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.

Mn-Activated Fluoride Phosphors Modified by Surfactant with Outstanding Water Resistance and Luminescent Thermal Properties.

Although Mn4+-activated fluoride phosphors have high luminescence quality, their poor water resistance and thermal fluorescence properties significantly limit their practical applications. Here, we propose a surfactant modification strategy by adding the surfactant cetyltrimethylammonium bromide (CTAB) to the synthesis and modifying the surface of the phosphor with ethylene diamine tetraacetic acid (EDTA) to obtain a phosphor with excellent luminescence thermal properties and water resistance, K2TiF6:Mn4+-xCTAB-EDTA (KTFM-xC-E) phosphors. The experimental and X-ray diffraction Rietveld refinement results confirm that the phosphor has higher structural rigidity and thus improved thermal stability. The surface modification with EDTA resulted in the formation of a dilute Mn4+ shell layer on the phosphor surface, which prevented the inward hydrolysis of the phosphor and resulted in excellent water resistance. Therefore, we have successfully modified K2TiF6:Mn4+ (KTFM) phosphors using low-cost surfactants, which also provides new ideas for other commercial high-quality phosphors.

Enhancement of emission and luminescent thermal stability of K2SiF6 : Mn4+ by synergy of co-doping with Na+ and coating with GQDs.

The luminescence properties and thermal stability of phosphors are key properties for practical applications. A series of K2SiF6: Mn4+, Na+ @ GQDs (KSF: Mn4+, Na+ @ GQDs, KSF = K2SiF6, GQDs = graphene quantum dots; here, Cl-contained graphene quantum dots are used) red light phosphors have been synthesized by using a combination of H2O2-free and hydrothermal coating methods. The fluorescence thermal stability and fluorescence intensity of the optimal phosphor are greatly improved by doping the matrix with Na+ and coating it with GQDs. The strong negative thermal quenching (NTQ) effect and the color stability of the phosphor at variable temperatures result in good thermal stability. The strong NTQ effect is attributed to the phonon-induced transition mechanism. The high thermal stability makes the optimal sample ideal for high-power light LEDs (WLEDs). The test results show that the prototype WLED with the optimal sample as the red light component produces warm white light. The light has high luminescent efficiency (101.6 lm W-1), low correlated color temperature (CCT = 3978 K), and high color rendering index (R a = 92.2).

Enhancement in the water resistance and thermal stability of Na3HTiF8:Mn4+ by co-doping with organic amine cations.

Mn4+-doped fluoride red light phosphors are widely utilized in various fields, and their luminous performance is influenced by their stability in high humidity and temperature environments. By incorporating TEOAH+ (TEOAH+ = (HOCH2CH2)3NH+) into the Na2TiF6 matrix, Na3HTiF8:Mn4+,TEOAH+ with improved thermal stability and water resistance was synthesized. Enhancement in the luminescence thermal stability is supported by its strong negative thermal quenching (NTQ) effect, which is attributed to the phonon-induced mechanism wherein the probability of radiative transitions increases much faster than the probability of non-radiative transitions. Additionally, the integrated emission intensity of the optimal sample Na3HTiF8:Mn4+,0.15TEOAH+ was maintained at 70.1% after being immersed in water for 360 min, which may be attributed to the addition of TEOAH+ cations in the structure, thus increasing its structural rigidity. The prototype light-emitting diode (LED) has a narrow emission band, 88.6% color gamut, and 83.1 lm W-1 light efficiency, according to the National Television Standards Committee (NTSC). The qualities of the phosphor make it an ideal candidate for back-lighting devices.

High Water Resistance and Luminescent Thermal Stability of LiyNa(2-y)SiF6: Mn4+ Red-Emitting Phosphor Induced by Codoping of Li.

