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[Display omitted] The nature of the zero-temperature phase diagram of the spin- 1 / 2 J 1 - J 2 Heisenberg model on a square lattice has been debated in the past three decades, and it remains one of the fundamental problems unsettled in the study of quantum many-body theory. By using the state-of-the-art tensor network method, specifically, the finite projected entangled pair state (PEPS) algorithm, to simulate the global phase diagram of the J 1 - J 2 Heisenberg model up to 24 × 24 sites, we provide very solid evidences to show that the nature of the intermediate nonmagnetic phase is a gapless quantum spin liquid (QSL), whose spin-spin and dimer-dimer correlations both decay with a power law behavior. There also exists a valence-bond solid (VBS) phase in a very narrow region 0.56 ≲ J 2 / J 1 ≤ 0.61 before the system enters the well known collinear antiferromagnetic phase. We stress that we make the first detailed comparison between the results of PEPS and the well-established density matrix renormalization group (DMRG) method through one-to-one direct benchmark for small system sizes, and thus give rise to a very solid PEPS calculation beyond DMRG. Our numerical evidences explicitly demonstrate the huge power of PEPS for highly frustrated spin systems. Finally, an effective field theory is also proposed to understand the physical nature of the discovered gapless QSL and its relation to deconfined quantum critical point (DQCP). [ABSTRACT FROM AUTHOR]

[Display omitted] Alstonia R. Br. (Apocynaceae) is widely used in the traditional therapeutic systems. Due to its rich natural active ingredients, it is used in China, India, Thailand, Malaysia, Philippines, Africa, Australia and other countries to treat malaria, dysentery, asthma, fever, epilepsy, skin diseases, snake bites, and so on. The aim of this review is to describe in detail the botanical properties, traditional uses, chemical compositions, pharmacological activities and toxicity of the genus Alstonia for analyzing the value of this plant in clinical applications. There was information on the genus Alstonia collected through the internet searches such as Baichain Library, Web of Science, China National Knowledge Infrastructure (CNKI), Baidu Scholar, PubMed, Wan Fang Database and ACS, etc. The keywords used include genus Alstonia , folk medicinal uses, botanical studies, chemical composition, pharmacological activities, bioactivities and other relevant terminology. The scientific names and geographic location of the genus Alstonia were provided in the Subject Database of the Flora of China, the Plant List (www.theplantlist.org), the WFO Plant List (www.worldfloraonline.org) and the World Checklist of Selected Plant Families (http://wcsp.science.kew.org/qsearch.do). Currently, at least 400 compounds were isolated from genus Alstonia , including alkaloids, triterpenes, flavonoids, volatile oils, phenolic acids, etc. Through extensive pharmacological experiments, it was demonstrated that genus Alstonia had good pharmacological effects in vitro and in vivo , including β 2 AR, vasodilatory, antifungal, antineoplastic, antiplasmodial, anti-inflammatory, antibacterial, antioxidant, analgesic, and radioprotective activities, etc. Many studies also confirmed that the combination of the genus Alstonia with other traditional Chinese medicines could improve effectiveness. This review demonstrates that the genus Alstonia has high clinical application and medicinal value, which will bring the attention of pharmacologists and clinicians to the territory of natural products Additionally, bioactivity-related mechanisms and structure–activity relationships of chemical components are not clear. Only by bridging the gap between bioactivity-related mechanisms and structure–activity relationships of chemical components can the development of Alstonia plants be further promoted. [ABSTRACT FROM AUTHOR]

Abstract: YK-1101, with its structure as S-((E)-4-((7S,10S,Z)-4-ethylidene-7-isopropyl-2,5,8,12-tetraoxo -9-oxa-16-thia-3,6,13,18-tetraazabicyclo[13.2.1]octadeca-1(17),15(18)-dien-10-yl)but-3-en-1-yl) ethanethioate, is synthesized as a potential histone deacetylase inhibitor. Its quality and stability under various stress conditions are not fully understood. In this study, a high performance liquid chromatographic (HPLC) method was established and validated for the analysis of YK-1101 bulk drug samples. The chromatographic separation was performed on a C18 column with acetonitrile and water as mobile phase in a gradient elution. Based on the established method, the stability studies of YK-1101 under various stress conditions were carried out. YK-1101 was shown to undergo degradation under basic and acidic stress conditions, while it was stable under oxidative, photolytic and thermal conditions. In addition, a time of flight mass spectrometer (TOF/MS) was coupled to HPLC for the characterization of major degradation products produced under basic and acidic stress conditions. Their degradation pathways were also discussed. [Copyright &y& Elsevier]

