Methanolic extract

Xylose is obtained from sulfite Hquors, particularly from hardwoods, such as birch, by methanol extraction of concentrates or dried sulfite lyes, ultrafiltration (qv) and reverse osmosis (qv), ion exchange, ion exclusion, or combinations of these treatments (201). Hydrogenation of xylose is carried out in aqueous solution, usually at basic pH. The Raney nickel catalyst has a loading of 2% at 125°C and 3.5 MPa (515 psi) (202,203). 

A compound with the elemental composition C15//22O3 was isolated from the methanol extract of the Chilean medicinal plant Centaurea chilensis (Compositae)What is the structure of the natural product, given the NMR experiments 47 ... 

Bio-assay guided fractionation of the methanolic extract of the African climbing shrub Stephania dinklagei contains six bioactive alkaloids, among... 

Fig. 3.1.2 The apparatus used in 1956 for the methanol extraction of Cypridina luciferin. The dried Cypridina (500 g) is extracted at a temperature lower than 40°C with refluxing methanol under reduced pressure for two days. The atmosphere inside the apparatus is completely replaced with hydrogen gas that was purified by its passing through a quartz tube containing red-heated copper fragments. The temperature of the mantle heater is adjusted, the system evacuated, and then all stopcocks are closed. The extraction with refluxing methanol continues for many hours without any further adjustment. From the author s 1957 notebook.

Purification of luciferin (Rudie etal., 1976). The luciferin fractions from the DEAE-cellulose chromatography of luciferase were combined and concentrated in a freeze-dryer. The concentrated solution was saturated with ammonium sulfate, and extracted with methyl acetate. The methyl acetate layer was dried with anhydrous sodium sulfate, concentrated to a small volume, then applied on a column of silica gel (2 x 18 cm). The luciferin adsorbed on the column was eluted with methyl acetate. Peak fractions of luciferin were combined, flash evaporated, and the residue was extracted with methanol. The methanol extract was concentrated (1 ml), then chromatographed on a column of SephadexLH-20 (2 x 80 cm) usingmethanol asthe solvent. The luciferin fractions eluted were combined and flash evaporated. The residue was... 

Coelenterazine and the corresponding luciferase can be easily tested in the field. A small piece of tissue sample is put in a test tube with methanol (for coelenterazine) or water (for luciferase), and crushed with a spatula. To measure coelenterazine, a buffer solution containing a coelenterazine luciferase is injected into a small amount of the fluid part of the crushed sample mixture. Similarly, luciferase can be measured with a buffer solution containing coelenterazine. The presence of Cypridina luciferin can be tested in the same fashion, with the methanol extract of samples and crude Cypridina luciferase. However, the detection of a very weak Cypridina luciferase activity in the field is not recommended (see Section C5.6). To test the presence of a Ca2+-sensitive photoprotein, crush a sample in a neutral buffer solution containing 20-50 mM EDTA, and then add lOmM calcium acetate to a small portion of the fluid part of the crushed sample to detect any light emission. 

A 250-mL, two-necked, round-bottomed flask equipped with a magnetic stirbar, thermometer, and a reflux condenser fitted with a rubber septum and balloon of argon is charged with a solution of methyltrioxorhenium (MTO) (0.013 g, 0.05 mmol, 0.1% mol equiv) in 100 mL of methanol (Note 1). Urea hydrogen peroxide (UHP) (14.3 g, 152 mmol) is added (Notes 1, 2, 3, 4), the flask is cooled in an ice bath, and dibenzylamine (9.7 mL, 50.7 mmol) is then added dropwise via syringe over 10 min (Notes 1, 5). After completion of the addition, the ice bath is removed and the mixture is stirred at room temperature (Note 6). A white precipitate forms after approximately 5 min (Note 7) and the yellow color disappears within 20 min (Note 8). Another four portions of MTO (0.1% mol equiv, 0.013 g each) are added at 30-min intervals (2.5 hr total reaction time). After each addition, the reaction mixture develops a yellow color, which then disappears only after the last addition does the mixture remain pale yellow (Note 9). The reaction flask is cooled in an ice bath and solid sodium thiosulfate pentahydrate (12.6 g, 50.7 mmol) is added in portions over 20 min in order to destroy excess hydrogen peroxide (Note 10). The cooled solution is stirred for 1 hr further, at which point a KI paper assay indicates that the excess oxidant has been completely consumed. The solution is decanted into a 500-mL flask to remove small amounts of undissolved thiosulfate. The solid is washed with 50 mL of MeOH and the methanol extract is added to the reaction solution which is then concentrated under reduced pressure by rotary evaporation. Dichloromethane (250 mL) is added to the residue and the urea is removed by filtration through cotton and celite. Concentration of the filtrate affords 10.3 g (97%) of the nitrone as a yellow solid (Note 11). 

Partially purified brain gangliosides Chloroform-methanol-extracted >500... 

Analysis of soils and sediments is typically performed with aqueous extraction followed by headspace analysis or the purge-and-trap methods described above. Comparison of these two methods has found them equally suited for on-site analysis of soils (Hewitt et al. 1992). The major limitation of headspace analysis has been incomplete desorption of trichloroethylene from the soil matrix, although this was shown to be alleviated by methanol extraction (Pavlostathis and Mathavan 1992). 

