Ent-eudesmane sesquiterpenoids from the Chinese liverwort Chiloscyphus polyanthus.

- Seven previously undescribed ent-eudesmane sesquiterpenoids (1-7), as well as seven known analogs (8-14), were isolated from the Chinese liverwort Chiloscyphus polyanthus var. rivularis. Their structures were established based on comprehensive spectroscopy analysis, electronic circular dichroism calculations, as well as biosynthetic considerations. The cytotoxicity against HepG2 (Human hepatocellular carcinomas) cancer cell line, and antifungal activity against Candida albicans SC5314 of all isolated ent-eudesmane sesquiterpenoids were preliminarily tested, results showed that the tested compounds did not display obvious cytotoxicity and antifungal activities under the tested concentration.

Pallamins A-C, ent-labdane and pallavicinin based dimers from the Chinese liverwort Pallavicinia ambigua (mitt.) stephani.

Three unprecedented ent-labdane and pallavicinin based dimers pallamins A-C formed via [4 + 2] Diels-Alder cycloaddition, together with eight biosynthetically related monomers were isolated from Pallavicinia ambigua. Their structures were determined by the extensive analysis of HRESIMS and NMR spectra. The absolute configurations of the labdane dimers were determined by single crystal X-ray diffraction of the homologous labdane units, and 13C NMR and ECD calculations. Moreover, a preliminary evaluation of the anti-inflammatory activities of the isolated compounds was performed using the zebrafish model. Three of the monomers demonstrated significant anti-inflammatory activity.

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.

Prenylated bibenzyls from the Chinese liverwort Radula apiculata.

Three new prenylated bibenzyls (1-3) and seven known congeners were purified from the Chinese liverwort Radula apiculata. Their structures were identified by the analysis of spectroscopic data and comparison of reported NMR data. All isolated compounds were tested for several human cancer cell lines with adriamycin served as a positive control.

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.

Giant ankyrin-B suppresses stochastic collateral axon branching through direct interaction with microtubules.

Giant ankyrin-B (gAnkB) is a 440-kD neurospecific ankyrin-B isoform and a high-confidence target for autism mutations. gAnkB suppresses axon branching through coordination of cortical microtubules, and autism-related mutation of gAnkB results in ectopic neuronal connectivity. We identified a bipartite motif from gAnkB, which bundles and avidly binds to microtubules in vitro. This motif is composed of a module of 15 tandem repeats followed by a short, conserved fragment also found in giant ankyrin-G (BG-box). Combination of these two parts synergistically increases microtubule-binding avidity. Transfection of astrocytes (which lack gAnkB) with WT gAnkB resulted in prominent bundling of microtubules, which did not occur with mutant gAnkB with impaired microtubule-binding activity. Similarly, rescue of gAnkB-deficient neurons with WT gAnkB suppressed axonal branching and invasion of EB3-tagged microtubules into filopodia, which did not occur with the same mutant gAnkB. Together, these findings demonstrate that gAnkB suppresses axon collateral branching and prevents microtubule invasion of nascent axon branches through direct interaction with microtubules.

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.

Terpenoids from the Chinese liverwort Odontoschisma grosseverrucosum and their antifungal virulence activity.

Eight undescribed terpenoids, namely, odongrossins A-H, together with two known terpenoids were isolated from Odontoschisma grosseverrucosum Stephani (Cephaloziaceae). Their structures were established based on NMR data, electronic circular dichroism (ECD) calculations, and single-crystal X-ray diffraction measurements. Odongrossin A and odongrossin G displayed moderate anti-virulence activities against CDR1-and CDR2-efflux-pump-deficient Candida albicans DSY654. Further investigation of odongrossin A revealed that it inhibited adhesion and biofilm formation on C. albicans DSY654. The results regarding the transcription levels of genes demonstrated that odongrossin A could regulate the expression of genes that are associated with the virulence of C. albicans DSY654.

