Chuan-Ling Si

Antioxidant properties and neuroprotective effects of isocampneoside II on hydrogen peroxide-induced oxidative injury in PC12 cells

Oxidative stress has been considered as a major cause of cell damage in various neurodegenerative disorders. One of the reasonable strategies for delaying the diseases progression is to prevent reactive oxygen species (ROS) mediated cellular injury by dietary or pharmaceutical augmentation of free radical scavengers. Isocampneoside II (ICD) is an active phenylethanoid glycoside isolated from the medicinal hardwood genus Paulownia. This study was designed to explore free radical scavenging potential of ICD in different in vitro systems and its protective role in hydrogen peroxide (H₂O₂)-induced oxidative stress and apoptotic death in cultured rat pheochromocytoma (PC12) cells. The results showed ICD eliminated approximately 80.75% superoxide radical at the concentration of 0.1mg/ml and inhibited metal chelating by 22.07% at 8 mg/ml. Additionally, ICD showed a strong ability on reducing power and provided protection against oxidative protein damage induced by hydroxyl radicals. Pretreatment of PC12 cells with ICD prior to H₂O₂ exposure elevated cell viability, enhanced activity of superoxide dismutase and catalase, and decreased levels of malondialdehyde and intracellular ROS. Furthermore, ICD inhibited cell apoptosis and Bax/Bcl-2 ratio induced by H₂O₂. These findings suggested ICD may be considered as a potential antioxidant agent and should encourage for further research in neurodegenerative diseases.

A new lignan glycoside and phenolics from the branch wood of Pinus banksiana Lambert

Abstract Phytochemical investigation of branch wood of Pinus banksiana Lambert resulted in the isolation of a new lignan glycoside, which was named phillyrin-6″-α-rhamnoside. The structure of the new compound was mainly elucidated by chemical and spectral evidence including 2D nuclear magnetic resonance studies. In addition, four known phenolics, including a phenylpropanoid glucoside (trans-isoconiferin), a phenolic acid (caffeic acid), a neolignan (cedrusin), and a lignan glucoside (phillyrin), were reported for the first time to be present in P. banksiana.

Chemical constituents of the root barks of Eucommia ulmoides

Eucommia ulmoides Oliv. (“Du Zhong” in Chinese and “Tu Chung” in Korean), the sole species in the genus Eucommia and family Eucommiaceae, is a deciduous tree indigenous in China and widely cultured in eastern Asian countries [1]. The species is highly valued and commonly used in traditional medicines to treat various diseases, especially to relieve hypertension, protect the nervous system, treat diabetics, cure lower back pain, and prevent miscarriage [2, 3]. Previous phytochemical investigations of E. ulmoides were mainly focused on its stem barks and leaves. However, the chemical constituents of E. ulmoides root have not been reported to date. As one chain of our systematic study of this valuable medicinal species, 13 secondary metabolites, including one triterpene [ursolic acid (1)], four phenylpropanoids [chlorogenic acid (2), caffeic acid (3), ferulic acid (4), and p-coumaric acid (5)], and eight flavonoids [luteolin (6), kaempferol (7), quercetin (8), astragalin (9), hirsutin (10), avicularin (11), quercitrin (12), and rutin (13)], were isolated from the root barks of E. ulmoides for the first time. What is noteworthy is that this was the first report of compounds 4, 5, 6, 11, and 12 from the title species. Plant Material. Root barks of E. ulmoides were collected in May, 2010 from Liyuan, Xianyang, Shanxi Province, P. R. China, and were identified by Dr. Dan Wang (Institute of Chemical Industry of Forest Products, CAF, P. R. China). A voucher specimen of this collection (CMSCE-100530) was deposited at the herbarium of Tianjin Key Laboratory of Pulp and Paper, College of Materials Science and Chemical Engineering, Tianjin University of Science and Technology, Tianjin, P. R. China. Equipment. 1H, 13C, and correlation NMR spectra were recorded in (CD3)2CO or CD3OD (Sigma) with TMS (Sigma) as an internal standard on a Bruker Avance DPX 400 spectrometer at the operating frequency of 400 MHz (1H) and 100 MHz (13C). EI and positive FAB-MS spectra were measured with a micromass autospec M363 spectrometer. Eluents were collected using an SBS-160 fraction collector. Thin-layer chromatography were carried out on DC-Plastikfolien Cellulose F (Merck) plates and developed with t-BuOH–AcOH–H2O (3:1:1, v/v, solvent A) and AcOH–H2O (3:47, v/v, solvent B). Visualization was by UV light (254 and 365 nm) and by spraying with vanillin–AcOH–EtOH (60:0.15:6, w/v/v) or 1% ethanolic FeCl3 solution followed by heating.

