Molecular recognition of two endogenous hormones by the human parathyroid hormone receptor-1.

Parathyroid hormone (PTH) and PTH-related peptide (PTHrP) are two endogenous hormones recognized by PTH receptor-1 (PTH1R), a member of class B G protein- coupled receptors (GPCRs). Both PTH and PTHrP analogs including teriparatide and abaloparatide are approved drugs for osteoporosis, but they exhibit distinct pharmacology. Here we report two cryo-EM structures of human PTH1R bound to PTH and PTHrP in the G protein-bound state at resolutions of 2.62 Å and 3.25 Å, respectively. Detailed analysis of these structures uncovers both common and unique features for the agonism of PTH and PTHrP. Molecular dynamics (MD) simulation together with site-directed mutagenesis studies reveal the molecular basis of endogenous hormones recognition specificity and selectivity to PTH1R. These results provide a rational template for the clinical use of PTH and PTHrP analogs as an anabolic therapy for osteoporosis and other disorders.

Mechanisms involved in the cytotoxic effects of berberine on human colon cancer HCT-8 cells.

Berberine, a constituent of some traditional Chinese medicinal plants, has been reported to have cytotoxicity effects on different human cancer cell lines. There is no available information about the effects and mechanism of action of berberine on human colon cancer cell line HCT-8. In this paper, the cytotoxicity ofberberine on HCT-8 cancer cells was investigated by MTT assay, fluorescence microscopy and flow cytometry analysis. Our data revealed that berberine could significantly inhibit the growth of HCT-8 cells in a dose- and time-dependent manner. Morphology of apoptotic cells was studied with acridine orange/ethidium bromide staining. The concentrations of lactate dehydrogenase and both acid and alkaline phosphatases were significantly increased in cell supernatants after berberine treatment, suggesting cell death. Furthermore, flow cytometry analysis showed that berberine could arrest HCT-8 cells at S phase in a time-dependent manner. To further investigate the apoptotic molecular mechanism, reverse transcription-polymerase chain reaction (RT-PCR) and western blotting methods were used. The up-regulated mRNA and/or protein expressions of Fas, FasL, TNF-alpha, caspase-3 and down-regulation of pro-caspase-3 suggest that the death receptor pathway may be involved in the apoptotic pathway induced by berberine. Decrease of Bcl-2 and increase of Bax in mRNA and/or protein expressions showed that the Bcl-2 family proteins were involved in berberine-induced apoptosis. We also found that berberine-induced apoptosis was associated with an upregulated expressions of p53 and prohibitin (PHB), and decreased vimentin expression. These results suggest that berberine can suppress cell growth and reduce cell survival by arresting the cell-cycle and by inducing apoptosis of HCT-8 cells.

Enantioselective Copper-Catalyzed [3 + 3] Cycloaddition of Tertiary Propargylic Esters with 1H-Pyrazol-5(4H)-ones toward Optically Active Spirooxindoles.

A copper-catalyzed enantioselective [3 + 3] cycloaddition of 3-ethynyl-2-oxoindolin-3-yl acetates with 1H-pyrazol-5(4H)-ones for the construction of optically active spirooxindoles bearing a spiro all-carbon quaternary stereocenter has been realized. With a combination of Cu(OTf)2 and chiral tridentate ketimine P,N,N-ligand as the catalyst, the reaction displayed broad substrate scopes, good yields, and high enantioselectivities. This represents the first catalytic asymmetric propargylic cycloaddition with tertiary propargylic esters as the bis-electrophiles for access to chiral spirocyclic frameworks.

[Dominant species of cephalopods and their niche characteristics in offshore of northern South China Sea]. / å—æµ·åŒ—éƒ¨è¿‘æµ·å¤´è¶³ç±»ä¼˜åŠ¿ç§åŠå ¶ç”Ÿæ€ä½ç‰¹å¾.

