Nordihydroguaiaretic Acid Research Articles

Insight into the Natural Biomolecules (BMs): Promising Candidates as Zika Virus Inhibitors.

Zika virus (ZIKV) is among the relatively new infectious disease threats that include SARS-CoV-2, coronavirus, monkeypox (Mpox) virus, etc. ZIKV has been reported to cause severe health risks to the fetus. To date, satisfactory treatment is still not available for the treatment of ZIKV infection. This review examines the last five years of work using natural biomolecules (BMs) to counteract the ZIKV through virtual screening and in vitro investigations. Virtual screening has identified doramectin, pinocembrin, hesperidins, epigallocatechin gallate, pedalitin, and quercetin as potentially active versus ZIKV infection. In vitro, testing has shown that nordihydroguaiaretic acid, mefloquine, isoquercitrin, glycyrrhetinic acid, patentiflorin-A, rottlerin, and harringtonine can reduce ZIKV infections in cell lines. However, in vivo, testing is limited, fortunately, emetine, rottlerin, patentiflorin-A, and lycorine have shown in vivo anti- ZIKV potential. This review focuses on natural biomolecules that show a particularly high selective index (>10). There is limited in vivo and clinical trial data for natural BMs, which needs to be an active area of investigation. This review aims to compile the known reference data and discuss the barriers associated with discovering and using natural BM agents to control ZIKV infection.

Interactions between Inhibitors and 5-Lipoxygenase: Insights from Gaussian Accelerated Molecular Dynamics and Markov State Models.

Inflammation is a protective stress response triggered by external stimuli, with 5-lipoxygenase (5LOX) playing a pivotal role as a potent mediator of the leukotriene (Lts) inflammatory pathway. Nordihydroguaiaretic acid (NDGA) functions as a natural orthosteric inhibitor of 5LOX, while 3-acetyl-11-keto-β-boswellic acid (AKBA) acts as a natural allosteric inhibitor targeting 5LOX. However, the precise mechanisms of inhibition have remained unclear. In this study, Gaussian accelerated molecular dynamics (GaMD) simulation was employed to elucidate the inhibitory mechanisms of NDGA and AKBA on 5LOX. It was found that the orthosteric inhibitor NDGA was tightly bound in the protein's active pocket, occupying the active site and inhibiting the catalytic activity of the 5LOX enzyme through competitive inhibition. The binding of the allosteric inhibitor AKBA induced significant changes at the distal active site, leading to a conformational shift of residues 168-173 from a loop to an α-helix and significant negative correlated motions between residues 285-290 and 375-400, reducing the distance between these segments. In the simulation, the volume of the active cavity in the stable conformation of the protein was reduced, hindering the substrate's entry into the active cavity and, thereby, inhibiting protein activity through allosteric effects. Ultimately, Markov state models (MSM) were used to identify and classify the metastable states of proteins, revealing the transition times between different conformational states. In summary, this study provides theoretical insights into the inhibition mechanisms of 5LOX by AKBA and NDGA, offering new perspectives for the development of novel inhibitors specifically targeting 5LOX, with potential implications for anti-inflammatory drug development.

Nordihydroguaiaretic Acid-Cross-Linked Phenylboronic Acid-Functionalized Polyplex Micelles for Anti-angiogenic Gene Therapy of Orthotopic and Metastatic Tumors.

