Chemical constituents with antioxidant activity from the branches and leaves of Hultholia mimosoides

Four undescribed homoisoflavanoids (1-4), one homoflavonoid (5), ten dibenzoxocin derivatives (6a-10a and 6b-10b), one dibenzoxocin-derived phenolic compound (11), one diterpenoid (13), three aliphatic dicarboxylic acid derivatives (14-16), together with the known diterpenoid 12-O-ethylneocaesalpin B (12) were obtained from the branches and leaves of Hultholia mimosoides. Their structures were elucidated by extensive spectroscopic techniques. Notably, each of the dibenzoxocins 6-10 existed as a pair of interconvertible atropisomers and the conformation for these compounds was clarified by NMR and ECD analyses. Protosappanin F (11) was a previously undescribed dibenzoxocin-derived compound in which one of the benzene rings was hydrogenated to a polyoxygenated cyclohexane ring and an ether linkage was established between C-6 and C-12a. The isolated polyphenols were tested for induction of quinone reductase and compounds 3 and 8 showed potent QR-inducing activity in Hepa-1c1c7 cells.

Three new compounds from the twigs and leaves of Nageia fleuryi Hickel

Two new diterpenoids, 12,15-di-O-acetylhypargenin B (1) and taiwanin F-12-O-β-D-glucopyranoside (2), one new monoterpenoid, (S)-7-methyl-3-methyleneoct-6-ene-1,2-diyl diacetate (3), together with eight known compounds (4-11), were obtained from the twigs and leaves of Nageia fleuryi Hickel. The structures of the new compounds were elucidated by extensive spectroscopic techniques including HR-ESI-MS and 1 D and 2 D NMR experiments. Spectroscopic data of the known compound 4 were provided for the first time. Compounds 1 and 11 exhibited strong inhibitory activity on LPS-stimulated production of NO in RAW 264.7 murine macrophages, while compounds 1, 3, and 5 showed significant quinone reductase inducing activity in Hepa 1c1c7 murine hepatoma cells. Moreover, compounds 7 and 8 showed inhibitory activity against the proliferation of the human prostate carcinoma DU145 cells.

The ethanol extract of flower buds of Tussilago farfara L. attenuates cigarette smoke-induced lung inflammation through regulating NLRP3 inflammasome, Nrf2, and NF-κB

ETHNOPHARMACOLOGICAL RELEVANCE

The flower buds of Tussilago farfara L. (Abbreviated as FTF) were widely used in traditional Chinese medicine (TCM) to treat respiratory diseases, including asthma, dry throat, great thirst, turbid saliva, stinky pus, and coughs caused by various causes.

AIM OF STUDY

The aim of study is to explore the efficiency of FTF in vitro and in vivo for the treatment of lung inflammation, and to illustrate the possible mechanisms of FTF in treating inflammation-related respiratory diseases targeting NOD-like receptor 3 (NLRP3) inflammasome, nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear transcription factor-κB (NF-κB).

METHODS

Lung inflammation model in vivo was induced by exposure of mice to cigarette smoke (CS) for two weeks. The levels of superoxide dismutase (SOD), malondialdehyde (MDA), inflammatory factors, and histology in lung tissues were investigated in presence or absence of ethanol extract of the flower buds of T. farfara L. (FTF-EtOH). In the cell-based models, nitric oxide (NO) assay, flow cytometry assay, enzyme-linked immunosorbent assay (Elisa), and glutathione (GSH) assay were used to explore the anti-inflammatory and anti-oxidant effects of FTF-EtOH. Possible anti-inflammatory mechanisms of FTF targeting NLRP3 inflammasome, Nrf2, and NF-κB have been determined using western blot, quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR), immunofluorescence assay, nuclear and cytoplasmic extraction, and ubiqutination assay.

RESULTS

FTF-EtOH suppressed CS-induced overproduction of inflammatory factors [e.g., tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β)], and upregulation of the content of intracellular MDA in the lung homogenate of mice. In cell-based models, FTF-EtOH reduced the lipopolysaccharide (LPS)-induced overproduction of inflammatory factors, and attenuated the CS extract-induced overgeneration of reactive oxygen species (ROS). Furthermore, FTF-EtOH up-regulated Nrf2 and its downstream genes through enhancing the stability of Nrf2 protein, and inhibited the activation of NF-κB and NLRP3 inflammasome, which have been confirmed by detecting the protein levels in the mouse model.

CONCLUSIONS

FTF-EtOH effectively attenuated lung inflammation in vitro and in vivo. The protection of FTF-EtOH against inflammation was produced by activation of Nrf2 and inhibitions of NF-κB and NLRP3 inflammasome. These datas definitely support the ethnopharmacological use of FTF as an anti-inflammatory drug for treating respiratory diseases in TCM.

Chemical Constituents from Physalis Calyx seu Fructus and Their Inhibitory Effects against Oxidative Stress and Inflammatory Response

Physalis Calyx seu Fructus, a traditional Chinese medicine consisting of the calyxes and fruits of Physalis alkekengi var. franchetii, has been used as therapy for inflammation-related respiratory diseases such as excessive phlegm, cough, sore throat, and pharyngitis for a long history in China. The aim of the present study was to investigate the chemical constituents of Physalis Calyx seu Fructus and identify the bioactive constituents responsible for its traditional application as therapy for inflammation-related diseases. In the present study, one new phenylpropanoid (1: ), two new steroids (17: and 18: ), together with 55 known constituents have been purified from the EtOH extract of Physalis Calyx seu Fructus. Among them, seven and twelve known constituents were isolated for the first time from Physalis Calyx seu Fructus and the genus Physalis, respectively. Fourteen constituents, including steroids [physalins (5:  - 9, 12:  - 14: , and 15: ) and ergostane (21: )], a sesquiterpenoid (35: ), alkaloids (36: and 37: ), and a flavonoid (44: ), showed inhibitory effects against oxidative stress. Ten constituents, including steroids (5, 6, 8, 13: , and 15: ), sesquiterpenoids (34: and 35: ), alkaloids (37: and 41: ), and a flavonoid (43: ), were found be potential anti-inflammatory constituents of this medicinal plant. The inhibition of oxidative stress and inflammatory response may be related to the regulation of Nrf2 and nuclear factor-κB pathways. The ethnomedical use of Physalis Calyx seu Fructus as a treatment for respiratory diseases might be attributed to the combined inhibitory effects of steroids, alkaloids, sesquiterpenoids, and flavonoids against oxidative stress and inflammatory response.

