Lignan Dimers from Forsythia viridissima Roots and Their Antiviral Effects.

Six new dimeric lignans (1-6) and one new lignan glycoside (16) were isolated from Forsythia viridissima roots along with nine known lignans (7-15). Spectroscopic analyses and chemical methods were used to determine these new structures and their absolute configurations. Among these compounds, dimatairesinol (1) and viridissimaols A-E (2-6) were assigned as dimers of dibenzylbutyrolactone analogues. Furthermore, the isolated compounds were evaluated for their antiviral activities against coxsackievirus B3 (CVB3) and human rhinovirus 1B (HRV1B). In these tests, compounds 12 and 15 showed antiviral effects against CVB3 infection with IC50 values of 15.4 and 36.4 µM, respectively, while 2, 3, 8, and 9 showed activities against HRV1B with IC50 values of 45.7, 47.5, 13.0, and 43.2 µM, respectively.

Nuclear Factor Erythroid 2-Related Factor 2 Activating Triterpenoid Saponins from Camellia japonica Roots.

Oxidative stress due to the presence of excess reactive oxygen species may cause cancers, aging, and many other conditions. Nuclear factor erythroid 2-related factor 2 (Nrf2) may control abnormal oxidative stress as a transcription factor by inducing antioxidant-related genes via antioxidant response elements (AREs) in the gene promoters. The 11 triterpenoid saponins (1-11) isolated from Camellia japonica roots were tested for ARE-luciferase activity and Nrf2 accumulation in human keratinocytes (HaCaT cells). The ARE-luciferase activity was significantly increased by compounds 1-11 (25 µM) as a result of nuclear Nrf2 accumulation in the cells. Thus, these compounds may contribute to the induction of Nrf2 activity against oxidative damage in cells.

Antiproliferation of keratinocytes and alleviation of psoriasis by the ethanol extract of Artemisia capillaris.

The therapeutic potentials of the ethanol extract of Artemisia capillaris (ACE) for psoriasis were verified in HaCaT cells (as an immortalized human keratinocyte cell line) and imiquimod (IMQ)-induced psoriasis-like mouse models. In HaCaT cells, IC50 value of ACE was 37.5 µg/ml after incubating for 72 hr. The antiproliferation activity of ACE in HaCaT cells was further verified by apoptosis assays. The percentage of apoptotic population in ACE-treated group was significantly higher than that of control group (p < .05). The result of cell cycle arrest assay also supported the observed antiproliferation efficacy of ACE in HaCaT cells. In IMQ-induced psoriasis-like mouse models, the Psoriasis Area and Severity Index score of ACE (50 mg/ml; ACE50)-treated group was significantly lower than that of IMQ group on Day 4 (p < .05). After topical application of ACE on psoriasis-like lesion for 4 days, the epidermal thickness of (IMQ + ACE50) group was significantly lower than that of IMQ group (p < .05). The expression levels of Ki-67 and intracellular adhesion molecule-1 in excised skin tissues of (IMQ + ACE50) group were also lower than those of IMQ group. All these findings suggest that ACE can be used as a promising antipsoriatic agent.

E-p-Methoxycinnamoyl-α-l-rhamnopyranosyl Ester, a Phenylpropanoid Isolated from Scrophularia buergeriana, Increases Nuclear Factor Erythroid-Derived 2-Related Factor 2 Stability by Inhibiting Ubiquitination in Human Keratinocytes.

The nuclear factor erythroid-derived 2-related factor 2 (Nrf2) is a key regulator of gene expression during oxidative stress and drug detoxification. Thus, identifying Nrf2 activators to protect from possible cell damage is necessary. In this study, we investigated whether E-p-methoxycinnamoyl-α-l-rhamnopyranosyl ester (MCR), a phenylpropanoid isolated from Scrophularia buergeriana, can activate Nrf2 signaling in human keratinocytes (HaCaT). First, we determined the dose- and time-dependent effects of MCR on the expression and activity of Nrf2. The antioxidant response element-luciferase reporter assay and western blot analysis results showed that MCR markedly induced Nrf2 activity and its protein expression, respectively. Further, MCR increased both the mRNA and protein levels of heme-oxygenase-1, one of the Nrf2 target genes, in the cells. Interestingly, we found that Nrf2 stability was remarkably enhanced by MCR. Furthermore, ubiquitin-dependent proteasomal degradation of Nrf2 was significantly reduced by MCR. Thus, MCR might afford skin protection by enhancing Nrf2 stability or by blocking its proteasomal degradation.