To understand the relationships among dominant species of cephalopods in offshore nor-thern South China Sea, we examined the niche characteristics of these dominant species from both spatial and temporal dimensions using the index of relative importance (IRI), the niche breadth and overlap indices based on fishery resources data from the bottom-trawl survey for four seasons during 2014-2015. The results showed that five dominant species of cephalopods were recorded for four seasons, including Loligo edulis, L. chinensis, L. beka, Sepia esculenta, and L. duvaucelii. The first two species were shared by all seasons. Compared with historical data, the composition of dominant cephalopods species had changed. The cephalopods resource exhibited obvious temporal and spatial variations. Stock density was higher in the sea area extending from the southern Hainan Island to eastern Guangdong Province than that in Beibu Gulf. The seasonal variation was characte-rized by the largest in summer but the smallest in winter. The temporal and spatial niche analysis showed that there was inconsistent in the order between temporal and spatial niche breadths for domi-nant species. L. edulis (1.32) and L. chinensis (3.90) occupied the largest temporal and spatial niche breadths, respectively. The smallest of temporal and spatial niche breadths were shown for S. esculenta (0.98) and L. duvaucelii (2.04), respectively. Though the temporal niche overlap was numerically larger than the spatial niche overlap, both of them had higher values in interspecies among L. edulis, L. chinensis, L. beka, and the lower overlap for the species pairs between L. duvaucelii and other species. The result of correlation analysis suggested that niche breadth exhibited a significant negative correlation with variation in abundance on both temporal and spatial scales. The ecological niche could reflect the tempo-spatial changes of species resource, which enriched the traditional methods of fishery communities.

Diastereo- and Enantioselective Copper-Catalyzed Decarboxylative Ring-Opening [3 + 2] Annulation of Tertiary Propargylic Carbamates through Regioselective α-Attack of γ-Butenolides.

A copper-catalyzed regio-, diastereo-, and enantioselective decarboxylative ring-opening [3 + 2] annulation of tertiary propargylic carbamates with γ-butenolides for the synthesis of optically active pyrrolidinones has been realized. The reaction proceeded through regioselective α-attack of γ-butenolide and generated highly congested vicinal tertiary and all-carbon quaternary stereocenters in pyrrolidinone scaffolds, featuring high stereoselective induction and broad functional group tolerance. Critical to the successful development of this method was the employment of copper catalysis in concert with a diPh-Pybox ligand.

[Probability distribution characteristics of stock density in offshore of northern South China Sea.] / 南海北部近海渔业资源密度概率分布特征.

Based on catch data from the bottom trawl survey by eight cruises in offshore of northern South China Sea during 2014-2017, we analyzed the stock density distribution and explored its probability distribution with statistical method, which was further used to estimate the mean stock density in this region. The results showed that the coefficient of variation (CV) for stock density ranged from 0.67 to 1.03 for all the periods, indicating a highly uneven spatial distribution of stock density. The frequency distribution of fishery resource density was characterized by obvious right-skewed, which was dominated by stock density of 0-1000 kg·km-2. The results of one sample Kolmogorov-Smirnov test indicated that three probability distribution patterns were suitable for stock density in this region, including Lognormal, Gamma and Weibull distributions. In terms of the mean stock density estimation, the values from Lognormal showed no statistically significant difference from those from others, but the opposite result was obtained between Gamma and Weibull distributions. Compared with 1960s-1970s, the appropriate probability distribution pattern of stock density has changed from single to multiple types. Variation of the proportion of low catch resulted from the changes in the structure of fishery resources, fishing effort and climate change might cause the alte-ration of probability distribution.

Identification of novel Nrf2 activators from Cinnamomum chartophyllum H.W. Li and their potential application of preventing oxidative insults in human lung epithelial cells.

Human lung tissue, directly exposed to the environmental oxidants and toxicants, is apt to be harmed to bring about acute or chronic oxidative insults. The nuclear factor erythroid 2-related factor 2 (Nrf2) represents a central cellular defense mechanism, and is a target for developing agents against oxidative insult-induced human lung diseases. Our previous study found that the EtOH extract of Cinnamomum chartophyllum protected human bronchial epithelial cells against oxidative insults via Nrf2 activation. In this study, a systemic phytochemical investigation of the aerial parts of C. chartophyllum led to the isolation of thirty chemical constituents, which were further evaluated for their Nrf2 inducing potential using NAD(P)H: quinone reductase (QR) assay. Among these purified constituents, a sesquiterpenoid bearing α, ß-unsaturated ketone group, 3S-(+)-9-oxonerolidol (NLD), and a diphenyl sharing phenolic groups, 3, 3', 4, 4'-tetrahydroxydiphenyl (THD) significantly activated Nrf2 and its downstream genes, NAD(P)H quinone oxidoreductase 1 (NQO-1), and γ-glutamyl cysteine synthetase (γ-GCS), and enhanced the nuclear translocation and stabilization of Nrf2 in human lung epithelial cells. Importantly, NLD and THD had no toxicities under the Nrf2 inducing doses. THD also demonstrated a potential of interrupting Nrf2-Keap1 protein-protein interaction (PPI). Furthermore, NLD and THD protected human lung epithelial cells against sodium arsenite [As(III)]-induced cytotoxicity. Taken together, we conclude that NLD and THD are two novel Nrf2 activators with potential application of preventing acute and chronic oxidative insults in human lung tissue.