Dolabellane and Clerodane Diterpenoids from the Twigs and Leaves of Casearia kurzii

A pair of enantiomeric 15-nordolabellane diterpenoids, (-)- and (+)-caseadolabellols A (1a and 1b), three dolabellane diterpenoids, caseadolabellols B-D (2-4), two dolastane diterpenoids, caseadolastols A and B (5 and 6), 10 clerodane diterpenoids, caseakurzins A-J (7-16), and nine known diterpenoids (17-25) were isolated from the twigs and leaves of Casearia kurzii. The structures of the new compounds were established on the basis of extensive spectroscopic data, and those of compounds 1a, 1b, and 2 were verified by single-crystal X-ray crystallographic analysis. The enantiomers 1a and 1b were separated by chiral-phase HPLC. The absolute configurations were determined by experimental and calculated ECD data, the modified Mosher's method, or literature comparison. Compounds 1a and 5 showed significant quinone reductase-inducing activity in Hepa 1c1c7 cells, while 1b showed moderate activity. Molecular docking studies showed that 1a had greater binding affinity with Nrf2 protein (5FNQ) than 1b. The cytotoxic activity of compounds 1a, 1b, 2-12, 15, and 16 was evaluated, among which compounds 8 and 16 exhibited significant inhibitory activity against the A549 cell line. Compounds 8 and 16 induced the A549 cells to arrest at G2/M and S phases, respectively, and both compounds induced apoptosis in A549 cells.

Three new terpenoids from Chonemorpha megacalyx

Two new triterpenoids, 3β-hydroxytirucall-7,25-dien-24-one (1) and 3β-acetoxytirucall-7,23,25-triene (2), along with one new sesquiterpenoid, alloaromadendrane-12α,14β-dioic acid (3), were isolated from the vines and leaves of Chonemorpha megacalyx Pierre. Their structures were established on the basis of extensive spectroscopic data.

Trans-4,4'-dihydroxystilbene ameliorates cigarette smoke-induced progression of chronic obstructive pulmonary disease via inhibiting oxidative stress and inflammatory response

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease resulted from airflow obstructions, and there is a driving requirement for novel and effective preventive and therapeutic agents of COPD. Nuclear factor-erythroid 2-related factor 2 (Nrf2) has been regarded to be a promising therapeutic target for COPD. Resveratrol is a natural Nrf2 activator with antioxidant and anti-inflammatory properties, however, its application is limited by its relative low efficiency and poor bioavailability. Herein, based on the skeleton of resveratrol, trans-4,4'-dihydroxystilbene (DHS) has been firstly identified to be an Nrf2 activator, which is more potent than the well-known sulforaphane (SF) and resveratrol. Our results indicate that DHS blocks Nrf2 ubiquitylation through specifically reacting with Cys151 cysteine in Keap1 protein to activate Nrf2-regulated defensive response, and thus enhances intracellular antioxidant capability. Furthermore, DHS relieves lipopolysaccharide (LPS)-stimulated inflammatory response via inhibition of NF-κB. Importantly, DHS significantly ameliorates pathological alterations (e.g. infiltration of leukocytes and fibrosis), downregulates the levels of oxidant biomarkers malondialdehyde (MDA) and 8-oxo-7,8-dihydro-2'-deoxyguanosin (8-oxo-dG), and inhibits the overproductions of inflammatory mediators [e.g. tumor necrosis factor α (TNF-α), cyclooxygenase-2 (COX-2), and matrix metalloproteinase-9 (MMP-9)] in a cigarette smoke (CS)-induced pulmonary impairment mice model. Taken together, this study demonstrates that DHS attenuates the CS-induced pulmonary impairments through inhibitions of oxidative stress and inflammatory response targeting Nrf2 and NF-κB in vitro and in vivo, and could be developed into a preventive agent against pulmonary impairments induced by CS.

Lignans from Euphorbia hirta L

Five new lignans, euphorhirtins A-D (1-4), 5-methoxyvirgatusin (5), three artefacts, 7S-ethoxyisolintetralin (6), 7R-ethoxyisolintetralin (7), and 7R-ethoxy-3-methoxyisolintetralin (8), together with 13 known ones (9-21) were isolated from the medicinal plant Euphorbia hirta L. The structures of the compounds were elucidated by means of extensive spectroscopic analysis, including 1D and 2D NMR and HR-ESI-MS experiments. The absolute configurations of compound 1 was determined by ECD calculation. The isolates were evaluated for their inhibitory effects against the proliferation of the cancer cell lines (Hep G2, A549, and DU145) and compounds 14 and 18 showed inhibitory activity against the Hep G2 cells with IC₅₀ values 7.2 ± 0.17 and 8.5 ± 0.36 μM.

4β-Hydroxywithanolide E from Goldenberry (Whole Fruits of Physalis peruviana L.) as a Promising Agent against Chronic Obstructive Pulmonary Disease

Environmental toxicant- and oxidant-induced [e.g., cigarette smoke (CS)] respiratory oxidative stress and inflammatory response play a vital role in the onset and progression of COPD. The nuclear factor erythroid 2-related factor 2 (Nrf2) represents an important mechanism for regulating intracellular oxidative stress and inflammatory response and is a promising target for developing agents against COPD. Herein, a bioactivity-guided purification of goldenberry (whole fruits of Physalis peruviana L.) led to the isolation of a novel and potent Nrf2 activator 4β-hydroxywithanolide E (4β-HWE). Our study indicated that (i) 4β-HWE activated the Nrf2-mediated defensive response through interrupting Nrf2-Keap1 protein-protein interaction (PPI) via modification of Cys151 and Cys288 cysteine residues in Keap1 and accordingly suppressing the ubiquitination of Nrf2. (ii) 4β-HWE enhanced intracellular antioxidant capacity and inhibited oxidative stress in normal human lung epithelial Beas-2B cells and wild-type AB zebrafish. (iii) 4β-HWE blocked LPS-stimulated inflammatory response and inhibited LPS-stimulated NF-κB activation in RAW 264.7 murine macrophages. (iv) 4β-HWE effectively suppressed oxidative stress and inflammatory response in a CS-induced mice model of pulmonary injury. Collectively, these results display the feasibility of using 4β-HWE to prevent or alleviate the pathological progression of COPD and suggest that 4β-HWE is a candidate or a leading molecule against COPD.

