Central Composite Design for Optimized Extraction of Polysaccharides from Undaria pinnatifida

Response surface methodology was used to optimize the extraction conditions of polysaccharides from Undaria pinnatifida. The effects of three independent variables, extraction time, extraction temperature and ratio of water to raw material were investigated by a central composite design. The experimental data were fitted to a second-order polynomial equation via multiple regression analysis and also examined with the appropriate statistical methods. The adjusted coefficient of determination(R_ADj²) for the model was 0.9171. An optimum extraction yield of 30.78% was obtained when the extraction temperature was 95℃, extraction time was 4.5 h, and the ratio of water to raw material was 35(mL/g). Under these conditions, validation experiments were done and the mean extraction yield of polysaccharides was 30.79%, which was in good agreement with the predicted model value.     

裙带菜中聚甘露糖醛酸的分离纯化与结构分析

以裙带菜(Undaria pinnatifida, wakame)为原料, 经水提醇沉、DEAE-Sepharose Fast Flow、Sephacryl S-300和Sephacryl S-200凝胶柱分离纯化, 得到2个酸性多糖UPPS03和UPPS04. 高效凝胶渗透色谱测试结果表明, 其为均一多糖, 平均分子量分别为3.6×104和1.1×104. 采用糖组成分析、高碘酸氧化及Smith降解、糖醛酸还原、甲基化、红外光谱和核磁共振等方法对该多糖的化学结构进行了表征. 结果表明, 2个多糖均为1,4连接的聚甘露糖醛酸.     

Undariase,a Direct-Acting Fibrin(ogen)olytic Enzyme from Undaria pinnatifida,Inhibits Thrombosis In Vivo and Exhibits In Vitro Thrombolytic Properties

A direct-acting fibrinolytic serine protease named undariase possessing anticoagulant and antiplatelet properties was purified from Undaria pinnatifida. Undariase showed a molecular weight of 50 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry. It displayed a strong fibrin zymogram lysis band corresponding to the same molecular mass. The N-terminal sequence of undariase, LTATTCEELAAAPTD, does not match with any known fibrinolytic enzyme. The enzyme was stable and active at high temperatures (35–70 °C). The fibrinolytic activity of undariase was strongly inhibited by phenylmethylsulfonyl fluoride (PMSF) and 4-(amidinophenyl) methanesulfonyl fluoride (APMSF). The K _m and V _max values for substrate S-2251 were determined as 6.15 mM and 90.91 mM/min/ml, respectively. Undariase resulted in clot lysis by directly cleaving α and β chains of fibrin. Similarly, it preferentially acted on the Aα chain of fibrinogen followed by cleavage of the Bβ chain. It significantly prolonged the PFA-100 closure times of citrated whole human blood. In addition, undariase delayed the coagulation time and increased activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). Undariase exerted a significant protective effect against collagen plus epinephrine-induced pulmonary thromboembolism in mice. It prevented carrageenan-induced thrombus formation in the tail of mice. It also resulted in prolongation of APTT ex vivo. In conclusion, these results suggested a therapeutic potential of undariase for thrombosis.     

Lipidomics of the Edible Brown Alga Wakame (Undaria pinnatifida) by Liquid Chromatography Coupled to Electrospray Ionization and Tandem Mass Spectrometry

The lipidome of a brown seaweed commonly known as wakame (Undaria pinnatifida), which is grown and consumed around the world, including Western countries, as a healthy nutraceutical food or supplement, was here extensively examined. The study was focused on the characterization of phospholipids (PL) and glycolipids (GL) by liquid chromatography (LC), either hydrophilic interaction LC (HILIC) or reversed-phase LC (RPLC), coupled to electrospray ionization (ESI) and mass spectrometry (MS), operated both in high and in low-resolution mode. Through the acquisition of single (MS) and tandem (MS/MS) mass spectra more than 200 PL and GL of U. pinnatifida extracts were characterized in terms of lipid class, fatty acyl (FA) chain composition (length and number of unsaturations), and regiochemistry, namely 16 SQDG, 6 SQMG, 12 DGDG, 5 DGMG, 29 PG, 8 LPG, 19 PI, 14 PA, 19 PE, 8 PE, 38 PC, and 27 LPC. The FA (C16:0) was the most abundant saturated acyl chain, whereas the monounsaturated C18:1 and the polyunsaturated C18:2 and C20:4 chains were the prevailing ones. Odd-numbered acyl chains, iJ., C15:0, C17:0, C19:0, and C19:1, were also recognized. While SQDG exhibited the longest and most unsaturated acyl chains, C18:1, C18:2, and C18:3, in the sn-1 position of glycerol, they were preferentially located in the sn-2 position in the case of PL. The developed analytical approach might pave the way to extend lipidomic investigations also for other edible marine algae, thus emphasizing their potential role as a source of bioactive lipids.     

