Natural Chalcone Research Articles

Cardamonin inhibits the proliferation and metastasis of non-small-cell lung cancer cells by suppressing the PI3K/Akt/mTOR pathway.

Cardamonin, a natural chalcone compound, has been reported to exert anticancer effects in several cancers. However, the specific pharmacological actions of cardamonin on human non-small-cell lung cancer (NSCLC) and the potential mechanisms still remain obscure. Here, we investigated the antineoplastic role of cardamonin in NSCLC both in vitro and in vivo. The proliferation of five NSCLC cell lines was inhibited in a dose-dependent and time-dependent manner with cardamonin treatment. In A549 and H460 cells, cardamonin induced apoptosis by activating caspase-3, upregulating Bax, and downregulating Bcl-2. In addition, cardamonin arrested cells in the G2/M phase and inhibited the expression levels of cyclin D1/CDK4. Moreover, cell migration and invasion were suppressed by reversing epithelial-mesenchymal transition with cardamonin treatment. Further study showed that cardamonin reduced the phosphorylation levels of the downstream effectors of phosphoinositide 3-kinase (PI3K), including protein kinase-B (Akt/PKB) and mammalian target of rapamycin (mTOR). Moreover, in the H460 xenograft model, cardamonin significantly retarded tumor growth. Also, in tumor tissues, we found that cardamonin treatment decreased the expression rates of Ki-67, p-Akt, and p-mTOR. These data suggest that cardamonin suppressed NSCLC cell proliferation and inhibited metastasis partly by restraining the PI3K/Akt/mTOR pathway and it might be an effective therapeutic compound for NSCLC in the future.

Structural and thermodynamic characterization of the binding of isoliquiritigenin to the first bromodomain of BRD4.

Bromodomain-containing protein 4 (BRD4) recognizes the acetylated lysine of histone H4 via its bromodomains, leading to the recruitment of positive transcription elongation factor b. Small molecules that inhibit BRD4 have potential as anticancer agents by leading to the downregulation of specific oncogenes. Using X-ray crystallographic screening, we identified the BRD4 inhibitory activity of isoliquiritigenin (ISL), a natural chalcone found in licorice. Structural analysis revealed that ISL bound to BRD4 with a novel binding mode and squeezed out one of the six conserved water molecules that form a strong hydrogen bond network. The thermodynamic analysis revealed that the binding of ISL is enthalpy driven, suggesting that strong hydrogen bonds would compensate for the desolvation penalty. Neutron protein crystallography further suggested that the favorable binding enthalpy originates from the stabilization and optimization of the hydrogen bond network of the conserved water molecules. Here, we describe the novelty and potential of ISL as a template for new BRD4 inhibitors.

Down-regulation of Skp2 expression inhibits invasion and lung metastasis in osteosarcoma

Osteosarcoma (OS), the most common primary cancer of bone, exhibits a high propensity for local invasion and distant metastasis. This study sought to elucidate the role of S phase kinase-associated protein (Skp2) in osteosarcoma invasion and metastasis and to explore flavokawain A (FKA), a natural chalcone from kava extract, as a potential Skp2 targeting agent for preventing osteosarcoma progression. Skp2 was found to be overexpressed in multiple osteosarcoma cell lines, including 5 standard and 8 primary patient-derived cell lines. Patients whose tumors expressed high levels of Skp2 sustained a significantly worse metastasis-free (p = 0.0095) and overall survival (p = 0.0013) than those with low Skp2. Skp2 knockdown markedly reduced in vitro cellular invasion and in vivo lung metastasis in an orthotopic mouse model of osteosarcoma. Similar to Skp2 knockdown, treatment with FKA also reduced Skp2 expression in osteosarcoma cell lines and blocked the invasion of osteosarcoma cells in vitro and lung metastasis in vivo. Together, our findings suggest that Skp2 is a promising therapeutic target in osteosarcoma, and that FKA may be an effective Skp2-targeted therapy to reduce osteosarcoma metastasis.