Withanolides from the genus Physalis: a review on their phytochemical and pharmacological aspects

Objectives

Withanolides are a group of modified C28 ergostane-type steroids with a C-22, C-26 δ-lactone side chain or a C-23, C-26 γ-lactone side chain. They enjoy a limited distribution in the plant kingdom and predominantly occur in several genera of Solanaceae. Of which, the genus Physalis is an important resource for this type of natural molecules. The present review aims to comprehensively illustrate the structural characteristics and classification of withanolides, and particularly focus on the progression on phytochemical and pharmacological aspects of withanolides from Physalis ranging from January 2015 to June 2019.

Key findings

Approximately 351 natural withanolides with novel and unique structures have so far been identified from genus Physalis, mainly isolated from the species of P. angulata and P. peruviana. Withanolides demonstrated diverse biological activity, such as anticancer, anti-inflammatory, antimicrobial, immunoregulatory, trypanocidal and leishmanicidal activity. Their observed pharmacological functions supported the uses of Physalis species in traditional or folk medicines.

Summary

Due to their unique structure skeleton and potent bioactivities, withanolides are regarded to be promising drug candidates, particularly for developing anticancer and anti-inflammatory agents. Further investigations for discovering novel withanolides of genus Physalis, exploiting their pharmacological values and evaluating their potency as therapeutic agents are significant work.

Novel diterpenoid-type activators of the Keap1/Nrf2/ARE signaling pathway and their regulation of redox homeostasis

Oxidative stress is involved in the onset and progression of many human diseases. Activators of the Keap1/Nrf2/ARE pathway effectively inhibit the progression of oxidative stress-induced diseases. Herein, a small library of diterpenoids was established by means of phytochemical isolation, and chemical modification on naturally occurring molecules. The diterpenoids were subjected to a NAD(P)H: quinone reductase (QR) assay to evaluate its potential inhibition against oxidative stress. Sixteen diterpenoids were found to be novel potential activators of Nrf2-mediated defensive response. Of which, an isopimarane-type diterpenoid, sphaeropsidin A (SA), was identified as a potent activator of the Keap1/Nrf2/ARE pathway, and displayed approximately 5-folds potency than that of sulforaphane (SF). SA activated Nrf2 and its downstream cytoprotective genes through enhancing the stabilization of Nrf2 in a process involving PI3K, PKC, and PERK, as well as potentially interrupting Nrf2-Keap1 protein-protein interaction. In addition, SA conferred protection against sodium arsenite [As(III)]- and cigarette smoke extract (CSE)-induced redox imbalance and cytotoxicity in human lung epithelial cells, as wells as inhibited metronidazole (MTZ)-induced oxidative insult in Tg (krt4: NTR-hKikGR)^cy17 transgenic zebrafish and lipopolysaccharide (LPS)-induced oxidative damage in wild-type AB zebrafish. These results imply that SA is a lead compound for therapeutic agent against oxidative stress-induced diseases, and diterpenoid is a good resource for discovering drug candidates and leads of antioxidant therapy.

Botrysphin D attenuates arsenic-induced oxidative stress in human lung epithelial cells via activating Nrf2/ARE signaling pathways

Oxidative stress is one of the main pathogenesis for many human diseases. Nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway plays a key role in regulating intracellular antioxidant responses, and thus activation of Nrf2/ARE signaling pathway is a potential chemopreventive or therapeutic strategy to treat diseases caused by oxidative damage. In the present study, we have found that treatment of Beas-2B cells with botrysphins D (BD) attenuated sodium arsenite [As (III)]-induced cell death and apoptosis. Meanwhile, BD was able to upregulate protein levels of Nrf2 and its downstream genes NQO1 and γ-GCS through inducing Nrf2 nuclear translocation, enhancing protein stability, and inhibiting ubiquitination. It was also found that BD-induced activation of the Nrf2/ARE pathway was regulated by PI3K, MEK1/2, PKC, and PERK kinases. Collectively, BD is a novel activator of Nrf2/ARE pathway, and is verified to be a potential preventive agent against oxidative stress-induced damage in human lung tissues.

Two new triterpenoids from the fungus Diplodia cupressi

One new pentanortriterpenoid, 23,24,25,26,27-pentanorlanost-7,9(11)-dien-3β,22-diol (1), one new triterpenoid, lanost-8-en-3β,22S,23S-triol (2), together with the known triterpenoid, 23,24,25,26,27-pentanorlanost-8-en-3β,22-diol (3), were obtained from culture of the fungus Diplodia cupressi associated with the moss Polytrichum commune. The structures of the new compounds were elucidated by extensive spectroscopic techniques including HR-ESIMS and 1 D and 2 D NMR experiments. The cytotoxicity of these compounds against human cancer cell lines (A549, Hep G2, Hepa 1c1c7, and Hela) was evaluated and compound 2 exhibited weak inhibitory activity with IC₅₀ value of 35.0 ± 2.3 μM against the proliferation of the Hepa 1c1c7 cells.

Lignan and flavonoid support the prevention of cinnamon against oxidative stress related diseases

BACKGROUND

Oxidative stress contributes to the pathogenesis of many human diseases. Cinnamon is a worldwide used spice, dietary supplement and traditional medicine, and is used for the therapy of oxidative stress related diseases. A well-established concept is that the functions of cinnamon preventing oxidative stress-induced diseases are attributed to the occurrence of cinnamaldehyde and its analogues.

HYPOTHESIS

In our continuous searching of natural molecules with antioxidant capacity, we have found that cinnamaldehyde and its analogues in cinnamon are weak inhibitors of oxidative stress, and thus we speculate that there are novel and/or potent molecules inhibiting oxidative stress in cinnamon.

