Species-Specific Constituents

The occurrence of species-specific constituents is also analytically useful. The composition of the plant phenols of individual fruits can be analyzed quickly and very accurately by using HPLC. These data have shown that certain compounds are suitable indicators of adulteration (Table 18.42). These indicators must be fixed with great care. In fact, phloretin-2-glucoside (phloridzine) and isorhamnetinglucoside have been proposed as markers for apples and pears. Improvements in the analyses, however, showed that phloridzine and isorhamnetinglucoside widely occur in low concentrations in fruit, and the last mentioned glucoside also occurs in apples, among other fruit. 

It must be guaranteed that the selected indicator substance is stable under the production conditions for the particular fruit product. Therefore, anthocyanins are generally not suitable. For fermented products, 0-glycosides are not suitable because they are degraded by yeast enzymes. Suitable compounds are C-glycosidicaUy bound flavonoids which are resistant to enzymatic hydrolysis and common chemical hydrolysis, e. g., schaftoside (cf. Table 18.42) can be detected even in wine and champagne when the must is adulterated with fig juice. 

Adulteration of orange juice by the addition of an aqueous extract of the pulp, which remains after pressing of the juice (pulp wash), is detected by the marker N,N-dimethylproline. The levels of this amino acid are higher in pulp wash than in juice. 

---

In studies of mice, rats, and dogs, diisopropyl methylphosphonate was rapidly absorbed into plasma (Hart 1976). The plasma data indicate that all three species rapidly absorbed diisopropyl methylphosphonate, although the exact rate was species specific. Although no studies were located regarding human absorption, diisopropyl methylphosphonate is also likely to be absorbed rapidly into the plasma of humans. The ability of porous polymeric sorbents, activated carbon, and dialysis to remove diisopropyl methylphosphonate from human plasma has been studied (McPhillips 1983). The grafted butyl-XAD-4 was found to be the most efficient sorbent for the removal of diisopropyl methylphosphonate from human plasma. Hemoperfusion of plasma over synthetic XAD-4 or butyl-XAD-4 sorbent resin was more efficient than dialysis/ultrafiltration for the removal of diisopropyl methylphosphonate from human plasma the smaller surface of the packed resins provided less area to minimize damage to molecular constituents of the plasma. These methods are useful in reducing diisopropyl methylphosphonate concentrations in the plasma. However, since diisopropyl methylphosphonate and its metabolites are not retained by the body, the need for methods to reduce body burden is uncertain. 

The wide interspecies variation in the composition (Table 1.1) and the chemistry of the constituents of milk, as discussed elsewhere, renders milk species-specific, i.e., designed to meet the requirements of the young of that species. There is also a surprisingly good relationship between milk yield and maternal body weight (Figure 1.1) species bred for commercial milk production, e.g. dairy cow and goat, fall above the line. 

A number of zinc compounds with organic constituents (e.g., zinc salts of organic acids) have therapeutic uses. These include antidandruff zinc pyridinethione, antifungal zinc undecylenate used to treat athlete s foot, zinc stearate and palmitate (zinc soap), and antibacterial zinc bacitracin. Zinc naphthenate is used as a low-toxicity wood preservative, and zinc phenolsulfonate has insecticidal properties and was once used as an intestinal antiseptic. The inhalation of zinc soaps by infants has been known to cause acute fatal pneumonitis characterized by lung lesions similar to, but more serious than, those caused by talc. Zinc pyridine thione (zinc 2-pyridinethiol-l-oxide) has been shown to cause retinal detachment and blindness in dogs this is an apparently species-specific effect because laboratory tests at the same and even much higher dosages in monkeys and rodents do not show the same effect. 

It has long been known that the basic "brothy" flavor of cooked meat is due to the interaction of low molecular weight, water-soluble constituents of muscle. The species specific flavor compounds are... 

As a result of the availability of sophisticated Instrumentation and separation techniques some remarkable progress has already been made In meat flavor research and this trend Is expected to continue. Although a variety of factors are known to affect the development of meat flavor, no single compound/group of compounds, or factor has yet been found that could play the principle role and the true chemical nature of meat flavor, and particularly species differentiation. Is not fully understood. Most Importantly very little Is known about the origin of cured-meat flavor. The curing process seems to simplify the composition of the volatile constituents and eliminates the overtones related to species-specific flavor notes. Thus, work in this area would have a major impact in meat-flavor research and may prove to be extremely... 