Mn4+-doped fluoride phosphors are efficient narrowband red-emitting phosphors for white light-emitting diodes (WLEDs) and backlight displays. However, erosion by moisture is the main obstacle that limits their application. In this work, LNSF:Mn4+ (Li0.06Na1.94Si0.94Mn0.06F6) with high quantum yield (QY), luminescent thermal stability, and waterproofness was synthesized using the H2O2-free reaction method at room temperature. Compared to NSF:Mn4+(Na2Mn0.06Si0.94F6), the QY value, luminescence thermal stability, and water resistance of LNSF:Mn4+ are obviously improved by codoping of Li+ because of the formation of charge-carrier transfer (CT) and rare-Mn4+ layer induced by codoping of Li+. The former produces the negative thermal quenching (NTQ) effect, which results in the improvement of the luminescent thermal stability. The latter can inhibit the hydrolysis of Mn4+ on the surface of the sample, which leads to the enhancement of waterproofness. The formation mechanism of the rare-Mn4+ layer is discussed. A prototype WLED emitting the ideal warm white light (CCT = 3173 K, Ra = 90.4) was assembled by coating a mixture of LNSF:Mn4+, yellow emitting phosphor (YAG:Ce3+), and epoxy resin on the blue light InGaN chip, indicating that the performance of the WLED can be improved by using LNSF:Mn4+.

Myxadazoles, Myxobacterium-Derived Isoxazole-Benzimidazole Hybrids with Cardiovascular Activities.

There is a continuous need for novel microbial natural products to fill the drying-up drug development pipeline. Herein, we report myxadazoles from Myxococcus sp. SDU36, a family of novel chimeric small molecules that consist of N-ribityl 5,6-dimethylbenzimidazole and a linear fatty acid chain endowed with an isoxazole ring. The experiments of genome sequencing, gene insertion mutation, isotope labelling, and precursor feeding demonstrated that the fatty acid chain was encoded by a non-canonical PKS/NRPS gene cluster, whereas the origin of N-ribityl 5,6-dimethylbenzimidazole was related to the vitamin B12 metabolism. The convergence of these two distinct biosynthetic pathways through a C-N coupling led to the unique chemical framework of myxadazoles, which is an unprecedented hybridization mode in the paradigm of natural products. Myxadazoles exhibited potent vasculogenesis promotion effect and moderate antithrombotic activity, underscoring their potential usage for the treatment of cardiovascular diseases.

Combining NMR-Based Metabolic Profiling and Genome Mining for the Accelerated Discovery of Archangiumide, an Allenic Macrolide from the Myxobacterium Archangium violaceum SDU8.

An unprecedented 19-membered allenic macrolide archangiumide (1) was discovered from the myxobacterium Archangium violaceum SDU8 by integrating NMR-based metabolic profiling and genome mining. Its biosynthesis pathway was proposed based on the architectural analysis of the encoding trans-AT PKS genes and validated by isotope labeling. The methodology of combing 2D NMR-based metabolic profiling and bioinformatics-aided structure prediction, as exemplified by this study, is anticipated to improve discovery efficiency of a broader range of microbial "dark matter".

Two New Quinazoline Derivatives from the Moss Endophytic Fungus Aspergillus sp. and Their Anti-inflammatory Activity.

Two new quinazoline derivatives versicomides E (1) and F (2), and 10 known compounds (3-12) were isolated from the moss endophytic fungus Aspergillus sp. Their structures were determined on the basis of extensive spectroscopic data analysis and ECD calculations. Among them, the compound 7 (6-hydroxy-3-methoxyviridicatin) was first reported as a natural product. Inhibition on LPS-induced NO production in RAW 264.7 murine macrophages found that compounds 5, 7 and 8 showed significant inhibitory effects on NO production, with IC50 values of 49.85, 22.14 and 46.02 µM respectively.

Improvement in luminescent properties and thermo-optical conversion mechanism of Na2SiF6:Mn4+,K+@GQDs.

Herein, a series of NSF:0.05Mn4+,0.04K+@GQD (NSF: Na2SiF6, GQDs: Cl-containing graphene quantum dot) phosphors was prepared. Double enhancement effects on the luminescent intensity and thermal stability triggered by the GQD coating were observed for the optimal sample as follows: (a) its PL intensity was 1.72 times that of the uncoated control sample and (b) its luminescent thermal stability was greatly enhanced, with integrated PL intensities of 120, 150 and 180 °C to 179.7%, 175.8%, and 119.3% of the initial value at 25 °C, respectively. It is proposed that the above-mentioned behaviors involve a change in some of the thermal energy into light energy via a phonon-induced mechanism. The thermal stability analysis results showed that the optimal sample is suitable for application in high-power WLEDs. Specifically, warm white light with a low correlated color temperature, high luminescent efficiency and high color rendering index was obtained from the prototype WLEDs using the optimal sample as a red-emitting component.

