Correction: Structural diversity, bioactivities, and biosynthesis of natural diterpenoid alkaloids.

Correction for 'Structural diversity, bioactivities, and biosynthesis of natural diterpenoid alkaloids' by Yong Shen et al., Nat. Prod. Rep., 2020, 37, 763-796, https://doi.org/10.1039/D0NP00002G.

Ternary Cocrystals with Large Soft Cavities: A 1,4-diiodotetrafluorobenzene (DITFB)⋠4-Biphenylpyridine N-oxide (BPNO) Host Assembled by Inclusion of Planar Aromatic Guests.

A large soft-cavity host composed of 1,4-diiodotetrafluorobenzene (DITFB) and 4-biphenylpyridine N-oxide (BPNO) is assembled under the mediation of a planar aromatic guest molecule (pyrene or perylene) through C-I⋅⋅⋅- O-N+ halogen bonds and π-hole⋅⋅⋅π bonds. Single-crystal X-ray diffraction reveals that guest molecules can be completely encapsulated in the four-layer host cavity to assemble ternary host-guest cocrystals; namely, Pyr@DITFB ⋅ BPNO and Per@DITFB ⋅ BPNO. The luminescence of these ternary cocrystals originates from their discrete guest molecules, which exhibit pure-blue and yellow emissions, respectively, that are localized at 425 nm and in the range of 485 to 578 nm, respectively. In addition, the contribution of different fragments to the stabilization of the crystal structure is estimated by computational chemistry. These cocrystals have significant potential for use in optical applications or materials, such as photonics or organic light-emitting diodes, respectively, that require to avoid the aggregation between luminophores.

Two new dammarane-type triterpenoids from the steamed roots of Panax notoginseng.

Two new dammarane-type triterpenoids, notoginsenoside SY3 (1) and notoginsenoside SY4 (2), were isolated from the steamed roots of Panax notoginseng. Their structures were determined to be 3ß, 12ß, 20(S)-trihydroxy-27-anordammar-23(24)(E)-ene-3-O-ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranoside (1) and 3ß, 12ß, 20(S)-trihydroxy-25-methoxyldammar-23(24)(E)-ene-3-O-ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranoside (2) by IR, HRESIMS and NMR experiments.

Structural diversity, bioactivities, and biosynthesis of natural diterpenoid alkaloids.

Covering: 2009 to 2018. Diterpenoid alkaloids, originating from the amination of natural tetracyclic diterpenes, are a diverse class of compounds having complex structural features with many stereocenters. The important pharmacological activities and structural complexity of the diterpenoid alkaloids have long interested scientists due to their medicinal uses, infamous toxicity, and unique biosynthesis. Since 2009, 373 diterpenoid alkaloids, assigned to 46 skeletons, have been isolated and identified from plants mostly in the Ranunculaceae family. The names, classes, molecular weight, molecular formula, NMR data, and plant sources of these diterpene alkaloids are collated here. This review will be a detailed update of the naturally occurring diterpene alkaloids reported from the plant kingdom from 2009-2018, providing an in-depth discussion of their diversity, biological activities, pharmacokinetics, toxicity, application, evolution, and biosynthesis.

MR imaging of intracranial solitary fibrous tumor: a retrospective study of 7 cases.

OBJECTIVE: To investigate the MR imaging diagnostic features of intracranial solitary fibrous tumors (ISFTs). MATERIALS AND METHODS: Seven patients (mean age of 52.9 years; M:F=3:4) with histopathologically proven ISFTs were identified at our institute. Clinical presentations and pathological features were reviewed. MR Imaging findings including signal intensity, gadopentetate dimeglumine enhanced pattern, and diffusion-weighted imaging (DWI) characterization of the tumors were retrospectively evaluated. RESULTS: Six tumors showed a multi-lobular contour. Five tumors showed heterogeneous signal intensity, and two tumors showed homogeneous signal intensity on T1WI. Low signal intensity linear, curved or interlacing lines were observed within the tumors in all seven cases. Seven tumors demonstrated moderate or strong enhancement, six showed heterogeneous enhancement, and one homogenous enhancement. All tumors showed heterogeneous signal intensity on DWI.A ring-like high signal intensity band distributed around within the tumor was noted in six cases on DWI. CONCLUSION: Diagnostic evidence for ISFT on MR image includes heterogeneous signal intensity, intense enhancement of T2 signal intensity, low signal intensity lines within the tumor, heterogeneous signal intensity on DWI and a ring-like band around the tumor on DWI.