Polyplexes are required to be equipped with multiple functionalities to accomplish adequate structure stability and gene transfection efficacy for gene therapy. Herein, a 4-carboxy-3-fluorophenylboronic acid (FPBA)-functionalized block copolymer of PEG-b-PAsp(DET/FBA) and PAsp(DET/FBA) (abbreviated as PB and HB) was synthesized and applied for engineering functional polyplex micelles (PMs) through ionic complexation with pDNA followed by strategic cross-linking with nordihydroguaiaretic acid (NDGA) in respect to the potential linkage of polyphenol and FPBA moieties. In relation to polyplex micelles void of cross-linking, the engineered multifunctional polyplex micelles (PBHBN-PMs) were determined to possess improved structural tolerability against the exchange reaction with charged species. Besides, the FPBA/NDGA cross-linking appeared to be selectively cleaved in the acidic endosomal compartments but not the neutral milieu. Furthermore, the PBHB-PMs with the optimal FPBA/NDGA cross-linking degree were identified to possess appreciable cellular uptake and endosomal escape activities, eliciting a significantly high level of gene expression relative to P-PMs and PB-PMs. Eventually, in vivo antitumor therapy by our proposed multifunctional PMs appeared to be capable of facilitating expression of the antiangiogenic genomic payloads (sFlt-1 pDNA) via systemic administration. The enriched antiangiogenic sFlt-1 in the tumors could silence the activities of angiogenic cytokines for the inhibited neo-vasculature and the suppressed growth of orthotopic 4T1 tumors. Of note, the persistent expression of the antiangiogenic sFlt-1 is also presumed to migrate into the blood circulation, thereby accounting for an overall antiangiogenic environment in preventing the potential pulmonary metastasis. Hence, our elaborated multifaceted PMs inspired fascinating potential as an intriguing gene delivery system for the treatment of clinical solid tumors and metastasis.

Microglial CMPK2 promotes neuroinflammation and brain injury after ischemic stroke

Neuroinflammation plays a significant role in ischemic injury, which can be promoted by oxidized mitochondrial DNA (Ox-mtDNA). Cytidine/uridine monophosphate kinase 2 (CMPK2) regulates mtDNA replication, but its role in neuroinflammation and ischemic injury remains unknown. Here, we report that CMPK2 expression is upregulated in monocytes/macrophages and microglia post-stroke in humans and mice, respectively. Microglia/macrophage CMPK2 knockdown using the Cre recombination-dependent adeno-associated virus suppresses the inflammatory responses in the brain, reduces infarcts, and improves neurological outcomes in ischemic CX3CR1Cre/ERT2 mice. Mechanistically, CMPK2 knockdown limits newly synthesized mtDNA and Ox-mtDNA formation and subsequently blocks NLRP3 inflammasome activation in microglia/macrophages. Nordihydroguaiaretic acid (NDGA), as a CMPK2 inhibitor, is discovered to reduce neuroinflammation and ischemic injury in mice and prevent the inflammatory responses in primary human monocytes from ischemic patients. Thus, these findings identify CMPK2 as a promising therapeutic target for ischemic stroke and other brain disorders associated with neuroinflammation.

Impact of pre-veraison cluster treatments with nordihydroguaiaretic acid on the composition of verdejo grapes and wines

In warmer growing regions, climate change is imposing a general increment of the temperature to the vineyards, with a greater frequency of extreme phenomena such as heat waves and droughts. The global warming is advancing and accelerating the ripening process of the grapes, which produces wines with higher alcoholic degree, lower acidity and poorer sensory characteristics. The abscisic acid (ABA) accumulation in grapes plays a crucial role in the onset of ripening, so that applying ABA inhibitors as nordihydroguaiaretic acid (NDGA) could provide musts with better sugar/acidity balance as maturation process occurs later, under lower temperatures. In a field experiment, we studied the effects of pre-veraison NDGA treatments to clusters on the composition of Verdejo must and wine. Treatments consisting of three repeated applications with 100 mM NDGA each delayed the harvest date by 4 days versus untreated controls. Total acidity, tartaric acid concentration and total polyphenol index of the must increased in treated plants, at a constant level of total soluble solid content. Data from the analysis of volatile organic compounds indicated that NDGA could contribute to the coupling of technological and aromatic maturity of grapes, then improving the aromatic profile of wines by decreasing the concentrations of total acids. Our results demonstrate that NDGA applications are potentially useful to mitigate the negative effects of global warming on the quality of wines, by increasing the acidity and polyphenol content of the musts and improving the aromatic profile of the wines.

