Metabolites antioxidants

Van DerMerwe J.D., Joubert E., Manley M., De Beer D., Malherbe C.J., Gelderblom W.C.A. In vitro hepatic biotransformation of aspalathin and nothofagin, dUiydrochalcones of rooibos (Aspalathus linearis), and assessment of metabolite antioxidant activity. Journal of Agricultural and food Chemistry, 58 2214-2220 (2010). 

DOX, as EPI seems to form fewer amounts of ROS and secondary alcohol metabolite, (ii) encapsulation of anthracyclines in uncoated or pegylated liposomes that ensure a good drug delivery to the tumor but not to the heart, (iii) conjugation of anthracyclines with chemical moieties that are selectively recognized by the tumor cells, (iv) coadministration of dexrazoxane, an iron chelator that diminishes the disturbances of iron metabolism and free radical formation in the heart, and (v) administration of anthracyclines by slow infusion rather than 5-10 min bolus (Table 1). Pharmacological interventions with antioxidants have also been considered, but the available clinical studies do not attest to an efficacy of this strategy. 

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... 

Some metabolites of curcumin (particularly tetrahydrocurcumin) may also participate in producing the observed effects of curcumin in different models because these metabolites display greater stabilities than the parent curcumin molecule at physiological pH. Recent data show similar modes of action of curcumin metabolites regarding antioxidant enzyme induction and inhibition of multidrug-resistant proteins. " Additional data indicate that curcumin may even act against other types of diseases such as atherosclerosis " " and Alzheimer s disease. " - " ... 

As described in the preceding paragraphs, oxidation products of carotenoids can be formed in vitro as a result of their antioxidant or prooxidant actions or after their autoxidation by molecular oxygen. They can also be found in nature, possibly as metabolites of carotenoids. Frequently encountered products are the monoepoxide in 5,6- or 5, 6 -positions and the diepoxide in 5,6 5, 6 positions or rearrangement products creating furanoid cycles in the 5,8 or 5, 8 positions and 5,8 5, 8 positions, respectively. Products like apo-carotenals and apo-carotenones issued from oxidative cleavages are also common oxidation products of carotenoids also found in nature. When the fission occurs on a cyclic bond, the C-40 carbon skeleton is retained and the products are called seco-carotenoids. 

Beekwilder, J. et al.. Antioxidants in raspberry on-hne analysis links antioxidant activity to a diversity of individnal metabolites, J. Agric. Food Chem., 53, 3313, 2005. 

Long, M. et al.. Metabolite profiling of carotenoid and phenolic pathways in mntant and transgenic lines of tomato identification of a high antioxidant fmit line. Phytochemistry, 67, 1750, 2006. 

Hiraishi, H., Razandi, M., Terano, A. and Ivey, K.J. (1990). Antioxidant defenses of culture gastric mucosal cells against toxic oxygen metabolites. Role of glutathione redox cycle and endogenous catalase. Gastroenterology 98, A544. 

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). 

Meier, B. W. Gomez, J. D. Kirichenko, O. V. Thompson, J. A. Mechanistic basis for inflammation and tumor promotion in lungs of 2,6-di-tert-butyl-4-methylphenol-treated mice electrophilic metabolites alkylate and inactivate antioxidant enzymes. Chem. Res. Toxicol. 2007, 20, 199-207. 

Lian, F. and X. D. Wang. 2008. Apo-lO -lycopenoic acid, an enzymatic metabolite of lycopene, induces Nrf2-mediated expression of phase II detoxifying/antioxidant enzymes in human bronchial epithelial cells. Int J Cancer (in press). 

Ressmeyer, A. R Mayo, J. C., Zelosko, V. et al. (2003). Antioxidant properties of the melatonin metabolite N -acetyl-S-melhoxykynuramine (AMK) scavenging of free radicals and prevention of protein destruction. Redox Rep. 8, 205 13. 

Antioxidants in fruits and vegetables including vitamin C and (3-carotene reduce oxidative stress on bone mineral density, in addition to the potential role of some nutrients such as vitamin C and vitamin K that can promote bone cell and structural formation (Lanham-New 2006). Many fruits and vegetables are rich in potassium citrate and generate basic metabolites to help buffer acids and thereby may offset the need for bone dissolution and potentially preserve bone. Potassium intake was significantly and linearly associated with markers of bone turnover and femoral bone mineral density (Macdonald and others 2005). 

Liu RH, Liu J and Chen B. 2005. Apples prevent mammary tumors in rats. J Agric Food Chem 53 2341-2343. Long M, Millar DJ, Kimura Y, Donovan G, Rees J, Fraser PD, Bramley PM and Bolwell GP. 2006. Metabolite profiling of carotenoid and phenolic pathways in mutant and transgenic lines of tomato identification of a high antioxidant fruit line. Phytochemistry 67 1750-1757. 

Polyphenols are the most abundant antioxidants in human diets. They are secondary metabolites of plants. These compounds are designed with an aromatic ring carrying one or more hydroxyl moieties. Several classes can be considered according to the number of phenol rings and to the structural elements that bind these rings. 

The fermentation of polyphenols in the colon improves antioxidant status and yields different metabolites with potential systemic effects. 

DeGraft-Johnson J, Kolodziejczyk K, Krol M, Nowak P, Krol B and Nowak D. 2007. Ferric-reducing ability power of selected plant polyphenols and their metabolites implications for clinical studies on the antioxidant effects of fruits and vegetable consumption. Basic Clin Pharmacol Toxicol 100(5) 345-352. 

---