Determination of Polysaccharides in Undaria pinnatifida by Ionic Liquid-Modified Silica Gel Size Exclusion Chromatography

Ionic liquid-modified silica particles with a large pore size were synthesized and used as the stationary phase for size exclusion chromatography coupled with a refractive index detector for the determination of polysaccharides, such as fucoidan, alginic acid, and laminarin from Undaria pinnatifida (seaweed). The molecular weight of polysaccharide was determined by a dextran standard curve (5–1100?kDa). The ionic liquid-modified silica column exhibited excellent size exclusion properties in separating laminarin from other components. The 1-butyl-3-methyl-imidazolium bis-(trifluoromethylsulfonyl)-amino silica column has superior resolution in laminarin separation than the other columns because the amino-group in ionic liquid provide π–π interactions due to aromaticity of the ring structure, which enhances the effect of the hydroxyl group in the target compound separation. The concentrations of polysaccharides were calculated using a standard linear equation to be 0.332–0.484?mg/g of fucoidan, 0.207–0.301?mg/g of alginic acid, and 0.154–0.297?mg/g of laminarin.     

Novel Bis(bibenzyl) and (Propylphenyl)bibenzyl Derivatives from Dendrobium nobile

Two novel compounds possessing a bis(bibenzyl) (see 1 ) and a (propylphenyl)bibenzyl skeleton (see 2 ) and eight known compounds were isolated from the stems of Dendrobium nobile Lindl . (Orchidaceae). Their structures were identified by spectroscopic analyses.     

Zinc(II) complexes of constrained antiviral macrocycles

The configurations of metallocyclams are of interest in relation to protein recognition and anti-HIV activity. We have synthesised four novel zinc(II) complexes with hexyl-Me(2)-cyclam (HMC; 3,14-dimethyl-2,6,13,17-tetraazatricyclo(16.4.0.0(7,12))docosane), 1, and naphthyl-hexyl-Me(2)-cyclam (NHMC; 2,13-bis(1-naphthylmethyl)-5,16-dimethyl-2,6,13,17-tetraazatricyclo(16.4.0.0(7,12))docosane), 2, as ligands. X-ray crystallographic data for Zn(II)-HMC diacetate, 3 show that zinc is six-coordinate in a distorted octahedral environment bound to four equatorial N atoms from the macrocycle and two axial acetato O atoms. The 14-membered metallo-macrocycle adopts a trans-III (RRSS) configuration with two six-membered rings in chair forms and two five-membered rings in gauche forms. In the chlorido Zn(II)-HMC complex 5, zinc appears to be 5-coordinate with square-pyramidal geometry. Interestingly, the chlorido Zn(II)-NHMC complex 6 crystallised in a trans-I configuration containing 4-coordinate tetrahedral zinc bound to three cyclam ring N atoms, a possible model for intermediates formed during the uptake and release of metals by cyclams. The ligand 1 and the zinc complex 3 were active towards viral strains HIV-1 (III(B)) (IC(50) values of 10.51 ± 0.23 and 3.50 ± 0.33 μM, respectively), and HIV-2 (ROD) (IC(50) values of 133.78 ± 14.10 and >110.67 μM, respectively). 2D [(1)H, (13)C] and [(1)H, (15)N] NMR spectroscopic studies suggested that the types of configurational isomers present in solution depend on the axial ligand.     

Synthesis of (±)-ascochlorin,an antiviral antibiotic

(±)-Ascochlorin, 5-chloro-2, 4-dihydroxy-6-methyl-3-[(2$\text{E}$, 4$\text{E}$)-5-(1,2,6-trimethyl-3-oxocyclohexyl)3-methyl-3,4-pentadienyl] benzaldehyde, was synthesized in 14 steps from (±)-3,4-dimethyl-2-cyclohexenone.     

Novel,Complex Flavonoids from Mallotus philippensis (Kamala Tree)

One new flavanone, 4′‐hydroxyisorottlerin ( 2 ), and two new chalcone derivatives, kamalachalcones C ( 3 ) and D ( 4 ), were isolated from Mallotus philippensis (kamala tree). The largest compound ( 4 ; M_r 1098 g/mol) was shown to possess a unique, fused‐ring system made of two hydroxy‐chalcone units, giving rise to eight fused benzene/pyran units. From the same plant, the following six known compounds were also isolated: kamalachalcone A ( 5 ) and B ( 6 ), isoallorottlerin ( 7 ), isorottlerin ( 8 ), 5,7‐dihydroxy‐8‐methyl‐6‐prenylflavanone ( 9 ); 6,6‐dimethylpyrano(2″,3″: 7,6)‐5‐hydroxy‐8‐methylflavanone ( 10 ), and rottlerin ( 1 ). The structures of the new compounds were confirmed by in‐depth spectral analyses, including 2D‐NMR techniques, and the full ¹³C‐NMR assignments of the known flavanones 1 and 7 – 10 are published for the first time.     