STUDY DESIGN AND METHODS

A systemic phytochemical investigation of cinnamon using column chromatography was performed to identify the chemical constituents of cinnamon, and then their capacity of inhibiting oxidative stress and action of mechanism targeting Nrf2 pathway were investigated using diverse bioassay, including NAD(P)H: quinone reductase (QR) assay, immunoblot analysis, luciferase reporter gene assay, immunofluorescence and flow cytometry.

RESULTS

Cinnamon improved the intracellular antioxidant capacity. A systemic phytochemical investigation of cinnamon gave the isolation of twenty-two chemical ingredients. The purified constituents were tested for their potential inhibitory effects against oxidative stress. Besides cinnamaldehyde analogues, a lignan pinoresinol (PRO) and a flavonol (-)-(2R,3R)-5,7-dimethoxy-3', 4'-methylenedioxy-flavan-3-ol (MFO) were firstly identified to be inhibitors of oxidative stress. Further study indicated that PRO and MFO activated Nrf2-mediated antioxidant response, and protected human lung epithelial cells against sodium arsenite [As(III)]-induced oxidative insults.

CONCLUSION

The lignan PRO and the flavonoid MFO are two novel Nrf2 activators protecting tissues against oxidative insults, and these two constituents support the application of cinnamon as an agent against oxidative stress related diseases.

Protective effect of the ethanol extract from Ligusticum chuanxiong rhizome against streptozotocin-induced diabetic nephropathy in mice

ETHNOPHARMACOLOGY RELEVANCE

Rhizome of Ligusticum chuanxiong Hort. (Abbreviated as LC) is a frequently prescribed component in plenty of traditional Chinese medicine (TCM) formulas which are used to treat diabetic nephropathy (DN). The aims of the present study are to investigate the protective effect of the ethanol extract of LC rhizome (EEL) against DN in vivo, evaluate its potential mechanism, and find the evidence supporting its enthopharmacological use as an anti-DN agent.

MATERIALS AND METHODS

Hepa 1c1c7 murine hepatoma cells, human breast carcinoma MDA-MB-231 cells, human renal glomerular endothelial cells (HRGEC), and RAW 264.7 murine macrophages were adopted to test the effects of EEL and its active constituents on inhibitions of oxidative stress and inflammation in vitro. A streptozotocin (STZ) -induced DN C57BL/6 mice model was established and used to investigate the preventive effect of EEL against DN in vivo.

RESULTS

EEL demonstrated potential inhibitory effects against oxidative stress and inflammation in vitro. Using a STZ-induced DN mice model, it has been found that EEL treatment significantly prevented STZ-induced increases of urine production, urinary albumin excretion (UAE) and urine albumin-to-creatinine ratio (UACR), and markedly attenuated STZ-induced renal damages (e.g. glomerulosclerosis and fibrosis). The predominant bioactive constituents, Z-ligustilide (LGT), ferulic acid (FA), and tetramethylpyrazine (TMP), were inhibitors of oxidative stress and inflammation through acting with Nrf2 and NF-κB pathways.

CONCLUSIONS

EEL attenuates structural and functional damages of kidney in STZ-induced DN model in vivo, which might be related to the functions of EEL on inhibitions of oxidative stress and inflammation. These finding definitely supports the ethnopharmacological use of LC as an anti-DN agent.

Discovery of natural flavonoids as activators of Nrf2-mediated defense system: Structure-activity relationship and inhibition of intracellular oxidative insults

Continuous overproduction of reactive oxygen species (ROS), termed as oxidative stress, plays a crucial role in the onset and progression of many human diseases. Activation of nuclear transcription factor erythroid 2-related factor (Nrf2) by small molecules could eliminate ROS, and thus block the pathogenesis of oxidative stress-induced diseases. In this study, a natural flavonoid library was established and tested for their potential Nrf2 inducing effects. Based on QR inducing effect of flavonoids, their structure-activity relationship (SAR) on Nrf2 induction was summarized, and twenty flavonoids were firstly identified to be potential activators of Nrf2-mediated defensive response. Then, 7-O-methylbiochanin A (7-MBA) was further investigated for its capability on the Nrf2 activation and prevention against oxidative insults in human lung epithelial cells. Further studies indicated that 7-MBA activated Nrf2 signaling pathway and protected human lung epithelial Beas-2B cells against sodium arsenite [As(III)]-induced cytotoxicity in an Nrf2-dependent manner. Activation of Nrf2 by 7-MBA upregulated intracellular antioxidant capacity, which was produced by enhancement of Nrf2 stabilization, blockage of Nrf2 ubiquitination, as well as Nrf2 phosphorylation by mitogen-activated protein kinase (MAPK), protein kinase C (PKC), protein kinase R-like endoplasmic reticulum kinase (PERK), and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K). Taken together, 7-MBA is a novel isoflavone-type Nrf2 activator displaying potential preventive effect against oxidative damages in human lung epithelial cells.

Investigation of constituents from Cinnamomum camphora (L.) J. Presl and evaluation of their anti-inflammatory properties in lipopolysaccharide-stimulated RAW 264.7 macrophages

ETHNOPHARMACOLOGY RELEVANCE

Cinnamomum camphora (L.) J. Presl has been used for the traditional medicine as a therapeutic agent of inflammation-related diseases, including sprains, rheumatic arthritis, abdominal pain, cough and bronchitis, for a long history. The aim of the present study was to illustrate anti-inflammatory substances of C. camphora and their mechanism of action, and to establish the correlations between chemical constituents and traditional uses of this plant.

MATERIALS AND METHODS

Chemical constituents were purified by chromatographic methods, and their structures were established based on spectroscopic analysis. Lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages was adopted for evaluating the anti-inflammatory activity in vitro. The nitric oxide (NO) production assay and nuclear factor kappa B (NF-κB) dual luciferase reporter assay were used to screen anti-inflammatory constituents. The mRNA and protein levels of inflammation-related cytokines and enzymes were determined by real-time reverse transcription-polymerase chain reaction (RT-PCR), immunoblot analysis, and enzyme linked immunosorbent assay (ELISA), respectively.

