Plant-derived lignans as potential antiviral agents: a systematic review

Dietary Polyphenols, Food Processing and Gut Microbiome: Recent Findings on Bioavailability, Bioactivity, and Gut Microbiome Interplay

Polyphenols are organic chemical compounds naturally present in plants, renowned for their anti-inflammatory, antioxidant, immunomodulatory, anticancer, and cardiovascular protective properties. Their bioactivity and bioavailability can vary widely depending on the methods of food processing and interactions with the gut microbiome. These factors can induce changes in polyphenols, affecting their ability to achieve their intended health benefits. Thus, it is essential to develop and apply food processing methods that optimize polyphenol content while maintaining their bioactivity and bioavailability. This review aims to explore how various food processing techniques affect the quantity, bioactivity, and bioavailability of polyphenols, as well as their interactions with the gut microbiome, which may ultimately determine their health effects.

Cs2CO3 Promoted [4 + 2] Cycloaddition of 1,6-Enynes: An Approach to Tetrahydro-1H-benzo-f-isoindole Isomers

A Cs2CO3-promoted [4 + 2] cycloaddition of 1,6-enynes under mild reaction conditions has been developed. This protocol provides a facile approach to a series of tetrahydro-1H-benzo[f]isoindole isomerized products promoted by Cs2CO3 with moderate to high yields. By simply switching the reaction solvent and controlling the reaction time, two isomerization products could be obtained, both with good selectivity.

Therapeutic Potential of Resveratrol and Lignans in the Management of Tuberculosis

This study aims to investigate the therapeutic potential of herbal remedies, specifically resveratrol and lignans, as alternative treatments for tuberculosis (TB), given the challenges posed by drug-resistant strains and adverse effects of conventional therapies. A comprehensive review of the literature was conducted to analyze the mechanisms of action, safety profiles, and efficacy of resveratrol and lignans in the context of TB management. This review focused on the bactericidal and bacteriostatic effects of these compounds, examining their interaction with Mycobacterium tuberculosis within macrophages. Resveratrol and lignans were found to exhibit significant antibacterial properties through mechanisms such as SIRT1 modulation, coenzyme A transferase inhibition, suppression of intracellular bacterial proliferation in macrophages, and induction of autophagy. These mechanisms contribute to their effectiveness in combating TB and highlight their potential as alternative therapeutic agents.

Review and perspective on bioinformatics tools using machine learning and deep learning for predicting antiviral peptides

Viruses constitute a constant threat to global health and have caused millions of human and animal deaths throughout human history. Despite advances in the discovery of antiviral compounds that help fight these pathogens, finding a solution to this problem continues to be a task that consumes time and financial resources. Currently, artificial intelligence (AI) has revolutionized many areas of the biological sciences, making it possible to decipher patterns in amino acid sequences that encode different functions and activities. Within the field of AI, machine learning, and deep learning algorithms have been used to discover antimicrobial peptides. Due to their effectiveness and specificity, antimicrobial peptides (AMPs) hold excellent promise for treating various infections caused by pathogens. Antiviral peptides (AVPs) are a specific type of AMPs that have activity against certain viruses. Unlike the research focused on the development of tools and methods for the prediction of antimicrobial peptides, those related to the prediction of AVPs are still scarce. Given the significance of AVPs as potential pharmaceutical options for human and animal health and the ongoing AI revolution, we have reviewed and summarized the current machine learning and deep learning-based tools and methods available for predicting these types of peptides.

Synthesis of Seven- and Eight-Membered Rings by a Brønsted Acid Catalyzed Cationic Carbocyclization of Biphenyl Embedded Enynes

A Brønsted acid catalyzed cyclization of o-alkenyl-o'-alkynylbiaryls for the synthesis of biologically relevant dibenzo-fused medium-sized rings has been developed. The outcome of the cyclization is determined by the nature of the substituent at the alkyne, with arenes favoring seven-membered rings and alkyl substituents producing eight-membered rings. These reactions proceed via a vinyl cation, which is captured by water and, notably, by C-nucleophiles, such as electron-rich (hetero)arenes.

