Isolation and identification studies

Testosterone and estradiol are present m the body m only minute amounts and their isolation and identification required heroic efforts In order to obtain 0 012 g of estradiol for study for example 4 tons of sow ovaries had to be extracted ... 

Vitamin E was first described ia 1922 and the name was originally applied to a material found ia vegetable oils. This material was found to be essential for fertility ia tats. It was not until the early 1980s that symptoms of vitamin E deficiency ia humans were recognized. Early work on the natural distribution, isolation, and identification can be attributed to Evans, Butt, and Emerson (University of California) and MattiU and Olcott (University of Iowa). Subsequentiy a group of substances (Eig. 1), which fall iato either the family of tocopherols or tocotrienols, were found to act like vitamin E (1 4). The stmcture of a-tocopherol was determined by degradation studies ia 1938 (5). 

In recent year s, clinical studies on the role of uiinai y luodified nucleosides as the biochemical mai kers of various types of cancer have been actively undertaken. Most of the urinai y modified nucleosides ai e piimai ily originated by methylation of either the base part, the sugar hydroxyl par t, or in some cases, both par ts of the course of biodegradation of tRNA molecules. Hence, their isolation and identification plays a major role in biochemical analysis. 

ATPase inhibitor. In such patients, inhibition of the sodium pump in the cells lining the blood vessel wall results in accumulation of sodium and calcium in these cells and the narrowing of the vessels to create hypertension. An 8-year study aimed at the isolation and identification of the agent responsible for these effects by researchers at the University of Maryland Medical School and the Upjohn Laboratories in Michigan recently yielded a surprising result. Mass spectrometric analysis of compounds isolated from many hundreds of gallons of blood plasma has revealed that the hypertensive agent is ouabain itself or a closely related molecule ... 

Chopra NM, Campbell BS, Hurley JC. 1978. Systematic studies on the breakdown of endosulfan in tobacco smokes Isolation and identification of the degradation products from the pyrolysis of endosulfan I in a nitrogen atmosphere. J Agric Food Chem 26 255-258. 

Much remains to be accomplished in the separation, isolation, and identification of both naturally occurring and synthetic bioactive materials effective in the germination of parasitic weed seeds. Structure-activity studies suffer from the lack of separation of isomers in most synthetic samples. Strigol is an important tool in basic studies on the effect of chemicals on seed germination, but it is highly unlikely that the compound will meet practical field... 

In our study on the chemical constituents of Salvia frigida Boiss., we report here the isolation and identification of two oleanane type (componnd 1, 2) and two cycloartane type triterpenoids (compound 3,4) with the componnds a-amyrin 5 and P-sitoserol 6. The compounds have been characterized by UV/vix, IR, H NMR, NMR and MS spectroscopy. 

This limitation is well Illustrated by the failure of those methods to uncover the presence of another important group, the flavanoid, coumarin and cinnamic acid phenols (85 - 117). On the other hand, some 32 of these compounds were identified when isolation procedures specific for these types of compounds were employed. Using isolation and identification techniques which are particularly useful for alkaloids, it would be possible to determine whether any representatives of this class are present and, if so, to conduct subsequent studies for structure determination. 

Although the isolation and identification of new disaccharides, tri-saccharides and tetrasaccharides and their derivatives, either by acid hydrolysis or by controlled oxidative degradation, " would be of great help in these studies it would appear to be worth while to develop other indirect methods of approach involving the use of enzymes capable of effecting scission at specific points in the molecular complex. Better methods for the quantitative separation of sugars and their derivatives are in the process of development and it is not unlikely that in the near future it will be possible to derive formulas not only for plant gums but for the many related complex polysaccharides. 