Novel blends from agave fibers and poly(methyl methacrylate)

Cellulose-rich fibers were isolated from Agave lechuguilla (AL) and Agave fourcroydes (AF) growing in the Mexican northeast. These fibers are a valuable feedstock for the preparation of blends with synthetic polymers like poly(methyl methacrylate), PMMA. Blends of different types of agave fibers (dewaxed, mercerized, and grafted) and PMMA were prepared and investigated by means of tension measurements and dynamic mechanical analysis. The fiber-containing blends are more stable than the plain PMMA. Surprisingly, the mechanical stability of the blends is practically independent of the pretreatment of the fibers. Methyl methacrylate (MMA) was grafted onto the biopolymer fibers initiated by the cerammonium nitrate redox initiator. Grafting yields of 26.5% were realized with fibers from AL while up to 75.8% MMA was grafted onto fibers from AF. The materials were characterized by means of FTIR spectroscopy and DSC.     

Novel poly(amide-imide)s from 2,6-bis(5-amino-1-naphthoxy) pyridine

Reaction of 5-amino-1-naphthol with 2,6-dichloropyridine resulted in preparation of 2,6-bis(5-amino-1-naphthoxy) pyridine (AN). This pyridine-based ether diamine was reacted with two moles of trimellitic anhydride (TMA) to synthesize related diimide-diacid (DIDA). Direct polycondensation reaction of DIDA with different diamines in the presence of triphenyl phosphite (TPP) afforded seven different poly(amide-imide)s. All the polymers were characterized and their physical and thermal properties were studied. The inherent viscosity of the polymers was about 0.44-0.50 dl g⁻¹ and they showed high thermal stability.     

Novel polymers of intrinsic microporosity (PIMs) derived from 1,1-spiro-bis(1,2,3,4-tetrahydronaphthalene)-based monomers

The synthesis of novel monomers based upon the rigid 1,1′-spiro-bis(1,2,4,5-tetrahydro-6,7-dihydroxynaphthalene) framework is reported. These monomers can be used for the synthesis of polymers of intrinsic microporosity (PIMs) due to their reactive catechol units and nonlinear shape, which introduces the necessary sites of contortion into the resulting PIM.     

Novel materials from bis(arene)metal‐containing polyacrylonitrile

Novel bis(arene)metal‐containing polyacrylonitrile materials have been prepared by the polycyanoethylation reaction between acrylonitrile and (arene)₂M (M = Cr or V; arene = PhH, C₆H₄Et₂ or mesitylene) in the absence of solvent. The resulting star‐shaped molecules consist of a central (arene)₂M species with up to four polyacrylonitrile arms covalently bonded to the arene ligands. The materials are readily soluble and films can be cast from solutions in acetonitrile. The IR and solid state ¹³C NMR spectra (or EPR spectrum for the oxidized chromium‐containing polymer) are consistent with the presence of a metal–arene bond and confirm the persistence of the sandwich structure. The properties of the thermolysed materials are consistent with the formation of conjugated naphthyridine‐type structures. The value of |n₂| determined by the degenerate four‐wave mixing technique at 1064 nm with a 6 ns pulse duration for a solution in conc. H₂SO₄ (1 g l⁻¹) of the chromium‐containing polymer pyrolysed at 350 °C was found to be 0.8 × 10⁻¹³ cm² W⁻¹ corresponding to |lRe _χ⁽³⁾| = 0.4 × 10⁻¹¹ esu.     

Two Novel Plumeran Indole Alkaloids Isolated from Aspidosperma cylindrocarpon (Apocynaceae)

Two novel indole alkaloids with plumeran skeleton, N‐benzoyl‐12‐demethoxycylindrocarine and N‐cinnamoyl‐12‐demethoxycylindrocarine ( 1 and 2 , resp.), were isolated from the MeOH extract of the stem bark of Aspidosperma cylindrocarpon Müll .Arg . These compounds were obtained by high‐speed counter‐current chromatography, and their structures were elucidated on the basis of their NMR (1D and 2D) data. They were tested in vitro against chloroquine‐resistant strains of Plasmodium falciparum, and only 2 showed a weak activity (IC₅₀ 127.97 ng/ml with respect to the standard drug). Several other known compounds, comprising steroids, flavonoids, the rarely found atraric acid, as well as the previously reported alkaloid 3 , were also isolated by conventional chromatographic techniques.     

Novel drug delivery microspheres from poly(1,5-dioxepan-2-one-co-L-lactide)

Novel microspheres from copolymers of 1,5-dioxepan-2-one (DXO) and L -lactide (L -LA) were prepared by oil-in-water solvent evaporation and oil-in-oil solvent removal. The two preparation techniques were evaluated for sphere formulation and incorporation of two different drugs. Sustained release of these therapeutic substances was obtained. The consequences of altering the DXO : LA ratio, preparation method, and drug hydrophilicity were explored and identified as factors governing sphere quality, in vitro degradation, and drug release characteristics. We show that these relationships provide a powerful means of controlling the microsphere performance. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1877–1884, 1999