Green-synthesized silver nanoparticles from Zingiber officinale extract: antioxidant potential, biocompatibility, anti-LOX properties, and in silico analysis

IntroductionZingiber officinale extract has emerged as a compelling candidate for green synthesis of nanoparticles, offering diverse applications across medicine, cosmetics, and nutrition. This study delves into the investigation of in vitro toxicity and explores the biomedical utility of green-synthesized silver nanoparticles derived from ginger extract (GE-AgNPs).MethodsWe employed established protocols to evaluate in vitro aspects such as antioxidant capacity, anti-inflammatory potential, and biocompatibility of GE-AgNPs. Additionally, molecular docking was employed to assess their anti-lipoxygenase (anti-LOX) activity.ResultsOur findings highlight that the extraction of ginger extract at a pH of 6, utilizing a cosolvent blend of ethanol and ethyl acetate in a 1:1 ratio, yields heightened antioxidant capacity attributed to its rich phenolic and flavonoid content. In the context of silver nanoparticle synthesis, pH 6 extraction yields the highest quantity of nanoparticles, characterized by an average size of 32.64 ± 1.65 nm. Of particular significance, GE-AgNPs (at pH 6) demonstrated remarkable efficacy in scavenging free radicals, as evidenced by an IC50 value of 6.83 ± 0.47 µg/mL. The results from the anti-LOX experiment indicate that GE-AgNPs, at a concentration of 10 µg/mL, can inhibit LOX activity by 25%, outperforming ginger extract which inhibits LOX by 17–18%. Notably, clionasterol exhibited higher binding energy and enhanced stability (-8.9 kcal/mol) compared to nordihydroguaiaretic acid. Furthermore, a cell viability study confirmed the safety of GE-AgNPs at a concentration of 17.52 ± 7.00 µg/mL against the L929 cell line.ConclusionThese comprehensive findings underscore the significant biomedical advantages of GE-AgNPs and emphasize their potential incorporation into cosmetic products at a maximum concentration of 10 µg/mL.

Boesenbergia rotunda and Its Pinostrobin for Atopic Dermatitis: Dual 5-Lipoxygenase and Cyclooxygenase-2 Inhibitor and Its Mechanistic Study through Steady-State Kinetics and Molecular Modeling.

Human 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) are potential targets for suppressing pruritic skin inflammation in atopic dermatitis (AD). In addition, Staphylococcus aureus colonization and oxidative stress worsen AD skin conditions. We aimed to investigate anti-inflammatory activity, using 5-LOX and COX-2 inhibitions, and the anti-staphylococcal, and antioxidant potentials of several medicinal plants bio-prospected from traditional medicine related to AD pathogenesis. Essential oils and hexane fractions were prepared and analyzed using gas chromatography-mass spectrometry. Boesenbergia rotunda hexane extract displayed anti-Staphylococcus aureus (MIC = 10 µg/mL) and antioxidant activities (IC50 = 557.97 and 2651.67 µg/mL against DPPH and NO radicals, respectively). A major flavonoid, pinostrobin, was further nonchromatographically isolated. Pinostrobin was shown to be a potent 5-LOX inhibitor (IC50 = 0.499 µM) compared to nordihydroguaiaretic acid (NDGA; IC50 = 5.020 µM) and betamethasone dipropionate (BD; IC50 = 2.077 µM) as the first-line of AD treatment. Additionally, pinostrobin inhibited COX-2 (IC50 = 285.67 µM), which was as effective as diclofenac sodium (IC50 = 290.35 µM) and BD (IC50 = 240.09 µM). This kinetic study and molecular modeling showed the mixed-type inhibition of NDGA and pinostrobin against 5-LOX. This study suggests that B. rotunda and its bioactive pinostrobin have promising properties for AD therapy.

Nordihydroguaiaretic Acid Affects Undifferentiated and Differentiated Neuroblastoma Cells Differently through Mechanisms that Impact on Cell Viability.