To obtain anthocyanins closer to their natural state, a number of researchers have used neutral solvents for initial extraction such as 60% methanol, n-butanol, cold acetone, mixtures of acetone, methanol, and water, or simply water. Methanol is the most common solvent used for anthocyanin extraction. Metivier et al. (1980) compared the efficiency of extraction with three different solvents (methanol, ethanol, and water) and different acids, and found that methanol extraction was 20% more effective than ethanol and 73% more effective than water when used for anthocyanin recovery from grape pomace. 

The synthetic 31 was converted to the cyanoglucoside osmaronin (41a) which was isolated from a methanolic extract of the leaves of Osmaronia cerasi-formis. Acetylation of 31 gave an acetate (99% yield) which was subjected to ozonolysis to afford a ketone 42. The Horner-Emmons reaction of 42 using diethyl cyanomethylphosphonate furnished (Z)-43a (22% yield from the acetate of 31) and ( )-43b (10% yield from the acetate of 31). Deprotection of (Z)-43a and ( )-43b gave the (3-D-glucosides 41a (83% yield) and 41b (94% yield), respectively. The spectral data of the synthetic 41a were identical with those ( H- and C-NMR) of the natural osmaronin (41a) (Fig. 5). 

Golden root (Roseroot, R. rosea L., Crassulaceae) has been used for a long time as a resource in Chinese traditional medicine to enhance the body s resistance against fatigue and to extend human life. Rosavin (121) was isolated as one of the chemical constituents of R. rosea by Kurkin et al. and 4-methoxycinnamyl 6-G-(a-L-arabinopyranosyl)-(3-D-glucopyranoside (122) and cinnamyl 6-0-(p-D-xylopyranosyl)-(3-D-glucopyranoside (123) were also isolated from an aqueous methanol extract of R. rosea by Ari et al. (Fig. 27). 

Chloroform-methanol extracts of Borrelia burgdorferi were used for the identification of lipids and other related components that could help in the diagnosis of Lyme disease [58]. The provitamin D fraction of skin lipids of rats was purified by PTLC and further analyzed by UV, HPLC, GLC, and GC-MS. MS results indicated that this fraction contained a small amount of cholesterol, lathosterol, and two other unknown sterols in addition to 7-dehydrocholesterol [12]. Two fluorescent lipids extracted from bovine brain white matter were isolated by two-step PTLC using silica gel G plates [59]. PTLC has been used for the separation of sterols, free fatty acids, triacylglycerols, and sterol esters in lipids extracted from the pathogenic fungus Fusarium culmorum [60]. 

Enzyme-linked immunosorbent assay (ELISA). Li and Li developed an ELISA procedure for imidacloprid to determine its residues in coffee cherry and bean extracts. A 25-g amount of sample extracted with 300 mL of methanol and 1% sulfuric acid (3 1, v/v) for 3 min. An aliquot of the sample extract (0.5 mL) is mixed with 1 mL of water and a gentle stream of nitrogen is used to evaporate methanol. The solution is then extracted with 1 mL of ethyl acetate, the extract is reconstituted in 1 mL of PBST (phosphate-buffered saline containing 0.05% Tween 20) and competitive ELISA is performed to quantify imidacloprid in the extract. Eor methanol extracts of coffee cherries and beans fortified with imidacloprid at 0.5 mgL recoveries of imidacloprid by the ELISA method were 108 and 94, respectively. 

A 20-mL aliquot of the aqueous methanol extract obtained from above (corresponding to 5 g of each sample) is transferred on to the column previously conditioned by washing successively with 10 mL of methanol and 10 mL of distilled water, and the sample solution is drained. The column is washed with three portions of 5 mL of methanol-water (7 3, v/v), and then M.A3 and M.A4 are eluted from the column with 3 mL of methanol. To the eluate, 10 mL of methanol are added and the mixture is concentrated below 45 °C under reduced pressure. 

A 10-g amount of each minced and homogenized plant sample is weighed into a 300-mL volumetric flask, 100 mL of methanol-water (7 3, v/v) are added and the mixture is shaken vigorously for 30 min. The resulting mixture is filtered with a glass filter by suction. The residue is re-extracted with lOOmL of the same solvent and filtered. The combined aqueous methanol extracts are transferred into a 500-mL round-bottom flask and concentrated to 30 mL under reduced pressure below 45 °C. 

The activity in the aqueous extract was also effectively partitioned into a diethyl ether organic phase. At this step, relative inhibition increased compared to the methanol extract. The organic phase extract caused 96, 93, and 89% inhibition of C . album hypocotyl length, root length, and germination, respectively (data not shown). 

Brack [81] has illustrated the analysis of antioxidants in a CB-free vulcanisate of unknown composition according to Scheme 2.7. Some components detected by off-line TD-GC-MS (cyclohexylamine, aniline and benzothiazole) were clearly indicative of the CBS accelerator other TD components were identified as the antioxidants BHT, 6PPD, Vulcanox BKF and the antiozonant Vulkazon AFS. In the methanol extract also the stabiliser ODPA was identified. The presence of an aromatic oil was clearly derived from the GC-MS spectra of the thermal and methanol extracts. The procedure is very similar to that of Scheme 2.3. 

GC is extensively used to determine phenolic and amine antioxidants, UV light absorbers, stabilisers and organic peroxide residues, in particular in polyolefins, polystyrene and rubbers (cf. Table 61 of Crompton [158]). Ostromow [159] has described the quantitative determination of stabilisers and AOs in acetone or methanol extracts of rubbers and elastomers by means of GC. The method is restricted to analytes which volatilise between 160 °C and 300 °C without decomposition. A selection of 47 reports on GC analysis of AOs in elastomers (period 1959-1982) has been published... 

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