Soluble individual metal atoms and ultrasmall clusters catalyze key synthetic steps of a natural product synthesis

Metal individual atoms and few-atom clusters show extraordinary catalytic properties for a variety of organic reactions, however, their implementation in total synthesis of complex organic molecules is still to be determined. Here we show a 11-step linear synthesis of the natural product (±)-Licarin B, where individual Pd atoms (Pd1) catalyze the direct aerobic oxidation of an alcohol to the carboxylic acid (steps 1 and 6), Cu2-7 clusters catalyze carbon-oxygen cross couplings (steps 3 and 8), Pd3-4 clusters catalyze a Sonogashira coupling (step 4) and Pt3-5 clusters catalyze a Markovnikov hydrosylilation of alkynes (step 5), as key reactions during the synthetic route. In addition, the new synthesis of Licarin B showcases an unexpected selective alkene hydrogenation with metal-free NaBH4 and an acid-catalyzed intermolecular carbonyl-olefin metathesis as the last step, to forge a trans-alkene group. These results, together, open new avenues in the use of metal individual atoms and clusters in organic synthesis, and confirm their exceptional catalytic activity in late stages during complex synthetic programmes.

New daphnane diterpenoidal 1,3,4-oxdiazole derivatives as potential anti-hepatoma agents: Synthesis, biological evaluation and molecular modeling studies

Hepatocellular carcinoma (HCC) is a major challenge for human healthy. Daphnane-type diterpenes have attracted increasingly attention due to remarkable pharmaceutical potential including anti-HCC activity. To further develop this class of compounds as inhibitors of HCC, the daphnane diterpenoids 12-O-debenzoyl-Yuanhuacine (YHC) and 12-hydroxydaphnetoxin (YHE) were prepared by a standard chemical transformation from dried flower buds of the Daphne genkwa plant. Subsequently, 22 daphnane diterpenoidal 1,3,4-oxdiazole derivatives were rationally designed and synthesized based on YHC and YHE. The assessment of the target compound's anti-hepatocellular carcinoma activity revealed that YHC1 exhibited comparable activity to sorafenib in the Hep3B cell line, while demonstrating higher selectivity. The mechanistic investigation demonstrates that compound YHC1 induces cell cycle arrest at the G0/G1 phase, cellular senescence, apoptosis, and elevates cellular reactive oxygen species levels. Moreover, molecular docking and CETSA results confirm the interaction between YHC1 and YAP1 as well as TEAD1. Co-IP experiments further validated that YHC1 can effectively inhibit the binding of YAP1 and TEAD1. In conclusion, YHC1 selectively targets YAP1 and TEAD1, exhibiting its anti-hepatocellular carcinoma effects through the inhibition of their interaction.

9,9'-epoxylignans from Syringa pinnatifolia: A typical case of stereochemical assignment by a quantum chemical calculation with MAEΔΔδ parameter

In the current study, twenty-two stereochemical 9,9'-epoxylignans including 19 undescribed ones were isolated from the ethanol extract of Syringa pinnatifolia in our continuing effort to understand the overall chemical spectrum of this species. These isolates were structurally elucidated by extensive spectroscopic data analysis, X-ray diffraction, modified Mosher's method, and quantum chemical calculations. Meanwhile, the utilization of 13C NMR calculation and the MAEΔΔδ parameter facilitated the stereochemical assignment of groups of lignan stereoisomers. The 13C NMR data were corrected by the averaged errors at each corresponding carbon position in groups of lignan stereoisomers, which improved the theoretic 13C NMR calculation. The finding of the stereochemical structures of 9,9'-epoxylignans is significant. It is helpful to determine the absolute configurations of molecules with the similar core. In addition, these lignans exhibited potential cardioprotective activities on H9c2 cardiomyocytes in vitro and presented significant antioxidant effect.

Fighting nature with nature: antiviral compounds that target retroviruses

The human immunodeficiency virus (HIV) is a type of lentivirus that targets the human immune system and leads to acquired immunodeficiency syndrome (AIDS) at a later stage. Up to 2021, there are millions still living with HIV and many have lost their lives. To date, many anti-HIV compounds have been discovered in living organisms, especially plants and marine sponges. However, no treatment can offer a complete cure, but only suppressing it with a life-long medication, known as combined antiretroviral therapy (cART) or highly active antiretroviral therapy (HAART) which are often associated with various adverse effects. Also, it takes many years for a discovered compound to be approved for clinical use. Thus, by employing advanced technologies such as automation, conducting systematic screening and testing protocols may boost the discovery and development of potent and curative therapeutics for HIV infection/AIDS. In this review, we aim to summarize the antiretroviral therapies/compounds and their associated drawbacks since the discovery of azidothymidine. Additionally, we aim to provide an updated analysis of the most recent discoveries of promising antiretroviral candidates, along with an exploration of the current limitations within antiretroviral research. Finally, we intend to glean insightful perspectives and propose future research directions in this crucial area of study.