An Efficient Synthesis of Novel Type Chalcones Containing 8-hydroxyquinoline Under Green Conditions

In this study, new type of chalcones containing 8-hydroxyquinoline as an alternative to natural and synthetic chalcones have synthesized for the first time using microwave irradiation with environmentally benign approach. Firstly, (E)-1-(4-((8-hydroxyquinolin-5-yl)diazenyl)phenyl)ethanone (3) were synthesized by diazotization of p-aminoacetophenone. Secondly, most important step of synthesis included the Claisen-Schmidt condensation of chalcones using the microwave method. The structures of all compounds were characterized by means of FT-IR, NMR and elemental analysis.

Millepachine showed novel antitumor effects in cisplatin-resistant human ovarian cancer through inhibiting drug efflux function of ATP-binding cassette transporters.

Millepachine (MIL), a bioactive natural chalcone from Chinese herbal medicine Millettia pachycarpa Benth, exhibits strong antitumor effects against many human cancer cells both in vitro and in vivo. In this study, we found that MIL significantly inhibited the proliferation of cisplatin-resistant A2780CP cells via inducing obvious G2/M arrest and apoptosis and down-regulating the activity of topoisomerase II protein. We further found that the mechanism by which MIL showed good antitumor effects in cisplatin-resistant human ovarian cancer was associated with inhibiting the expression of ATP-binding cassette transporters in cisplatin-resistant A2780CP cells. Importantly, MIL did not only significantly inhibit the tumor growth in cisplatin-sensitive A2780S xenograft model, with an inhibitory rate of 73.21%, but also inhibited the tumor growth in the cisplatin-resistant A2780CP xenograft model, with an inhibitory rate of 65.68% (p<0.001 vs. control; p<0.001 vs. DDP). In addition, MIL did not induce acquired drug resistance in A2780S tumor-bearing mice with an inhibitory rate of 60.03%. The promising in vitro and in vivo performance indicated that MIL exhibited potential significance for drug research and development.

Inhibition of glioma growth by flavokawain B is mediated through endoplasmic reticulum stress induced autophagy

ABSTRACT Flavokawain B (FKB), a natural kava chalcone, displays potent antitumor activity in various types of cancer. The mechanism of action, however, remains unclear. Here, we evaluated the efficacy of FKB in the treatment of human glioblastoma multiforme (GBM) as well as the molecular basis for its inhibitory effects in cancer. Approximately 60% of GBM cells became senescent after treatment with FKB as assessed in the senescence-associated (SA)-GLB1/SA-β-galactosidase assay. The cellular process of autophagy potentially contributed to the establishment of senescence. Transmission electron microscopy revealed the formation of autophagic vesicles under FKB treatment, and MAP1LC3B (microtubule associated protein 1 light chain 3 beta)-II was increased. Transfection of ATG5 or ATG7 small interfering RNAs (siRNAs) inhibited FKB-induced autophagy in U251 cells. Western blot revealed that molecular components of the endoplasmic reticulum stress pathway were activated, including ATF4 (activating transcription factor 4) and DDIT3 (DNA damage inducible transcript 3), while levels of TRIB3 (tribbles pseudokinase 3) increased. In addition, based on the phosphorylation status, the AKT-MTOR-RPS6KB1 pathway was inhibited, which induced autophagy in GBM cells. Inhibition of autophagy by autophagy inhibitors 3-methyladenine and chloroquine or knockdown of ATG5 or ATG7 caused FKB-treated U251 cells to switch from senescence to apoptosis. Finally, knockdown of ATG5 or treatment with chloroquine in combination with FKB, significantly inhibited tumor growth in vivo. Our results demonstrated that FKB induced protective autophagy through the ATF4-DDIT3-TRIB3-AKT-MTOR-RPS6KB1 signaling pathway in GBM cells, indicating that the combination treatment of FKB with autophagy inhibitors may potentially be an effective therapeutic strategy for GBM. Abbreviations: 3-MA: 3-methyladenine; 4-PBA: 4-phenylbutyrate; AKT: AKT serine/threonine kinase; ATF4: activating transcription factor 4; ATG: autophagy related; CASP3: caspase 3; CCK-8: cell counting kit-8; CDKN1A: cyclin-dependent kinase inhibitor 1A; CQ: chloroquine; DDIT3: DNA damage inducible transcript 3; DMEM: Dulbecco’s modified Eagle’s medium; EIF2A: eukaryotic translation initiation factor 2A; EIF2AK3: eukaryotic translation initiation factor 2 alpha kinase 3; ER: endoplasmic reticulum; FKB: flavokawain B; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GBM: glioblastoma multiforme; GFP: green fluorescent protein; HSPA5: heat shock protein family A (Hsp70) member 5; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MTOR: mechanistic target of rapamycin kinase; PARP1: poly(ADP-ribose) polymerase; 1RPS6KB1: ribosomal protein S6 kinase B1; SA-GLB1: senescence-associated galactosidase beta 1; siRNA: short interfering RNA; SQSTM1: sequestosome 1; TEM: transmission electron microscopy; TRIB3: tribbles pseudokinase 3; TUNEL: deoxynucleotidyl transferase-mediated dUTP nick-end labeling