We aimed to investigate the mechanisms involved in the neurotoxic effects of NDGA on differentiated and undifferentiated human neuroblastoma cells (MSN), assessing cell viability, changes in the actin cytoskeleton, cell migration and the expression of the 5-LOX enzyme and the inhibitor of cell cycle progression p21WAF1/CIP1. High expression and activity of the lipoxygenase enzyme (LOX) have been detected in several tumors, including neuroblastoma samples, suggesting the use of LOX inhibitors as potential therapy molecules. Among these, the natural compound nordihydroguaiaretic acid (NDGA) has been extensively tested as an antiproliferative drug against diverse types of cancer cells. In this study, we analyzed the toxic effect of NDGA on neuroblastoma cells at a dose that did not affect cell survival when they differentiated to a neuron-like phenotype and the potential mechanisms involved in the anticancer properties. We exposed human neuroblastoma cells (MSN) to different concentrations of NDGA before and after a differentiation protocol with retinoic acid and nerve growth factor and analyzed cell viability, cell migration, actin cytoskeleton morphology and the levels of the cell cycle inhibitor p21WAF1/CIP1 and 5-LOX. We found that differentiated human neuroblastoma cells are more resistant to NDGA than undifferentiated cells. The toxic effects of NDGA were accompanied by reduced cell migration, changes in actin cytoskeleton morphology, induction of p21WAF1/CIP1 and decreased levels of the 5-LOX enzyme. This study provides new evidence regarding the potential use of NDGA to induce cell death in human neuroblastoma.

Antioxidants green tea extract and nordihydroguaiaretic acid confer species and strain-specific lifespan and health effects in Caenorhabditis nematodes

The Caenorhabditis Intervention Testing Program (CITP) is an NIH-funded research consortium of investigators who conduct analyses at three independent sites to identify chemical interventions that reproducibly promote health and lifespan in a robust manner. The founding principle of the CITP is that compounds with positive effects across a genetically diverse panel of Caenorhabditis species and strains are likely engaging conserved biochemical pathways to exert their effects. As such, interventions that are broadly efficacious might be considered prominent compounds for translation for pre-clinical research and human clinical applications. Here, we report results generated using a recently streamlined pipeline approach for the evaluation of the effects of chemical compounds on lifespan and health. We studied five compounds previously shown to extend C. elegans lifespan or thought to promote mammalian health: 17α-estradiol, acarbose, green tea extract, nordihydroguaiaretic acid, and rapamycin. We found that green tea extract and nordihydroguaiaretic acid extend Caenorhabditis lifespan in a species-specific manner. Additionally, these two antioxidants conferred assay-specific effects in some studies—for example, decreasing survival for certain genetic backgrounds in manual survival assays in contrast with extended lifespan as assayed using automated C. elegans Lifespan Machines. We also observed that GTE and NDGA impact on older adult mobility capacity is dependent on genetic background, and that GTE reduces oxidative stress resistance in some Caenorhabditis strains. Overall, our analysis of the five compounds supports the general idea that genetic background and assay type can influence lifespan and health effects of compounds, and underscores that lifespan and health can be uncoupled by chemical interventions.

Screening of potent inhibitor from Aquilaria malaccensis Lam. against arachidonic inflammatory enzymes: an insight from molecular docking, ADMET, molecular dynamics simulation and MM-PBSA approaches