Neuroprotective neolignan glycosides from the pseudobulbs of Bletilla striata

Four undescribed neolignan glycosides, bletineosides A-D (1-4) were isolated from the pseudobulbs of Bletilla striata. Their structures with absolute configurations were elucidated on the basis of spectroscopic analyses, along with acidic hydrolysis reactions and ECD experiments. All isolates were evaluated for their neuroprotective activities against glutamate-induced PC12 cell injury. Compound 3 and 4 showed significantly neuroprotective effects at the concentration of 10 μM when compared with the model group. Compounds 1-4 represented the first examples of neolignan glycosides from the genus Bletilla. This study disclosed the potency of Bletilla striata as a new source of anti-neurodegenerative agents.

New benzofuran neolignans with neuroprotective activity from Phyllanthodendron breynioides

A pair of undescribed dihydrobenzofuran neolignan enantiomers, (+/-)-phybrenan A (1a/1b), two new benzofuran neolignans, phybrenan B and C (2 and 3), along with four known neolignans (4 - 7) were obtained from the plants of Phyllanthodendron breynioides P. T. Li. The planar structures of all isolates were demonstrated by the analysis of detailed spectroscopic evidence (NMR, HRMS, and IR), and the absolute configurations of novel neolignans were elucidated by combined calculated and experimental ECD data analysis. The neuroprotective activities of all benzofuran neolignans against sodium nitroprusside (SNP)-induced cell death were examined in rat pheochromocytoma PC12 cells. The results exhibited that three compounds (4 - 6) possessed remarkable neuroprotective activities at 10 µM, better than the positive drug edaravone.

Recent status of sesaminol and its glucosides: Synthesis, metabolism, and biological activities

Sesamum indicum is a major and important oilseed crop that is believed to promote human health in many countries, especially in China. Sesame seeds contain two types of lignans: lipid-soluble lignans and water-soluble glucosylated lignans. The major glucosylated lignans are sesaminol glucosides (SGs). So far, four sesaminol isomers and four SGs are identified. During the naturally occurring process of SGs production, sesaminol is generated first from two molecules of E-coniferyl alcohol, and then the sugar is added to the sesaminol one by one, leading to production of SGs. Sesaminol can be prepared from SGs, from sesamolin, and through artificial synthesis. SGs are metabolized in the liver and intestine and are then transported to other tissues. They exhibit several biological activities, most of which are based on their antioxidant and anti-inflammatory activities. In this paper, we present an overview of the current status of research on sesaminol and SGs. We have also discussed their synthesis, preparation, metabolism, and biological activities. It has been suggested that sesaminol and SGs are important biological substances with strong antioxidant properties in vitro and in vivo and are widely used in the food industry, medicine, and cosmetic products. The recovery and utilization of SGs from sesame seed cake after oil processing will generate massive economic benefits.

Identification of Potential Bioactive Compounds from Aspergillus terreus against HCV NS3 Serine Protease

This study was aimed to isolate bioactive compounds from the fermentation products of Aspergillus terreus, which could inhibit NS3 protease of hepatitis C virus (HCV). The bioactive compounds were isolated by reverse-phase silica-gel column chromatography, semi-preparative reversed-phase, and Sephadex LH-20, and then their structures were elucidated through spectroscopic analysis. As a result, two small molecule compounds were isolated. Compound 1 was identified as a new benzaldehyde, (E)-2,4-dihydroxy-6-propenylbenzaldehyde. Compound 2 was identified as pleurone, which was obtained from microorganisms for the first time. Their inhibitory activities against HCV NS3 protease (IC50 ) were 32.6 μM and 78.9 μM, respectively. This study provided a new option for the development of anti-HCV drugs.