New polyhydroxytriterpenoid derivatives from fruits of Terminalia chebula Retz. and their α-glucosidase and α-amylase inhibitory activity.

Three new polyhydroxytriterpenoid derivatives, 23-O-neochebuloylarjungenin 28-O-ß-d-glycopyranosyl ester (1), 23-O-4'-epi-neochebuloylarjungenin (2), and 23-O-galloylpinfaenoic acid 28-O-ß-d-glucopyranosyl ester (17) were isolated from the fruits of Terminalia chebula Retz. along with fourteen known ones. Their structures were elucidated by 1D and 2D NMR spectroscopic data and acid hydrolysis. After evaluating for Baker's yeast α-glucosidase, rat intestinal α-glucosidase, and porcine pancreatic α-amylase inhibitory activities of all the isolated compounds, 23-O-galloylarjunolic acid (11, IC50 21.7µM) and 23-O-galloylarjunolic acid 28-O-ß-d-glucopyranosyl ester (12, IC50 64.2µM) showed potent inhibitory activities against Baker's yeast α-glucosidase compared to the positive control, acarbose (IC50 174.0µM). However, all the tested compounds except for the positive control, acarbose, had no or only weak inhibitory activity against rat intestinal α-glucosidase and porcine pancreatic α-amylase.

Lignans from Opuntia ficus-indica seeds protect rat primary hepatocytes and HepG2 cells against ethanol-induced oxidative stress.

Bioactivity-guided isolation of Opuntia ficus-indica (Cactaceae) seeds against ethanol-treated primary rat hepatocytes yielded six lignan compounds. Among the isolates, furofuran lignans 4-6, significantly protected rat hepatocytes against ethanol-induced oxidative stress by reducing intracellular reactive oxygen species levels, preserving antioxidative defense enzyme activities, and maintaining the glutathione content. Moreover, 4 dose-dependently induced the heme oxygenase-1 expression in HepG2 cells.

Fast and Simple Discriminative Analysis of Anthocyanins-Containing Berries Using LC/MS Spectral Data.

INTRODUCTION: Anthocyanins are potent antioxidant agents that protect against many degenerative diseases; however, they are unstable because they are vulnerable to external stimuli including temperature, pH and light. This vulnerability hinders the quality control of anthocyanin-containing berries using classical high-performance liquid chromatography (HPLC) analytical methodologies based on UV or MS chromatograms. OBJECTIVE: To develop an alternative approach for the quality assessment and discrimination of anthocyanin-containing berries, we used MS spectral data acquired in a short analytical time rather than UV or MS chromatograms. METHOD: Mixtures of anthocyanins were separated from other components in a short gradient time (5 min) due to their higher polarity, and the representative MS spectrum was acquired from the MS chromatogram corresponding to the mixture of anthocyanins. RESULTS: The chemometric data from the representative MS spectra contained reliable information for the identification and relative quantification of anthocyanins in berries with good precision and accuracy. CONCLUSION: This fast and simple methodology, which consists of a simple sample preparation method and short gradient analysis, could be applied to reliably discriminate the species and geographical origins of different anthocyanin-containing berries. These features make the technique useful for the food industry. Copyright © 2017 John Wiley & Sons, Ltd.

Stereoisomer-specific anticancer activities of ginsenoside Rg3 and Rh2 in HepG2 cells: disparity in cytotoxicity and autophagy-inducing effects due to 20(S)-epimers.

Autophagy has been an emerging field in the treatment of hepatic carcinoma since anticancer therapies were shown to ignite autophagy in vitro and in vivo. Here we report that ginsenoside Rg3 and Rh2, major components of red ginseng, induce apoptotic cell death in a stereoisomer-specific fashion. The 20(S)-forms of Rg3 and Rh2, but not their respective 20(R)-forms, promoted cell death in a dose-dependent manner accompanied by downregulation of Bcl2 and upregulation of Fas, resulting in apoptosis of HepG2 cells with poly ADP ribose polymerase cleavage. The LD50 value [45 µM for Rg3(S), less than 10 µM for Rh2(S)] and gross morphological electron microscopic observation revealed more severe cellular damage in cells treated with Rh2(S) than in those treated with Rg3(S). Both Rg3(S) and Rh2(S) also induced autophagy when undergoing induced apoptosis. Inhibition of autophagy with lysosomotrophic agents significantly potentiated the cellular damage, implying a favorable switch of the cell fate to tumor cell death. Blocking intracellular calcium with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM) restored the cell death induced by both Rg3(S) and Rh2(S). Our results suggest that the 20(S)-forms of Rg3 and Rh2 in red ginseng possess more potent antitumor activity with autophagy than their 20(R)-forms via calcium-dependent apoptosis.