Emergence and mechanism of carbapenem-resistant Escherichia coli in Henan, China, 2014.

The emergence and dissemination of carbapenem-resistant Escherichia coli (E. coli) strains is a main risk for global public health, but little is known of carbapenemase producing E. coli in Henan, China. The study was undertaken to investigate the prevalence and mechanism of carbapenem-resistant E. coli strains in a hospital in Xinxiang, Henan, China, 2014. A total of 5 carbapenemase-producing E. coli strains were screened from 1014 isolates. We found that they were all resistant to meropenem and imipenem. Amikacin showed the best sensitivity, with gentamicin coming up next. The positive rate of blaNDM was 80% (4/5). The sequencing results showed that two isolates belonged to blaNDM-1 whereas other 2 isolates carried the blaNDM-5. Other carbapenemase genes including blaIMP,blaVIM, blaKPC and blaOXA-48 were not detected. The blaCTX-M-15,blaTEM-1,sul2, aad, and aac(6")-Ib-cr were also detected. MLST analysis showed that NDM-producing E. coli were sporadic. Conjugation test indicated blaNDM could be transferred. In conclusion, the blaNDM was the principal resistance mechanism of carbapenem-resistant E. coli in the hospital, Henan, China.

[Carbon emissions and low-carbon regulation countermeasures of land use change in the city and town concentrated area of central Liaoning Province, China].

Carbon emissions due to land use change have an important impact on global climate change. Adjustment of regional land use patterns has a great scientific significance to adaptation to a changing climate. Based on carbon emission/absorption parameters suitable for Liaoning Province, this paper estimated the carbon emission of land use change in the city and town concentrated area of central Liaoning Province. The results showed that the carbon emission and absorption were separately 308.51 Tg C and 11.64 Tg C from 1997 to 2010. It meant 3.8% of carbon emission. was offset by carbon absorption. Among the 296.87 Tg C net carbon emission of land use change, carbon emission of remaining land use type was 182.24 Tg C, accounting for 61.4% of the net carbon emission, while the carbon emission of land use transformation was 114.63 Tg C, occupying the rest 38.6% of net carbon emission. Through quantifying the mapping relationship between land use change and carbon emission, it was shown that during 1997-2004 the contributions of remaining construction land (40.9%) and cropland transform ation to construction land (40.6%) to carbon emission were larger, but the greater contributions to carbon absorption came from cropland transformation to forest land (38.6%) and remaining forest land (37.5%). During 2004-2010, the land use types for carbon emission and absorption were the same to the period of 1997-2004, but the contribution of remaining construction land to carbon emission increased to 80.6%, and the contribution of remaining forest land to carbon absorption increased to 71.7%. Based on the carbon emission intensity in different land use types, we put forward the low-carbon regulation countermeasures of land use in two aspects. In carbon emission reduction, we should strict control land transformation to construction land, increase the energy efficiency of construction land, and avoid excessive development of forest land and water. In carbon sink increase, we should improve forest coverage rate, implement cropland, grassland transform to forest land, strengthen forest land and water protection, and adjust cropland internal structure and scientifically implement cropland management.

Paeoveitols A-E from Paeonia veitchii.

Paeoveitols A-E (1-5), involving three monoterpenes and two benzofuran constituents, were isolated from Paeonia veitchii. Their structures were determined based on extensive spectral analyses (IR, UV, MS, 1D and 2D NMR), and the absolute configuration of compound 1 was confirmed by single-crystal X-ray diffraction. By the agitating human melatonin receptor 1 (MT1) assay on HEK293 cell line in vitro, compound 4 showed weak activity with the agitation rate of 22.52% at the concentration of 1.79 mM.