A new cis-p-coumaroyl flavonol glycoside from the inner barks of Sophora japonica L.

Abstract Tree barks could be a rich source of novel bioactive compounds, which are not well explored. In this work, the chemical constituent investigation of extractives from the inner barks of Sophora japonica L. (Leguminosae) led to the isolation of a new cis-p-coumaroyl flavonol glycoside, which was elucidated as kaempferol 3-O-(4″-cis-p-coumaroyl)-α-rhamnopyranoside (IV). The structure of the new compound was established mainly based on extensive spectroscopic techniques. In addition, among the four known phenolics purified in this study, including three flavonol glycosides [rutin (I), kaempferol-3-O-(6″-galloyl)-β-glucopyranoside (II), and quercitrin (V)], as well as a phenolic acid [trans-ferulic acid (III)], compounds II and III have never been reported in S. japonica previously.

Phytochemical Investigation of Hydroalcoholic Extractives from Branches of Fraxinus velutina

The genus Fraxinus (Oleaceae) contains approximately 70 woody species, which are widely distributed in the temperate regions and the subtropics of the Northern Hemisphere, including Eastern Asia, Europe, and North and Central America [1–4]. Fraxinus plants are highly valued in folk medicines for their diuretic and mild purgative effects as well as for treatment of arthritis, dropsy, constipation, rheumatic pain, cystitis, and itching scalp [4, 5]. The chemical composition of Fraxinus species consists mainly of flavonoids [1, 6], secoiridoids [7, 8], coumarins [9, 10], phenylethanoid glycosides [11, 12], and lignans [13, 14], but very few chemical investigations have been reported on F. velutina Torr. until now. In this investigation, F. velutina branches were collected in November 2012, in Tianjin, China, where F. velutina is authorized as the Tree of Tianjin City. Taxonomic identification was done by Prof. Dan Wang, Institute of Chemical Industry of Forest Products, CAF, China. The air-dried and finely powdered branches of F. velutina (8.5 kg) were extracted in a 30 L jar with 95% EtOH (v/v) solution for more than four days at room temperature. After evaporation of the solvent under reduced pressure, the residue was partitioned consequently with n-hexane, chloroform, ethyl acetate, and n-buthanol, then freeze-dried to give powders of the four portions. Part of the resulting ethyl acetate portion powders (31.2 g) were subjected to column chromatography packed with silica gel or Sephadex LH-20 successively, which led to the isolation of nine secondary metabolites. By spectroscopic methods and comparison with authentic data, the structures of the nine compounds were elucidated as (–)-epigallocatechin (1) [15], naringenin (2) [16], taxifolin (3) [17], rutin (4) [18], apigenin-7-O-[ -Dglucuronopyranosyl(1 2)-O-D-glucuronopyranoside] (5) [19, 20], esculin (6) [21], esculetin (7) [21], ligstroside (8) [22], and oleuropein (9) [22]. All these compounds were isolated from F. velutina branches for the first time, and compounds 1–3, and 5 have never been reported from the genus Fraxinus previously. The flavonoids (1–5), coumarins (6 and 7) and secoiridoids (8 and 9) reported herein suggested that the main constituents of F. velutina were in good accordance with those of other species of the genus Fraxinus. Although the chemical shifts of 5 have been described in the literature [19, 20], the assignment of the sugar moieties was always confusing, and no completely assigned NMR data have been published. In this work, we give the exact and unambiguous 1H and 13C NMR assignments of this flavonoid glycoside derivative for the first time, achieved with the aid of 2D NMR techniques.

Purification and Spectroscopic Elucidation of a New Coumarin Glucoside in Fraxinus velutina Heartwood

A new natural compound, esculetin-5-O-β-D-glucopyranoside (1), along with two known flavonoids, quercetin (2) and kaempferol-3-β-D-glucopyranoside (3), was purified from the heartwood of Fraxinus velutina. Their chemical structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR, and MS techniques.

Secondary Metabolites from the Leaves of Juglans sigillata

A new caffeoylated galloyl glucoside, 1,3-di-O-galloyl-6-O-trans-caffeoyl-β-D-glucoside (1), was isolated and purified, together with three known galloyl glucosides, 1,2,4,6-tetra-O-galloyl-β-D-glucoside (2), 1,2,6-tri-O-galloyl-β-D-glucoside (3), and 1,2,3,4,6-penta-O-galloyl-β-D-glucoside (4), from the leaves of Juglans sigillata. Chemical structures of the compounds were mainly established on the basis of spectroscopic methods, including 1D and 2D NMR and MS analyses.