RESULTS

Twenty-five constituents were isolated from the EtOH extract of C. camphora. Eight constituents, covering phenylpropanoid (7), lignans (10 and 22), flavonoids (16-18), coumarin (21), and terpenoid (24) significantly inhibited LPS-stimulated NO production with maximum inhibition rates (MIRs) of ≥ 80%, and thus were verified to be the anti-inflammatory substances of this ethnomedical plant. (+)-Episesaminone (SMO, 22) and 3S-(+)-9-oxonerolidol (NLD, 24) blocked NF-κB activation via inducing IκBα expression. Moreover, SMO and NLD inhibited productions of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and prostaglandin E2 (PGE2), and alleviated increased mRNA and protein levels of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), and matrix metallopeptidase-9 (MMP-9) in LPS-stimulated RAW 264.7 macrophages.

CONCLUSIONS

The ethnomedical use of C. camphora for the treatment of inflammation-related diseases was attributed to the combined in vitro anti-inflammatory activities of phenylpropanoid, lignan, flavonoid, coumarin, and terpenoid. SMO and NLD were found to be new molecules with in vitro anti-inflammatory activities, which are achieved by inhibiting NF-κB regulated inflammatory response.

Homoeriodictyol protects human endothelial cells against oxidative insults through activation of Nrf2 and inhibition of mitochondrial dysfunction

Excess intracellular reactive oxygen species (ROS) production is a significant causative factor of many diseases, exemplified by vascular diseases. Mitochondria are a major source of endogenous ROS, which simultaneously induce mitochondrial dysfunction. Nuclear factor-erythroid 2-related factor 2 (Nrf2) represents an important intracellular defense system that protects cells against oxidative insults caused by ROS. Therefore, molecules with the capacities of inducing Nrf2, and preventing mitochondrial dysfunction can inhibit cell apoptosis, and thus are potential drug candidates for the therapy of ROS-mediated vascular diseases. Homoeriodictyol (HE), previously isolated from Viscum articulatum Burm, has been found to be an Nrf2 inducer. In the present study, we investigated its protection on ROS-induced endothelial cell injury using a H₂O₂-induced human umbilical vein EA.hy926 cell oxidative insult model. Our results indicated that HE activated Nrf2 signaling pathway and protected cells against H₂O₂-induced cell damage. HE alleviated H₂O₂-induced loss of mitochondrial membrane potential (MMP), blocked the releases of cytochrome C and apoptosis inducing factor (AIF) from mitochondria, and thus inhibited mitochondria-mediated cell apoptosis. Furthermore, HE inhibited H₂O₂-induced changes of apoptosis-related proteins, such as Bcl-2, Bcl-xL, caspases -3, -9 and PARP. Further study demonstrated that the protection of HE against H₂O₂-induced endothelial cell damage was Nrf2-dependent. Collectively, our observations suggest that HE is capable of counteracting oxidative insults in endothelial cells, and has a potential to be a therapeutic agent against ROS-mediated vascular diseases.

Physalis alkekengi L. var. franchetii (Mast.) Makino: An ethnomedical, phytochemical and pharmacological review

ETHNOPHARMACOLOGICAL RELEVANCE

The calyxes and fruits of Physalis alkekengi L. var. franchetii (Mast.) Makino (Physalis Calyx seu Fructus), have been widely used in traditional and indigenous Chinese medicines for the therapy of cough, excessive phlegm, pharyngitis, sore throat, dysuria, pemphigus, eczema, and jaundice with a long history.

AIM OF THE REVIEW

The present review aims to achieve a comprehensive and up-to-date investigation in ethnomedical uses, phytochemistry, pharmacology, and toxicity of P. alkekengi var. franchetii, particularly its calyxes and fruits. Through analysis of these findings, evidences supporting their applications in ethnomedicines are illustrated. Possible perspectives and opportunities for the future research are analyzed to highlight the gaps in our knowledge that deserves further investigation.

MATERIAL AND METHODS

Information on P. alkekengi var. franchetii was collected via electronic search of major scientific databases (e.g. Web of Science, SciFinder, Google Scholar, Pubmed, Elsevier, SpringerLink, Wiley online and China Knowledge Resource Integrated) for publications on this medicinal plant. Information was also obtained from local classic herbal literature on ethnopharmacology.

RESULTS

About 124 chemical ingredients have been characterized from different parts of this plant. Steroids (particularly physalins) and flavonoids are the major characteristic and bioactive constituents. The crude extracts and the isolated compounds have demonstrated various in vitro and in vivo pharmacological functions, such as anti-inflammation, inhibition of tumor cell proliferation, antimicrobial activity, diuretic effect, anti-diabetes, anti-asthma, immunomodulation, and anti-oxidation.

CONCLUSIONS

P. alkekengi var. franchetii is an important medicinal plant for the ethnomedical therapy of microbial infection, inflammation, and respiratory diseases (e.g. cough, excessive phlegm, pharyngitis). Phytochemical and pharmacological investigations of this plant definitely increased in the past half century. The chemical profiles, including ingredients and structures, have been adequately verified. Modern pharmacological studies supported its uses in the traditional and folk medicines, however, the molecular mechanisms of purified compounds remained unclear and were worth of further exploration. Therefore, the researchers should be paid more attention to a better utilization of this plant.

Identification of novel Nrf2 activators from Cinnamomum chartophyllum H.W. Li and their potential application of preventing oxidative insults in human lung epithelial cells

Human lung tissue, directly exposed to the environmental oxidants and toxicants, is apt to be harmed to bring about acute or chronic oxidative insults. The nuclear factor erythroid 2-related factor 2 (Nrf2) represents a central cellular defense mechanism, and is a target for developing agents against oxidative insult-induced human lung diseases. Our previous study found that the EtOH extract of Cinnamomum chartophyllum protected human bronchial epithelial cells against oxidative insults via Nrf2 activation. In this study, a systemic phytochemical investigation of the aerial parts of C. chartophyllum led to the isolation of thirty chemical constituents, which were further evaluated for their Nrf2 inducing potential using NAD(P)H: quinone reductase (QR) assay. Among these purified constituents, a sesquiterpenoid bearing α, β-unsaturated ketone group, 3S-(+)-9-oxonerolidol (NLD), and a diphenyl sharing phenolic groups, 3, 3′, 4, 4′-tetrahydroxydiphenyl (THD) significantly activated Nrf2 and its downstream genes, NAD(P)H quinone oxidoreductase 1 (NQO-1), and γ-glutamyl cysteine synthetase (γ-GCS), and enhanced the nuclear translocation and stabilization of Nrf2 in human lung epithelial cells. Importantly, NLD and THD had no toxicities under the Nrf2 inducing doses. THD also demonstrated a potential of interrupting Nrf2-Keap1 protein–protein interaction (PPI). Furthermore, NLD and THD protected human lung epithelial cells against sodium arsenite [As(III)]-induced cytotoxicity. Taken together, we conclude that NLD and THD are two novel Nrf2 activators with potential application of preventing acute and chronic oxidative insults in human lung tissue.