The three primary enzymes COX (cyclooxygenase), LOX (lipoxygenase) and CYT-P450 (cytochrome P450), which are part of the arachidonic inflammatory pathway, play crucial role in the development of asthma, rheumatoid arthritis and cardiovascular diseases. Ethnomedicinally, plant-derived chemicals have a major role in the treatment of fatal illnesses. Aquilaria malaccensis Lam. widely known as agarwood is prized for its fragrance and therapeutic properties. The phytochemicals and extracts of this plant have significant healing properties in the treatment of serious illnesses. In the current work, an in-silico approach including molecular docking, ADMET (absorption, distribution, metabolism, excretion and toxicity), molecular dynamics (MD) simulation and molecular mechanics/Poisson–Boltzmann surface area (MM-PBSA) was performed to screen 33 bioactive compounds from this plant against COX-2 and 5-LOX in order to find the most effective inhibitor. 2-(2-Phenylethyl)chromone was found to inhibit both 5-LOX and COX-2, showing the highest binding affinities (−9.1 kcal/mol and −9.0 kcal/mol, respectively) than standard Ibuprofen and nordihydroguaiaretic acid (NDGA). 2-(2-Phenylethyl)chromone showed the highest drug-likeness score and low risk of toxicity compared to other phytochemicals. MD modeling and MM-PBSA calculations showed that 2-(2-Phenylethyl)chromone had a strong persistent binding interaction with 5-LOX than COX-2, and this interaction is comparable to the bounded standards Ibuprofen and NDGA. From this study, we may infer that the 2-(2-Phenylethyl)chromone can serve as a potent inhibitor and has scope to be employed in the treatment of inflammatory ailments. Communicated by Ramaswamy H. Sarma

Novel metallo-β-lactamases inhibitors restore the susceptibility of carbapenems to New Delhi metallo-lactamase-1 (NDM-1)-harbouring bacteria.

The production of metallo-β-lactamases is a major mechanisms adopted by bacterial pathogens to resist carbapenems. Repurposing approved drugs to restore the efficacy of carbapenems represents an efficient and cost-effective approach to fight infections caused by carbapenem resistant pathogens. The nitrocefin hydrolysis assay was employed to screen potential New Delhi metallo-lactamase-1 (NDM-1) inhibitors from a commercially available U.S. Food and Drug Administration (FDA) approved drug library. The mechanism of inhibition was clarified by metal restoration, inductively coupled plasma mass spectrometry (ICP-MS) and molecular dynamics simulation. The in vitro synergistic antibacterial effect of the identified inhibitors with meropenem was determined by the checkerboard minimum inhibitory concentration (MIC) assay, time-dependent killing assay and combined disc test. Three mouse infection models were used to further evaluate the in vivo therapeutic efficacy of combined therapy. Twelve FDA-approved compounds were initially screened to inhibit the ability of NDM-1 to hydrolyse nitrocefin. Among these compounds, dexrazoxane, embelin, candesartan cilexetil and nordihydroguaiaretic acid were demonstrated to inhibit all tested metallo-β-lactamases and showed an in vitro synergistic bactericidal effect with meropenem against metallo-β-lactamases-producing bacteria. Dexrazoxane, embelin and candesartan cilexetil are metal ion chelating agents, while the inhibition of NDM-1 by nordihydroguaiaretic acid involves its direct binding to the active region of NDM-1. Furthermore, these four drugs dramatically rescued the treatment efficacy of meropenem in three infection models. Our observations indicated that dexrazoxane, embelin, candesartan cilexetil and nordihydroguaiaretic acid are promising carbapenem adjuvants against metallo-β-lactamases-positive carbapenem resistant bacterial pathogens.

Nordihydroguaiaretic Acid (NDGA) Inhibits CsgA Polymerization, Bacterial Amyloid Biogenesis, and Biofilm Formation.

Escherichia coli and other Enterobacteriaceae thrive in robust biofilm communities through the coproduction of curli amyloid fibers and phosphoethanolamine cellulose. Curli promote adhesion to abiotic surfaces and plant and human host tissues and are associated with pathogenesis in urinary tract infection and food-borne illness. The production of curli in the host has also been implicated in the pathogenesis of neurodegenerative diseases. We report that the natural product nordihydroguaiaretic acid (NDGA) is effective as a curlicide in E. coli. NDGA prevents CsgA polymerization in vitro in a dose-dependent manner. NDGA selectively inhibits cell-associated curli assembly and inhibits uropathogenic E. coli biofilm formation. More broadly, this work emphasizes the ability to evaluate and identify bioactive amyloid assembly inhibitors by using the powerful gene-directed amyloid biogenesis machinery in E. coli.