Adenosine 5'-monophosphate-activated protein kinase-dependent mTOR pathway is involved in flavokawain B-induced autophagy in thyroid cancer cells.

Flavokawain B (FKB), a natural kava chalcone, shows potent antitumor activity in various types of cancer, although the mechanism of action remains unclear. In this study, we report that FKB has profound effects on the metabolic state of human thyroid cancer (TCa) cells, leading to high autophagy flux through upregulation of AMP‐activated protein kinase, which in turn inhibits mTOR and activates Beclin‐1 in TCa cells. We further report that the autophagy induced by FKB plays a prosurvival role in TCa cells both in vitro and in vivo. In conclusion, our findings provide evidence that combination treatment with FKB and pharmacological autophagy inhibitors will be a potential therapeutic strategy for the treatment of TCa.

The Keap1/Nrf2-ARE Pathway as a Pharmacological Target for Chalcones.

Chalcones have shown a broad spectrum of biological activities with clinical potential against various diseases. The biological activities are mainly attributed to the presence in the chalcones of the α,β-unsaturated carbonyl system, perceived as a potential Michael acceptor. Chalcones could activate the Kelch-like ECH-associated protein 1 (Keap1)/Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway through a Michael addition reaction with the cysteines of Keap1, which acts as a redox sensor and negative regulator of Nrf2. This modification allows the dissociation of Nrf2 from the cytoplasmic complex with Keap1 and its nuclear translocation. At this level, Nrf2 binds to the antioxidant response element (ARE) and activates the expression of several detoxification, antioxidant and anti-inflammatory genes as well as genes involved in the clearance of damaged proteins. In this regard, the Keap1/Nrf2–ARE pathway is a new potential pharmacological target for the treatment of many chronic diseases. In this review we summarize the current progress in the study of Keap1/Nrf2–ARE pathway activation by natural and synthetic chalcones and their potential pharmacological applications. Among the pharmacological activities highlighted, anti-inflammatory activity was more evident than others, suggesting a multi-target Michael acceptor mechanism for the chalcones involving key regulators of the Nrf2 and nuclear factor- κB (NF-κB) pathways.

Exploring Promising Immunomodulatory Potential of Natural and Synthetic 1,3-Diphenyl-2-propen-1-one Analogs: A Review of Mechanistic Insight.