Chemical constituents isolated from Disporum viridescens leaves and their inhibitory effect on nitric oxide production in BV2 microglial cells.

Excessive NO (nitric oxide) has been associated with the pathogenesis of various neurodegenerative diseases including Alzheimer's disease (AD). In our screening system using LPS-activated BV2 microglial cells, the methanolic extract of Disporum viridescens leaves was found to have significant NO inhibitory activity. Bioactivity-guided isolation yielded a new phenylpropanoid characterized as 4-ally-2,6-dimethoxyphenyl 1-O-ß-D-apiofuranosyl (1→6)-ß-D-glucopyranoside (12) with 21 known compounds from the leaves of D. viridescens. Among them, compounds 2 and 4 significantly inhibited NO production. Thus, we further elucidated the anti-inflammatory mechanism of these lignans. Especially, compound 4 inhibited the expression of both inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) through the suppression of the MAPK signaling pathway. Taken together, the anti-inflammatory activities of the active constituents isolated from D. viridescens leaves could have therapeutic potential against neurodegenerative diseases.

Activation of Nuclear Factor Erythroid 2-Related Factor-2 by Oxylipin from Mangifera indica Leaves.

Mangifera indica L., a member of the Anacardiaceae family, is widely cultivated across the globe. The leaves of M. indica are renowned for their medicinal properties, attributed to the abundance of bioactive compounds. This study investigated the effects of mango leaf extract on oxidative stress in HeLa cells. Notably, the n-hexane fraction (MLHx) significantly enhanced antioxidant response element (ARE)-luciferase activity at a concentration of 100 µg/mL, surpassing other fractions. MLHx also promoted the expression of HO-1 mRNA by increasing nuclear NRF2 levels. The molecular mechanism of MLHx involves increased phosphorylation of ERK1/2 and stabilization of NRF2. Bioactivity-guided isolation resulted in the identification of six oxylipins: 13(R)-hydroxy-octadeca-(9Z,11E,15Z)-trienoic acid (C-1), 9(R)-hydroxy-octadeca-(10E,12Z,15Z)-trienoic acid (C-2), 13(R)-hydroxy-(9Z,11E)-octadecadienoic acid (C-3), 9(R)-hydroxy-(10E,12Z)-octadecadienoic acid (C-4), 9-oxo-(10E,12E)-octadecadienoic acid (C-5), and 9-oxo-(10E,12Z)-octadecadienoic acid (C-6). These structures were elucidated using comprehensive spectroscopic techniques, including MS and 1H NMR. Additionally, compounds C-7 (9-oxo-(10E,12Z,15Z)-octadecatrienoic acid) and 8 (13-oxo-(9E,11E)-octadecadienoic acid) were characterized by LC-MS/MS mass fragmentation. This study reports the isolation of compounds 1-6 from M. indica for the first time. When tested for their effect on NRF2 activity in HeLa cells, compounds 3, 5, and 6 showed strong stimulation of ARE-luciferase activity in a dose-dependent manner.

Panaxydol extracted from Panax ginseng inhibits NLRP3 inflammasome activation to ameliorate NASH-induced liver injury.