[Chemical constituents of Lepidium meyenii].

To study the chemical constituents of Lepidium meyenii, the air-dried rhizome of L. meyenii was extracted with 70% EtOH. The extract was condensed to a small amount of volume and extracted with petroleum ether, EtOAc and n-BuOH, successively. The compounds were isolated and purified by column chromatography, and identified based on spectral analyses (1H-NMR, 13C-NMR, HRESIMS). Eighteen compounds were isolated from L. meyenii, including 7 alkaloids and 4 fatty acids and 7 other compounds. They were characterized as (3-hydroxybenzyl) carbamic acid(1), phenylmethanamine(2), N-benzylformamide (3), N-benzylacetamide (4), pyridin-4-ylmethanamine(5), n-(4-methoxybenzyl) aniline(6), uracil(7), succininc acid(8), decanedioic acid(9), n-hexa- decanoic acid methyl ester(10), heptanoic acid(11), solerole(12), pyromucic acid methyl ester(13), 5-hydroxymethyl-2-furancar- boxadehyde(14), 5-(methoxymethyl)-1H-pyrrole-2-carbaldehyde(15), 1,7-dihydroxy-2,3, 4-trimethoxyxanthone (16), 1,7-di- hydroxy-3,4- dimethoxy-xanthone(17), (+)-pinoresinol(18). Meanwhile, compounds 1-18 were obtained from L. neyenii for the first time.

Noreudesmane sesquiterpenoids from the leaves of Nicotiana tabacum.

Six new 14-noreudesmane sesquiterpenoids, nicotabacosides A-F (1-6), along with five known sesquiterpenoids (7-11), were isolated from the leaves of Nicotiana tabacum. The structures of compounds 1-6 were elucidated as isorishitin 3-O-ß-D-glucopyranoside (1), rishitin 3-O-ß-D-glucopyranoside (2), rishitin 2-O-ß-D-glucopyranoside (3), 1, 6-dehydro-rishitin 3-O-ß-D-glucopyranoside (4), 2-hydroxyl-ligudentatol 3-O-ß-D-glucopyranoside (5) and oxyglutinosone 3-O-ß-D-glucopyranoside (6) based on extensive spectroscopic analyses (HRESIMS, UV, IR, 1D and 2D NMR). Their absolute configurations were determined by X-ray single-crystal diffraction and comparison of their electronic circular dichroism (ECD) spectra.

Synthesis, structure-activity relationships and biological evaluation of dehydroandrographolide and andrographolide derivatives as novel anti-hepatitis B virus agents.

Dehydroandrographolide and andrographolide, two natural diterpenoids isolated from Andrographis paniculata possessed activity against HBV DNA replication with IC50 values of 22.58 and 54.07µM and low SI values of 8.7 and 3.7 in our random assay. Consequently, 48 derivatives of dehydroandrographolide and andrographolide were synthesized and evaluated for their anti-HBV properties to yield a series of active derivatives with lower cytotoxicity, including 14 derivatives against HBsAg secretion, 19 derivatives against HBeAg secretion and 38 derivatives against HBV DNA replication. Interestingly, compound 4e could inhibit not only HBsAg and HBeAg secretions but also HBV DNA replication with SI values of 20.3, 125.0 and 104.9. Furthermore, the most active compound 2c with SI value higher than 165.1 inhibiting HBV DNA replication was revealed with the optimal logP value of 1.78 and logD values. Structure-activity relationships (SARs) of the derivatives were disclosed for guiding the future research toward the discovery of new anti-HBV drugs.

(±)-Paeoveitol, a pair of new norditerpene enantiomers from Paeonia veitchii.