Furofuran Lignans for Plant Protection: Discovery of Sesamolin and Its Derivatives as Novel Anti-Tobacco Mosaic Virus and Antibacterial Agents

Natural products have been a valuable source of efficient and low-risk pesticides. In this work, a series of novel sesamolin derivatives A0-A31 and B0-B4 were designed and synthesized via structural simplification of furofuran lignan phrymarolin II, and their antiviral and antibacterial activities were systematically evaluated. The bioassay results showed that compound A24 displayed remarkable inactivation activity against tobacco mosaic virus (TMV) with an EC₅₀ value of 130.4 μg/mL, which was superior to that of commercial ningnanmycin (EC₅₀ = 202.0 μg/mL). The antiviral mode of action assays suggested that compound A24 may obstruct self-assembly by binding to TMV coat protein (CP), thus resisting the TMV infection. In addition, compound A25 possessed prominent antibacterial activities, especially against Ralstonia solanacearum with an EC₅₀ value of 43.8 μg/mL, which is better than those of commercial bismerthiazol and thiodiazole copper. This research lays a solid foundation for the utilization of furofuran lignans in crop protection.

Synthesis of Naphthalimides through Tandem Pd(II)-Catalyzed C(sp3)-H Oxidation and Diels-Alder Reaction Using a Transient Directing Group Strategy

Naphthalimides have found extensive applications in materials science and pharmaceuticals. It is still highly desirable to develop efficient methods for the synthesis of naphthalimides with structural diversity. In this work, we developed a new approach for the synthesis of naphthalimides via a tandem reaction of o-methylbenzaldehydes and maleimides. The tandem reaction involves Pd(II)-catalyzed benzylic C(sp³)-H oxidation using an amino acid as the transient directing group and Diels-Alder reaction. The subsequent dehydration forms naphthalimides. The reaction introduces the imide moiety and constructs a benzene ring simultaneously, allowing for easy access to a range of naphthalimides with a variety of substituents.

Analysis of the active ingredients and health applications of cistanche

Cistanche is a tonic Chinese medicine commonly used in traditional Chinese medicine, with 2016, CFSA through the alxa desert cistanche safety evaluation, cistanche began to officially enter the food field. At present, the research on cistanche mainly focuses on the extraction, isolation and purification and pharmacological effects, and its pharmacological effects such as neuroprotective effects, immunomodulation, antioxidant anticancer and hepatoprotective liver protection have attracted the attention of researchers. This review mainly reviews the research status, chemical composition and health benefits, analyzes its application prospects in food, and aims to provide certain theoretical support for the safe application of cistanche in functional food.

Chemical Characterization of Different Extracts of Justicia secunda Vahl and Determination of Their Anti-Oxidant, Anti-Enzymatic, Anti-Viral, and Cytotoxic Properties

Justicia secunda Vahl. is a traditional medicinal plant in tropical regions, including West Africa. The present study examined the chemical profiles and biological properties of J. secunda extracts obtained with different solvents (dichloromethane, ethyl acetate, methanolic and aqueous: macerated and infused). Chemical components were characterized by liquid chromatography-mass spectrometry (LC-MS), and over 50 compounds were identified, including flavonoids, phenolic acids, and alkaloids. Antioxidant, enzyme inhibitory, cytotoxic, and antiviral properties were selected as biological properties. Total phenolic and flavonoid contents in methanol (58.07 mg gallic acid equivalent (GAE)/g and 13.07 mg rutin equivalent (RE)/g) and water (infused) (36.34 mg GAE/g and 8.52 mg RE/g) were higher than in other extracts. Consistent with the levels of total bioactive components, the methanol and water extracts exhibited stronger antioxidant abilities. However, the dichloromethane and ethyl acetate extracts were more active on α-amylase and α-glucosidase than other extracts. Aqueous extracts exerted selective anticancer properties toward human pharyngeal cancer cell lines, whereas the methanolic extract decreased the human herpesvirus type-1 (HHV-1) infectious titer by 2.16 log and the viral load by 1.21 log. Overall, J. secunda could be considered a multifunctional bioactive raw material in the preparation of potent applications to manage diseases related to oxidative stress, including cancer, diabetes, and Alzheimer's.

