Sacculatane Diterpenoids from the Liverwort Plagiochila nitens Collected in China.

Seven new terpenoids, including six sacculatane diterpenoids plagiochilarins A-F (1-6), and one ent-2,3-seco-aromandrane sesquiterpenoid plagiochilarin H (8) with a 6/7/3/5 tetracyclic scaffold, alongside three known compounds, were obtained from the Chinese liverwort Plagiochila nitens Inoue. Plagiochilarin B (2) was unpredictably converted to the more stable artifact 7 under acid catalysis through cyclic ether formation. The reaction mechanism was reasonably deduced and experimentally verified. The structures of these terpenoids were determined by analysis of MS and NMR spectroscopic data and single-crystal X-ray diffraction. The inhibitory effect of all of the isolates was evaluated on the growth of two C. albicans strains, wild strain SC5314 and efflux pump-deficient strain DSY654. However, only plagiochilarin H (8) showed a MIC value of 16 µg/mL against C. albicans DSY654.

Heterodimers of Aromadendrane Sesquiterpenoid with Benzoquinone from the Chinese Liverwort Mylia nuda.

Mylnudones A-G (1-7), unprecedented 1,10-seco-aromadendrane-benzoquinone-type heterodimers, and a highly rearranged aromadendrane-type sesquiterpenoid (8), along with four known analogs (9-12), were isolated from the liverwort Mylia nuda. Compounds 1-6 and 7, bearing tricyclo[6.2.1.02,7] undecane and tricyclo[5.3.1.02,6] undecane backbones, likely formed via a Diels-Alder reaction and radical cyclization, respectively. Their structures were determined by spectroscopic analysis, computational calculation, and single-crystal X-ray diffraction analysis. Dimeric compounds displayed cytoprotective effects against glutamic acid-induced neurological deficits.

Efficient Production of Flavonoid Glucuronides in Escherichia coli Using Flavonoid O-Glucuronosyltransferases Characterized from Marchantia polymorpha.

As a model liverwort, Marchantia polymorpha contains various flavone glucuronides with cardiovascular-promoting effects and anti-inflammatory properties. However, the related glucuronosyltransferases have not yet been reported. In this study, two bifunctional UDP-glucuronic acid/UDP-glucose:flavonoid glucuronosyltransferases/glucosyltransferases, MpUGT742A1 and MpUGT736B1, were identified from M. polymorpha. Extensive enzymatic assays found that MpUGT742A1 and MpUGT736B1 exhibited efficient glucuronidation activity for flavones, flavonols, and flavanones and showed promiscuous regioselectivity at positions 3, 6, 7, 3', and 4'. These enzymes catalyzed the production of a variety of flavonoid glucuronides with medicinal value, including apigenin-7-O-glucuronide and scutellarein-7-O-glucuronide. With the use of MpUGT736B1, apigenin-4'-O-glucuronide and apigenin-7,4'-di-O-glucuronide were prepared by scaled-up enzymatic catalysis and structurally identified by NMR spectroscopy. MpUGT742A1 also displayed glucosyltransferase activity on the 7-OH position of the flavanones using UDP-glucose as the sugar donor. Furthermore, we constructed four recombinant strains by combining the pathway for increasing the UDP-glucuronic acid supply with the two novel UGTs MpUGT742A1 and MpUGT736B1. When apigenin was used as a substrate, the extracellular apigenin-4'-O-glucuronide and apigenin-7,4'-di-O-glucuronide production obtained from the Escherichia coli strain BB2 reached 598 and 81 mg/L, respectively. Our study provides new candidate genes and strategies for the biosynthesis of flavonoid glucuronides.

Interaction of PKR with STCS1: an indispensable step in the biosynthesis of lunularic acid in Marchantia polymorpha.

Unlike bibenzyls derived from the vascular plants, lunularic acid (LA), a key precursor for macrocyclic bisbibenzyl synthesis in nonvascular liverworts, exhibits the absence of one hydroxy group within the A ring. It was hypothesized that both polyketide reductase (PKR) and stilbenecarboxylate synthase 1 (STCS1) were involved in the LA biosynthesis, but the underlined mechanisms have not been clarified. This study used bioinformatics analysis with molecular, biochemical and physiological approaches to characterize STCS1s and PKRs involved in the biosynthesis of LA. The results indicated that MpSTCS1s from Marchantia polymorpha catalyzed both C2→C7 aldol-type and C6→C1 Claisen-type cyclization using dihydro-p-coumaroyl-coenzyme A (CoA) and malonyl-CoA as substrates to yield a C6-C2-C6 skeleton of dihydro-resveratrol following decarboxylation and the C6-C3-C6 type of phloretin in vitro. The protein-protein interaction of PKRs with STCS1 (PPI-PS) was revealed and proved essential for LA accumulation when transiently co-expressed in Nicotiana benthamiana. Moreover, replacement of the active domain of STCS1 with an 18-amino-acid fragment from the chalcone synthase led to the PPI-PS greatly decreasing and diminishing the formation of LA. The replacement also increased the chalcone formation in STCS1s. Our results highlight a previously unrecognized PPI in planta that is indispensable for the formation of LA.