(+)-Paeoveitol and (-)-paeoveitol, a pair of new norditerpene enantiomers, were isolated from the root of Paeonia veitchii. Their structures and absolute configurations were determined on the basis of extensive analysis of 1D and 2D NMR spectra, crystal X-ray diffraction, and electronic circular dichroism (ECD). A possible biogenesis involving two molecules of paeoniflorin was postulated.

Room temperature phosphorescence of 9-bromophenanthrene, and the interaction with various metal ions.

The Flow Inject Drop Luminescence Sensor (FIDLS) is featured by advantages such as high precision and work simplification over typical luminescent spectrometers. With the FIDLS system, this study is the first to examine the sodium deoxycholate (NaDC) inducing room temperature phosphorescence (RTP) of 9-bromophenanthrene (BrP). Among the factors that influenced phosphorescence, the injection speed of the FIDLS was optimized at 5.0 mL h(-1). A solvent content of 1.0% or less was selected to avoid RTP quenching. When samples were placed at temperatures higher than room temperature (e.g., 303 K), the standing time of the sample decreased. The minimum detectable level of BrP was 8.0 × 10(-10) mol L(-1), and BrP RTP reached its maximum intensity at a BrP concentration of 1.0 × 10(-5) mol L(-1). The optimal clathrate concentration of NaDC was 4.9 × 10(-3) mol L(-1), which was also the critical micelle concentration. We found that NaDC primary micelles gradually formed, but that secondary micelles formed and decomposed at a considerably faster rate. Fluorescence and absorbance tests demonstrated the coordination reactions of BrP with Cr(6+) and Fe(3+), indicating the potential application of BrP as a fluorescence probe.

Fatty acid synthase inhibitors from the hulls of Nephelium lappaceum L.

Natural products inhibiting fatty acid synthase (FAS) are appearing as potential therapeutic agents to treat cancer and obesity. The bioassay-guided chemical investigation of the hulls of Nephelium lappaceum L. resulted in the isolation of ten compounds (1-10) mainly including flavonoids and oleane-type triterpene oligoglycosides, in which all of the compounds were isolated from this plant for the first time. Additionally, compounds 8 and 9 were new hederagenin derivatives and were elucidated as hederagenin 3-O-(2,3-di-O-acetyl-α-l-arabinofuranosyl)-(1→3)-[α-l-rhamnopyranosyl(1→2)]-ß-l-arabinopyranoside and hederagenin 3-O-(3-O-acetyl-α-l-arabinofuranosyl)-(1→3)-[α-l-rhamnopyranosyl-(1→2)]-ß-l-arabinopyranoside, respectively. All these isolates were evaluated for inhibitory activities of FAS, which showed these isolates had inhibitory activity against FAS with IC(50) values ranging from 6.69 to 204.40 µM, comparable to the known FAS inhibitor EGCG (IC(50)=51.97 µM). The study indicates that the hulls of Nephelium lappaceum L. could be considered as potential sources of promising FAS inhibitors and the oleane-type triterpene oligoglycosides could be considered as another type of natural FAS inhibitors.

Fatty acid synthase inhibitors of phenolic constituents isolated from Garcinia mangostana.

Natural inhibitors of fatty acid synthase (FAS) are emerging as potential therapeutic agents to treat cancer and obesity. The bioassay-guided chemical investigation of the hulls of Garcinia mangostana led to the isolation of 13 phenolic compounds (1-13) mainly including xanthone and benzophenone, in which compounds 7, 8, 9, 10, and 11 were isolated from this plant for the first time and compound 9 was a new natural product. These isolates possess strong inhibitory activity of FAS with the IC(50) values ranging from 1.24 to 91.07 µM. The study indicates that two types of natural products, xanthones and benzophenones, could be considered as promising FAS inhibitors.

[Effects of salicylic acid on the leaf photosynthesis and antioxidant enzyme activities of cucumber seedlings under low temperature and light intensity].

