+]i, up-regulated CREB, BDNF, and Bcl-2, down-regulated Bax and Cyt c protein expression levels, and reduced caspase-3 activity. This suggests that SRG has neuroprotective and antiapoptotic effects in the pathogenesis of anxiety disorders, and its mechanisms are partly connecte to inhibition of the mitochondrial apoptotic pathway and activation of pathways involving CREB and BDNF.

Toxicological testing of syringaresinol and enterolignans.

Lignans are secondary plant constituents with dibenzylbutane skeletons found in cereals, oilseeds, and nuts. Two members of this class, syringaresinol (Syr) and secoisolariciresinol (Seco), occur at relatively high levels in cereals and processed food products as well as in coniferous trees. In vitro studies have shown that Seco and its metabolites enterodiol (END) and enterolactone (ENL), which are formed by intestinal microbes, exhibit strong antioxidant activity because of their phenolic character. The biological activity and discussion of dietary supplementation with these substances led to questions about the potential adverse health effects of these compounds, which are explored here. Syr and the metabolites END and ENL were investigated by combining structural information generated in silico with practical testing in vitro. An in silico structure-activity analysis was performed using ToxTree and NexusPrediction to suggest plausible mechanisms of toxicity and estimate toxicological endpoints of these compounds. Structural alerts were generated based on the presence of phenolic units with coordinating substituents that could potentially form quinoid structures, promote reactive oxygen species (ROS) formation, bind to cellular structures, or damage chromosomes. To assess the in silico results, the cytotoxicity and genotoxic potential of the studied compounds were tested in vitro using the resazurin reduction and comet assays, respectively. Incubating HepG2 and HT29 cells for 1 h or 24 h with 0-100 µM Syr, END, or ENL induced no cytotoxic effects. Additionally, even the highest tested concentrations of END and ENL showed no modulation of background and total DNA damage. The initial in silico screen thus generated structural alerts linked to toxicological endpoints, but experimental assessments of the studied compounds revealed no detectable toxicity, demonstrating the need for individual mechanistic experimental verification of in silico predictions. This approach makes it possible to connect known biological activity, such as reported antioxidative effects, to underlying mechanisms such as proton abstraction or donation. This in turn can yield insights - for example, that a compound's tendency to act as a pro- or anti-oxidant (and hence to exert adverse or beneficial health effects) may depend on its concentration and the cellular state.