Butylated hydroxytoluene, oxidation

Preservatives, Protect from oxidation, Butylated hydroxytoluene Liquid products with... 

When measuring the level of nonpolar retinoids in blood, a modified method of Thompson et al, (1971) could be used (see also Varma and Beaton, 1972 Bieri et al., 1979 Ross, 1981). Briefly, the plasma or serum (100-200 xl) is mixed with 1 volume of internal standard solution (e.g., retinyl acetate) in ethanol. To the mixture is added 1-4 volumes of hexane the contents are mixed well and then centrifuged. The hexane (upper phase) is carefully removed and used for chromatography or other analyses. For added protection against oxidation, butylated hydroxytoluene (100 xg/ml) can be added to the hexane. Other solvents used for extraction of retinol and its esters from serum include chlo-roform methanol (see, for example, DeRuyter and De Leenheer, 1978) and hexane methylene chlorideiisopropanol (Besner /., 1980). Recoveries, when reported, range near 100%. 

Several stabilizers are useful in minimizing oxidative degradation during thermoplastic processing or in the bulk soHd. Phenothiazine, hindered phenohc antioxidants such as butylated hydroxytoluene, butylatedhydroxyanisole, and secondary aromatic amines in concentrations of 0.01—0.5% based on the weight of polymer, are effective. 

The vitamin D resin is stabilized against oxidation by the addition of < 1 wt% butylated hydroxyanisole or butylated hydroxytoluene. 

Stabilization of Elastomers. Polyunsaturated elastomers are sensitive to oxidation. Stabili2ers are added to the elastomers prior to vulcani2ation to protect the mbber during drying and storage. Nonstaining antioxidants such as butylated hydroxytoluene (1),... 

ButylatedHydroxyAnisole (BHA). This material is an oxidation inhibitor and has been accepted for use in foods where the use of butylated hydroxytoluene (BHT) is restricted (see Food additives). It is manufactured by the alkylation of 4-hydroxyanisole [150-76-5] with isobutylene that yields a mixture of 2- and S-Z fZ-butyl isomers as products (124). 

To obtain maximum lifetime, the oxidants must not be lost during service. A major potential source of loss is the evaporation of the antioxidant. Evaporation is often observed with BHT (butylated hydroxytoluene), a monomeric phenol, and to avoid evaporation less volatile, higher molecular weight antioxidants are used (i.e. bisphenols). 

Antioxidants are not important only to the health conscious food manufacturers also rely on these chemicals to maintain the shelf life of their products. Synthetic antioxidants such as butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate and tert-butyl hydroquinone were widely used in food processing to control oxidation and maintain food quality. However, as these synthetic antioxidants are suspected to be carcinogenic they now have restricted use in food (Madahavi and Salunkhe, 1995). Therefore, natural antioxidant sources, especially of plant origin, are of great interest to the food industry. 

Oxidative addition of a silyl-protected 4-(bromomethyl)phenol precursor to (tme-da)Pd(II)Me2 (tmeda = tetramethylethylenediamine), followed by ethane reductive elimination, resulted in formation of the benzylic complex 16 (Scheme 3.10). Exchange of tmeda for a diphosphine ligand (which is better suited for stabilizing the ultimate Pd(0) QM complex), followed by removal of the protecting silyl group with fluoride anion, resulted in the expected p-QM Pd(0) complex, 17, via intermediacy of the zwitterionic Pd(II) benzyl complex. In this way a stable complex of p-BHT-QM, 17b, the very important metabolite of the widely used food antioxidant BHT20 (BHT = butylated hydroxytoluene) was prepared. Similarly, a Pd(0) complex of the elusive, simplest /)-QM, 17a, was obtained (Scheme 3.10). 

Bolton, J. L. Thompson, J. A. Oxidation of butylated hydroxytoluene to toxic metabolites factors influencing hydroxylation and quinone methide formation by hepatic and pulmonary microsomes. Drug Melah. Dispos. 1991, 19,467-472. 

Chemically carotenoids have conjugated double bonds that render them liable to oxidation. This tendency to oxidation can be diminished by adding antioxidants to the product. In the sort of product where natural colours are used suitable antioxidants would be tocopherols or ascorbic acid. Chemical antioxidants such butylated hydroxytoluene might be suitable technically but would not fit the image of an allnatural product. Ascorbic acid could be declared as vitamin C rather than as an antioxidant. Oxidation can be started by exposure to light and so this is best avoided. Carotenoids are generally stable to heat. The levels required can be as low as 10 ppm. P-Carotene is available as a nature identical form. 

Preservatives (LD, DW, ADW, HC, FC) Guards against product aging by decay, discoloration, oxidation, and bacterial attack Ability to decrease water availability Butylated hydroxytoluene Ethylene diamine Glutaraldehyde 0.05-0.2% 0.05-0.2%... 

Figure 5. Inhibitory effect of NO on Fe -induced lipid peroxidation. Shown is the decreased generation of an oxidative marker (thiobarbituric acid reactive substances, TBARS) as a result of 0.9 iM NO. HL-60 cells (5 x loVral) were placed in an O2 monitor and at the designated time points, butylated hydroxytoluene was added and samples were quick frozen for determination of TBARS. The values represent the mean and standard error of 3-5 independent determinations. Also shown for comparison is the residual concentration of O2 after exposure to the the same conditions. This shows a decrease in utilization of O2 in the presence of NO. We conclude that NO reduces TBARS, and the percent inhibition is similar to the poeent inhibition of O2 consumption. (Modified from our data in Kelley, E.E., Wagner, B.A., Buettner, G.R., and Bums, C.P., 1999, Arch. Biochem. Biophys. 370 97-104).

A preservative is a substance that prevents or inhibits microbial growth and extends the shelf life of the drug products. In most pharmaceutical drug products, only a few compounds are typically selected as preservatives. For efficiency, a generic method should be developed for the types of preservatives that are more commonly used. For example, butylated hydroxytoluene (BHT) is an antioxidant commonly used in many solid dosage formulations to retard oxidative degradation of the excipients. 

CLA as An Antioxidant. The complete mechanism of anticarcinogenic activity of CLA is not known. Some of the CLA effect is believed due to its antioxidant properties. For example, use of a water/ethanol system that is incubated at 40"C under air for 14 days, showed CLA reduced the oxidation of linoleic acid by 86% (8), Under the same conditions a-tocopherol reduced oxidation by only 63% and butylated hydroxytoluene (BHT) reduced oxidation by 92%. Dose-response studies were conducted, and it was found that the optimal ratio for CLA to protect linoleic acid from oxidation is 1 1000 (CLAilinoleic acid). 

SGC Butylated hydroxytoluene, ethanol, gelatin, iron oxide, oleic acid, polyoxyl 35 castor oil PDR... 

If lipid oxidation is a factor in promotion of tumorigenesis by dietary fat, one might expect the process to be inhibited by dietary antioxidants. This topic is discussed in more detail elsewhere in this symposium (28 ), but the results have not provided clear-cut answers to the question. Some of the synthetic antioxidants such as butylated hydroxytoluene (BHT) appear to inhibit the promotion of tumorigenesis by dietary fat, but results with vitamin E, a naturally-occurring antioxidant, have been largely negative (29). 

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