Naturally Occurring Substances

Naturally Occurring Substances.—Beyeria (Euphorbiaceae) species have been the source of a number of tetracyclic diterpenoids. Some of these were new or poorly defined species and their classification has now been clarified. The presence of enf-kaurenal has again been recorded in Fusarium monoliforme, whilst ent-kaur-16-en-19-oic acid (72) has been isolated from Mikania hirsutissima (Composi-tae). Microbiological hydro xylation of ent-kaur-16-en-19-oic acid by 

Cunninghamella blakesleana affords the 7/3-hydroxy-, 16a-hydroxy-, 16,17-dihydroxy-, and 7/3,16a-dihydroxy-derivatives. The angelic acid ester of ent-15/3-hydroxykaur-16-en-19-oic acid (73) and its 16,17-epoxide (perymenic acid) have been obtained from Perymenium ecuadoricum (Compositae). A group of 

El-Emary, G. Kusano, and T. Takemoto, Chem. and Pharm. Bull. (Japan), 1976, 24, 1664. 

A number of kauranoid diterpenoids have been isolated from the liverworts. (16i )-ent-Kauran-15-one, ent-15a-hydroxykaur-16-ene, and the corresponding 15-ketone have been isolated from the liverwort Jungermannia infusca and (16i )-ent-18-hydroxykauran-15-one, ent-kaur-16-en-18-oic acid, and ent- a-hydroxykaur-16-en-15-one have been found in another species, Porella densi-folia. The full paper on the crystal structure of enf-1 la,15or-dihydroxykaur-16-ene, which has been obtained from Jungermannia sphaerocarpa and Solenostoma trista, has appeared.  

Epoxyisofoliol (78) has been obtained from Sideritis paulii and its 3-acetate, epoxyisosidol, is one of a series of acetates of ent-3/S,7a,18-trihydroxykaur-15- and 

Premna latifolia. The structure of the unusual ether (34), obtained from Acacia 

Perales, M. Martinez-Ripoll, J. Fayos, R. K. Bansal, K. C. Joshi, R. Patni, and B. Rodriguez, Tetrahedron Lett., 1980, 21, 2843. 

Diterpenoid quinones have been isolated from a number of the Labiatae. An o-quinone, ethiopinone (38), has been described as a constituent57 of the roots of Salvia aethiopis (Labiatae) and the known quinones horminone and 7a-acetoxy-royleanone have been isolated58 from S. lanata. The dehydroabietic acid derivative (39) was obtained59 from S. tomentosa. The partial synthesis of the epimeric ring B 

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M.p. 207°C. The naturally occurring substance is dextrorotatory. Arginine is one of the essential amino-acids and one of the most widely distributed products of protein hydrolysis. It is obtained in particularly high concentration from proteins belonging to the prolamine and histone classes. It plays an important role in the production of urea as an excretory product. 

The naturally occurring substance is L-aspartic acid. One of the acidic-amino acids obtained by the hydrolysis of proteins. 

CgHiiNO. M.p. 282 C (decomp.). The naturally occurring substance is laevorotatory. It is an amino-acid isolated from various plant sources, but not found in the animal body. It is formed from tyrosine as the first stage in the oxidation of tyrosine to melanin. It is used in the treatment of Parkinson s disease. 

CfiHqNaO . M.p. 277 C. The naturally occurring substance is laevorotatory. Histidine is one of the basic amino-acids occurring in the hydrolysis products of proteins, and particularly of the basic proteins, the protamines and histones. It is an essential constituent of the food of animals. 

C(,Hi3N02, CH3 CH2-CHMe-CHNH2-COOH. Colourless crystals, m.p. 284 C (decomp.). The naturally occurring substance is dextrorotatory. An amino-acid, occurring with leucine as a product of protein hydroly-... 

M.p. 283 C (decomp.). Soluble in water and alcohol. The naturally occurring substance is laevorotatory. Methionine is one of the natural sulphur-containing amino-acids, and is present in small quantities in the hydrolysis pro-... 

Many naturally occurring substances contain several carbon-... 