Abstract: It has been a puzzle that transition metals can unexpectedly react with lithium-based matrixes of LiF and Li2O in the potential versus Li/Li+ range from 0.01 to 3.5V at room temperature. The electrochemical and theoretical investigations on the reactions of transition metals M (M=Co, Fe and Ni) with LiF and Li2O were carried out. The electrochemical reactivity of metal cobalt with LiF and Li2O has been examined by the discharge and charge, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. Density functional theoretical calculation results suggested that the stable compounds MLiF and MLi2O could be formed by the insertion of transition metal (M) in lithium-based matrixes with exothermic as an intermediate. The theoretical calculations provide an understanding in chemical reaction of M with LiF and Li2O. The small molecular or clusters reaction may play an important role in the electrochemical reaction of metal with transition Li2O or LiF, which could be used to explain for the unexpectedly reaction of transition metal with LiF and Li2O. [Copyright &y& Elsevier]

Hydrolyzing flavonoid glucuronides into corresponding aglycones posed some significant challenges. To improve acid-catalyzed hydrolysis process of flavonoid glucuronide, structures of glucuronide, hydrolysis parameters and post-processing were optimized. The optimized condition was performed by hydrolysis flavonoid glycoside methyl ester in a mixed solvent consisting of 2 mol/L H 2 SO 4 /EtOH/H 2 O (1/8/1, v/v/v) at 95 °C for 7 h and resulted in up to 90% aglycone yields, minimal byproduct formations and milder hydrolysis conditions. Furthermore, the optimized method avoids tedious purification steps and is easily conducted on a relatively large-scale using economical and commercially available reagents. [ABSTRACT FROM AUTHOR]