Activation of NOD-like receptor protein 3 (NLRP3) inflammasome exacerbates liver inflammation and fibrosis in nonalcoholic steatohepatitis (NASH), suggesting that development of inflammasome inhibitor can become leading candidate to ameliorate NASH. Panax ginseng (P. ginseng) contains numerous bioactive natural components to reduce inflammation. This study aims to identify inhibitory components of P. ginseng for NLRP3 inflammasome activation. We separated polar and non-polar fractions of P. ginseng and tested modulation of NLRP3 inflammasome, and then identified pure component for inflammasome inhibitor which ameliorates diet-induced NASH. Non-polar P. ginseng fractions obtained from ethyl acetate solvent attenuated IL-1ß secretion and expression of active caspase-1. We revealed that panaxydol (PND) is pure component to inhibit NLRP3 inflammasome activation. PND blocked inflammasome cytokines release, pyroptotic cell death, caspase-1 activation and specking of inflammasome complex. Inhibitory effect of PND was specific to NLRP3-dependent pathway via potential interaction with ATP binding motif of NLRP3. Moreover, in vivo studies showed that PND plays beneficial roles to reduce tissue inflammations through disruption of NLRP3 inflammasome and to ameliorate the development of NASH. These results provide new insight of natural products, panaxydol, for NLRP3 inflammasome inhibitor and could offer potential therapeutic candidate for reliving NASH.

Identification of novel dimers and chemical profiling of acid amide alkaloids in Piper nigrum.

Peppers (Piper nigrum L.) are distinguished by their pungent flavor and aroma. Piperine is a major acid-amide alkaloid with a piperidine ring that gives pepper its flavor and scent. In plant metabolomics research, the accessibility of the chemical standards is critical for scientific credibility. We isolated and identified 10 novel dimers of acid amide alkaloids (9-15 and 20-22), along with 12 known monomers (1-6) and dimers (7, 8, 16-19) from black pepper. Subsequently, we found the distribution of monomers and dimers of acid amide alkaloids in black and white peppers by twenty-two acid amide alkaloids which we obtained using the molecular networking technique and multivariate analysis to reveal the molecular relationships between the acid amide alkaloids in black and white peppers. Our research delved into the chemical diversity of acid amide alkaloids in black and white peppers, which could help inform future culinary and potential medicinal utilization of pepper.

plantMASST - Community-driven chemotaxonomic digitization of plants.

Understanding the distribution of hundreds of thousands of plant metabolites across the plant kingdom presents a challenge. To address this, we curated publicly available LC-MS/MS data from 19,075 plant extracts and developed the plantMASST reference database encompassing 246 botanical families, 1,469 genera, and 2,793 species. This taxonomically focused database facilitates the exploration of plant-derived molecules using tandem mass spectrometry (MS/MS) spectra. This tool will aid in drug discovery, biosynthesis, (chemo)taxonomy, and the evolutionary ecology of herbivore interactions.

Neuroprotective benzyl benzoate glycosides from Disporum viridescens roots in HT22 hippocampal neuronal cells.

Bioassay-guided fractionation of the EtOAc extract from Disporum viridescens roots led to the isolation of five new benzyl benzoate glycosides, BBGs (1-5). The neuroprotective activities of the BBGs were screened using neuronal HT22 hippocampal cells. BBG-D (4) significantly protected murine hippocampal HT22 cells against glutamate-induced neurotoxicity by maintaining the antioxidative defense systems such as superoxide dismutase, glutathione reductase, glutathione peroxidase, and the glutathione content. BBG-D, in a dose-and time-dependent manner, increased HO-1 expression through the selective activation of pERK signaling among the MAPK pathways. These results suggest that BBG-D could be a promising candidate for the treatment of neurodegenerative diseases related to glutamate-induced oxidative neuronal cytotoxicity.

Neuroprotective compounds from Salix pseudo-lasiogyne twigs and their anti-amnesic effects on scopolamine-induced memory deficit in mice.

Bioassay-guided fractionation of an 80% methanolic extract of Salix pseudo-lasiogyne twigs has resulted in the isolation of two new compounds (1-2) along with ten known ones (3-12). The new compounds were determined to be 3'-O-acetylsalicin (1) and 2',6'-O-acetylsalicortin (2) by using spectroscopic analyses. Compounds (3-12) were identified as salicin (3), 2'-O-acetylsalicin (4), salicortin (5), 2'-O-acetylsalicortin (6), 3'-O-acetylsalicortin (7), 6'-O-acetylsalicortin (8), 2'-O-(E)-ρ-coumaroylsalicortin (9), grandidentatin (10), isograndidentatin (11), and saligenin (12). Among the isolated compounds, compounds 2, 5, 6, 7, and 8 bearing 1-hydroxy-6-oxo-2-cyclohexenecarboxylate moiety significantly inhibited lipopolysaccharide-induced nitric oxide production in BV2 microglial cells in vitro. Further, we studied anti-amnesic activities of the 80% methanolic extract, the EtOAc fraction, and compound 6 from S. pseudo-lasiogyne. They exerted a significant cognitive-enhancing effect on scopolamine-induced memory deficit in mice. In addition, they also significantly increased the reduced activities of glutathione reductase and superoxide dismutase and the glutathione content in the hippocampus and cortex of scopolamine-induced amnesic mice.