Ashraf, M., R. Ahmad, S. Mahood, and M. K. Bhatty. Studies of the essential oils of the Pakistani species of the family Umbelliferae. XLV. Ferula assa-foetida, Linn (Herra Hing) gum oil. Pak J Sci Ind Res 1980 23 68-69. Ashraf, M., R. Ahmad, S. Mahood, and M. K. Bhatty. Studies of the essential oils of the Pakistani species of the family Umbelliferae. Part XXXV. Ferula assafoetida, Linn (Hing) seed oil. Pak J Sci Ind Res 1979 22(6) 308-310. Kleiman, R., and G. E. Spencer. Search for new industrial oils 16. Umbelliflorae-seed oils rich in petroselinic acid. J Amer OU Chem Soc 1982 59 29-32. Rajanikanth, B., B. Ravindranath, and M. L. Shankaranarayana. Volatile polysulphides of asafoetida. Phytochemistry 1984 23(4) 899—900. Shankaranarayana, M. L., B. Raghavan, and C. P. Natarajan. Odorous compounds of asafetida. VII. Isolation and identification. Indian Food Pack 1982 36(5) 65-76. 

Very detailed studies on the inhibition of alanine racemase by fluoroalanines have been conducted. This enzyme catalyzes the racemization of alanine to provide D-alanine, which is required for synthesis of the bacterial wall. This work has demonstrated that a more complex process than that represented in Figure 7.47 could intervene. For instance, in the case of monofluoroalanine, a second path (Figure 7.48, path b) occurs lysine-38 of the active site can also attack the Schiff base PLP-aminoacrylate that comes from the elimination of the fluorine atom. This enamine inactivation process (path b) has been confirmed by isolation and identification of the alkylation compound, after denaturation of the enzyme (Figure 7.48). ... 

Fukui, M. and Takahashi, S. (1983). Studies on the mating behavior of the cockroach, Nauphoeta cinerea (Olivier) (Dictyoptera Blaberidae) III. Isolation and identification of intermale recognition pheromone. Applied Entomology and Zoology 18 351-356. 

Color in food products ranks second in importance to taste in relation to consumer acceptability of a product. Discoloration problems caused by plant-protein products must be solved if these products are to be accepted. Isolation and identification of the pigments producing color is an important step in solving this problem and the methods developed in the studies presented in this chapter with cottonseed flours are applicable to color problems caused by other plant-protein products. 

Regulatory requirements in the field of drug residues analysis are limited, in most cases, to the identification of only the major metabolites. Quantitative selection of major over minor metabolites is certainly devoid of rational biological ground, since several studies have shown that the toxic metabolites are usually transitory and often present in small quantities. However, isolation and identification of all these metabolites are difficult and proper assessment of the toxicity of drug residues is still a real challenge. 

We have developed a rapid and systematic process for isolation and identification of biologically active components from natural products. The process reduces time and cost through application of advanced chromatographic instrumentation. It generates important activity and chemical information and also provides advanced active fraction(s) to accelerate isolation studies. As a result, lead prioritization, project management, and the cycle time of natural product lead discovery have been significantly improved. 

Highly-colored Jackson-Meisenheimer,or a, complexes of structure II or III are formed by addition to the ring system. The controversial history of the study of these compds has been well reviewed (Refs 44,46,51,70 82). They are formed in aq and anhydrous medium, and with a variety of organic and inorganic nucleophiles. Most of these studies have been made with 1,3,5 -trinitrobenzene rather than TNT, since the absence of a reactive methyl group in the former simplifies product isolation and identification. 

Other preliminary experiments on alkali lignin included oxidations by barium peroxide and alkali (5, 6), alkali fusion, and alkali fusions in the presence of calcium peroxide, sodium borate perhydrate, and monopersulfate compound. Ether extractives and water extractives were examined, but in all cases too many of the oxidation products obtained were new and unidentifiable, and it was impossible to evaluate the experiments adequately with the available techniques. Vanillic acid appeared to be the chief oxidation product under conditions which did not demethylate further or destroy the aromatic nature of the oxidation products. Some oxidation conditions yielded p-hydroxybenzyl moieties as products, and some gave no trace of these products whatever. More detailed studies of the ether-insoluble, water-soluble components of the several oxidation mixtures were postponed until adequate procedures were developed for analytical isolation and identification. 

Investigation into the chemical composition of citrus has led to the isolation and identification of hundreds of individual compounds. As work has continued, biochemical, nutritional and organoleptic studies have made great strides in determining which compounds are paramount in the final determination of fruit and fruit product quality. For the purpose of this discussion, we will concern ourselves with only those quality aspects affected by endogenous chemical composition and consideration of physical or descriptive parameters will be omitted. 

---