Four undescribed sesquiterpene-shikimates (1 – 4), eight undescribed monoterpene-shikimates (5 – 12), together with two known ones were isolated and identified from the 95% ethanol extract of the plant endophytic fungus Phyllosticta capitalensis cultured in rice medium. Capitalensis A (1) was identified as the first sesquiterpene-shikimate-conjugated spirocyclic meroterpenoid degradation product, while capitalensis B (2) is a sesquiterpene-shikimate-conjugated spirocyclic meroterpenoid with a unique D-ring formed by a C-2– O –C-9′ connection. The structures of these previously undescribed compounds were elucidated by multiple techniques, including IR, HR-ESI-MS, and NMR analysis. Furthermore, their absolute configurations were established through the comprehensive approach that involved the calculations of ECD spectra, optical rotation values, and single-crystal X-ray analysis. Moreover, the anti-inflammatory activity of all isolated compounds was evaluated using a lipopolysaccharide (LPS)-induced inflammation model in BV2 microglial cells. Meanwhile, these compounds exhibited activity in inhibiting NO production. Four compounds, capitalensis C (3), capitalensis D (4), 15-hydroxyl tricycloalternarene 5b (13) and guignarenone A (14) showed strong inhibitory effects with IC 50 values of 21.6 ± 1.33, 12.2 ± 1.08, 18.6 ± 1.27, and 15.8 ± 1.20 μ M, respectively. In addition, the structure-activity relationship of the anti-inflammatory activity of the compounds was discussed. 12 undescribed meroterpenoids compounds were isolated from Phyllosticta capitalensis , compounds 1 – 2 are rare sesquiterpene–shikimate-conjugated spirocyclic meroterpenoids containing a 5/6/5/6/5 ring system, while compound 8 contains a 5/7/6/5 tetracyclic skeleton. Two of the compounds showed potential inhibitory activity in LPS-induced BV2 microglial cells. [Display omitted] • 12 undescribed meroterpenoids were isolated from the secondary metabolite of Phyllosticta capitalensis. • The unprecedented 13′-nor-sesquiterpene-shikimate-conjugated spirocyclic meroterpenoid skeleton was found. • An undescribed compound characterized by the linkage of the first example C-2– O –C-9′ in 5/6/5/6/5 ring system. • Meroterpenoid-shikimate derivatives exhibited significant anti-inflammatory activity. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance Danshen is a crude herbal drug isolated from dried roots of Salvia miltiorrhiza Bunge . This plant is widely used in oriental medicine for the treatment of cardiovascular and cerebrovascular diseases. The supercritical CO 2 extract from Danshen (SCED) (57.85%, 5.67% and 4.55% for tanshinone IIA, tanshinone I and cryptotanshinone respectively) was studied in this article, whose potential molecular mechanism remains unclear, especially in anti-thrombosis. Aim of the study The present study was designed to observe the protective effect of SCED on ischemic stroke in rats and to explore the underlying anti-thrombosis mechanism. Materials and methods Following induction of cerebral ischemia in rats by permanent middle cerebral artery occlusion (pMCAO). Neurological defect score, cerebral blood flow, infarct size, and brain edema were measured to evaluate the injury. Arteriovenous shunt thrombosis model and adenosine 5′-diphosphate (ADP) induced acute pulmonary embolism model were conducted to estimate the antithrombotic effect of SCED. In order to investigate the effects of SCED on platelet aggregation, rat platelet-rich-plasma (PRP) were incubated with SCED prior to the addition of the stimuli (ADP or 9, 11-dideoxy-11α, 9α-epoxymethanoprostaglandin F2α (U46619)). Aggregation was monitored in a light transmission aggregometer. Inhibitory effect of SCED on thromboxane A2 (TXA 2 ) release was detected by ELISA kit. Phospholipase C (PLC)/ Protein kinase C (PKC) signaling pathway was analyzed by a Western blot technique. The effect of the SCED was also studied in vivo on bleeding time in mice. Results SCED improved the neurological defect score, increased cerebral blood flow, reduced infarct size and alleviated brain edema in rats exposed to pMCAO. After administration of SCED, thrombosis formation in arteriovenous shunt was inhibited and recovery time in pulmonary embolism was shortened. The inhibitory effect of SCED on platelet activation was further confirmed by TXB 2 ELISA kit and Western blot analysis of PLC/PKC signaling pathway. Conclusions SCED attenuates cerebral ischemic injury. The possible mechanism is that SCED inhibits thrombosis formation, platelet aggregation and activation of PLC/PKC pathway. On this basis, this new extract could be a promising agent to inhibit thrombosis formation and protect against cerebral ischemia injury. [ABSTRACT FROM AUTHOR]

• A novel meroterpenoid with an unique 6/8/9/4-tetracyclic nucleus was isolated. • The absolute configuration was confirmed by computational 13C NMR and optical rotation data. • Compound 1 exhibited potential cytotoxic activities. Littordial F (1), a novel meroterpenoid with an unique 6/8/9/4-tetracyclic nucleus, was isolated from the leaves of Psidium littorale. The structure of 1 was established by spectroscopic data, and its absolute configuration was confirmed by computational 13C NMR and optical rotation data. Compound 1 exhibited potential cytotoxic activities on A549, B16, and HepG-2 cell lines. A plausible biosynthetic pathway for littordial F was proposed. [ABSTRACT FROM AUTHOR]

Phytochemical investigation on the stem bark of Toona sinensis was carried out by various chromatographic techniques resulting in the isolation and elucidation of two novel tirucallane triterpenoids, named (20 S )-3-oxo-tirucalla-25-nor-7-en-24-oic acid ( 1 ) and (20 S )-5 α ,8 α -epidioxy-3-oxo-24-nor-6.9(11)-dien-23-oic acid ( 2 ), along with fifteen known triterpenoids ( 3–17 ), their structures were determined by extensive spectroscopic methods, including 1D-, 2D-NMR and HR-ESI-MS experiments. Compound 2 is uncommon in nature, which possesses a peroxide bridge cross C-5 and C-8 in the triterpenoid skeleton. All isolated compounds were evaluated for cytotoxicity against five human tumor cell lines (A-549, Hela, HepG2, SGC-7901 and SW-480), among them, compound 17 displayed strongest cytotoxic activity against A-549 cells and the results indicated that its cytotoxicity against A-549 cells was mediated by the intrinsic mitochondrial apoptotic pathway. In addition, ROS production-inhibitory activities were also evaluated, but none of them was active. [ABSTRACT FROM AUTHOR]

