Sources of natural occurring

Although animals produce steroids, the low concentrations of these compounds does not make these commercially (nor ethically) attractive sources of these substances. Furthermore, they could only serve as sources of naturally occurring steroids. Thus we would not have selected this option. 

Paclitaxel (21) was originally obtained from the bark of the Pacific yew, Taxus brevifolia Nutt. However, as the tree takes 200 years to mature, stripping the bark to produce this compound for the market was not sustainable. A better source of naturally occurring paclitaxel has not been found in other species and the total synthesis, on the other hand,... 

O Shea, B., Jankowski, J. and Sammut, J. (2007) The source of naturally occurring arsenic in a coastal sand aquifer of eastern Australia. Science of the Total Environment, 379(2-3), 151-66. 

The primary source of naturally occurring barium in drinking water results from the leaching and eroding of sedimentary rocks into groundwater (Kojola et al. 1978). Although barium occurs naturally in most surface water bodies (i.e., approximately 99% of those examined) (Kopp and Kroner 1967), releases of barium to surface water from natural sources are much lower than those to groundwater (Kojola et al. 1978). 

Sources of Naturally Occurring Evolutionary Variant Lysozymes... 

Plants, microorganisms and, to a lesser extent, macromarines have been the main sources of natural product based drugs (produced as secondary metabolites). Reviews of these traditional sources of naturally occurring chemical compounds are found in Chapters 5-7, together with hints and suggestions as to how these sources may be better utilised to continue supplying new drug leads in the future. 

Tagetes is a very rich source of naturally occurring thiophene derivatives. Various bithiophenes, for example, 12-14 or terthienyl 15, have been identified from Tagetes patula L. Asteraeeae) by GLC-MS analysis <2002ZNC63>. 

An assessment of the potential presence of PHAs in process flavors, and the implications for the safety assessment of these flavors, was sponsored by the Flavor and Extract Manufacturers Association of the United States (FEMA). The assessment was conducted in three stages (1) identification and quantification of PHAs in process flavors (2) identification of the food categories which could potentially contain process flavors and calculation of their respective daily per capita intakes and (3) determination of the daily per capita intake of PHAs through consumption of foods identified as sources of naturally-occurring PHAs compared to foods containing process flavors. 

Table I. Plant Sources of Naturally Occurring Phthalides...

Many bacteria are a potential source of naturally occurring polyesters, mainly poly(p-hydroxy alkanoate)s, with general structure... 

TABLE I Structure and Source of Naturally Occurring Cephamycins... 

Plants are the other major source of naturally occurring mutagenic/carcinogenic agents (Table 6). Extracts or chemical compounds from a variety of plants have been shown to possess mutagenic/carcinogenic activity, including cycasin from cycad nuts, bracken from ferns, flavonoids from a variety of plant sources, hydrazine derivatives from mushrooms, and safrole from sassafras oil. 

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