Structural Properties of the Purified Lignins of Cornstalk in the Cooking Process with a Solid Alkali

To avoid undesired polymerization and maximize the selectivity of alkyl levulinate from the acid-catalyzed conversion of biomass-derived furfuryl alcohol, the effects of catalyst and reaction parameters on the formations of humin and alkyl levulinate were investigated. The results show that Amberlyst 15, of moderate acidic strength, was more favorable for the selective conversion of furfuryl alcohol to alkyl levulinate, and heteropolyacids of strong acidic strength tended to promote furfuryl alcohol polymerization. Compared with water as a reaction medium, alcohol significantly lowered humin formation and enhanced the yield of the resulting products. The formations of humin and alkyl levulinate were both favored at high catalyst loadings and reaction temperatures. An augmentation in initial furfuryl alcohol concentration caused an increase in humin formation and a decrease in alkyl levulinate yield. A high alkyl levulinate yield of up to 94% (100% furfuryl alcohol conversion) was achieved at 110 °C for 4 h with 5 g/L Amberlyst 15 catalyst and an initial furfuryl alcohol concentration of 0.1 mol/L. At this point, about 5% furfuryl alcohol was polymerized to form the humin, and its polymerization occurred mainly during the initial reaction stage.

Isolation and Structure Elucidation of a New Flavonol Glycoside from Sophora japonica

A new flavonol glycoside, quercetin-3-O-(4″-galloyl)-α-L-rhamnopyranoside (1), along with two known ones, kaempferol-3-O-β-D-glucopyranoside (2) and quercetin-3-O-rutinoside (3), were isolated from the root barks of Sophora japonica. The chemical structures of the isolated compounds were elucidated by spectroscopic analysis, including extensive 1D and 2D NMR and MS techniques.

Hydroxyl Radical Scavenging Properties of the Secondary Metabolites from Paulownia tomentosa var. tomentosa

Paulownia tomentosa (Thunb.) Steud. var. tomentosa (Scrophulariaceae) is a well-known medicinal hardwood species native to China and widely distributed in South and East Asian countries [1, 2]. Its barks have long been used in folk remedies for the treatment of various diseases and conditions, including gonorrhea, bronchopneumonia, high blood pressure, hemorrhoid, bacteriologic diarrhea, inflammatory bronchitis, erysipelas, carbuncle, upper respiratory tract infection, cough, phlegm, traumatic bleeding, parotitis, asthma, enteritis, tonsillitis, conjunctivitis, and swelling [3, 4]. However, the chemical constituents and biological activities of this species have been little reported to date. In this phytochemical study of P. tomentosa var. tomentosa barks, seven secondary metabolites were isolated, and their structures were determined as kaempferol (1) [5], quercetin (2) [6], astragalin (3) [7], hirsutrin (4) [8], astragalin-6 -gallate (5) [9], hirsutrin-6 -gallate (6) [10], and cistanoside F ( and -forms, 7) [11]. Compounds 1–7 have never been isolated from P. tomentosa var. tomentosa previously. Based on 1D and 2D NMR, MS spectroscopic methods, and other physiochemical techniques, the first unambiguous and complete 1H and 13C NMR assignments of compound 7 ( and -forms) were achieved in this work. The hydroxyl radical scavenging effects of the isolated metabolites were also evaluated. Plant Material. Barks of P. tomentosa var. tomentosa were collected in June of 2010 from Laiwu, Shandong Province, China, and were authenticated by Prof. Dr. Dan Wang (Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry, P. R. China). A voucher specimen (CMSCE-100618) was deposited at the Herbarium of Tianjin Key Laboratory of Pulp and Paper, College of Materials Science and Chemical Engineering, Tianjin University of Science and Technology, P. R. China. Equipment. 1H and 13C NMR, DEPT, and correlation NMR spectra including HMQC, HMBC, and TOCOSY were recorded in CD3OD or (CD3)2CO with TMS as an internal standard with a Bruker Avance DPX 400 spectrometer at the operating frequency of 400 MHz (1H) and 100 MHz (13C). MALDI TOF MS spectroscopy was performed on a Model VoyagerDE STR spectrometer, and positive FAB and EI-MS spectroscopy was measured using a micromass autospec M363 spectrometer. Eluents were collected with a fraction collector (SBS-160). TLC analyses were performed on DC-Plastikfolien Cellulose F (Merck) plates and developed with t-BuOH–AcOH–H2O (3:1:1, v/v, solvent A) and AcOH–H2O (3:47, v/v, solvent B). Visualization was conducted by UV light (254 and 365 nm) or by spraying with vanillin–AcOH–EtOH (60:0.15:6, w/v/v) or 1% ethanolic FeCl3 solution followed by heating. Melting points (uncorrected) were determined on an Electrothermal IA 9200 apparatus. Optical rotations were measured on a JASCO DIP 1000 polarimeter in MeOH.