Terpenes, nitrogen-containing

Alkaloids, nitrogen-containing compounds generally found as secondary metabolites in plants, are also classical examples of renewables. In contrast to terpenes, they show a great variety in molecular structure, and the different classes of alkaloids are usually based on their basic ring systems. Many pharmaceutically active... 

Sponges of the genus Acanthelfa have previously been shown to be rich sources of terpenes having various nitrogen-containing groupings, with... 

The active principle of Salvia divinorum, salvinorin A, is derived from the leaves of the plant. Chemically, salvinorin A is a neoclerodane diterpene, one of a group of nitrogen-containing terpene compounds that have psychotropic properties. Two other such compounds are tetrahydrocannabinol and absinthe. Purified salvinorin A can be obtained from an ether extract of the leaves, which is then concentrated by chromatography and repeated crystallization. 

As was the case with terpenes, the function of alkaloids in plants is not known. It has been proposed that they are merely nitrogen-containing waste products of plants, like urea in animals. However, most plants reutilize nitrogen, rather than wasting it. Furthermore, it is difficult to imagine why such complex structures would be needed to store waste nitrogen. Like terpenes, alkaloids have been proposed to serve as protection from herbivores and insects. However, only a few examples of such protection can be demonstrated. Whatever the role of alkaloids is, some 70% to 80% of plants manage to do quite nicely without them. 

The most common detection method used in gas chromatography is FID. The nitrogen-phosphorus detector (NPD) can be used to identify nitrogen-containing compounds (Stashenko et al., 1996). Another possibiUty is the use of oxygen flame ionization detection (O-FID) for the selective determination of oxygenates (Betts, 1994 Schneider et al., 1982). Mass spectrometry is a very useful tool for detecting complex terpene mixtures. 

Because they come from prokaryotes or eukaryotes, the natural substances isolated from marine organisms are often characterized by the presence of chemical elements or structures that are seldom observed, or even unknown, in a terrestrial environment. This observation applies as much to the primary metabolites (sulfated polyholosides, nucleosides) as to the secondary metabolites (e.g., haloge-nous and nitrogenous terpenes, sterols and sulfated tri-terpenes, arsenic-containing sugars). 

Stelletta Acetylenic fatty acids, triterpenes (malabaricane), bipyridyl derivatives, S/N heterocycles, nitrogen-containing terpenes and meroterpenes. 

Nitrogen-Containing Terpenes Isonitriles and Reiated Derivatives... 

Alcyonacea Sinularia 550 Sesqui- and diterpenes, bis-terpenes, terpenic glycosides secosterols, some nitrogen-containing derivatives... 

Recall that the subclass Octocorallia alone contains almost all of the terpenes found in the phylum Cnidaria, which, with about 90% of terpenic secondary metabolites, is the marine phylum that contains the largest number of such compounds (see above). However, though the number of terpenes is very high, the structural variations observed are confined primarily to sesqui- and diterpenes, with very few halogenated and some rare nitrogen-containing derivatives. The number of original carbon skeletons is also small, and some of them seem specific to cnidarians they are mostly diterpenes (see below). 

The biosynthesis of sesquiterpenes containing isonitrile and isothiocyanate groups was also investigated by incorporation of cyanide and potassium thiocyanate labeled with carbon 14 in the sponge Acanthdla cavernosa, which is consumed by the nudibranch Phyllidiella =Phyllidia) pustulosa. The results show that the mollusk does not synthesize de novo any nitrogen-containing terpene and consequently it acquires the sesquiterpenes substituted... 

The use of nitrogen fertilization results in higher content of N-containing compounds, including free amino acids, and also increases in terpene content in wood plants, whilst starch, total carbohydrates, phenylpropanoids and total carbon-based phytochemicals decreased (Koricheva et al., 1998). Higher levels of nitrogen favoured its uptake and increased the nitrate content of the crop, which is critical for salad vegetables and baby foods. 

Of the few known terpene compounds that contain heteroatoms such as nitrogen or sulfur, the thiol 8-mercapto-p-menthan-3-one described below has qualitatively important applications as a fragrance and flavor substance. The second thiol, -p-menthene-8-thiol, is described because its odor threshold value is far lower than that of most other fragrance and flavor materials. 

Other compounds, containing sulphur or nitrogen, may be present in some oils (like onion, garlic).Investigations on the solubility of pure essential-oil components in carbon dioxide showed that the separation of terpene hydrocarbons and oxygenated derivatives by fractionated extraction is difficult, since their solubility behaviours and vapour pressures are almost the same. Saturating the CO2 with water as modifier can increase the differences in solubility [78],... 

The thiazole ring is assembled on the 5-carbon backbone of 1-deoxyxylulose 5-phosphate, which is also an intermediate in the alternative biosynthetic pathway for terpenes (Fig. 22-2) and in synthesis of vitamin B6 (Fig. 25-21). In E. coli the sulfur atom of the thiazole comes from cysteine and the nitrogen from tyrosine.374 The same is true for chloroplasts,375 whereas in yeast glycine appears to donate the nitrogen.372 The thiamin biosynthetic operon of E. coli contains six genes,372a 376 one of which (ThiS) encodes a protein that serves as a sulfur carrier from cysteine into the thiazole.374 The C-terminal glycine is converted into a thiocarboxylate ... 

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