Terpenoids from the Chinese liverwort Heteroscyphus coalitus and their anti-virulence activity against Candida albicans.

In this study, 14 previously undescribed terpenoids were isolated from the Chinese liverwort Heteroscyphus coalitus (Hook.) Schiffner, including a rare harziane type diterpenoid, heteroscyphsic acid A; eight ent-clerodane diterpenoids, heteroscyphsic acids B-I; four labdane diterpenoids, heteroscyphins A-D; and one guaiane sesquiterpene, heteroscyphin E; as well as a known ent-junceic acid. Their structures were determined by a combination of MS, NMR spectroscopy, electronic circular dichroism (ECD) and single crystal X-ray diffraction analyses. The anti-virulence activity of the isolated compounds against Candida albicans DSY654 demonstrated that most of them could block hyphal growth at concentrations ranging from 4-32 µg/ml. Further investigation of the most active compound, heteroscyphin D, revealed that it could suppress the ability of C. albicans DSY654 to adhere to A549 cells and form biofilms, and modulate the transcription of related genes in this fungus.

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.

Diterpenoids from the Chinese liverwort Frullania hamatiloba and their Nrf2 inducing activities.

Six previously undescribed labdane diterpenoids, frullanians A-F, along with five known diterpenoids, were isolated from the Chinese liverwort Frullania hamatiloba Stephani. Their structures were determined using NMR data, electronic circular dichroism (ECD) calculations as well as the single crystal X-ray diffraction measurement. NAD(P)H: QR (quinone reductase) assay demonstrated that frullanian D and four known compounds displayed antioxidant effect mediated via Nrf2 (Nuclear factor-erythroid 2-related factor 2) induction. Further investigation of the most bioactive frullanian D in MOVAS cells revealed that it ameliorated H2O2-induced oxidative insults without toxicity by increasing cell viability, attenuating morphological changes, and reducing intracellular ROS production. In addition, frullanian D promoted the nuclear translocation of Nrf2 and upregulated the expressions of antioxidant proteins NQO1 (NAD(P)H quinone oxidoreductase 1) and γ-GCS (γ-glutamyl cysteine synthetase). Docking analysis using MOE software further supported the activation of the Nrf2 pathway by frullanian D.

Plagiochianins A and B, Two ent-2,3- seco-Aromadendrane Derivatives from the Liverwort Plagiochila duthiana.

Two novel ent-aromadendrane derivatives, plagiochianin A (1), possessing an unprecedented 2,3:6,7-di- seco-6,8-cyclo-aromadendrane carbon scaffold conjugated with three cyclic acetals, and plagiochianin B (2), an exceptional pyridine type aromadendrane alkaloid, were isolated from the Chinese liverwort Plagiochila duthiana. Their structures were established by comprehensive spectroscopic analysis coupled with single-crystal X-ray diffraction and electronic circular dichroism calculations. A plausible biogenetic pathway of these two compounds is presented, and their acetylcholinesterase inhibitory activities are preliminarily tested using TLC-bioautographic assays.

CMG-Pol epsilon dynamics suggests a mechanism for the establishment of leading-strand synthesis in the eukaryotic replisome.

The replisome unwinds and synthesizes DNA for genome duplication. In eukaryotes, the Cdc45-MCM-GINS (CMG) helicase and the leading-strand polymerase, Pol epsilon, form a stable assembly. The mechanism for coupling DNA unwinding with synthesis is starting to be elucidated, however the architecture and dynamics of the replication fork remain only partially understood, preventing a molecular understanding of chromosome replication. To address this issue, we conducted a systematic single-particle EM study on multiple permutations of the reconstituted CMG-Pol epsilon assembly. Pol epsilon contains two flexibly tethered lobes. The noncatalytic lobe is anchored to the motor of the helicase, whereas the polymerization domain extends toward the side of the helicase. We observe two alternate configurations of the DNA synthesis domain in the CMG-bound Pol epsilon. We propose that this conformational switch might control DNA template engagement and release, modulating replisome progression.