Role of the transcription factor MdABF2 in abscisic acid-induced volatile compound biosynthesis in ‘Ruixue’ (Malus × domestica) apple during storage

Fruit aroma, which is conferred by an array of volatile compounds, strongly influences both consumer acceptance and market competitiveness. The phytohormone abscisic acid (ABA) regulates volatile compound biosynthesis during fruit ripening. However, the regulatory mechanism by which ABA may alter the production of volatile compounds in apple remains unknown. In this study, ABA treatment accelerated fruit ripening and volatile compound production, whereas treatment with the ABA biosynthesis inhibitor nordihydroguaiaretic acid (NDGA) resulted in the opposite effects. We identified a nuclear-localized ABA-responsive transcription factor (TF), MdABF2, which was upregulated by exogenous ABA. Overexpression of MdABF2 resulted in enhanced production of volatile compounds and biosynthesis gene expression, and these effects were further enhanced by ABA treatment. Moreover, MdABF2 was found to bind directly to the MdLOX1a, MdLOX5a, MdAAT1, and MdAAT2 promoters, activating their expression. The results presented here contribute to our understanding of the mechanism by which ABA regulates volatile compound biosynthesis. Furthermore, these data will be beneficial for the molecular breeding and improvement of apple for better flavor and aroma.

Design, synthesis and anti-tumor efficacy evaluation of novel 1,3-diaryl propane-based polyphenols obtained from Claisen rearrangement reaction

Polyphenols such as resveratrol, honokiol and nordihydroguaiaretic acid are widely existing in nature products or synthetic compounds with interesting biological activities. Inspired by their structural feature, a total of 49 1,3-diaryl propane-based polyphenols were designed and synthesized through Claisen rearrangement reaction. New compounds were initially assessed for their anti-proliferative activities against various cancer cell lines (PC-3, U87MG, U251, HCT116) at a concentration of 50 μM, and the results guided the SAR of this series of compounds. Further screening of selected compounds against seven cancer cell lines (three additional colon cancer cell lines namely COLO205, HT29 and SW480 were chosen) led to the identification of two advanced leads 2t and 3t with IC50 values ranging from 8.2 ± 0.1 to 19.3 ± 1.9 μM. Both compounds also showed promising anti-proliferative activities against COLO205 in dose- and time-dependent manners. Furthermore, 2t and 3t exhibited good anti-tumor efficacy in COLO205 xenografted mice model with TGI values ranging from 38% to 58%. These results warrant the further investigation of this series of compounds.

Quantitative proteomic analysis of tomato fruit ripening behavior in response to exogenous abscisic acid.

To determine how abscisic acid (ABA) affects tomato fruit ripening at the protein level, mature green cherry tomato fruit were treated with ABA, nordihydroguaiaretic acid (NDGA), or sterile water (control, CK). The proteomes of treated fruit were analyzed and quantified using tandem mass tags (TMTs) at 7 d after treatment, and the gene transcription abundances of differently expressed proteins (DEPs) were validated with qRT-PCR. The postharvest tomato fruit underwent faster color transformation and ripening than the CK when treated with ABA. In total, 6310 proteins were identified among the CK and treatment groups, of which 5359 were quantified. Using a change threshold of 1.2 or 0.83 times, 1081 DEPs were identified. Among them, 127 were upregulated and 127 were downregulated in the ABA vs CK comparison group. According to KEGG and protein-protein interaction network analyses, the ABA-regulated DEPs were primarily concentrated in the photosynthesis system and sugar metabolism pathways, and 102 DEPs associated with phytohormones biosynthesis and signal transduction, pigment synthesis and metabolism, cell wall metabolism, photosynthesis, redox reactions, allergens, and defense responses were identified in the ABA vs CK and NDGA vs CK comparison groups. ABA affects tomato fruit ripening at the protein level to some extent. The results of this study provided comprehensive insights and datas for further research on the regulatory mechanism of ABA in tomato fruit ripening. This article is protected by copyright. All rights reserved.