The immune system is an intricate and coordinated nexus serving as a natural defense to preclude internal and external pathogenic insults. The deregulation in the natural balance of immunological functions as a consequence of either over expression or under expression of immune cells tends to cause disruption of homeostasis in the body and may lead to development of numerous immune system disorders. Chalcone moieties (1,3-diphenyl-2-propen-1-one) have been well-documented as ideal lead compounds or precursors to design a wide range of pharmacologically active agents to down-regulate various immune disorders. Owing to their unique structural and molecular framework, these α, β-unsaturated carbonyl-based moieties have also gained remarkable recognition due to their other multifarious pharmacological properties including antifungal, anti-inflammatory, anti-malarial, antibacterial, anti-tuberculosis, and anticancer potential. Though a great number of methodologies are currently being employed for their synthesis, this review mainly focuses on the natural and synthetic chalcone derivatives that are exclusively synthesized via Claisen-Schmidt condensation reaction and their immunomodulatory prospects. We have critically reviewed the literature and provided convincing evidence for the promising efficacy of chalcone derivatives to modulate functioning of various innate and adaptive immune players including granulocytes, mast cells, monocytes, macrophages, platelets, dendritic cells, natural killer cells, and T-lymphocytes.

Multi-targetable chalcone analogs to treat deadly Alzheimer’s disease: Current view and upcoming advice

The complications of Alzheimer’s disease AD were deadly dangerous cause of neurodegenerative disorders connected with the decline of the cognitive functions and loss of memory. The common form of dementia is accounted as the sixth leading cause of the death affecting any stage of people in a lifetime. Synthetic natural chalcone analogs were currently a hot research topic for the treatment of (AD) which has affected millions of peoples throughout the world. The present aim was set to understand the important problems of the AD and its treatment based on natural derivatives of novel chalcones. One interesting strategy currently of searching for the treatment of AD is to find inhibitors for acetylcholinesterase (AChE) and using metal chelators to target amyloid-β (Aβ) peptides, and then metal-Aβ complexes for the AD pathogenesis. The present compressed review focuses and highlights the design and synthesis of new approaches for the construction of important chalcones playing multiple beneficiary roles in the AD treatments. These hallmarks of concurred research represent the immediate needs of development of novel therapeutic drugs for effective treatment of ADs by understanding the specific pharmacology targets.

The Combination of Flavokawain B and Daunorubicin Induces Apoptosis in Human Myeloid Leukemic Cells by Modifying NF-κB.

Flavokawain B (FKB), is a natural chalcone isolated from kava root that induces apoptosis in cancer cells. Herein we investigated the effects of combination of FKB and daunorubicin (DNR) on human leukemic cells. Cell viability and death were assessed by the MTS assay and flow cytometry. NK-κB was detected by western blotting. FKB alone and in combination with DNR reduced the viable cell numbers of four leukemic cell lines. FKB itself induced apoptosis of an acute myeloid cell line, HL-60. Because the additive effect of DNR and FKB was most obvious in HL-60 cells, subsequent experiments were performed with HL-60 cells. Combined treatment of the two compounds increased NF-κB activation at 12 h. A combination treatment of DNR and FKB may improve the anticancer effects of DNR in DNR-resistant acute myeloid leukemia.

Design, Synthesis and Docking Studies of Flavokawain B Type Chalcones and Their Cytotoxic Effects on MCF-7 and MDA-MB-231 Cell Lines.

