Butylated hydroxytoluene , inhibition

Inhibited THF is problematic for semipreparative separations. Because small quantities of polymer are being collected along with larger volumes of solvent, more inhibitor, usually butylated hydroxytoluene (BHT), than sample is often collected in each fraction. Thus, one must carefully consider if the BHT will cause a problem in the subsequent analysis of the isolated fractions. If it does, uninhibited THF or other alternate solvents should be used. It must be remember that if uninhibited THF is used, the analyst must pay careful attention to the inevitable peroxide formation in the solvent/fractions. 

Note THF = tetrahydrofuran BHT = butylated hydroxytoluene, an antioxidant Camptothecin (CM) = causes inhibition of the DNA enzyme topoisomerase (Top 1) which induces DNA damage and apoptosis DHT = dihydrotestosterone PrEC = normal prostate stromal cells LNCaP, PC-3, DU-145 = neoplastic prostate epithelial cells (See Table 21.1). 

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. 

Butylated hydroxytoluene (BHT) (33) is another widely used lipophilic antioxidant. Inhibition of 12-LO and 15-LO has been reported at millimolar concentrations, with somewhat more potent activity against CO [58,111,112]. More recently, BHT was found to inhibit 5-LO from potato [113] and RBL-1 cells [114] at concentrations near 1 / M. However, anti-inflammatory activity has not been reported. 

Note May contain acetic acid, 2-methyl-l,3-dioxolane, and bis(2-chloroethyl) ether as impurities. May be inhibited with butylated hydroxytoluene. 

Resveratrol has also been reported to offer protection against cardiovascular disease, such as coronary heart disease. The effects of resveratrol on factors implicated in the development of coronary heart disease - human platelet aggregation and the synthesis of eicosanoids (lipids) from arachidonate by platelets - were investigated and compared with the actions of other wine phenolics - catechin (1.39), epicatechin (7.18a), and quercetin (1.43) - and the antioxidants a-tocopherol (7.10a), hydroquinone and butylated hydroxytoluene. Resveratrol and quercetin demonstrated a dose-dependent inhibition of platelet aggregation, whereas the other compounds tested were inactive. Resveratrol also inhibited the synthesis of the eicosanoids in a dose-dependent manner, whereas the other phenolics were less effective of not effective at all. Removal of the alcohol from the wine did not diminish the effect on platelet aggregation (Pace-Asciak et al., 1995 Goldberg et al., 1995). 

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). 

Table V shows an even more dramatic disparity between tumor inhibition and effect of inhibition on total binding of DMBA to DNA. Butylated hydroxytoluene and butylated hydroxyanisole cause inhibition of DMBA initiation of tumors by 53% and 28%, respectively. There is little inhibition of binding of DMBA to DNA by these compounds and in the case of butylated hydroxyanisole, and the 24 h sample for butylated hydroxytoluene, binding of DMBA to skin DNA is actually enhanced.

Compounds that are in direct contact with air when in the final product, for example as in powder products or in soap, are particularly at risk from oxidation, and the head space above the product is likely therefore to become rich in the breakdown products of oxidation. For this reason the packaging usually allows for a certain amount of "breathing" so as to let these "off-odors" escape rather than their being reabsorbed into the product. A number of products exist, generally classed as antioxidants, for example, BHT (butyl hydroxytoluene), that help to inhibit these oxidation reactions. These antioxidants are often added to citrus oils, or to compounds to prolong their shelf life, or to the final product. 

Butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are antioxidants that are added to foods and many other organic materials to inhibit decomposition caused by reactions with oxygen. Perhaps you have seen these compounds listed among the ingredients on your cereal box at breakfast. (The mechanism of operation for these antioxidants is described in Section 21.8.) Both of these compounds are prepared by Friedel-Crafts alkylation reactions. BHT is synthesized by the reaction of p-methylphenol with 2-methylpropene in the presence of an acid catalyst. 

OH scavengers such as mannitol and glucose may simply scavenge the extracellular OH without inhibiting lipid peroxidation. Conversely, lipid-soluble OH scavengers such as dimethylthiourea, and antioxidants such as butylated hydroxytoluene (BHT) should effectively inhibit membrane lipid peroxidation (Fig. 1). 

Antioxidant Agent that inhibits oxidation and thus is used to prevent deterioration of preparations by oxidative process Ascorbic acid, ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene, hypophosphorus acid, monothioglycerol, propyl gallate, sodium ascorbate, sodium bisulfite, sodium formaldehyde, sulfoxylate, sodium metabisulfite... 

Furan containing compounds 344-347 were obtained from a bioassay-directed isolation and purification of Amelanchier candensis <2006MIP308-26>. The isolated compounds were shown to inhibit lipid peroxidation by 85% at 100 ppm when compared to 89, 87, and 98% for the common antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and fer7-butylhydroxyquinone (TBHQ) at 1.67, 2.2, and 1.67 ppm, respectively. While not selective, some of the isolated compounds inhibited cyclooxygenase (COX)-l and -2 enzymes. 

Impurities are described in many texts on solvents [4, 5]. Many organic impurities can be identified by GC or GC/MS techniques for instance, MIBK can be found to contain mesityl oxide, the precursor to the manufacture of MIBK (Figure 4.6) [20]. Common impurities in solvents include H20, DMF [21], and AcOFl (in EtOAc and other solvents). Some solvents are inhibited with trace amounts of antioxidants, e.g., CH2C12 (stabilized with amylene or cyclohexane) andTFIF and 2-Me-THF (stabilized with BHT, butylated hydroxytoluene ). These impurities can influence the desired chemistry positively [22] and negatively, so and they should be considered. 

Anticarcinogens that either directly antagonize carcinogens, or more likely prevent their activation, are also present in many foods naturally or are added to them. Included in this list of good guys are vitamins A, E, and C, some Bs, chlorophyll, carotene, butylated hydroxytoluene (BHT), and anisole (BHA). Many of these substances are effective antioxidants that presumably may inhibit oxidative carcinogenic activation. Vitamin C is also a potent inhibitor of nitrosamine formation. 

The solution oxidation technique allows the study of polyolefin autoxi-dation under conditions where the temperature, concentration of reactants, and rates of radical initiation can be controlled. The results should be considered as a useful prelude to any fundamental understanding of the autoxidation processes which occur in neat polymers where the effects of very high viscosity, partial crystallinity, and oxygen diffusion rates are included. The objective of our work was to determine the kinetics and stoichiometry of the inhibited autoxidation of polypropylene in solution. A relatively detailed study of the oxidation of polypropylene inhibited by 2,6-di-terf-butyl-4-methylphenol [butylated hydroxytoluene (BHT)] has been made for comparison with data obtained in polypropylene oxidations inhibited by a variety of other stabilizers which include commercial polyfunctional antioxidants. Singly hindered phenols appeared to be superior in the inhibited-solution oxidation of polypropylene, and the application of this finding to stabilization technology was investigated briefly. 

The parameters F and ORR for TGL and TGSO oxidation in the presence of 0.05 and 0.10% ethanolic extracts of Fraxinus ornus bark are presented in Table 11. The data indicate that the ethanolic extract of Fraxinus ornus bark has a pronounced antioxidative activity during the oxidation of both lipid substrates. This activity is commensurate with the inhibiting effect of the same concentration of butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) during TGL oxidation [46]. 

It is stored in a cool, dark, and well-ventilated area, separated from heat sources and oxidizing materials. An inhibitor such as butylated hydroxytoluene ( 0.025%) is added to inhibit peroxide formation. Discard the unused solvent 2 months after opening the container. It is shipped in cans, drums, and tank cars. 

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