Biological activity, metabolism

Biological activity is an important indicator of the decomposition of soil organic matter within the soil. High biological activity promotes metabolism between soil and plants and is an essential part of sustainable plant production and fertiliser management. Earthworms, as a key species for soil macro-fauna, are an appropriate indicator of soil s biological activities due to their sensitivity to any kind of soil disturbance. Microbial activity of soils is an indicator of soil micro-fauna. Both indicators are reviewed below. 

Walsky, R.L. and Obach, R.S. (2004) Validated assays for human cytochrome P450 activities. Drug Metabolism and Disposition The Biological Fate of Chemicals, 32, 647-660. 

Pharmacokinetics Absorbed through the cornea where the isopropyl esterprodrug is hydrolyzed to acid form to become biologically active. Highly lipophilic. The acid of latanoprost can be measured in the aqueous humor during the first 4 hours and in the plasma only during the first hour after local administration. In cornea, latanoprost is hydrolyzed to the biologically active acid. Metabolized in liver if it reaches systemic circulation. Metabolized to 1,2-dinor metabolite and 1,2,3,4-tetranor metabolite. Primarily eliminated by the kidneys. Half-life 17 min. 

Other evidence judged to be relevant to an evaluation of carcinogenicity and of sufficient importance to affect the overall evaluation is then described. This may include data on preneoplastic lesions, tumour pathology, genetic and related effects, structure-activity relationships, metabolism and pharmacokinetics, physicochemical parameters and analogous biological agents. 

An alternative process that can lead to the termination or alteration of biologic activity is metabolism. In general, lipophilic xenobiotics are transformed to more polar and hence more readily excreted products. The role that metabolism plays in the inactivation of lipid-soluble drugs can be quite dramatic. For example, lipophilic barbiturates such as thiopental and pentobarbital would have extremely long half-lives if it were not for their metabolic conversion to more water-soluble compounds. 

Because all members of the pathway have potent biologic activity, serious metabolic imbalances occur if enzyme deficiencies are present (see figure 18.25). 

The metabolism of triazine herbicides in plants is very complex and involves a variety of biological reactions. The most active crops metabolically include com, cotton, soybean, sugarcane, and wheat. Less complex metabolic pathways have been observed in citrus and various fruit crops. 

Figure 2.5. Metabolic scope for activity (defined as the difference between maximum metabolic rate and the SMR) and the metabolic scope for survival (defined as the difference between the SMR and maximally suppressed metabolic rates). Hummingbird estimates shown for normothermic conditions and for torpor metabolic rates (the latter gives the full biological scope for activity). Suppressed metabolic rates for the aquatic organisms assume temperatures of about 20°C (except for the pumpkinseed, where suppressed metabolism occurs during overwintering hibernation at about 4°C). (Modified from Hochachka (1990.)...

Conaway, C.C., Yang, Y.M., and Chung, F.L., Isothiocyanates as cancer chemopre-ventive agents their biological activities and metabolism in rodents and humans, Curr. Drug Metab., 3, 233-255, 2002. 

LaVoie EJ, Tulley L, Bedenko V, et al. 1980b. Mutagenicity, tumor-initiating activity, and metabolism of tricyclic polynuclear aromatic hydrocarbons. In Bjorseth A, Dennis AJ, eds. Polynuclear aromatic hydrocarbons Chemistry and biological effects. Columbus, OH Batelle Press. 

Wood AW, Levin W, Thakker DR, et al. 1979b. Biological activity of benzo[e]pyrene An assessment based on mutagenic activities and metabolic profiles of the polycyclic hydrocarbon and its derivatives. J Biol Chem 254(11) 4408-4415. 

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