Natural occurrence, detected

Phyllospadine was characterized as its triacetate. Its alkaloidal nature was detected by a positive Dragendorff s reaction and its flavonoidal nature by its UV spectrum and the co-occurrence of the parent flavonoid hispidulin (38). The H-NMR spectrum showed signals identical to those of 38 apart from the lack of the signal at 8 7.22 attributed to 8-H. The attachment of the nitrogenous ring was therefore reckoned to be at this position. The characterization of the ring as N-... 

To date, the O-sulfation of hydroxyamino acids as residues in proteins or as free amino acids has not been detected. Similarly, desulfation by sulfatases has been observed only for sulfated serine, but it could not be attributed unambiguously to a sulfatase.11301 This lack of natural occurrence explains why only marginal attention has been paid to the synthesis of sulfated hydroxyamino acid peptides. 

However, it should be kept in mind that the origin and natural occurrence of odd-numbered y-lactones is still not understood and their contribution to food flavour impression is rather limited or negligible, when trace amounts—far below their odour thresholds—are detected. 

In this chapter the enzymic reactions mentioned above will be reviewed. In addition, consideration will be given to the detection, determination, and natural occurrence of pyrrolidone carboxylic acid, the nonenzymic formation of pyrrolidone carboxylic acid, and to other information now available about the metabolism of this compound. 

A detailed list of the natural materials in which ww/o-inositol has been detected is presented by Fleury and Balatre,87 and additional reports of its natural occurrence continue to appear. It is clear that myo-inositol is one of the most ubiquitous of organic compounds. Insofar as the authors are aware, no plant or animal tissue which has been examined by an ade-... 

Gas phase molecular aggregates that contain acid molecules have been produced with free jet expansion techniques and detected by using electron impact ionization mass spectrometry. The clusters of aqueous nitric acid paralleled many properties of the condensed phase. Multiple nitric acid molecules were found in the clusters that were sufficiently dilute. The acid molecule was absent in the ionized clusters involving HC1 and only water was evident. Experiments also demonstrated the reactivity of ammonia with aqueous nitric acid and sulfur dioxide clusters and of sulfur trioxide with water clusters. The natural occurrence of acid cluster negative ions offers a means to probe the gas phase acid loading of the atmosphere through laboratory and field studies of the ion chemistry. 

Scott (2001) summarized the available literature on the natural occurrence of Alternaria toxins in fruits. The most frequently detected toxins were alternariol, alternariol methyl ether, and tenuazonic acid in apples, mandarin, melon, and alternariol and its methyl ether in red currant, raspberry, strawberry, gooseberry, and blackberry. Stinson et al. (1980) were able to detect Alternaria toxins after the authors isolated Alternaria strains from blueberries, broke the skin, and inoculated the berries after steam disinfection. In contrast, Tournas and Stack (2001) did not detect Alternaria toxins after infection of blueberries with A. alternata. As discussed earlier in this chapter, fruits become more susceptible to mold invasion during ripening, and this may be a crucial point for inoculation experiments. 

The present study is focussed on screening analyses of water samples which were taken from the longitudinal section of a river. A selection of the identified compounds is presented here as well as available information about their natural occurrence and/or industrial application. Some contaminants of special interest are discussed in detail. Besides, in order to reconstruct input pathways of frequently detected compounds... 

Further on, a wide variety of esters were detected containing specific molecular moieties characterizing man made chemicals. E.g. the 2-ethylhexyl group represents a molecular substructure frequently used in the technosphere dominantly as the corresponding alcohol or acid, but the natural occurrence of this molecular moiety is very scarce. Thus, the detected 2-hydroxypropylester of 2-ethylhexanoic acid represents a specific anthropogenic contaminant. The fro-propyl and butyl esters identified also reflect mainly the emission of technical contaminants chiefly derived from migration processes of polymer additives. 

Very little is known about the natural occurrence of 1,3,5-triazine compounds. Cyanuric acid has been detected in soil humus,68-70 and although melamine71,72 and ammeline73 have been reported as components of certain carbonaceous meteorites, a more recent reinvestigation74 showed that only very small traces of 1,3,5-triazines are present. 1,3,5-Triazines have been identified in soil, crops (fruits, vegetables) and rivers due to the persistence or only partial degradation of 1,3,5-triazine pesticides.469... 

Kuksis A, Kamido H, and Ravandi A (2003) Glyceropho-spholipid core aldehydes Mechanism of formation, methods of detection, natural occurrence, and biological significance. In Kamal-Eldin A (ed.) Lipid Oxidation Pathways, pp. 138-189. Champaign AOCS Press. 

Poly(ADP-ribose) has been expected to play some regulatory roles in nuclear functions. However, its amoimt and distribution in vivo have not yet been fully elucidated. An immunohistochemical method should be useful for the study of the natural occurrence of poly(ADP-ribose) at the cellular level. We have developed a highly sensitive immunohistochemical mediod for detecting poly(ADP-ribose) in conventional histological sections (1,2). 

Even though the conversion of Z to (OX)Z had been clearly demonstrated, the natural occurrence of (OX)Z needed to be confirmed. Therefore, extracts were obtained from young embryos of P. vulgaris and purified by a combination of Sephadex, DEAE and reversed phase HPLC columns. GC-MS analyses of the purified extracts resulted in the detection of (OX)Z and its ribonucleoside as well as O-xylosyldihydrozeatin ((OX) (diH)Z). Thus the O-xylosyl derivatives of Z are naturally occurring compounds. Incubation of embryos of two other species, P. coccineus and P. acutifolius, with radiolabeled Z also led to the formation of (OX)Z and its dihydro-derivative [24]. These results indicate that O-xylosylation occurs in three of the four Phaseolus species examined thus far, P. lunatus being the exception. The interspecific differences are further elaborated on in some of the following sections. 

FMEA worksheets will typically identify whether corrective action is required based on a combination of severity, occurrence, detection, and/or RPN values. After RPN assessment, recommended actions are suggested. After implementation of the recommended action, the entire issue is reassessed to get an indication the effectiveness of the corrective action. Naturally, with a revised set of severity, occurrence and detection ratings a new RPN is calculated. From these two values it is possible to get % reduction in RPN ... 

Hsia CC, Wu JL, Lu XQ, Li YS (1988) Natural occurrence and clastogenic effects of nivalenol, deoxynivaltmol, 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, and zearalenone in com liom a high-risk area of esophageal cancer. Cancer Detect Prev 13 79... 

In our poster presentation earlier in this conference we reported finding dodecenyl alcohol and tetradecenyl alcohol in four varieties of untreated apples at concentrations ranging from 70-130 ppb. The natural occurrence of these compounds in apples had been reported in 1976, but not quantitated (5). The irony is that they are two of the five components in an experimental lepidopteran insect sex pheromone for which residue determinations were made of all components on treated apples. This full season application included 52 g/ha and 10 g/ha of dodecenyl alcohol and tetradecenyl alcohol, respectively. These were minor constituents, the major component was 106 g/ha of E,E-8,10-dodecadien-l-ol. No increased levels of the saturated alcohols were detected in fruit from treated orchards, and none of the latter, major component, was detectable above 10 ppb, our level of sensitivity (Spittler, T. D., Leichtweis, H. C. and Kirsch, P. Manuscript in preparation). 

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