•

The chemical compositions of Cinnamomum chartophyllum are firstly identified.

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The active ingredients supporting the biological functions of C. chartophyllum are verified.

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NLD and THD are identified to be Nrf2 activators for the first time.

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NLD and THD protect human lung epithelial cells against As(III)-induced cytotoxicity.

Screening of traditional Chinese medicines with therapeutic potential on chronic obstructive pulmonary disease through inhibiting oxidative stress and inflammatory response

Background

Chronic obstructive pulmonary disease (COPD) is a major public health problem and gives arise to severe chronic morbidity and mortality in the world. Inflammatory response and oxidative stress play dominant roles in the pathological mechanism of COPD, and have been regarded to be two important targets for the COPD therapy. Traditional Chinese medicines (TCMs) possess satisfying curative effects on COPD under guidance of the TCM theory in China, and merit in-depth investigations as a resource of lead compounds.

Methods

One hundred ninety-six of TCMs were collected, and extracted to establish a TCM extract library, and then further evaluated for their potency on inhibitions of oxidative stress and inflammatory response using NADP(H):quinone oxidoreductase (QR) assay and nitric oxide (NO) production assay, respectively.

Results

Our investigation observed that 38 of the tested TCM extracts induced QR activity in hepa 1c1c7 murine hepatoma cells, and 55 of them inhibited NO production in RAW 264.7 murine macrophages at the tested concentrations. Noteworthily, 20 of TCM extracts simultaneously inhibited oxidative stress and inflammatory responses.

Conclusion

The observed bioactive TCMs, particularly these 20 TCMs with dual inhibitory effects, might be useful for the treatment of COPD. More importantly, the results of the present research afford us an opportunity to discover new lead molecules as COPD therapeutic agents from these active TCMs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1347-y) contains supplementary material, which is available to authorized users.

A Curcumin Derivative That Inhibits Vinyl Carbamate-Induced Lung Carcinogenesis via Activation of the Nrf2 Protective Response

AIMS

Lung cancer has a high worldwide morbidity and mortality. The employment of chemopreventive agents is effective to reduce lung cancer. Nuclear factor erythroid 2-related factor 2 (Nrf2) mitigates insults from both exogenous and endogenous sources and thus has been verified as a target for chemoprevention. Curcumin has long been recognized as a chemopreventive agent, but poor bioavailability and weak Nrf2 induction have prohibited clinical application. Thus, we have developed new curcumin derivatives and tested their Nrf2 induction.

RESULTS

Based on curcumin, we synthesized curcumin analogs with five carbon linkages and established a structure-activity relationship for Nrf2 induction. Among these derivatives, bis[2-hydroxybenzylidene]acetone (BHBA) was one of the most potent Nrf2 inducers with minimal toxicity and improved pharmacological properties and was thus selected for further investigation. BHBA activated the Nrf2 pathway in the canonical Keap1-Cys151-dependent manner. Furthermore, BHBA was able to protect human lung epithelial cells against sodium arsenite [As(III)]-induced cytotoxicity. More importantly, in an in vivo vinyl carbamate-induced lung cancer model in A/J mice, preadministration of BHBA significantly reduced lung adenocarcinoma, while curcumin failed to show any effects even at high doses.

INNOVATION

The curcumin derivative, BHBA, is a potent inducer of Nrf2. It was demonstrated to protect against As(III) toxicity in lung epithelial cells in an Nrf2-dependent manner. Furthermore, compared with curcumin, BHBA displayed improved chemopreventive activities in a carcinogen-induced lung cancer model.

CONCLUSION

Taken together, our results demonstrate that BHBA, a curcumin analog with improved Nrf2-activating and chemopreventive activities both in vitro and in vivo, could be developed into a chemoprotective pharmacological agent.

The genus Litsea in traditional Chinese medicine: an ethnomedical, phytochemical and pharmacological review

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Litsea, mainly distributed in the tropical and subtropical regions, has been used in traditional and indigenous Chinese medicines for the treatment of diarrhea, stomachache, dyspepsia, gastroenteritis, diabetes, edema, cold, arthritis, asthma, pain, traumatic injury, etc. for a long history. The present review aims to provide a comprehensive summary on the ethnomedical uses, phytochemistry, and pharmacology of the Litsea species used in traditional Chinese medicine (TCM). Based on these data, evidences supporting their ethnopharmacological effectiveness are illustrated, and opportunities for the future research and development as well as the therapeutic potential of this genus are analyzed to highlight the gaps in our knowledge that deserves further investigation.

MATERIAL AND METHODS

Information on the Litsea species was collected via electronic search (using Pubmed, SciFinder, Google Scholar, Web of Science and CNKI) and a library search for articles published in peer-reviewed journals. Furthermore, information was also obtained from some local books on ethnopharmacology.

RESULTS

Twenty plants of the genus Litsea are found to be important traditional medicines in China, and have a long medicinal application for diarrhea, stomachache, dyspepsia, gastroenteritis, diabetes, edema, cold, arthritis, asthma, pain, traumatic injury, etc. Over 200 ingredients have been identified from these 20 Litsea species used in TCM, and flavonoids, terpenoids and alkaloids are considered as the characteristic and bioactive constituents. The crude extracts and the isolated metabolites of these medicinal plants have exhibited some in vitro and in vivo pharmacological effects, including antimicrobial, hepatoprotection, anti-inflammatory, antiasthmatic, immunomodulation, anti-diabetic, anticholelithogenic, as well as function on central nervous system, etc.