Anti-glutamatergic Effects of Three Lignan Compounds: Arctigenin, Matairesinol and Trachelogenin - An ex vivo Study on Rat Brain Slices

Arctigenin is a bioactive dibenzylbutyrolactone-type lignan exhibiting various pharmacological activities. The neuroprotective effects of arctigenin were demonstrated to be mediated via inhibition of AMPA and KA type glutamate receptors in the somatosensory cortex of the rat brain. The aim of this study was to compare the effects of arctigenin with matairesinol and trachelogenin on synaptic activity in ex vivo rat brain slices. Arctigenin, matairesinol and trachelogenin were isolated from Arctium lappa, Centaurea scabiosa and Cirsium arvense, respectively, and applied on brain slices via perfusion medium at the concentration range of 0.5 - 40 µM. The effects of the lignans were examined in the CA1 hippocampus and the somatosensory cortex by recording electrically evoked field potentials. Arctigenin and trachelogenin caused a significant dose-dependent decrease in the amplitude of hippocampal population spikes (POPS) and the slope of excitatory postsynaptic potentials (EPSPs), whereas matairesinol (1 µM and 10 µM) decreased EPSP slope but had no effect on POPS amplitude. Trachelogenin effect (0.5 µM, 10 µM, 20 µM) was comparable to arctigenin (1 µM, 20 µM, 40 µM) (p > 0.05). In the neocortex, arctigenin (10 µM, 20 µM) and trachelogenin (10 µM) significantly decreased the amplitude of evoked potential early component, while matairesinol (1 µM and 10 µM) had no significant effect (p > 0.05). The results suggest that trachelogenin and arctigenin act via inhibition of AMPA and KA receptors in the brain and trachelogenin has a higher potency than arctigenin. Thus, trachelogenin and arctigenin could serve as lead compounds in the development of neuroprotective drugs.

Podophyllotoxin and its derivatives: Potential anticancer agents of natural origin in cancer chemotherapy

The use of plant secondary metabolites has gained considerable attention among clinicians in the prevention and treatment of cancer. A secondary metabolite isolated mainly from the roots and rhizomes of Podophyllum species (Berberidaceae) is aryltetralin lignan - podophyllotoxin (PTOX). The purpose of this review is to discuss the therapeutic properties of PTOX as an important anticancer compound of natural origin. The relevant information regarding the antitumor mechanisms of podophyllotoxin and its derivatives were collected and analyzed from scientific databases. The results of the analysis showed PTOX exhibits potent cytotoxic activity; however, it cannot be used in its pure form due to its toxicity and generation of many side effects. Therefore, it practically remains clinically unusable. Currently, high effort is focused on attempts to synthesize analogs of PTOX that have better properties for therapeutic use e.g. etoposide (VP-16), teniposide, etopophos. PTOX derivatives are used as anticancer drugs which are showing additional immunosuppressive, antiviral, antioxidant, hypolipemic, and anti-inflammatory effects. In this review, attention is paid to the high potential of the usefulness of in vitro cultures of P. peltatum which can be a valuable source of lignans, including PTOX. In conclusion, the preclinical pharmacological studies in vitro and in vivo confirm the anticancer and chemotherapeutic potential of PTOX and its derivatives. In the future, clinical studies on human subjects are needed to certify the antitumor effects and the anticancer mechanisms to be certified and analyzed in more detail and to validate the experimental pharmacological preclinical studies.

Utilization of functional agro-waste residues for oyster mushroom production: Nutritions and active ingredients in healthcare

A large amount of agro-industrial residues are produced from the planting, production and processing of traditional Chinese herbs. As a tonic, edible, and economical herb, Codonopsis pilosula root has been extensively developed into medicine and functional food. However, thousands of tons of aerial parts (stems, leaves, flowers and fruits) have been directly discarded after harvest each year. To utilise agro-wastes, Pleurotus ostreatus was cultivated on a basal substrate supplemented with C. pilosula stems and leaves (CSL). Physicochemical analyses revealed that the basal substrate mixed with CSL was more abundant in cellulose, hemicellulose, and most of micronutrients such as K, Ca, Mg, S, Fe, Zn and Mo. After the first flush, the fruit bodies in CSL group exhibited a higher fresh weight, a wider average pileus diameter and a lower moisture level. Nutrition analyses presented a higher protein content and a lower fat content in mushrooms from CSL group compared with control group. Interestingly, 14 amino acids (glutamine, arginine, valine, leucine, and etc.) and 3 micronutrients (Se, Fe and Zn) were increased after CSL addition to the substrate. Based on untargeted metabolomics, a total of 710 metabolites were annotated. Compared with control group, there were 142 and 117 metabolites significantly increased and decreased in the CSL group. Most of them were grouped into classes of amino acids and peptids, fatty acids, carbohydrates, terpenoids, and etc. Moreover, an abundance of phytometabolites from Codonopsis were detected in P. ostreatus from CSL group, including polyacetylenes or polyenes, flavonoids, alkaloids, terpenoids, organic acids, and etc. UPLC-MS/MS results demonstrated that lobetyolin content in the CSL group samples was 0.0058%. In summary, the aerial parts of C. pilosula processed for use in the production of edible mushroom is an emerging strategy to converting agricultural waste into functional foods.