Three new C 20 quassinoids nigakilactone P ( 1 ), picraqualide F ( 2 ), nigakilactone Q ( 3 ), along with eight known quassinoids ( 4 – 11 ), were isolated from the 95% EtOH extract of the stems of Picrasma quassioides . The structures of the new compounds were elucidated by means of HRESIMS and different NMR techniques. Assignments of relative and absolute configurations for these compounds were achieved on the basis of ROESY spectra and quantum chemical ECD calculation. In vitro activity assays, none of the compounds showed cytotoxic (IC 50 > 50 μM) and NO production-inhibitory activities (IC 50 > 30 μM), and the structure–activity relationships of quassinoids were summarized. In addition, the chemotaxonomic significance of the isolated compounds was also discussed. [ABSTRACT FROM AUTHOR]

In order to improve the electrochemical performance of Na/CF x cell, fluorinated multi-walled carbon nanotubes (F-MWCNTs) and a new composite consisting of CF x , graphene nanosheets (GNS) and FeF 3 (labeled as CGF for short) were employed as cathode materials in rechargeable room-temperature sodium batteries for the first time. The polarizations of Na/F-MWCNTs and Na/CGF cell were found to be 1600 and 800 mV, respectively. These values were much lower than that of Na/CF x cell (2000 mV). MWCNTs formed after the discharge process with intrinsic high surface area, high catalytic activity and “cage” type structure enhance charge reaction activity. Analogically, the combination of GNS and FeF 3 with CF x provides more active sites to facilitate the decomposition of NaF during charge process. Moreover, the CGF electrode may have specific channels to avoid the dissolution of fluorine into the electrolyte similarly as the structure function of the F-MWCNTs electrode, leading to much better cycling performance. Overall, our results have demonstrated that the electrochemical performance of Na/CF x cell can be greatly improved by using MWCNTs and FeF 3 –GNS as catalysts. [ABSTRACT FROM AUTHOR]

Phytochemical investigation of the roots of Streblus asper Lour. resulted in the isolation of six previously undescribed cardiac glycosides, designated 2′-de- O -methylstrebloside (1), cannogenol-3 α - O - β -D-gluopyranosyl-(1 → 4)-6-deoxy −2,3-dimethoxyl- β -D-fucopyranoside (2), periplogenin-3- O - α -L-rhamnopyranosyl -(1 → 4)-6-deoxy- β -D-allopyranoside (3), 5-de- O -hydroxylstrebloside (4), 5 β H-16 β -hydroxylkamaloside (5), and 17 S , 21 R -21-hydroxylstrebloside (6), and three known analogues (7 – 9). The structures were elucidated using NMR spectroscopic techniques, mass spectrometry, and comparison of the spectroscopic data with previously reported data. Compound 6 is a novel C-21 hydroxyl cardiac glycoside, its absolute configuration was established from the analysis of computational ECD calculations and NMR spectroscopic data. The effects of the cardiac glycosides on apoptosis and cytotoxicity were examined in human A549 lung cancer cells. All the compounds showed remarkable inhibitory activities, with IC 50 values in the range of 0.01–6.08 μM. Furthermore, compound 3 was able to significantly inhibit A549 cell growth proliferation via the induction of apoptosis, due to the activation of caspases-3, -8 and -9 in A549 cells, as revealed by Western blot analysis. Image 1 • Six previously undescribed cardiac glycosides were isolated from Streblus asper Lour. • Their structures were determined by NMR spectroscopic data and ECD calculations. • The isolated compounds were screened for their in vitro cytotoxicity against human A549 lung cancer cells. • An previously undescribed cardiac glycoside significantly inhibited A549 cells growth proliferation via induction of apoptosis. [ABSTRACT FROM AUTHOR]