Identification of a flavonoid C-glycosyltransferase from fern species Stenoloma chusanum and the application in synthesizing flavonoid C-glycosides in Escherichia coli.

BACKGROUND: Flavonoid C-glycosides have many beneficial effects and are widely used in food and medicine. However, plants contain a limited number of flavonoid C-glycosides, and it is challenging to create these substances chemically. RESULTS: To screen more robust C-glycosyltransferases (CGTs) for the biosynthesis of flavonoid C-glycosides, one CGT enzyme from Stenoloma chusanum (ScCGT1) was characterized. Biochemical analyses revealed that ScCGT1 showed the C-glycosylation activity for phloretin, 2-hydroxynaringenin, and 2-hydroxyeriodictyol. Structure modeling and mutagenesis experiments indicated that the glycosylation of ScCGT1 may be initiated by the synergistic action of conserved residue His26 and Asp14. The P164T mutation increased C-glycosylation activity by forming a hydrogen bond with the sugar donor. Furthermore, when using phloretin as a substrate, the extracellular nothofagin production obtained from the Escherichia coli strain ScCGT1-P164T reached 38 mg/L, which was 2.3-fold higher than that of the wild-type strain. Finally, it is proved that the coupling catalysis of CjFNS I/F2H and ScCGT1-P164T could convert naringenin into vitexin and isovitexin. CONCLUSION: This is the first time that C-glycosyltransferase has been characterized from fern species and provides a candidate gene and strategy for the efficient production of bioactive C-glycosides using enzyme catalysis and metabolic engineering.

Pinguisane Sesquiterpenoids from the Chinese Liverwort Trocholejeunea sandvicensis and Their Anti-Inflammatory Activity.

Nine new pinguisane sesquiterpenoid compounds, 1-9, including a highly oxygenated compound (1) and two amides (7 and 8), along with three known compounds (10, 11, and 12), were isolated from the Chinese liverwort Trocholejeunea sandvicensis Mizut (Lejeuneaceae). The structures of these compounds were determined by analysis of IR, UV, HRESIMS, NMR spectroscopic data, electronic circular dichroism calculations, and single-crystal X-ray diffraction analysis. Inhibitory effects against lipopolysaccharide (LPS)-induced NO production in RAW 264.7 murine macrophages indicated that the maximum inhibition rates of NO production of compounds 1, 9, and 10 were 83.15%, 83.54%, and 96.28% under the nontoxic tested concentration, respectively. Compound 9 also displayed moderate anti-inflammatory activity in vivo in a CuSO4-induced transgenic zebrafish model.

Unprecedented 4,9-Seco-Oplopanane and Seven Drimane Sesquiterpenoids from the Chinese Liverwort Lejeunea flava (Sw.) Nees.

An unprecedented 4,9-seco-oplopanane (1), two undescribed drimane epimers (2 and 3), and five known drimane sesquiterpenoids (4-8) were isolated from the Chinese liverwort Lejeunea flava (Sw.) Nees. The structures of the new sesquiterpenoids were determined using nuclear magnetic resonance spectroscopy, electronic circular dichroism calculations, and single-crystal X-ray diffraction measurements. The inhibitory capacity of the new compounds against nitric oxide production in lipopolysaccharide-induced RAW 264.7 murine macrophages, along with the cytotoxicity of the new compounds against A549 and HepG-2 human cancer cell lines, were discussed.

Dolabrane Diterpenoids from the Chinese Liverwort Notoscyphus lutescens.

Nine new dolabrane-type diterpenoids, notoscarins A-I (1-9), including an unprecedented 6,18-cyclo-dolabrane-type diterpenoid (1) obtained through intramolecular cyclization, two rare 19-nor-2-chloro-dolabrane diterpenoids (2 and 3), six new related dolabrane-type diterpenoids (4-9), and one new butyrolactone derivative (10), were isolated from the Chinese liverwort Notoscyphus lutescens. The 6,18-cyclo-dolabrane and 19-nor-dolabrane carbon skeletons are reported for the first time. The structures of these compounds were determined on the basis of MS and NMR spectroscopic data, single-crystal X-ray diffraction, and electronic circular dichroism calculations. Preliminary bioassays showed that compounds 1-10 exhibited moderate to weak quinone reductase-inducing activity in Hepa-1c1c7 cells.

Cytotoxic Activities of 9,10-seco-Cycloartane-Type Triterpenoids from the Chinese Liverwort Lepidozia reptans.