In order to elucidate the regulation functions of salicylic acid (SA) on the photosynthesis of cucumber under low temperature and light intensity, the seedlings of cucumber 'Jinyou 3' under low temperature and light intensity were foliar-sprayed with different concentration SA, and the leaf gas exchange parameters, photochemical efficiency, MDA content, and antioxidant enzyme activities were measured. The results showed that under low temperature and light intensity, the leaf photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), actual photochemical efficiency of PS II (PhiPSII), and maximal photochemical efficiency of PS II (Fv/Fm) of the seedlings all decreased but the intercellular CO2 concentration (Ci) increased, suggesting that nonstomatal limitation was the main cause of the decrease of Pn under low temperature and light intensity stress. Low temperature and light intensity also led to the increase of leaf malondialdehyde (MDA) content and superoxide dismutase (SOD) activity, the decrease of catalase (CAT) activity, and the decrease after an initial increase of peroxidase (POD) activity. However, foliar-spraying 0.5-2.5 mmol x L(-1) of SA before the stress increased the leaf Pn, Gs, Tr, PhiPSII, Fv/Fm, and activities of SOD, POD and CAT while decreased the Ci and MDA content, suggesting that SA could regulate the leaf photosynthetic functions of cucumber seedlings, and enhance the seedlings resistance against low temperature and light intensity. The optimum concentration of SA for the foliar-spraying was 1 mmol x L(-1).

[Investigation of interaction between levofloxacin and bovine serum albumin by fluorescence analysis based on liquid drop].

The interaction between pharmaceutical and protein is an important pharmacokinetic characteristic. Most kinds of drugs must reach the receptor to perform the pharmacological function by plasma. Albumins can serve as a depot protein and a transport protein for numerous endogenous and exogenous compounds. It is of great significance to investigate the binding interaction between albumin and drugs, since it can not only help understand the transportation and distribution of drugs but also elucidate the mechanism. Under the physiological condition of body, the interaction between levofloxacin (LVFX) and bovine serum albumin (BAS) was investigated by fluorescence spectra and ultraviolet absorbance (UV) spectra based on liquid drop. The experimental results showed that LVFX quenches the fluorescence of BAS by forming a LVFX-BSA complex. According to Lineweaver-Burk equation, the apparent binding constants (K(LB)) between LVFX and BSA were 1.694 9 x 10(5) L x mol(-1) (291 K) and 2.881 0 x 10(5) L x mol(-1) (310 K), and the binding sites (n) were 0.884 9 (291 K) and 0.808 9 (310 K). Thermodynamic parameters could be evaluated from the thermodynamic second law, with deltaH (enthalpy) being 20.94 kJ mol(-1) and deltaS (entropy) being 172.1 J x mol(-1). According to the relation between thermodynamic parameters and the interaction force, LVFX depended principally on the hydrophobic interaction to bind with BSA. The results showed that the quenching belonged to static fluorescence quenching with non-radiation energy transfer happening within single molecule. The binding locality was an area 2.68 nm away from tryptonphan residue-212 in BAS according to Forster's non-radiation energy transfer mechanism. The conformational changes of BSA were evaluated by measuring the synchronous fluorescence intensity of protein amino acid residues, both before and after the addition of LVFX. A slightly stronger blue-shift of tryptophan fluorescence upon the addition of drug was observed, and the emission maximum of tyrosine kept its position. It was suggested that the environments of tryptophan residues in pure albumin solution are relatively polar. Binding of LVFX changes the environments to apolar ones. The shift in polarity is brought about by confirmation changes due to the interaction between albumin and ligand molecule.

Loss of characteristic absorption bands of C60 conjugation systems in the addition with aliphatic amines.

The characteristic absorption bands disappear and the shortest band at approximately 244 nm in cyclohexane or 282 nm in toluene remained only with long smoothing tail as C60 reacts adequately with aliphatic amines under sunlight radiation at approximately 40 degrees C. Simultaneously, fluorescence emission shifts from a weak band initially at longer wavelength to another strong one finally at shorter wavelength. The results might imply that the pi-conjugation system of C60 parent molecule is isolated into smaller separated parts. Therefore, some possible isolation models associated with observed experimental results are designed under some reasonable assumptive conditions.