Reduction of N2O by H2 Catalyzed by Keggin-Type Phosphotungstic Acid Supported Single-Atom Catalysts: An Insight from Density Functional Theory Calculations.

In the present paper, the mechanisms of N2O reduction by H2 were systemically examined over various polyoxometalate-supported single-atom catalysts (SACs) M1/PTA (M = Fe, Co, Mn, Ru, Rh, Os, Ir, and Pt; PTA = [PW12O40]3-) by means of density functional theory calculations. Among these M1/PTA SACs, Os1/PTA SAC possesses high activity for N2O reduction by H2 with a relatively low rate-determining barrier. The favorable catalytic pathway involves the first and second N2O decomposition over the Os1/PTA SAC and hydrogenation of the key species after the second N2O decomposition. Molecular geometry and electronic structure analyses along the favorable reaction pathway indicate that a strong charge-transfer cooperative effect of metal and support effectively improves the catalytic activity of Os1/PTA SAC. The isolated Os atom not only plays the role of adsorption and activation of the N2O molecule but also works as an electron transfer medium in the whole reaction process. Meanwhile, the PTA support with very high redox stability has also been proven to be capable of transporting the electron to promote the whole reaction. We expect that our computation results can provide ideas for designing new SACs for N2O reduction by using H2 selective catalytic reduction technology.

Improving the acetylcholinesterase inhibitory effect of Illigera aromatica by fermentation with Clonostachys rogersoniana.

Illigera aromatica was fermented by Clonostachys rogersoniana. The acetylcholinesterase (AChE) inhibitory effects of unfermented and fermented I. aromatica revealed that C. rogersoniana-fermented I. aromatica (CFIA) induced significantly more AChE inhibitory activity (IC50: 35.4 ± 2.1 µg/mL). The biotransformation of actinodaphnine (1) into (4R,6aS)-4-hydroxyactinodaphnine (2) was found during the fermentation, which played an important role in the improvement of the AChE inhibitory activity of I. aromatica. Subsequently, the fermentation conditions-including the solid-liquid ratio, fermentation temperature, and fermentation time-were optimized. I. aromatica immersed in 100-200% water and fermented with C. rogersoniana at ambient temperature for 30 days was conducive to the biotransformation of actinodaphnine (1) and improved the AChE inhibitory activity of I. aromatica. The present study provides a novel approach for improving the pharmacological effect of I. aromatica and suggests that CFIA may be used as an alternative AChE inhibitor.

[C_(19)-diterpenoid alkaloids from Aconitum austroyunnanense].

Eight C_(19)-diterpenoid alkaloids( 1-8) were isolated from the ethyl acetate soluble fraction of 95% ethanol extract of the ground roots of Aconitum austroyunnanense through various column chromatographies on silica gel,ODS,Sephadex LH-20 and MCI gel.Their structures were elucidated as 14α-benzoyloxy-13ß,15α-dihydroxy-1α,6α,8ß,16ß,18-pentamethoxy-19-oxoaconitan( 1),N-deethylaconitine( 2),spicatine B( 3),leucanthumsine A( 4),acofamine B( 5),macrorhynine B( 6),aconitilearine( 7),and ambiguine( 8) based on their chemical and physicochemical properties and spectroscopic data. Compound 1 was a new compound and alkaloids 2-8 were isolated from this plant for the first time. Some isolated alkaloids were tested in vitro for cytotoxic potential by employing the MTT method. As a result,alkaloid 1 exhibited weak cytotoxic activity against three tested tumor cell lines( A-549,He La,and Hep G2) with IC_(50) values less than 20 µmol·L~(-1).

Application of a proton quantitative nuclear magnetic resonance spectroscopy method for the determination of actinodaphnine in Illigera aromatica and Illigera henryi.

Illigera aromatica S. Z. Huang et S. L. Mo and Illigera henryi W. W. Sm., belonging to the genus Illigera (Hernandiaceae), are used as herbal medicines for promoting blood circulation and treating tuberculosis. Actinodaphnine, the major bioactive alkaloid, plays an important role in the quality controls of the herbs. In the present study, a rapid, simple, accurate, and precise proton quantitative nuclear magnetic resonance (1H-qNMR) method was developed to determine the content of actinodaphnine in I. aromatica and I. henryi. DMSO-d6 enabled satisfactory separation of the signals to be integrated in 1H NMR spectrum. 1,4-Dinitrobenzene was selected as an internal standard. The limits of determination and quantitation were 0.005 and 0.038 mg/mL, respectively. This work implied that 1H-qNMR represents a feasible alternative to HPLC-based methods for quantitation of actinodaphnine in I. aromatica and I. henryi and is suitable for the quality control of I. aromatica and I. henryi.

Simultaneous determination of alkaloids dicentrine and sinomenine in Stephania epigeae by 1H NMR spectroscopy.

