Isolation fractionation

Inhibited THF is problematic for semipreparative separations. Because small quantities of polymer are being collected along with larger volumes of solvent, more inhibitor, usually butylated hydroxytoluene (BHT), than sample is often collected in each fraction. Thus, one must carefully consider if the BHT will cause a problem in the subsequent analysis of the isolated fractions. If it does, uninhibited THF or other alternate solvents should be used. It must be remember that if uninhibited THF is used, the analyst must pay careful attention to the inevitable peroxide formation in the solvent/fractions. 

In a more recent study it was shown that the roots from G. uralensis, after isolation, fractionation and purification, contain two bioactive polysaccharides of the pectin family termed GU-3IIa-2 and 3IIb-l. 

The steroid-loaded formulations are prepared by a patented solvent evaporation process (45,46). Basically, the wall-forming polymer and the steix>id are added to a volatile, water-immiscible solvent. The dispersion or solution is added to an aqueous solution to form an oil-in-water emulsion. The volatile solvent is then removed to afford solid microparticles. The microparticles are usually subd vided with sieves to isolate fractions of the desired diameters. It is i nper-ative that a reliable and reproducible microencapsulation procedure be used to fabricate long-acting formulations. 

Stoddart, R.W. and Northcote, D.H. (1967) Metabolic relationships of the isolated fractions of the pectic substances of actively growing sycamore cells. BiochemJ. 105 45-59. 

FIGURE 11.1 (a) Schematic representation of PLC of Heracleum moellendorfi fruit, crude extract (500-pl 2% solution), system Florisil/AcOEt + B plate preeluted with benzene (b) analytical HPLC of isolated fractions, system ClS/MeOH + HjO (6 4). Abbreviations B — bergaptene, I — imperatorin, Ph — phelopterin, X — xanthotoxin. (For details, see Waksmundzka-FIajnos, M. and Wawrzynowicz, T., 7. Planar Chromatogr., 5, 169-174, 1992.)... 

Figure 11.2b and Figure 11.2c enables quantification of paclitaxel (T) and 10-deacetylbaccatin III (D) in isolated fractions [3]. 

As is shown in Table 11.1, PLC is mainly used before the identification of isolated compounds with spectral methods such as NMR or IR. Figure 11.6 shows a densi-togram of PLC of Fumaria officinalis herb extract with marked fractions being isolated (Figure 11.6a) and analytical chromatogram of isolated fractions (Figure 11.6b). 

FIGURE 11.6 (a) Densitogram of PLC of Fumaria officinalis herb extract and (b) photocopy of isolated fractions (after spraying with Dragendorff s reagent). Numbers indicate isolated fractions. System silica/CHjClj + PrOH + AcOH (5 4 1). Plates double developed. 

FIGURE 11.24 Densitogram of fraction obtained from Taxus baccata by column chromatography (silica/aqueous methanol) enriched in 10-DAB III rechromatographed by PLC in system silica/CH2Cl2 + DX + Me2CO + MeOH (84 10 5 1). Plate scanned at 366, 254, and 230 nm. Numbers indicate isolated fractions. 

This information, together with additional work on the isolated fractions, can be used in the more difficult task of extractable identification, when desired or required. 

H2 + CH4, D2, P2 + Tetralin, GO + H2O were selected and reduction was conducted by varying the reaction time. Each isolated fraction was subjected to ultimate analysis, H-NMR, C-13 NMR, molecular weight measurement and the structural parameters were calculated. The results of the study of these structural parameters in the course of the reactions were evaluated and the reaction mechanisms thereof are discussed below. 

Many researchers have attempted to unravel the mystery of the structure of humus. One approach has been to isolate fractions by extracting humus using various extraction procedures. These procedures result in the isolation of three or more fractions humic acid, fulvic acid, and humin. Humic material is isolated from soil by treating it with alkali. The insoluble material remaining after this treatment is called humin. The alkali solution is acidified to a pH of 1.0 and the precipitate is called humic acid, while the soluble... 

Mehorta and coworkers (1989) observed that isolated fractions of brain and heart cells from rats orally administered 0.5-10 mg endrin/kg showed significant inhibition of Ca+2 pump activity and decreased levels of calmodulin, indicating disruption of membrane Ca+2 transport mechanisms exogenous addition of calmodulin restored Ca+2-ATPase activity. In vitro exposure of rat brain synaptosomes and heart sarcoplasmic reticuli decreased total and calmodulin-stimulated calcium ATPase activity with greater inhibition in brain preparations (Mehorta et al. 1989). However, endrin showed no inhibitory effects on the calmodulin-sensitive calcium ATPase activity when incubated with human erythrocyte membranes (Janik and Wolf 1992). In vitro exposure of rat brain synaptosomes to endrin had no effect on the activities of adenylate cyclase or 3, 5 -cyclic phosphodiesterase, two enzymes associated with synaptic cyclic AMP metabolism (Kodavanti et al. 1988). 

CSPs and chiral mobile phase additives have also been used in the separation of amino acid enantiomers. Another technique that should be mentioned is an analysis system employing column-switching. D-and L- amino acids are first isolated as the racemic mixture by reverse-phase HPLC. The isolated fractions are introduced to a second column (a CSP or a mobile phase containing a chiral selector) for separation of enantiomers. Long et al. (2001) applied this technique to the determination of D- and L-Asp in cell culture medium, within cells and in rat blood. 

Shellfish tissue (mussel) Extract with NaOH isolate fractions with column chromatography inject fractions to GC GC or GC/MS NR 34-120 (GC) 36-87 (GC/MS) Farrington et al. 1982a... 

The development of technology for the isolation, fractionation, and purification of the principal polypeptides of VLDL, LDL, and HDL is undoubtedly a major achievement in the area of lipoprotein research. The availability of such polypeptides in pure form has permitted studies on their characterization and the definition of their chemical, physical, and immunological properties. The primary structure of many of these poly-... 

Bacitracin Bacitracins are polypeptide antibiotics that are isolated from a culture fluid of B. licheniformis. Ten individual bacitracins have been isolated bacitracins A, Ap B, C, D, E, Fp p2, Fj, and G. However, the drng itself, named bacitracin, that is used in medicine is a mixtnre of polypeptide antibiotics. All bacitracins are polypeptides that contain a thia-zole ring. However, bacitracin A, A-[[2-(l-amino-2-methylbntyl)-4,5-dihydro-4-thiazolyl] carbonyl]bacitracin F (32.7.11), makes up the main part of the isolated fractions [338-341]. 

Ceresa (78,79) studied in detail the system poly(methyl methacrylate)-acrylonitrile. Figure 25 shows the change in composition with mastication time. A study of gel formation by the block copolymers was made by subjecting the isolated fractions of block copolymers to further mastication. A wide range of block copolymers with varying composition and structure was obtained (Fig. 26). 

Fig. 7 Freeze-fracture images of hydrogenosomes from T. foetus, a Fractured cell showing a prominent Golgi (G) with several lamellae and fenestrae, as well profiles of endoplasmic reticulum (ER) in close proximity (arrows) with hydrogenosomes (H). Bar = 100 nm. b Hydrogenosomes from an isolated fraction observed by freeze-fracture. Note the clusters of intramembranous particles forming rosettes (arrow). The peripheral vesicle is smooth and does not present clusters of particles or rosettes. Bar = 50 nm. (From Benchimol et al. 2001). c Two freeze-fractured hydrogenosomes exhibiting different fracture planes (arrows). Bar = 100 nm. (From Benchimol et al. 1996a)...

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