Flavokawain B (1) is a natural chalcone extracted from the roots of Piper methysticum, and has been proven to be a potential cytotoxic compound. Using the partial structure of flavokawain B (FKB), about 23 analogs have been synthesized. Among them, compounds 8, 13 and 23 were found in new FKB derivatives. All compounds were evaluated for their cytotoxic properties against two breast cancer cell lines, MCF-7 and MDA-MB-231, thus establishing the structure–activity relationship. The FKB derivatives 16 (IC50 = 6.50 ± 0.40 and 4.12 ± 0.20 μg/mL), 15 (IC50 = 5.50 ± 0.35 and 6.50 ± 1.40 μg/mL) and 13 (IC50 = 7.12 ± 0.80 and 4.04 ± 0.30 μg/mL) exhibited potential cytotoxic effects on the MCF-7 and MDA-MB-231 cell lines. However, the methoxy group substituted in position three and four in compound 2 (IC50 = 8.90 ± 0.60 and 6.80 ± 0.35 μg/mL) and 22 (IC50 = 8.80 ± 0.35 and 14.16 ± 1.10 μg/mL) exhibited good cytotoxicity. The lead compound FKB (1) showed potential cytotoxicity (IC50 = 7.70 ± 0.30 and 5.90 ± 0.30 μg/mL) against two proposed breast cancer cell lines. It is evident that the FKB skeleton is unique for anticancer agents, additionally, the presence of halogens (Cl and F) in position 2 and 3 also improved the cytotoxicity in FKB series. These findings could help to improve the future drug discovery process to treat breast cancer. A molecular dynamics study of active compounds revealed stable interactions within the active site of Janus kinase. The structures of all compounds were determined by 1H-NMR, EI-MS, IR and UV and X-ray crystallographic spectroscopy techniques.

Design, synthesis and evaluation of chalcones as H1N1 Neuraminidase inhibitors

A series of chalcone derivatives (1a–2i) were designed based on isoliquiritigenin (the most active natural chalcone non-competitive neuraminidase (NA) inhibitor). Molecular modeling studies revealed that isoliquiritigenin and its designed analogs occupied 430-loop cavity of NA and interacted favorably with catalytic site residues. The favorable derivatives were synthesized and evaluated for cytotoxicity and for inhibition of cytopathic effect by H1N1 virus. The inhibitory effect was further quantified by heamagglutinition (HA) assay, H1N1-NA inhibition, and kinetics of inhibition. The HA assay showed compound 1e has the lowest EC50 of 1.71 nM. In contrast, the H1N1-NA inhibition assay showed compound 1f has the best activity with the IC50 of 3.58 μM. Enzyme kinetic study suggested that the inhibition mechanism of compounds 1f and 2f was non-competitive.

Synthesis of bavachromanol from resorcinol via a tandem cationic cascade/EAS sequence

The natural chalcone bavachromanol has been prepared through a tandem reaction sequence that joins cationic cyclization of an epoxide to an adjacent MOM-acetal with electrophilic aromatic substitution by a presumed methoxymethylene cation. Only a single regioisomer of the tandem product was observed, with substitution taking place exclusively ortho to the position of the original acetal. This regiocontrol provided a key intermediate from a symmetrical precursor, and allowed preparation of the meroterpenoid through a short reaction sequence.

Discovery of a highly active anticancer analogue of cardamonin that acts as an inducer of caspase-dependent apoptosis and modulator of the mTOR pathway

Cardamonin is a natural chalcone that has been shown to exhibit high anticancer activity. In an attempt to discover analogues of cardamonin with enhanced anticancer activity, 19 analogues were synthesized and tested against A549 and HK1 cell lines. Results of the MTS cell viability assay showed that several derivatives possessed cytotoxic activities that were several-fold more potent than cardamonin. SAR analysis showed the importance of the ketone and alkene groups for bioactivity, while substituting cardamonin's phenolic groups with more polar moieties resulted in activity enhancement. As part of the SAR study and further exploration of chemical space, the effect of metal coordination on cytotoxicity was also investigated, but it was only possible to successfully obtain the Cu (II) complex of cardamonin (19). Compound 19 was the most active analogue possessing IC50 values of 13.2μM and 0.7μM against A549 and HK1 cells, corresponding to a 5- and 32-fold increase in activity, respectively. It was also able to significantly inhibit the migration of A549 and HK1 cells. Further mode of action studies have shown that the most active analogue, 19, induced DNA damage resulting in G2/M-phase cell- cycle arrest in both cell lines. These events further led to the induction of apoptosis by the compound via caspase-3/7 and caspase-9 activation, PARP cleavage and downregulation of Mcl-1 expression. Moreover, 19 inhibited the expression levels of p-mTOR and p-4EBP1, which indicated that it exerted its anticancer activity, at least in part, via inhibition of the mTOR signalling pathway.