Salicortin-derivatives from Salix pseudo-lasiogyne twigs inhibit adipogenesis in 3T3-L1 cells via modulation of C/EBPα and SREBP1c dependent pathway.

Obesity is reported to be associated with excessive growth of adipocyte mass tissue as a result of increases in the number and size of adipocytes differentiated from preadipocytes. To search for anti-adipogenic phytochemicals, we screened for inhibitory activities of various plant sources on adipocyte differentiation in 3T3-L1 preadipocytes. Among the sources, a methanolic extract of Salix pseudo-lasiogyne twigs (Salicaceae) reduced lipid accumulation in a concentration-dependent manner. During our search for anti-adipogenic constituents from S. pseudo-lasiogyne, five salicortin derivatives isolated from an EtOAc fraction of this plant and bearing 1-hydroxy-6-oxo-2-cyclohexene-carboxylate moieties, namely 2',6'-O-acetylsalicortin (1), 2'-O-acetylsalicortin (2), 3'-O-acetylsalicortin (3), 6'-O-acetylsalicortin (4), and salicortin (5), were found to significantly inhibit adipocyte differentiation in 3T3-L1 cells. In particular, 2',6'-O-acetylsalicortin (1) had the most potent inhibitory activity on adipocyte differentiation, with an IC50 value of 11.6 µM, and it significantly down-regulated the expressions of CCAAT/enhancer binding protein α (C/EBPα) and sterol regulatory element binding protein 1 (SREBP1c). Furthermore, 2',6'-O-acetylsalicortin (1) suppressed mRNA expression levels of C/EBPß during the early stage of adipocyte differentiation and stearoyl coenzyme A desaturase 1 (SCD-1), acetyl-CoA carboxylase (ACC), and fatty acid synthase (FAS) expression, target genes of SREBP1c. In the present study, we demonstrate that the anti-adipogenesis mechanism of 2',6'-O-acetylsalicortin (1) may be mediated via down-regulation of C/EBPα and SREBP1c dependent pathways. Through their anti-adipogenic activity, salicortin derivatives may be potential novel therapeutic agents against obesity.

Effect of pre-fragmentation on efficacy and safety for phacoemulsification in femtosecond laser-assisted cataract surgery: a non-randomized clinical trial.

Background: Ultrasound energy during phacoemulsification results in the endothelial cell loss of cornea. Crystallin lens fragmentation with softening before phacoemulsification can be used with femtosecond laser-assisted cataract surgery (FLACS) device. Methods: This non-randomized clinical trial included patients who underwent cataract surgery and not had corneal opacity. Patients who were not possible to apply the interface on the ocular surface, were excluded. Each subject was allowed to decide the surgical method by himself/herself. Cataract surgery was performed with FLACS (groups I and II) or conventional surgical technique (group III). The FLACS group was further subdivided into two groups according to whether a lens softening procedure was performed (group I) or not (group II). The nuclear density of cataract was objectively classified by Pentacam nuclear staging (PNS), preoperatively. Surgical parameters including total phacoemulsification time (TPT), cumulative dissipated energy (CDE), and the balanced salt solution (BSS) volume consumed, were measured during the surgery. Postoperative visual outcomes were evaluated at three months after the surgery, and corneal endothelial cell count (ECC) loss were calculated based on ECC measured before the surgery and two months after the surgery. Results: Eighty-nine eyes from 89 patients were enrolled. Fifty-three were treated using FLACS (groups I; quadrant pattern with softening of pre-fragmentation, n=31 and II; sextant pattern without softening of pre-fragmentation, n=22) and 36 (group III) with the conventional manual technique. The FLACS groups (groups I and II) had statistically significant lower TPT (P<0.001), CDE (P<0.001), and BSS volumes (P<0.001) used in the nucleus removal step compared to group III. Furthermore, ECC loss in groups I (4.59%±2.57%) and II (6.10%±3.30%) were also statistically lower compared to group III (13.49%±10.55%, P<0.001). From subgroup analysis with the PNS 2, group I showed lower pre-fragmentation time, lower CDE, lower BSS volume used during nucleus removal, and lower ECC loss compared to group II (all P<0.001). Conclusions: Pre-fragmentation using FLACS may reduce intraoperative ultrasound energy and intraocular manipulations compared to conventional cataract surgery.