Polyketides from the endolichenic fungus Eupenicillium javanicum and their anti-inflammatory activities.

Seven undescribed polyketides javanicols A-E, 5-epi-citreoviridin and 5-epi-isocitreoviridin, together with five known compounds, were isolated from the endolichenic fungus Eupenicillium javanicum. The structures of these polyketides were determined by means of extensive spectroscopic analyses, electronic circular dichroism (ECD) calculations and gauge-independent atomic orbital (GIAO) NMR shift calculations. These compounds were evaluated for potential anti-inflammatory activity against LPS-activated RAW 264.7 cells. Javanicol E and (+)-terrein displayed moderate inhibitory effects on NO production, with IC50 values of 17.00 and 13.46 µM, respectively.

Asperunguisins A-F, Cytotoxic Asperane Sesterterpenoids from the Endolichenic Fungus Aspergillus unguis.

Six new asperane-type sesterterpenoids, asperunguisins A-F (1-6), were isolated from the endolichenic fungus Aspergillus unguis, together with a known analogue, aspergilloxide (7); these are rare asperane-type sesterterpenoids, characterized by a unique hydroxylated 7/6/6/5 tetracyclic system. The structures of asperunguisins A-F (1-6) were elucidated on the basis of spectroscopic methods (NMR and HRESIMS), X-ray single-crystal diffraction analysis, ECD calculations, and biogenetic considerations. Asperunguisin C (3) showed cytotoxicity against the human cancer cell line A549 with an IC50 value of 6.2 µM. Further investigation revealed that the observed cell death was a result of G0/G1 cell cycle arrest via DNA damage followed by cellular apoptosis.

Secondary metabolites from the endolichenic fungus Ophiosphaerella korrae.

The isolation of the cytotoxic fractions from the endolichenic fungus Ophiosphaerella korrae yielded six new metabolites, including five polyketides (ophiofuranones A (1) and B (2), with unusual furopyran-3,4-dione-fused heterocyclic skeletons, ophiochromanone (3), ophiolactone (4), and ophioisocoumarin (5)), one sesquiterpenoid ophiokorrin (10), and nine known compounds. Their structures were established on the basis of the analysis of HRESIMS and NMR spectroscopic data. ECD calculations, GIAO NMR shift calculations and single-crystal X-ray diffraction were employed for the stereo-structure determination. A plausible biogenetic pathway for the ophiofuranones A (1) and B (2) was proposed. The cytotoxic assay suggested that the five known perylenequinones mainly contributed to the cytoxicity of the extract. Further phytotoxic studies indicated that ophiokorrin inhibited root elongation in the germination of Arabidopsis thaliana with an IC50 value of 18.06 µg mL-1.

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.

Cytotoxic p-Terphenyls from the Endolichenic Fungus Floricola striata.

Eleven new p-terphenyls, floricolins K-U (1-11), together with 13 biosynthetically related known compounds (12-24) were isolated from an endolichenic fungus, Floricola striata. Their structures were elucidated by extensive spectroscopic analyses and single-crystal X-ray diffraction measurements. The newly isolated p-terphenyls inhibited the growth of A2780, MCF-7, and A549 cell lines. Further evaluation for the multidrug resistance (MDR) reversal activity of compound 5 revealed it enhanced the sensitivity of MCF-7/ADR cells toward adriamycin 39-fold at 10 µM through modulating P-glycoprotein-mediated drug exclusion.

Ophiosphaerellins A-I, Polyketide-Derived Compounds from the Endolichenic Fungus Ophiosphaerella korrae.