Antineoplastic activity of isoliquiritigenin, a chalcone compound, in androgen-independent human prostate cancer cells linked to G2/M cell cycle arrest and cell apoptosis

Isoliquiritigenin is a natural chalcone derived from Glycyrrhiza, which has been reported to have anti-tumor activity in recent years. Here, we investigate the anticancer efficacy and associated mechanisms of isoliquiritigenin in human prostate cancer PC-3 and 22RV1 cells. Isoliquiritigenin (25–50μM) inhibited cell proliferation, induced cell apoptosis, and caused G2/M cell cycle arrest in vitro. This agent also repressed the growth of PC-3 xenograft tumors in vivo with the results of hematoxylin/eosin staining and immunohistochemistry staining showing differences between isoliquiritigenin-treated groups and control group. Next, we used microarray transcriptional profiling to identify isoliquiritigenin-regulated genes on PC-3 prostate cancer cells. Multiple genes involved in cell cycle, DNA damage, and apoptosis signaling pathways were changed remarkably with the treatment of isoliquiritigenin. Molecular studies revealed that G2/M arrest was associated with a decrease in cyclin B1, cyclin-dependent kinase 1 (CDK1), and phosphorylated CDK1 (Thr14, Tyr15, and Thr161), whereas the expression of 14-3-3σ and growth arrest and DNA damage-inducible 45 alpha (GADD45A) was increased. The complexes of cyclin B1–CDK1 were also examined to show a decrease in the binding of CDK1 with cyclin B1. In addition, treatment with relatively high concentrations of isoliquiritigenin induced apoptosis, mainly associated with enhancing apoptosis regulator (Bax/Bcl-2) ratio. Collectively, these findings indicate that isoliquiritigenin modulates cyclin B1–CDK1 for G2/M arrest, together with an alteration of cell cycle regulators and apoptotic factors in human prostate cancer cells. However, we observed pleiotropic effects for isoliquiritigenin in microarray results, suggesting that other biological mechanisms also contribute to its efficacy, which could be of interest for future investigations.

Chalcone Derivatives: Anti-inflammatory Potential and Molecular Targets Perspectives.

Chalcone or (E)-1,3-diphenyl-2-propene-1-one scaffold has gained considerable scientific interest in medicinal chemistry owing to its simple chemistry, ease in synthesizing a variety of derivatives and exhibiting a broad range of promising pharmacological activities by modulating several molecular targets. A number of natural and (semi-) synthetic chalcone derivatives have demonstrated admirable anti-inflammatory activity due to their inhibitory potential against various therapeutic targets like Cyclooxygenase (COX), Lipooxygenase (LOX), Interleukins (IL), Prostaglandins (PGs), Nitric Oxide Synthase (NOS), Leukotriene D4 (LTD4), Nuclear Factor-κB (NF- κB), Intracellular Cell Adhesion Molecule-1 (ICAM-1), Vascular Cell Adhesion Molecule-1 (VCAM-1), Monocyte Chemoattractant Protein-1 (MCP-1) and TLR4/MD-2, etc. The chalcone scaffold with hydroxyl, methoxyl, carboxyl, prenyl group and/or heterocyclic ring substitution like thiophene/furan/indole showed promising anti-inflammatory activity. In this review, a comprehensive study (from the year 1991 to 2016) on multi-targets of inflammatory interest, related inflammation reactions and their treatment by chalcone-based inhibitors acting on various molecular targets entailed in inflammation, Structure-Activity Relationships (SARs), Mechanism of Actions (MOAs), and patents are highlighted.