Triterpenoid saponins from Camellia sinensis roots with cytotoxic and immunomodulatory effects.

Camellia sinensis L. (Theaceae) leaves have been used as a beverage in both Eastern and Western cultures for a long time, while its root has not been intensively studied. In this study, seven undescribed triterpenoid saponins (1-7) and twelve known saponins (8-19) with different combinations of substituents, such as oxygenated isoprenyl substituents and sugar moieties, and lengths of sugar chains, were isolated from the C. sinensis roots. Their structures were unequivocally determined using one- and two-dimensional nuclear magnetic resonance data and acid hydrolysis analysis. Investigation of the biological activities of isolated compounds revealed that only those without functional acetyl groups exhibited cytotoxic activities against mouse and human cancer cells (B16F10) and human cervical cancer cell line (HeLa) at 50 µM. Compounds with an aldehyde group at C-23 of aglycone showed immunomodulatory activity against Th1 and Th17 cells at 10 µM. Ten compounds with biological activities from C. sinensis roots extracts, including three previously undescribed ones (3, 6, and 7), were identified.

Antiviral Mechanisms of Saucerneol from Saururus chinensis against Enterovirus A71, Coxsackievirus A16, and Coxsackievirus B3: Role of Mitochondrial ROS and the STING/TKB-1/IRF3 Pathway.

Enterovirus A71 (EV71), coxsackievirus A16 (CVA16), and coxsackievirus B3 (CVB3) are pathogenic members of the Picornaviridae family that cause a range of diseases, including severe central nervous system complications, myocarditis, and pancreatitis. Despite the considerable public health impact of these viruses, no approved antiviral treatments are currently available. In the present study, we confirmed the potential of saucerneol, a compound derived from Saururus chinensis, as an antiviral agent against EV71, CVA16, and CVB3. In the in vivo model, saucerneol effectively suppressed CVB3 replication in the pancreas and alleviated virus-induced pancreatitis. The antiviral activity of saucerneol is associated with increased mitochondrial ROS (mROS) production. In vitro inhibition of mROS generation diminishes the antiviral efficacy of saucerneol. Moreover, saucerneol treatment enhanced the phosphorylation of STING, TBK-1, and IRF3 in EV71- and CVA16-infected cells, indicating that its antiviral effects were mediated through the STING/TBK-1/IRF3 antiviral pathway, which was activated by increased mROS production. Saucerneol is a promising natural antiviral agent against EV71, CVA16, and CVB3 and has potential against virus-induced pancreatitis and myocarditis. Further studies are required to assess its safety and efficacy, which is essential for the development of effective antiviral strategies against these viruses.

Open access repository-scale propagated nearest neighbor suspect spectral library for untargeted metabolomics.

Despite the increasing availability of tandem mass spectrometry (MS/MS) community spectral libraries for untargeted metabolomics over the past decade, the majority of acquired MS/MS spectra remain uninterpreted. To further aid in interpreting unannotated spectra, we created a nearest neighbor suspect spectral library, consisting of 87,916 annotated MS/MS spectra derived from hundreds of millions of MS/MS spectra originating from published untargeted metabolomics experiments. Entries in this library, or "suspects," were derived from unannotated spectra that could be linked in a molecular network to an annotated spectrum. Annotations were propagated to unknowns based on structural relationships to reference molecules using MS/MS-based spectrum alignment. We demonstrate the broad relevance of the nearest neighbor suspect spectral library through representative examples of propagation-based annotation of acylcarnitines, bacterial and plant natural products, and drug metabolism. Our results also highlight how the library can help to better understand an Alzheimer's brain phenotype. The nearest neighbor suspect spectral library is openly available for download or for data analysis through the GNPS platform to help investigators hypothesize candidate structures for unknown MS/MS spectra in untargeted metabolomics data.