Chemistry and Biological Activities of Naturally Occurring and Structurally Modified Podophyllotoxins

Plants containing podophyllotoxin and its analogues have been used as folk medicines for centuries. The characteristic chemical structures and strong biological activities of this class of compounds attracted attention worldwide. Currently, more than ninety natural podophyllotoxins were isolated, and structure modifications of these molecules were performed to afford a variety of derivatives, which offered optimized anti-tumor activity. This review summarized up to date reports on natural occurring podophyllotoxins and their sources, structural modification and biological activities. Special attention was paid to both structural modification and optimized antitumor activity. It was noteworthy that etoposide, a derivative of podophyllotoxin, could prevent cytokine storm caused by the recent SARS-CoV-2 viral infection.

Small molecules in the treatment of COVID-19

The outbreak of COVID-19 has become a global crisis, and brought severe disruptions to societies and economies. Until now, effective therapeutics against COVID-19 are in high demand. Along with our improved understanding of the structure, function, and pathogenic process of SARS-CoV-2, many small molecules with potential anti-COVID-19 effects have been developed. So far, several antiviral strategies were explored. Besides directly inhibition of viral proteins such as RdRp and Mpro, interference of host enzymes including ACE2 and proteases, and blocking relevant immunoregulatory pathways represented by JAK/STAT, BTK, NF-κB, and NLRP3 pathways, are regarded feasible in drug development. The development of small molecules to treat COVID-19 has been achieved by several strategies, including computer-aided lead compound design and screening, natural product discovery, drug repurposing, and combination therapy. Several small molecules representative by remdesivir and paxlovid have been proved or authorized emergency use in many countries. And many candidates have entered clinical-trial stage. Nevertheless, due to the epidemiological features and variability issues of SARS-CoV-2, it is necessary to continue exploring novel strategies against COVID-19. This review discusses the current findings in the development of small molecules for COVID-19 treatment. Moreover, their detailed mechanism of action, chemical structures, and preclinical and clinical efficacies are discussed.

New dibenzocyclooctadiene lignans from Kadsura induta with their anti-inflammatory activity

Five new dibenzocyclooctadiene lignans, named kadsuindutains A-E (1-5), and three known ones schizanrin F (6), schizanrin O (7), and schisantherin J (8) were isolated from the stems of Kadsura induta. Their structures were determined by analyses of HR-ESI-MS, NMR, and ECD spectra. Compounds 1-5 contain a 2',4'-dioxygenated-2',3'-dimethylbutyryl moiety which is rarely reported for dibenzocyclooctadiene lignans. Molecular docking predicted that compounds 1-8 displayed good binding affinity to the active site of iNOS and TNF-α proteins but unstable binding to the active site of COX-2 protein. Additionally, in vitro experiments showed that compounds 1-8 inhibited NO production in LPS-activated RAW264.7 cells with IC50 values from 10.7 μM to 34.0 μM, compared to the positive control L-NMMA (IC50 = 31.2 μM).

(-)-Lariciresinol Isolated from the Roots of Isatis indigotica Fortune ex Lindl. Inhibits Hepatitis B Virus by Regulating Viral Transcription

Chronic hepatitis induced by hepatitis B virus (HBV) infection is a serious public health problem, leading to hepatic cirrhosis and liver cancer. Although the currently approved medications can reliably decrease the virus load and prevent the development of hepatic diseases, they fail to induce durable off-drug control of HBV replication in the majority of patients. The roots of Isatis indigotica Fortune ex Lindl., a traditional Chinese medicine, were frequently used for the prevention of viral disease in China. In the present study, (-)-lariciresinol ((-)-LRSL), isolated from the roots of Isatis indigotica Fortune ex Lindl., was found to inhibit HBV DNA replication of both wild-type and nucleos(t)ide analogues (NUCs)-resistant strains in vitro. Mechanism studies revealed that (-)-LRSL could block RNA production after treatment, followed by viral proteins, and then viral particles and DNA. Promoter reporter assays and RNA decaying dynamic experiments indicated that (-)-LRSL mediated HBV RNA reduction was mainly due to transcriptional inhibition rather than degradation. Moreover, (-)-LRSL in a dose-dependent manner also inhibited other animal hepadnaviruses, including woodchuck hepatitis virus (WHV) and duck hepatitis B virus (DHBV). Combining the analysis of RNA-seq, we further found that the decrease in HBV transcriptional activity by (-)-LRSL may be related to hepatocyte nuclear factor 1α (HNF1α). Taken together, (-)-LRSL represents a novel chemical entity that inhibits HBV replication by regulating HNF1α mediated HBV transcription, which may provide a new perspective for HBV therapeutics.