Ten new triterpenoids, including nine 9,10-seco-cycloartanes (1-9) and one 9,19-cyclolanostane (10), as well as one sesquiterpenoid (11) and four known compounds (12-15), were extracted and purified from the whole plant of the Chinese liverwort Lepidozia reptans. Multiple techniques (NMR, HRESIMS, IR, and X-ray crystallographic analysis) were applied to determine the structures of the isolated compounds. Bioassay determinations showed that compound 7, which contains an α,ß-unsaturated carbonyl moiety in its structure, inhibited the growth of a panel of cancer cell lines with IC50 values ranging from 4.2 ± 0.2 to 5.7 ± 0.5 µM. Further investigation revealed that compound 7 induces PC-3 cell death via mitochondrial-related apoptosis.

Diverse Prenylated Bibenzyl Enantiomers from the Chinese Liverwort Radula apiculata and Their Cytotoxic Activities.

An EtOH extract of the Chinese liverwort Radula apiculata showed cytotoxic activity against the A549 lung cancer cell line. Bioassay-guided fractionation led to the isolation of 19 prenylated bibenzyls, including eight previously unknown dimeric prenylated bibenzyls [radulapins A-H (1-8)], four new prenylated bibenzyls (9-12), and seven known compounds (13-19). Compounds 1-11 were analyzed as racemates by chiral-phase separation. Their structures were determined by detailed analysis of their spectroscopic data and by single-crystal X-ray diffraction, chiral resolutions, and electronic circular dichroism measurements. Using an MTT assay, these dimers (1-8) showed significant cytotoxic activity against a panel of human cancer cell lines. Further investigation revealed that compound 4 induces PC-3 cell death via mitochondrial-derived apoptosis.

Terpenoids from Chinese Liverworts Scapania spp.

An investigation of the chemical composition of Chinese liverworts led to the isolation of six new caged clerodane-type diterpenoids, scaparins A-C (1-3) from Scapania koponenii and scaparins D-F (4-6) from S. verrucosa. An unknown ent-trachylobane diterpenoid (7) and three known terpenoid derivatives (8-10) were obtained from S. verrucosa. The structures of the compounds were established on the basis of physical data (IR, UV, HRESIMS, and 1D and 2D NMR), and the absolute configurations were unequivocally confirmed by comparison of the experimental and calculated electronic circular dichroism spectra. Preliminary bioassays showed that compounds 1-7 exhibited moderate to weak quinone reductase-inducing activity in Hepa-1c1c7 cells.

Enantioselective Total Syntheses of Manginoids†A and†C and Guignardones†A and†C.

An enantioselective synthetic approach for preparing manginoids and guignardones, two types of biogenetically related meroterpenoids, is reported. This bioinspired and divergent synthesis employs an oxidative 1,3-dicarbonyl radical-initiated cyclization and cyclodehydration of the common precursor to forge the central ring of the manginoids and guignardones, respectively, at a late stage. Key synthetic steps include silica-gel-promoted semipinacol rearrangement to form the 6-oxabicyclo[3.2.1]octane skeleton and the Suzuki-Miyaura reaction of vinyl bromide to achieve fragment coupling. This synthesis protocol enables the asymmetric syntheses of four fungal meroterpenoids from commercially available materials.

Terpenoids from the Liverwort Plagiochila fruticosa and Their Antivirulence Activity against Candida albicans.

Fourteen new terpenoids plagicosins A-N (1-14), including seven sesquiterpenoids (1-7) consisting of six ent-bicyclogermacrenes and one ent-2,3-seco-aromadendrane, as well as seven diterpenoids (8-14) comprising five fusicoccanes, a eunicellane, and a rare gersemiane, were isolated from the Chinese liverwort Plagiochila fruticosa Mitt. The structures of these terpenoids were determined on the basis of comprehensive analysis of MS and NMR spectroscopic data coupled with electronic circular dichroism (ECD) and coupling constant calculations. Plagicosin F (6) displayed potent antivirulence activity through inhibiting the hyphal morphogenesis, adhesion, and biofilm formation of Candida albicans. The genes related to hyphal formation were regulated by 6.

Neurobiology and Neural Circuits of Aggression.

Aggression takes several forms and can be offensive or defensive. Aggression between animals of the same species or society aims to inflict harm upon another for the purpose of protecting a resource such as food, reproductive partners, territory, or status. This chapter explores the neurobiology of aggression. We summarize the behavior of aggression, rodent models of aggression, and the correlates of aggressive behavior in the context of neuroendocrinology, neurotransmitter systems, and neurocircuitry. Translational implications of rodent studies are briefly discussed, applying basic research to brain imaging data and therapeutic approaches to conditions where aggression is problematic.

Divergent Total Synthesis of Euphoranginol†C, Euphoranginone†D, ent-Trachyloban-3ß-ol, ent-Trachyloban-3-one, Excoecarin†E, and ent-16α-Hydroxy-atisane-3-one.