CONCLUSIONS

The extensive literature survey reveals Litsea species to be a group of important medicinal plants used for the ethnomedical treatment of gastrointestinal diseases, diabetes, inflammatory disorders, and microbial infection in TCM. Pharmacological investigations have supported the use of some Litsea species in the traditional medicines. In addition, further researches targeting individual ingredients responsible for the pharmacological effects, as well as their mechanisms of action are necessary. The outcome of these studies will further support the therapeutic potential of the genus Litsea, and provide convincing evidences to its future clinical applications in modern medicine.

Plant extracts of the family Lauraceae: a potential resource for chemopreventive agents that activate the nuclear factor-erythroid 2-related factor 2/antioxidant response element pathway

Cells and tissues counteract insults from exogenous or endogenous carcinogens through the expression of genes encoding antioxidants and phase II detoxifying enzymes regulated by antioxidant response element promoter regions. Nuclear factor-erythroid 2-related factor 2 plays a key role in regulating the antioxidant response elements-target gene expression. Hence, the Nrf2/ARE pathway represents a vital cellular defense mechanism against damage caused by oxidative stress and xenobiotics, and is recognized as a potential molecular target for discovering chemopreventive agents. Using a stable antioxidant response element luciferase reporter cell line derived from human breast cancer MDA-MB-231 cells combined with a 96-well high-throughput screening system, we have identified a series of plant extracts from the family Lauraceae that harbor Nrf2-inducing effects. These extracts, including Litsea garrettii (ZK-08), Cinnamomum chartophyllum (ZK-02), C. mollifolium (ZK-04), C. camphora var. linaloolifera (ZK-05), and C. burmannii (ZK-10), promoted nuclear translocation of Nrf2, enhanced protein expression of Nrf2 and its target genes, and augmented intracellular glutathione levels. Cytoprotective activity of these extracts against two electrophilic toxicants, sodium arsenite and H2O2, was investigated. Treatment of human bronchial epithelial cells with extracts of ZK-02, ZK-05, and ZK-10 significantly improved cell survival in response to sodium arsenite and H2O2, while ZK-08 showed a protective effect against only H2O2. Importantly, their protective effects against insults from both sodium arsenite and H2O2 were Nrf2-dependent. Therefore, our data provide evidence that the selected plants from the family Lauraceae are potential sources for chemopreventive agents targeting the Nrf2/ARE pathway.

2-[4-(2-Chloro-acet-yl)phen-yl]-2-methyl-1-(pyrrolidin-1-yl)propan-1-one

The asymmetric unit of the title compound, C16H20ClNO2, contains two mol-ecules in which the dihedral angles between the benzene ring and the plane of the amide unit are 77.4 (1) and 81.1 (1)°. In both mol-ecules, the five-membered ring adopts an envelope conformation with one of the β-C atoms as the flap. In the crystal, mol-ecules are connected via C-H⋯O hydrogen bonds, forming chains along the b-axis direction. These chains are further linked by C-H⋯π inter-actions, forming a three-dimensional network.

2-Methyl-2-phenyl-1-(pyrrolidin-1-yl)propan-1-one

In the title compound, C₁₄H₁₉NO, the dihedral angle between the benzene ring and the plane of the amide group is 80.6 (1)°. In the crystal, mol­ecules are connected via weak C—H⋯O hydrogen bonds, forming chains along the c-axis direction. The conformation of the five-memebred ring is an envelope, with one of the ring C atoms adjacent to the ring N atom as the flap atom.

Protective effect of naringenin-7-O-glucoside against oxidative stress induced by doxorubicin in H9c2 cardiomyocytes

Doxorubicin (DOX) is one of the most effective chemotherapeutic agents, but cardiotoxicity limits its clinical use. Although the mechanisms are not entirely understood, reactive oxygen species (ROS) and cardiomyocyte apoptosis appear to be involved in DOX cardiotoxicity. Protection or alleviation of DOX cardiotoxicity can be achieved by administration of natural phenolic compounds via activating endogenous defense systems and antiapoptosis. Naringenin-7-O-glucoside (NARG), isolated from Dracocephalum rupestre Hance, could protect from cardiomyocyte apoptosis and induce endogenous antioxidant enzymes against DOX toxicity, but the effects on intracellular ROS generation and cell membrane stability were not demonstrated. In the present study, we investigated the effects of NARG on H9c2 cell morphology, viability, lactate dehydrogenase (LDH) and creatine kinase (CK) leakage, glutathine peroxidase (GSH-Px) activity, intracellular Ca2+ concentration, and ROS generation. Compared with DOX alone treatment group, the morphological injury of the cells in groups treated by DOX plus NARG was alleviated, cell viability was increased, the amount of released LDH and CK was significantly decreased, the activity of GSH-Px was increased, the content of intracellular Ca2+ and ROS generation was lowered remarkably. These results suggest that NARG could prevent cardiomyocytes from DOX-induced toxicity by their property of stabilizing the cell membrane and reducing ROS generation.

1-(3,3-Dichloro-all-yloxy)-4-methyl-2-nitro-benzene

In the title compound, C₁₀H₉Cl₂NO₃, the dihedral angle between the benzene ring and the plane of the nitro group is 39.1 (1)°, while that between the benzene ring and the plane through the three C and two Cl atoms of the dichloro­all­yloxy unit is 40.1 (1)°. In the crystal, C—H⋯O hydrogen bonds to the nitro groups form chains along the b axis. These chains are linked by inversion-related pairs of Cl⋯O inter­actions at a distance of 3.060 (3) Å, forming sheets approximately parallel to [-201] and generating R₂²(18) rings. π–π contacts between benzene rings in adjacent sheets, with centroid–centroid distances of 3.671 (2) Å, stack mol­ecules along c.

5-Chloro-2-nitro-phenol

The asymmetric unit of the title compound, C₆H₄ClNO₃, contains two independent mol­ecules in which the dihedral angles between the benzene ring and the nitro groups are 2.5 (1) and 8.5 (1)°. Intra­molecular O—H⋯O hydrogen bonds involving the hy­droxy and nitro substituents result in the formation of S(6) six-membered rings. In the crystal, O—H⋯O, O—H⋯Cl and C—H⋯O hydrogen bonds together with Cl⋯O contacts [3.238 (3) and 3.207 (3) Å] generate a three-dimensional network.

