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Secondary metabolites factors

Neither the mechanism by which benzene damages bone marrow nor its role in the leukemia process are well understood. It is generally beheved that the toxic factor(s) is a metaboHte of benzene (107). Benzene is oxidized in the fiver to phenol [108-95-2] as the primary metabolite with hydroquinone [123-31-9] catechol [120-80-9] muconic acid [505-70-4] and 1,2,4-trihydroxybenzene [533-73-3] as significant secondary metabolites (108). Although the identity of the actual toxic metabolite or combination of metabolites responsible for the hematological abnormalities is not known, evidence suggests that benzene oxide, hydroquinone, benzoquinone, or muconic acid derivatives are possibly the ultimate carcinogenic species (96,103,107—112). [Pg.47]

The discovery that, in industrialised societies, diets deficient in fruits and vegetables can effectively double the risk of developing many different types of cancer has focused renewed attention on the beneficial properties of these foods (Block e/a/., 1992 Patterson ef a/., 1990 Southon and Faulks, 2002). As we have seen, plant foods are rich in micronutrients, but they also contain an immense variety of biologically active secondary metabolites providing colour, flavour and natural toxicity to pests and sometimes humans (Johnson et ah, 1994). The chemistry and classification of such substances is still a matter for much research and debate, but this has not prevented attempts to isolate and exploit substances that have variously been termed protective factors , phytoprotectants , phytochemicals and nutraceuticals . Phytochemical compounds include ... [Pg.32]

It is estimated that there are in excess of 20 000 unique chemicals present as plant primary and secondary metabolites (Ohlrogge, 1994). The levels present in foods can vary quite considerably depending on the variety and on agronomic and environmental factors. To attribute benefits to any one chemical or group of chemicals seems a daunting task. Thus, in spite of intensive work in the last decade or so, there is still insufficient evidence with which to support the antioxidant hypothesis , or any other hypothesis, and to attribute... [Pg.222]

I. PRODUCTION OF ANTIBIOTICS. The production of secondary metabolites with antimicrobial properties has long been recognized as an important factor in disease suppression (see Chap. 7). Metabolites with biocontrol properties have been isolated from a large number of rhizosphere microorganisms, including the fluorescent pseudomonads (Table 2). Further discussion is not given here since this is the subject of recent reviews (122,123). [Pg.108]

The quantity, quality and purity of the template DNA are important factors in successful PGR amplification. The PGR is an extremely sensitive method capable of detecting trace amounts of DNA in a crop or food sample, so PGR amplification is possible even if a very small quantity of DNA is isolated from the sample. DNA quality can be compromised in highly processed foods such as pastries, breakfast cereals, ready-to-eat meals or food additives owing to the DNA-degrading action of some manufacturing processes. DNA purity is a concern when substances that inhibit the PGR are present in the sample. For example, cocoa-containing foodstuffs contain high levels of plant secondary metabolites, which can lead to irreversible inhibition of the PGR. It is important that these substances are removed prior to PGR amplification. Extraction and purification protocols must be optimized for each type of sample. [Pg.659]

Growth and diet are subject to seasonal changes. The presence (or absence) and relative concentrations of secondary metabolites in the extracts of organisms are factors which chemists should document along with observations made during collection. Often, in preliminary experiments guided by bioassay, mixtures, rather than individual compounds, are tested. Association of a certain activity with structurally related compounds may serve as a lead for further tests, but should not be considered definitive. [Pg.72]

Specificity of molecular bioactivity and differentially induced defenses are only two examples of factors that can confound the interpretation of patterns at the macroscale. As our knowledge of marine systems continues to expand, the relative abundance of secondary metabolites in different geographic locations may be better understood. However, the literature supports the idea that local pressures and habitat, genetic composition, mode of response and metabolism of the algae play a significant role in shaping distribution patterns of secondary metabolites (e.g. Wright... [Pg.124]

Waterman PG, Mole S (1989) Extrinsic factors influencing production of secondary metabolites in plants. In Bernays EA (ed) Insect-plant interactions. CRC, Boca Raton, FL, pp 107-164 Weidner K, Lages BG, da Gama BAP, Molis M, Wahl M, Pereira RC (2004) Effect of mesograz-ers and nutrient levels on induction of defenses in several Brazilian macroalgae. Mar Ecol Prog Ser 283 113-125... [Pg.172]

Enns MW, Cox BJ, Parker JD, Guertin JE. (1998). Confirmatory factor analysis of the Beck anxiety and depression inventories in patients with major depression. J Affective Disord. 47(1-3) 195-200. Erdelmeier CA. (1998). Hyperforin, possibly the major non-nitrogenous secondary metabolite of Hypericum perforatum L. Pharmacopsychiatry. 31(suppl 1) 2-6. [Pg.507]

Plant cell culture is useful in laboratory and in industry because it allows plant natural products to be produced in a relatively controlled manner, and provides a supply of plant material that is not affected by sourcing problems, such as environmental, seasonal, geographical, and political factors.Also, plant cell culture allows for the tweaking and rearrangement of secondary metabolite biochemical pathways in order to produce novel metabolites, and to increase target compound yields, as well as allowing derivatives to be formed by introduction of analogs of natural intermediates.Plant cell culture can be performed with callus and suspension cultures, as well as with shoot cultures and hairy root cultures. These latter two approaches are especially useful when a metabolite is found to be produced more readily in differentiated cells. [Pg.35]


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See also in sourсe #XX -- [ Pg.363 ]




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