Ethylene Signaling Pathway Genes in Strawberry and Their Expression Patterns during Fruit Ripening

Ethylene at least partly regulates some aspects during non-climacteric ripening in strawberry. However, the ethylene signaling pathway genes in the strawberry fruit have not been comprehensively and systematically analyzed. In the present study, 15 FaETRs and 14 FaEIN3/EINs were identified in the octoploid strawberry genome. Subcellular localization analysis predicted that FaETRs and FaEIN3/EINs are respectively localized to the endoplasmic reticulum and the nucleus. The phylogenetic trees showed that FaETRs were classified into two subgroups, while FaEIN3/EINs were divided into three clades, which was supported by gene structure and conserved motif analysis. FaETRs and FaEIN3/EINs could interact with several components, such as CTR1, RTE1, EIN2 and ERF1B, in the ethylene signaling pathway by protein–protein interaction network analysis. Transcriptomic data showed that FaETRs were mainly expressed at the early stage of fruit development in three strawberry cultivars. Additionally, a couple of FaETRs (FaETR2 and FaETR13) and FaEINs (FaEIN2 and FaEIN7) could be induced by 1 μM ABA and inhibited by 100 μM nordihydroguaiaretic acid (NDGA, an ABA biosynthesis blocker). These findings suggested that the FaETR- and FaEIN3/EIN-mediated ethylene signaling pathway might play a role in strawberry fruit ripening.

In Vitro Antiviral Activity of Nordihydroguaiaretic Acid against SARS-CoV-2.

The coronavirus infectious disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and has been spreading rapidly worldwide, creating a pandemic. This article describes the evaluation of the antiviral activity of nordihydroguaiaretic acid (NDGA), a molecule found in Creosote bush (Larrea tridentata) leaves, against SARS-CoV-2 in vitro. A 35 µM concentration of NDGA was not toxic to Vero cells and exhibited a remarkable inhibitory effect on the SARS-CoV-2 cytopathic effect, viral plaque formation, RNA replication, and expression of the SARS-CoV-2 spike glycoprotein. The 50% effective concentration for NDGA was as low as 16.97 µM. Our results show that NDGA could be a promising therapeutic candidate against SARS-CoV-2.

Synthesis of new multitarget-directed ligands containing thienopyrimidine nucleus for inhibition of 15-lipoxygenase, cyclooxygenases, and pro-inflammatory cytokines

A new series of thieno[2,3-d]pyrimidine derivatives 4, 5, 6a-o, and 11 was designed and synthesized starting from cyclohexanone under Gewald condition with the aim to develop multitarget-directed ligands (MTDLs) having anti-inflammatory properties against both 15-LOX and COX-2 enzymes. Moreover, the potential of the compounds against the proinflammatory mediators NO, ROS, TNF-α, and IL-6 were tested in LPS-activated RAW 264.7 macrophages. Compound 6o showed the greatest 15-LOX inhibitory effect (IC50 = 1.17 μM) which was superior to that of the reference nordihydroguaiaretic acid (NDGA, IC50 = 1.28 μM); meanwhile, compounds 6h, 6g, 11, and 4 exhibited potent activities (IC50 = 1.29–1.77 μM). The ester 4 (SI = 137.37) and the phenyl-substituted acetohydrazide 11 (SI = 132.26) showed the highest COX-2 selectivity, which was about 28 times more selective than the reference drug diclofenac (SI = 4.73), however, it was lower than that of celecoxib (SI = 219.25). Interestingly, compound 6o, which showed the highest 15-LOX inhibitory activity and 5 times higher COX-2 selectivity than diclofenac, showed a greater poteny in reducing NO (IC50 = 7.77 μM) than both celecoxib (IC50 = 22.89 μM) and diclofenac (IC50 = 25.34), but comparable activity in inhibiting TNF-α (IC50 = 11.27) to diclofenac (IC50 = 10.45 μM). Similarly, compounds 11 and 6h were more potent in reducing TNF-α and IL6 levels than diclofenac, meanwhile, compound 4 reduced ROS, NO, IL6, and TNF-α levels with comparable potency to the reference drugs celecoxib and diclofenac. Furthermore, docking studies for our compounds within 15-LOX and COX-2 active sites revealed good agreement with the biological evaluations. The proposed compounds could be promising multi-targeted anti-inflammatory candidates to treat resistant inflammatory conditions.