Many naturally occurring substances are epoxides You have seen two examples of such compounds already m disparlure the sex attractant of the gypsy moth (Section 6 18) and m the carcinogenic epoxydiol formed from benzo[a]pyrene (Section 118) In most cases epoxides are biosynthesized by the enzyme catalyzed transfer of one of the oxy gen atoms of an O2 molecule to an alkene Because only one of the atoms of O2 is trans ferred to the substrate the enzymes that catalyze such transfers are classified as monooxy genases A biological reducing agent usually the coenzyme NADH (Section 15 11) is required as well... 

Over 50% of clinically available dmgs have chiral centers and only about 10% of synthetic chiral dmgs are marketed in homochiral (enantiomerically pure) form (33). In contrast, dmgs that are naturally occurring substances, obtained from or related to naturally occurring molecules, are frequendy homochiral. 

Technical Enzymes. When an enzyme is used for a technical appHcation, ie, industrial but nonfood and nonfeed, its regulatory status is determined by its properties as a naturally occurring substance. These properties determine the classification and consequent labeling in accordance with existing schemes for chemicals. It should be noted that enzymes are not Hsted as dangerous chemicals. 

UK Ministry of Agriculture Fisheries and Food and Flealth and Safety Executive, Annual Report of the Working Party on Pesticide Residues in Food (1997), MAFF Publications, London, 1997. lARC, Monographs on the Evabiation of the Carcinogenic Risk of Chemicals to Hnmans Volume 56 Some Naturally Occurring Substances Food Items and Constituents, Heterocyclic Aromatic Amines and Mycotoxins, WFIO, Geneva, 1979, p. 397. 

Decalin ring systems appear as structural units in a large number of naturally occurring substances, particularly the steroids. Cholic acid, for example, a steroid present in bile that promotes digestion, incorporates d5-decalin and rran -decalin units into a rather complex tetracyclic structure. 

Identify the isoprene units in each of the following naturally occurring substances ... 

Polyamine (Section 22.4) A compound that contains many amino groups. The term is usually applied to a group of naturally occurring substances, including spermine, spermidine, and putrescine, that are believed to be involved in cell differentiation and proliferation. 

M. Car eri, A. Mangia and M. Musci, Overview of the applications of liquid cliromatog-raphy-mass spectrometry interfacing systems in food analysis naturally occurring substances in food , 7. Chromatogr. 794 263-297 (1998). 

In general, primary raw materials are naturally occurring substances that have not been subjected to chemical changes after being recovered. Natural gas and crude oils are the basic raw materials for the manufacture of petrochemicals. The first part of this chapter deals with natural gas. The second part discusses crude oils and their properties. 

The general corrosion rate of zinc and zinc alloys in practice often have been shown to be much less than in simulated conditions this is because many naturally occurring substances act as inhibitors. Figure 4.42 is a good example of this. The diagram is valuable for the qualitative relationship between acid, neutral and alkaline conditions but, in practice, the corrosion rates are usually very much lower than indicated by the pH because of the effect of other dissolved constituents and the barrier effect of corrosion products. Seawater around the British Isles is much less corrosive to zinc than tropical seawater. 

Carvacrol is a naturally occurring substance isolated from oregano, thyme, and marjoram. What is its TUPAC name ... 

D-Glucitol, the alditol produced by reduction of D-glucose, is itself a naturally occurring substance present in many fruits and berries. It is used under its alternative name, D-sorbitol, as a sweetener and sugar substitute in foods. 

Lipid (Section 27.1) A naturally occurring substance isolated from cells and tissues by extraction with a nonpolar solvent. Lipids belong to many different structural classes, including fats, terpenes, prostaglandins, and steroids. 

When the Woodward-Eschenmoser synthesis began, it was known from the work of Bernhauer et al.5 that cobyric acid (4), a naturally occurring substance, could be converted directly into vitamin B12. Thus, the synthetic problem was reduced to the preparation of cobyric acid, a molecule whose seventh side chain terminates in a carboxylic acid group and is different from the other side chains. Two strategically distinct and elegant syntheses of the cobyric acid molecule evolved from the combined efforts of the Woodward and Eschenmoser groups and both will be presented. Although there is naturally some overlap, the two variants differ principally in the way in which the corrin nucleus is assembled. 

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