[Preparative separation of gentiopicrin from Radix Gentianae by high-speed counter-current chromatography with macroporous resin].

OBJECTIVE: To develop a method for the preparative separation of gentiopicrin from Radix Gentianae by high-speed counter-current chromatography (HSCCC). METHOD: The crude alcohol extracts were eluted on a macroporous resin column and then purified by high speed counter-current chromatography (HSCCC). A two-phase solvent system composed of ethyl acetate: n-butanol: water (2 : 1 : 3) was used, and the lower phase was used as the mobile phase at a flow rate of 1.5 mL x min(-1), while the apparatus rotated at 800 r x min(-1) and the eluate was detected at 254 nm. RESULT: 136 mg gentiopicrin with purity of 99.6% determined by HPLC were obtained from 300 mg crude extraction only in one-step separation and less than 200 minutes. CONCLUSION: The established method is simple, high efficiency and suitable for large-scale separation of gentiopicrin.

Two new prenylated coumarins from Spiranthes sinensis (Pers.) Ames.

Two new prenylated coumarins, sinensins A and B, have been isolated from the roots of Spiranthes sinensis (Pers.) Ames. Their structures were elucidated as 5-gamma, gamma-dimethylallyl-8-[2-(2,6-dihydroxyphenyl)-3-dimethyl-but-2-enyol]-umbelliferon (1) and 4,6-di(gamma, gamma-dimethylallyl)-8-lavandulyl-umbelliferon (2) on the basis of spectroscopic analysis.

Two new bioactive prenylated dihydroflavanoids from the medicinal plant Dolichos tenuicaulis (Baker) Craib.

Two new prenylated dihydroflavanoids have been isolated from the medicinal plant of Dolichos tenuicaulis (Baker) Craib. Their structures were elucidated as (2S)-5,2',6'-trihydroxy-8-prenyl-6,7-(3-prenyl-2,2-dimethylpyrano)-3',4'-(2,2-dimethyl-1-keone-cyclohexadiene)-flavanone (1) and (2S)-5,2',6'-trihydroxy-8-prenyl-6,7-(3-prenyl-2,2-dimethyl-1-keone-cyclohexadiene)-flavanone (2) on the basis of spectroscopic analysis.

Mechanisms involved in the cytotoxic effects of berberine on human colon cancer HCT-8 cells

Berberine, a constituent of some traditional Chinese medicinal plants, has been reported to have cytotoxicity effects on different human cancer cell lines. There is no available information about the effects and mechanism of action of berberine on human colon cancer cell line HCT-8. In this paper, the cytotoxicity of berberine on HCT-8 cancer cells was investigated by MTT assay, fluorescence microscopy and flow cytometry analysis. Our data revealed that berberine could significantly inhibit the growth of HCT-8 cells in a dose- and time-dependent manner. Morphology of apoptotic cells was studied with acridine orange/ethidium bromide staining. The concentrations of lactate dehydrogenase and both acid and alkaline phosphatases were significantly increased in cell supernatants after berberine treatment, suggesting cell death. Furthermore, flow cytometry analysis showed that berberine could arrest HCT-8 cells at S phase in a time-dependent manner. To further investigate the apoptotic molecular mechanism, reverse transcription-polymerase chain reaction (RT-PCR) and western blotting methods were used. The up-regulated mRNA and/or protein expressions of Fas, FasL, TNF-a, caspase-3 and down-regulation of pro-caspase-3 suggest that the death receptor pathway may be involved in the apoptotic pathway induced by berberine. Decrease of Bcl-2 and increase of Bax in mRNA and/or protein expressions showed that the Bcl-2 family proteins were involved in berberine-induced apoptosis. We also found that berberine-induced apoptosis was associated with an up-regulated expressions of p53 and prohibitin (PHB), and decreased vimentin expression. These results suggest that berberine can suppress cell growth and reduce cell survival by arresting the cell-cycle and by inducing apoptosis of HCT-8 cells.