Four New Kaurane Diterpenoids from the Chinese Liverwort Jungermannia comata Nees.

In our continuing program to find new bioactive compounds from the Chinese liverworts, four new kaurane-type diterpenoids, (6ß)-kaur-16-ene-6,9-diol (1), (6ß,12ß)-kaur-16-ene-6,9,12-triol (2), (6ß)-kaur-16-ene-5,6,9-triol (3), and kaur-16-ene-9,19-diol (4), have been isolated from the Chinese liverwort Jungermannia comata Nees. Five known kaurane-type diterpenoids (5 - 9) and four known trachylobane-type diterpenoids (10 - 13) were also obtained. The structures of the new compounds were established unequivocally on the basis of spectroscopic data. The absolute configuration of compound 1 was established by comparing experimental and calculated electronic circular dichroism spectra.

ent-Eudesmane-Type Sesquiterpenoids from the Chinese Liverwort Chiloscyphus polyanthus var. rivularis.

Seven new ent-eudesmane-type sesquiterpenoids (1-7) and six known analogues (8-13) were isolated from the Chinese liverwort Chiloscyphus polyanthus var. rivularis. Their structures were determined from analysis of MS and NMR spectroscopic data and single-crystal X-ray diffraction. A cytotoxic evaluation showed that compound 1 exhibited weak inhibitory activity against the A549 cancer cell line with an IC50 value of 27.7 µM.

Cryo-EM structures of the eukaryotic replicative helicase bound to a translocation substrate.

The Cdc45-MCM-GINS (CMG) helicase unwinds DNA during the elongation step of eukaryotic genome duplication and this process depends on the MCM ATPase function. Whether CMG translocation occurs on single- or double-stranded DNA and how ATP hydrolysis drives DNA unwinding remain open questions. Here we use cryo-electron microscopy to describe two subnanometre resolution structures of the CMG helicase trapped on a DNA fork. In the predominant state, the ring-shaped C-terminal ATPase of MCM is compact and contacts single-stranded DNA, via a set of pre-sensor 1 hairpins that spiral around the translocation substrate. In the second state, the ATPase module is relaxed and apparently substrate free, while DNA intimately contacts the downstream amino-terminal tier of the MCM motor ring. These results, supported by single-molecule FRET measurements, lead us to suggest a replication fork unwinding mechanism whereby the N-terminal and AAA+ tiers of the MCM work in concert to translocate on single-stranded DNA.

Terpenoids from Diplophyllum taxifolium with quinone reductase-inducing activity.

Two new ent-prenylaromadendrane-type diterpenoids, diplotaxifols A (1) and B (2), a new ent-eudesmol, ent-eudesma-4(15),11(13)-dien-6α,12-diol (3), eight new eudesmanolides enantiomers (4-11) of the corresponding compounds from higher plants along with four known ent-eudesmanolides (12-15) were isolated from the 95% EtOH extract of Chinese liverwort Diplophyllum taxifolium. Their structures were elucidated on the basis of MS, NMR and IR spectral data, and confirmed by single-crystal X-ray diffraction analysis. The quinone reductase-inducing activity of the compounds was evaluated.

Secondary metabolites from Aspergillus fumigatus, an endophytic fungus from the liverwort Heteroscyphus tener (Steph.) Schiffn.

Three new metabolites, asperfumigatin (1), isochaetominine (10), and 8'-O-methylasterric acid (21), together with nineteen known compounds, were obtained from the culture of Aspergillus fumigatus, an endophytic fungus from the Chinese liverwort Heteroscyphus tener (Steph.) Schiffn. Their structures were established by extensive analysis of the spectroscopic data. The absolute configurations of 1 and 10 were determined by analysis of their respective CD spectra. Cytotoxicity of these isolates against four human cancer cell lines was also determined.