Synthesis and Structure-activity Relationships of Chalcone Derivatives as Inhibitors of Ovarian Cancer Cell Growth

Background: Ovarian cancer remains a disease with a poor five year survival rate. As such, novel therapies are needed. Natural chalcones as well as their synthetic derivatives have shown biological activity in a number of areas including the inhibition of cancer cell growth. Objective: To synthesize a library of chalcone derivatives, including novel structures, and determiner the inhibition of ovarian cancer cell growth and Structure-activity-relationships. Methods: The Claisen-Schmidt condensation reaction between substituted acetophenones and aromatic aldehydes was used to produce a series of novel chalcones in moderate to excellent yields and good purity. Cellular proliferation of CA-OV3 cells was measured with a MTS assay. Results: Out of the thirty-four synthesized compounds, eight are new derivatives. The synthesized compounds were characterized by 1H NMR, 13C NMR, and HRMS. Biological evaluation of these β-phenylacrylophenone derivatives in CA-OV3 cells showed interesting antiproliferative activities providing initial structure – activity information. Conclusion: Fourteen of the thirty-four tested compounds showed significant activity, with several showing near complete inhibition of growth at 100 µM. The structure-activity relationships suggest that modification to the A ring is widely tolerated and that electron-donating modifications to the B ring are beneficial to activity. Electron-withdrawing modifications to the B ring did not show inhibition of cell growth. Keywords: Synthesis, chalcones, claisen-schmidt condensation, structure-activity, ovarian cancer, growth inhibition.

Immunosuppressive Effects of Natural α,β-Unsaturated Carbonyl-Based Compounds, and Their Analogs and Derivatives, on Immune Cells: A Review.

The immune system is complex and pervasive as it functions to prevent or limit infections in the human body. In a healthy organism, the immune system and the redox balance of immune cells maintain homeostasis within the body. The failure to maintain the balance may lead to impaired immune response and either over activity or abnormally low activity of the immune cells resulting in autoimmune or immune deficiency diseases. Compounds containing α,β-unsaturated carbonyl-based moieties are often reactive. The reactivity of these groups is responsible for their diverse pharmacological activities, and the most important and widely studied include the natural compounds curcumin, chalcone, and zerumbone. Numerous studies have revealed the mainly immunosuppressive and anti-inflammatory activities of the aforesaid compounds. This review highlights the specific immunosuppressive effects of these natural α,β-unsaturated carbonyl-based compounds, and their analogs and derivatives on different types of immune cells of the innate (granulocytes, monocytes, macrophages, and dendritic cells) and adaptive (T cells, B cells, and natural killer cells) immune systems. The inhibitory effects of these compounds have been comprehensively studied on neutrophils, monocytes and macrophages but their effects on T cells, B cells, natural killer cells, and dendritic cells have not been well investigated. It is of paramount importance to continue generating experimental data on the mechanisms of action of α,β-unsaturated carbonyl-based compounds on immune cells to provide useful information for ensuing research to discover new immunomodulating agents.

Diversity-Oriented Synthesis of Natural-Product-like Libraries Containing a 3-Methylbenzofuran Moiety for the Discovery of New Chemical Elicitors.

Natural products are a major source of biological molecules. The 3‐methylfuran scaffold is found in a variety of plant secondary metabolite chemical elicitors that confer host‐plant resistance against insect pests. Herein, the diversity‐oriented synthesis of a natural‐product‐like library is reported, in which the 3‐methylfuran core is fused in an angular attachment to six common natural product scaffolds—coumarin, chalcone, flavone, flavonol, isoflavone and isoquinolinone. The structural diversity of this library is assessed computationally using cheminformatic analysis. Phenotypic high‐throughput screening of β‐glucuronidase activity uncovers several hits. Further in vivo screening confirms that these hits can induce resistance in rice to nymphs of the brown planthopper Nilaparvata lugens. This work validates the combination of diversity‐oriented synthesis and high‐throughput screening of β‐glucuronidase activity as a strategy for discovering new chemical elicitors.