1-(3,3-Dichloro-all-yloxy)-2-nitro-benzene

In the title compound, C₉H₇Cl₂NO₃, the dihedral angle between the benzene ring and the plane of the nitro group is 50.2 (1)°, and that between the benzene ring and the best plane through the dichloro­allyl fragment is 40.1 (1)°.

1-(4-Chloro-2-fluoro-phen-yl)-4-difluoro-methyl-3-methyl-1H-1,2,4-triazol-5(4H)-one

In the crystal structure of the title compound, C₁₀H₇ClF₃N₃O, pairs of mol­ecules are connected into dimers via pairs of C—H⋯O hydrogen bonds. The dihedral angle between the benzene ring and attached triazolone ring is 53.2 (1)°.

Flavopiridol, the first cyclin-dependent kinase inhibitor: recent advances in combination chemotherapy

The cell cycle is the series of events necessary for the division and duplication of a cell. The dysregulation of the cell cycle can promote the development of cancer. A group of proteins, cyclin-dependent kinases (CDKs), that control the cell cycle, provide new targets for treating cancer. As a result, cyclin-dependent kinase inhibitors (CDKIs) represent a novel class of chemotherapeutic agents. Of these, flavopiridol, a semisynthetic flavonoidal alkaloid, emerged as the first CDKI to enter clinical trials. Preclinical data indicate that flavopiridol could block the proliferation of neoplastic cells and induce programmed cell death as a single agent. Furthermore, recent emerging data revealed that flavopiridol can potentiate, generally in a dose- and sequence-dependent manner, the anti-tumor effects of many established chemotherapeutic agents. This review is primarily focused on the role of flavopiridol in combination with various therapeutic agents that are in or near clinical development.

Dracotanosides A-D, spermidine glycosides from Dracocephalum tanguticum: structure and amide rotational barrier

Four new spermidine glycosides, dracotanosides A-D (1-4), have been isolated from Dracocephalum tanguticum. These molecules represent the first spermidine glycosides from this plant genus. The structures, including absolute configurations, were determined by spectroscopic and chemical methods. The amide bond rotational barrier of aglycone 1a was calculated by density functional theory (DFT) computation.

Simultaneous determination of nine major active compounds in Dracocephalum rupestre by HPLC

A new method was developed for the simultaneous determination of nine major constituents in Dracocephalum rupestre, including 5,7-dihydroxychromone (1), eriodictyol-7-O-beta-d-glucoside (2), luteolin-7-O-beta-d-glucoside (3), naringenin-7-O-beta-d-glucoside (4), apigenin-7-O-beta-d-glucoside (5), eriodictyol (6), luteolin (7), naringenin (8) and apigenin (9). The quantitative determination was conducted by reversed phase high-performance liquid chromatography with photodiode array detector (LC-PDA). Separation was performed on an Agilent Eclipse XDB-C(18) column (150 mm x 4.6 mm i.d., 5 microm) with gradient elution of acetonitrile and 0.5% aqueous acetic acid. The components were identified by retention time, ultraviolet (UV) spectra and quantified by LC-PDA at 260 nm. All calibration curves showed good linearity (r(2)>0.999) within test ranges. The reproducibility was evaluated by intra- and inter-day assays and R.S.D. values were less than 3.0%. The recoveries were between 95.15 and 104.45%. The limits of detection (LOD) ranged from 0.002 to 0.422 microg/ml and limits of quantification (LOQ) ranged from 0.005 to 1.208 microg/ml, respectively. The identity of the peaks was further confirmed by high-performance liquid chromatography with triple-quadrupole mass spectrometry system coupled with electrospray ionization (ESI) interface. The developed method was applied to the determination of nine constituents in 14 samples of D. rupestre collected at various harvesting times. Most compounds accumulated at much higher amounts in about June-July. The satisfactory results indicated that the developed method was readily utilized as a quality control method for D. rupestre.

Stereochemistry of flavonoidal alkaloids from Dracocephalum rupestre

Phytochemical studies on the aerial parts of Dracocephalum rupestre led to the isolation of four groups of flavonoidal alkaloids, dracocephins A-D. They were elucidated as conjugates of flavanone with pyrrolidin-2-one on the basis of extensive spectroscopic analysis. The two stereogenic centers rendered each group of the dracocephins as two pairs of enantiomers simultaneously. All of the sixteen isomers were separated successfully by chiral HPLC and their stereochemical features were determined by their CD data and single-crystal X-ray diffraction analysis of one stereoisomer. The additive relation of the chiroptical contributions resulting from the two stereogenic centers was generalized. The CD contribution of the chiral carbon in the pyrrolidin-2-one ring was proposed by subtraction of their respective contributions.

A novel soluble tin(IV) porphyrin modified single-walled carbon nanotube nanohybrid with light harvesting properties

A dihydroxotin(IV) porphyrin functionalized single-walled carbon nanotubes (SWNTs) nanohybrid is obtained. Solubility of the nanohybrid in organic solvents is determined by UV-Vis-NIR absorption spectroscopy. Electron absorption and fluorescence spectra investigations demonstrate that efficient electron transfer occurs within the nanohybrid at the photoexcited state and the charge-separated state of the nanohybrid is observed by transient absorption spectrum. The results illustrate that this soluble electron donor–acceptor nanohybrid might be a good candidate as a light harvesting material in molecular photoelectronic devices.

Separation and structure determination of two diastereomeric pairs of enantiomers from Dracocephalum rupestre by high-performance liquid chromatography with circular dichroism detection

All of the four stereoisomers of an unprecedented type of flavanones, the dracorupesins, were separated from the aerial parts of Dracocephalum rupestre simultaneously. The dracorupesins were characterized as two diastereomeric pairs of enantiomers by on-line chiral high-performance liquid chromatography-circular dichroism (HPLC-CD) analysis, which was a reliable stereoanalytical tool for natural products. The planar structures of the compounds were elucidated by means of spectroscopic methods including IR, MS, one-dimensional NMR (1D-NMR) and two-dimensional NMR (2D-NMR) techniques.