Ophiosphaerellins A-I (1-9), the first example of bicyclo[4.1.0]heptenones, as well as their biosynthetic relatives ophiosphaerekorrins A-B (10-11) were isolated from the endolichenic fungus Ophiosphaerella korrae. Biosynthetically, they were derived from the polyketide pathway, and their absolute configurations were determined on the basis of the combination analysis of spectral data, circular dichroism calculations, and single-crystal X-ray diffraction measurement. Preliminary test with thin-layer chromatography bioautography found that this type of compounds showed moderate acetylcholinesterase (AChE) inhibitory effects.

Cyperane and eudesmane-type sesquiterpenoids from Chinese liverwort and their anti-diabetic nephropathy potential.

Six new sesquiterpenoids, including cyperane (1 and 2) and eudesmane (3-6) types, and one known eudesmane derivative (7), were isolated from the Chinese liverwort Chiloscyphus polyanthus var. rivularis (Schrad.) Nees. The structures of 1-7 were determined based on a combination of their spectroscopic data (NMR, HRESIMS and IR), single-crystal X-ray diffraction, and electronic circular dichroism (ECD) calculations. Preliminary anti-diabetic nephropathy activity testing showed that the cyperane-type sesquiterpenoids could inhibit cell proliferation and extracellular matrix accumulation in high glucose cultured mesangial cells in a dose-dependent manner.

Two new α-pyrone derivatives from an endolichenic fungus Tolypocladium sp.

Two new α-pyrone derivatives, tolypocladones A (1) and B (2), together with five known compounds were isolated from an endolichenic fungus Tolypocladium sp. (4259a). The structures of all the compounds were determined by analysis of their MS and NMR data. Among them, compound 1 was an enantiomeric mixture and the configuration was established by single-crystal X-ray diffraction analysis using Cu-Kα radiation. Also, this is the first report of the presence of compound 3 (glycine, N-(2,3-dihydroxybenzoyl)-methyl ester) and compound 4 (2H-pyran-2-one, 4-methoxy-6-(1,3-pentadienyl)) as natural products.

p-Terphenyl Derivatives from the Endolichenic Fungus Floricola striata.

Ten new p-terphenyl derivatives, floricolins A-J (1-10), together with six known compounds (11-16), were isolated from the extract of the endolichenic fungus Floricola striata. Chemical structures of these compounds were elucidated using spectroscopic data (HRESIMS and NMR). Among them, 9 and 10 were enantiomeric mixtures, and their configurations were established by single-crystal X-ray diffraction analysis using Cu Kα radiation. Evaluation of the isolated compounds against Candida albicans revealed that the most active compound, 3 (MIC 8 µg/mL), exerted fungicidal action by destruction of the cell membrane.

Effects of Sitagliptin on Lipid Profiles in Patients With Type 2 Diabetes Mellitus: A Meta-analysis of Randomized Clinical Trials.

Sitagliptin has been reported to improve lipid profiles, but findings from these studies are conflicting. We conducted this meta-analysis to evaluate the effects of sitagliptin on serum lipids in patients with type 2 diabetes mellitus.We made a comprehensive literature search in PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure, Wanfang, and VIP database until June 2015. Eligible studies were randomized clinical trials (RCTs) that investigated the effect of sitagliptin on serum triglycerides (TGs), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), or high-density lipoprotein cholesterol (HDL-C).Eleven RCTs with 2338 patients were identified. Compared with controls, sitagliptin alone or in combination significantly improved serum TG (weighted mean difference [WMD] -0.24 mmol/L; 95% confidence interval [CI] -0.40 to -0.09; P = 0.002) and HDL-C (WMD 0.05 mmol/L; 95% CI 0.02-0.07; P < 0.001).However, no statistical significances were observed in LDL-C (WMD -0.07 mmol/L; 95% CI -0.22 to 0.08; P = 0.337) and TC (WMD -0.14; 95% CI -0.33 to 0.06; P = 0.177). Subgroup analyses revealed that sitagliptin alone achieved greater improvement in serum TG, TC, and HDL-C levels.These findings suggested that sitagliptin alone or in combination significantly improved serum TG and HDL-C levels in patients with type 2 diabetes mellitus.