Stephania epigaea Lo is an important herbal medicine used as antiphlogistic and analgesic drugs. Its major components are dicentrine (1) and sinomenine (2). In the present study, a rapid, accurate, and precise method for simultaneous quantitation of dicentrine (1) and sinomenine (2) in S. epigeae using 1H NMR spectra was developed. The deuterated solvent of DMSO-d6 enabled satisfactory separation of the signals to be integrated in 1H NMR spectrum and dimethyl terephthalate was selected as an internal standard. The feature signals of δ 7.57 and 5.70 were selected for quantifying the dicentrine (1) and sinomenine (2), respectively. Validation of the quantitative method was performed in terms of specificity, accuracy, precision, and stability. This work implied that quantitative 1H NMR represents a feasible alternative to high-performance liquid chromatography-based methods for quantitation of dicentrine (1) and sinomenine (2) in S. epigeae and is suitable for the quality control of S. epigeae.

[Amaryllidaceae alkaloids from Lycoris radiata].

Three aporphine-type alkaloids (1-3), three lycorine-type alkaloids (4-6), two crinane type alkaloids (7, 8) and one phenanthridine-type alkaloid (9) were isolated from the chloroform soluble fraction of 70% ethanol extract of the bulbs of Lycoris radiata through various column chromatographies over silica gel, ODS, Sephadex LH-20 and MCI. Their structures were elucidated as (+)-N-methoxylcarbonyl-1,2-methylenedioxyl-isocorydione (1), isocorydione (2), 8-demethyl-dehydrocrebanine (3), (+)-3-hydroxy-anhydrolycorine N-oxide (4), vasconine (5), pancratinine D (6), yemenine A (7), 11-O-acetylhaemanthamine (8), and 5,6-dihydro-5-methyl-2-hydroxyphenanthridine (9) based on their chemical and physicochemical properlies and spectroscopic data. Compound 1 was a new compound and alkaloids 2-9 were isolated and identified from this plant for the first time.

[Terpenoids isolated from Viburnum ternatum].

Four iridoids (1-4), five iridoid glucosides (5-9), and three triterpenoids (10-12) were isolated from the ethyl acetate soluble fraction of 70% Me2CO extract of the aerial parts of Viburnum ternatum through various column chromatographies over silica gel, ODS, Sephadex LH-20 and MCI. Their structures were elucidated as ternatumin A (1), 2,9-dioxatricyclo[4.3.1.03，7]decanes (2), 7,10,2'-triacetylsuspensolide F (3), 7,10,2',3'-tetraacetylsuspensolide F (4), viburtinoside IV (5), viburtinoside II (6), viburtinoside B (7), luzonoside A (8), luzonoside B (9), 2α,3ß,24-trihydroxy-12-ursen-28-oic acid (10), 6-hydroxy-20(29)-lupen-3-one (11), and pomalic acid (12) based on the their chromatographic properties, chemical and physicochemical methods, and spectroscopic data. Compound 1 was a new compound and compounds 3-12 were isolated from this plant for the first time. Furthermore, we note here the first isolation of compound 2 as a new natural product.

Biomedical molecular of woody extractives of Cunninghamia Lanceolata biomass.

Extractives, important compounds from wood, provide abundant resources for woody medicine. In this study, the three extractives from Cunninghamia lanceolata wood were removed by method of three-stage extraction with alcohol, petroleum ether, and alcohol/petroleum ether and their chemical components were analyzed by gas chromatography-mass spectrometry (GC-MS). Thirteen chemical components were discovered in the first-stage extractives, including: 4-((1e)-3-hydroxy-1-propenyl)-2-methoxyphenol (36.80%), α-(2-phenylethenyl)-1-piperidineacetonitrile (15.39%). One-hundred chemical components were discovered in the second-stage extractives, including: [1s-(1α,4aα,10aß)]-1, 2,3,4,4a,9,10,10a-octahydro-1,4a- dimethyl-7-(1-methylethyl)-1- phenanthrenecar-boxylic acid (15.16%), 1,3-dimethoxy-5-[(1e)-2- phenylethenyl]-benzene (6.99%). Seven chemical components were discovered in the third-stage extractives, including: 1,3-dimethoxy -5-[(1E)-2-phenylethenyl]-benzene (32.88%), stigmasta-4,6,22-trien-3α-ol (17.83%). And both the main retention time of the first-stage and which of third-stage extractives are 20-30 minutes, and the main retention time of the second-stage extractives is <10 minutes. Besides, the three extractives contained many biomedical molecular, such as [1s-(1α,4aα,10aß)]-1,2,3,4,4a,9,10,10a-octahydro-1,4a-dimethyl-7-(1-methylethyl)-1-phenanthrenecar-boxylic acid, squalene, stigmast-4-en-3-one and γ-sitosterol and so on, which means that the three extractives from Cunninghamia lanceolata wood have huge potential in biomedicine.