Meso-Dihydroguaiaretic Acid Ameliorates Acute Respiratory Distress Syndrome through Inhibiting Neutrophilic Inflammation and Scavenging Free Radical

The pathogenesis of acute respiratory distress syndrome (ARDS) is very complex. Patients with ARDS still suffer high mortality rates. Infiltration and activation of neutrophils in lungs are critical pathogenic factors in ARDS. In this study, we demonstrate that meso-dihydroguaiaretic acid (MDGA), a natural lignan, inhibits inflammatory responses in human neutrophils and ameliorates ARDS in mice. MDGA inhibited superoxide anion generation and elastase release in various G-protein coupled receptor agonists-induced human neutrophils. However, MDGA did not alter superoxide anion generation and elastase activity in cell-free systems. These results suggest that the anti-inflammatory effects of MDGA are mediated by regulating cellular signals in human neutrophils. In consistent with this, MDGA suppressed phosphorylation of extracellular signal-regulated kinase and c-Jun N-terminal kinase in activated human neutrophils. Moreover, MDGA inhibited CD11b expression and adhesion in activated human neutrophils. Interestingly, MDGA reduced reactive oxygen species (ROS) generation but not superoxide anion generation in protein kinase C (PKC) activator-induced human neutrophils, suggesting that MDGA may also have ROS scavenging ability. Indeed, MDGA showed strong free radical scavenging activity in cell-free assays. Significantly, MDGA suppressed PKC-induced neutrophil extracellular trap formation. Additionally, treatment of MDGA attenuated neutrophil infiltration and lung damage on lipopolysaccharide-induced ARDS in mice. In conclusion, our results demonstrate that MDGA has anti-neutrophilic inflammatory effects and free-radical scavenging activity. We also suggest that MDGA has potential to serve as a lead for developing new therapeutics to treat ARDS.

Total Synthesis and Anti-Tobacco Mosaic Virus Activity of the Furofuran Lignan (±)-Phrymarolin II and Its Analogues

Phrymarolin II, a furofuran lignan isolated from Phryma leptostachya L., features a 3,7-dioxabicyclo[3.3.0]octane skeleton. Herein, we report an alternative total synthesis of (±)-phrymarolin II (2), which was performed in 9 steps from commercially available sesamol. The key steps of the synthesis included a zinc-mediated Barbier-type allylation and a copper-catalyzed anomeric O-arylation. Our total synthesis allowed the synthesis of analogues of (±)-phrymarolin II. Most derivatives displayed good to excellent in vivo activity against tobacco mosaic virus (TMV). (±)-Phrymarolin II (2) and compounds (±)-31d and (±)-31g exhibited similar or higher activity than commercial ningnanmycin, which indicated that phrymarolin lignans are a promising new class of plant virus inhibitors.

Lignans from Bursera fagaroides: Chemistry, Pharmacological Effects and Molecular Mechanism. A Current Review

Bursera fagaroides is a medicinal tree endemic to México, it belongs to the Burseraceae family and has proven antitumor activity. Modern research, performed principally with the bark extracts, have indicated that lignans are the main active constituents of B. fagaroides, with a high content of aryltetralin, aryldihydronaphtalene, dibenzylbutirolactone, and dibenzylbutane-type lignans as the constituents of the active extracts. In general, lignans from B. fagaroides exhibited potent anti-cancer activity, although antitumor, anti-bacterial, anti-protozoal, anti-inflammatory, and anti-viral properties have also been described. This review covers literature-reported lignans from B. fagaroides, chemical structures, nomenclature, chromatographic techniques of isolation, characterization strategies, and highlights the anti-cancer molecular mechanisms of lignans. Evaluation of the anticancer function of lignans has been extensively investigated since the cytotoxic in vitro results and in vivo assays in mice and zebrafish models to the tubulin molecular recognition by NMR. Also, we discuss the future direction for studying this important plant species and its lignan metabolites.