Excited species can lose their energy by collision (or quenching) with other molecules. However, in the upper atmosphere, where the density of air molecules is relatively small and more high energy photons are available to produce excited species, many constituents fluoresce or chemiluminesce. Thus, photons of specific wavelengths are released, producing characteristic airglow emissions. Many of these emissions can also be used to deduce information about the concentrations of atmospheric species. Table 2.1 presents a summary of some of the more... 

As can be seen from Table I, the most commonly affected organ is the liver followed closely by the lungs. The effects on other organs have been less frequently observed and appear to be more species specific. The possibility that plant constituents other than alkaloids influence the course of toxic effects cannot be overlooked, especially when attempts to evaluate the significance of diverse feeding experiments are made. 

Melittin a linear, toxic (hemolytic) polypeptide amide, and the chief component of bee venom (about 50 % of dried venom, and at least in 50-fold molar excess over other venom constituents). The primary product of M. biosynthesis is prepromelittin, consisting of 70 amino acid residues Removal of the N-terminal signal sequence of 21 residues (see Signal hypothesis) leaves promelittin. The protease required for removal of the signal sequence is present in many animal cells and is not species-specific, e. g. promelittin and not prepromelittin is the first detectable product when melittin mRNA is injected into oocytes of Xenopus laevis. 

The occurrence of organic compounds within trench sediments was also assessed as part of the DOE-RL study (1990). The presence of organic compounds in sediments/soils is important because they can form complexes with radionuclides, thus enhancing their mobility. Specific compounds were identified, including alkenes, alkanes, alkynes, elemental sulfur, and three cyclic sulfur species. Organic constituent concentrations are presented in Table 5-17. 

Fresh wood after cutting has a characteristic odor that diminishes continuously over time. However, some species retain a fragrance for a long time, which gives them an additional value. The odor constituents of wood are formed as secondary metabolites by species-specific biosynthetic pathways, like the coloring matter described in the previous section. Therefore the odor of wood can sometimes be used for the identification of wood species. 

Information of this type is provided by the quantitative analysis of various constituents, determination of species-specific compounds, and by the determination of abundance ratios of isotopes. 

A.lthough characterized by species specific differences, the experiments performed with Vicia faba and Hordeum vulgare point to the existence of at least four different chlorophyll a/b-proteins all of which are translated by cytoplasmic ribosomes and enriched in the grana region of the membranes. Three chlorophyll a/b-proteins were found to be constituents of the light-harvesting complex. One chlorophyll a/b-protein (Chi a/b-P 1) differs in at least three details from the others. 

Essential features of an automated method are the specificity, ie, the assay should be free from interference by other semm or urine constituents, and the sensitivity, ie, the detector response for typical sample concentration of the species measured should be large enough compared to the noise level to ensure assay precision. Also important are the speed, ie, the reaction should occur within a convenient time interval (for fast analysis rates), and adequate range, the result for most samples should fall within the allowable range of the assay. 

In this way, the near-linear chlorophyll-phosphorus relationship in lakes depends upon the outcome of a large number of interactive processes occurring in each one of the component systems in the model. One of the most intriguing aspects of those components is that the chlorophyll models do not need to take account of the species composition of the phytoplankton in which chlorophyll is a constituent. The development of blooms of potentially toxic cyanobacteria is associated with eutrophication and phosphorus concentration, yet it is not apparent that the yield of cyanobacterial biomass requires any more mass-specific contribution from phosphorus. The explanation for this paradox is not well understood, but it is extremely important to understand that it is a matter of dynamics. The bloom-forming cyanobacteria are among the slowest-growing and most light-sensitive members of the phytoplankton. ... 

Definition and Uses of Standards. In the context of this paper, the term "standard" denotes a well-characterized material for which a physical parameter or concentration of chemical constituent has been determined with a known precision and accuracy. These standards can be used to check or determine (a) instrumental parameters such as wavelength accuracy, detection-system spectral responsivity, and stability (b) the instrument response to specific fluorescent species and (c) the accuracy of measurements made by specific Instruments or measurement procedures (assess whether the analytical measurement process is in statistical control and whether it exhibits bias). Once the luminescence instrumentation has been calibrated, it can be used to measure the luminescence characteristics of chemical systems, including corrected excitation and emission spectra, quantum yields, decay times, emission anisotropies, energy transfer, and, with appropriate standards, the concentrations of chemical constituents in complex S2unples. 

---