A divergent synthetic approach to biogenetically related diterpenoids such as ent-kauranes, ent-trachylobanes, ent-beyerane, and ent-atisane has been developed. The unified synthetic route involves the De Mayo reaction to rapidly generate the bicyclo[3.2.1]-octane moiety of ent-kaurane. The key reactions also include bioinspired nucleophilic cyclopropanation generating the [3.2.1.02,7 ]-tricyclic core of ent-trachylobane and regioselective cyclopropane fragmentation furnishing ent-beyerane and ent-atisane through the nucleophilic attack and protonation of the cyclopropane ring. This strategy enables the asymmetric total syntheses of six diterpenoids from the commercially available geraniol.

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.

Prenylated Bibenzyls from the Chinese Liverwort Radula constricta and Their Mitochondria-Derived Paraptotic Cytotoxic Activities.

Nine new prenylated bibenzyls, radstrictins A-I (1-9), and 11 known congeners were obtained from the Chinese liverwort Radula constricta. Their structures were identified by analysis of HRMS, NMR, and electronic circular dichroism data. Radstrictins A-F (1-6) were isolated as a racemate or scalemic mixtures. All the isolated compounds were subjected to cytotoxicity assessment. Methyl 2,4-dihydroxy-3-(3-methyl-2-butenyl)-6-phenethylbenzoate (10) exhibited significant activity against human lung cancer cell lines A549 and NCI-H1299 with IC50 values of 6.0 and 5.1 µM, respectively. Further research revealed that cell death triggered by 10 occurred via mitochondria-derived paraptosis.

Terpenoids with vasorelaxant effects from the Chinese liverwort Scapania carinthiaca.

Four new diterpenoids scapanacins A-D (1-4) including one kaurane and three clerodane derivatives, along with eleven known compounds (9-15), were isolated from the Chinese liverwort Scapania carinthiaca J.B. Jack ex Lindb. Their structures were determined based on extensive spectroscopic analyses, and electronic circular dichroism (ECD) calculations. Vasorelaxant activity assays of the clerodane-type diterpenoids 2, and 4-8 revealed that they relaxed 3rd-order rat mesenteric arterioles pre-contracted with norepinephrine (NE). Further assays with scapanacin D (4) confirmed that the vasodilatation was mediated through inhibition of Ca2+ influx via voltage-dependent Ca2+ channels (VDCs), and this Ca2+ channel blocking effect was also confirmed by inhibiting the extracellular Ca2+ influx in MOVAS cells. Besides, very little decrease of the relaxant activity caused by 4 on endothelium-denuded mesenteric arterioles with NE also suggested the vasodilatation was mainly produced by inhibiting Ca2+-induced contraction of smooth muscle. In addition, cytotoxicity testing showed that compounds 1 and 9 with α,ß-unsaturated ketone exhibited inhibitory activities against a small panel of human cancer cell lines.

Bibenzyl-Based Meroterpenoid Enantiomers from the Chinese Liverwort Radula sumatrana.

Six new pairs of bibenzyl-based meroterpenoid enantiomers, (±)-rasumatranin A-D (1-4) and (±)-radulanin M and N (5 and 6), and six known compounds were isolated from the adnascent Chinese liverwort, Radula sumatrana. Their structures were elucidated based on spectroscopic data and chiral phase HPLC-ECD analyses. The structures of 1 and 7 were also confirmed by single-crystal X-ray diffraction analysis. Cytotoxicity tests of the isolated compounds showed that 6-hydroxy-3-methyl-8-phenylethylbenzo[b]oxepin-5-one (8) showed activity against the human cancer cell lines MCF-7, PC-3, and SMMC-7721, with IC50 values of 3.86, 6.60, and 3.58 µM, respectively, and induced MCF-7 cell death through a mitochondria-mediated apoptosis pathway.

Morphology, in vivo distribution and antitumor activity of bexarotene nanocrystals in lung cancer.

The objective of this study was to develop and evaluate the morphology, biodistribution and antitumor activity of bexarotene nanocrystals delivery system. The morphology was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscope and bexarotene nanocrystals exhibited the advantages of making the efficacy more steady and durable compared with control group in lung with less cardiac accumulation as shown by biodistribution studies in vivo. In addition, MTT assay, flow cytometry analysis, observation of morphological changes and apoptotic body demonstrated that bexarotene nanocrystals could significantly enhance the in vitro cytotoxicity and induced G1 cycle arrest and apoptosis against A549 cells. Also, bexarotene nanocrystals had significant antitumor activity in mice bearing A549 cell line. This finding was correlated with both in vitro and in vivo. Thereby, the overall results suggest that the bexarotene nanocrystals represent a potential source of medicine, which made bexarotene nanocrystals a promising candidate for the treatment of lung cancer.