Nordihydroguaiaretic acid (NDGA) maintains the postharvest quality of fresh daylily flower buds (Hemerocallis citrina) by enhancing antioxidant metabolism and regulating phytohormone equilibrium

Daylily (Hemerocallis citrina) bud is a functional vegetable rich in various nutrients and many bioactive compounds. However, fresh daylily buds are very susceptible to senescence and quality deterioration occurs rapidly after harvest. The effects of nordihydroguaiaretic acid (NDGA) on postharvest quality, reactive oxygen species (ROS) metabolism and phytohormone alterations in daylily buds were investigated. The results showed that NDGA treatments delayed the loss of overall quality, and alleviated yellowing and disaggregation. The NDGA treatment inhibited the production of hydrogen peroxide and malondialdehyde, enhanced activities of ROS-scavenging enzymes and delayed the decrease in total antioxidant capacity. The biosynthesis of abscisic acid was decreased, while the contents of indole-3-acetic acid and brassinosteroids were increased by NDGA treatment, and therefore equilibrium involving several phytohormones was altered by NDGA. Transcriptomic profiling of genes associated with the signal transduction pathways of the main phytohormones was performed to reveal alterations in the regulation of postharvest senescence of daylily buds in response to NDGA. Collectively, NDGA treatment is a potential approach for the preservation of fresh daylily flower buds.

Effects of diarylbutane lignans from Schisandra chinensis fruit on SARS-CoV-2 3CLpro and PLpro and their in vitro anti-inflammatory properties

BackgroundSchisandra chinensis fruit is a well-known traditional Chinese medicine (TCM), whose extract has a potent inhibitory effect on the severe acute respiratory syndrome-coronavirus-2 (SARS‑CoV‑2) 3-chymotrypsin-like protease (3CLpro) and papain-like protease (PLpro). PurposeThis work aims to find the active components from the fruit of S. chinensis against SARS‑CoV‑2 3CLpro and PLpro. Materials and methodsThe chemical constituents of the fruit of S. chinensis were retrieved based on the electronic databases, such as Web of Science, PubMed, Medline Plus, and CNKI. Molecular docking was used to screen the active components against SARS‑CoV‑2 3CLpro and PLpro. Potential hit compounds were further evaluated by enzymatic activity assay. Furthermore, the anti-inflammatory activities of the active compounds were further explored using the phorbol-12-myristate-13-acetate (PMA)-induced THP1 cells model. ResultsIn this work, we retrieved 75 components of S. chinensis fruit, including 62 dibenzocyclooctadiene-type lignans, 3 diarylbutane-type lignans, 2 tetrahydrofuran-type lignans, and 8 nortriterpenoids. Combining molecular docking study and in vitro experiments, we found that pregomisin (63), meso‑dihydroguaiaretic acid (64), and nordihydroguaiaretic acid (65) could potently inhibit 3CLpro with IC50 values of 3.07 ± 0.38, 4.12 ± 0.38, and 6.06 ± 0.62 μM, respectively, and inhibit PLpro with IC50 values of 5.23 ± 0.33, 4.24 ± 0.46, and 16.28 ± 0.54 μM, respectively. Interestingly, compounds 63, 64, and 65 also have potent activities of regulating the inflammatory response in vitro. ConclusionOur results suggest that compounds 63, 64, and 65 may be promising SARS-CoV-2 3CLpro and PLpro inhibitors and anti-inflammatory.