2.5- Dihydroxybenzoic add

Y.-S. Lin, Y.-C. Chen Laser desorption/ionization time-of-flight mass spectrometry on sol-gel-derived 2,5-dihydroxybenzoic add film. Anal. Chem. 2002, 74, 5793-5798. 

Grehf M., and Krebs, B. (1993) Matrix-assisted laser desorption/ ionization mass spectrometry with additives to 2,5-dihydroxybenzoic add. 

ACN acetonitrile DHAP 2,6-dihydroxyacetophenone DHB 2,5-dihydroxybenzoic add HCCA alpha-cyano-4-hydroxydnnamic add SA sinapinic add THAP 2,4,6-trihydroxyacetophenone. 

The flux of hydroxyl radicals, as measured directly by conversion of salicylate to 2,3- and 2,5-dihydroxybenzoic add (formula [177]), was significantly lower in gallium-desferrioxamine-treated retinas of cat eyes subjected to 90 min retinal ischaemia followed by 5 min of reperfusion (Banin et al. 2000). Gallium-desferrioxamine caused a significant reduction, by 2.56-fold, in lipid peroxidation, as reflected by levels of malondialdehyde. Acorbic acid, a natural antioxidant present in the retina, was severely depleted in untreated eyes. In contrast, in gallium-desferrioxamine-treated eyes, levels were 10 times higher than the control. 

In a typical MALDI experiment (see Fig. 7.3), e.g., for peptide or protein analysis, 0.3-1 pi of an aqueous analyte solution is mixed with 0.5-1 pi of a 5 mM so-Intion of an appropriate matrix, e.g., 2, 5-dihydroxybenzoic add (DHB), sinapinic acid, or a-cyano-4-hydroxycinnaniic acid (CHCA), in 50% aqueous acetonitrile containing 0.1% trifluoroacetic add, and then deposited onto a metal taiget. Other... 

Table 3.8. Plasma levels of 2,3-dihydroxy benzoate and 2,5-dihydroxybenzoate 2 h after administering salicylic add (rat Ste-Marie et al. 1996) or aspirin, (man Isobeet al. 1996)...

Resorcinol 1,2,4-trihydroxybenzene 1,2.3-trihydroxybenzene 4-Hydroxyphenylacetic acid 4-Methylcatechol Phlorogludnol tsovaniflic add Guaiacol Phenol 4-Hyroxypehnylurea Hydroquinone Control - laccase Catechol Control + laccase 2,5- dihydroxybenzoate... 

Figure 11.2 shows a schematic view of a MALDl-TOF mass spectrometer. The macromolecule is first embedded in a solid matrix that often consists of an organic add such as 2,5-dihydroxybenzoic acid, nicotinic acid, or an a-cyanocarboxylic acid. 

A matrix of 2,5-dihydroxybenzoic acid and 1-hydroxyisoquinoline (wt ratio of 3 1) proved most suitable for MALDI-MS of oligosaccharides. A new study of the use of electrospray ionization MS of cyclodextrins and guests shows that some amino adds least likely to form inclusion complexes show the most intense complex ions. This suggests previous data identifying complexes in this way are probably due to electrostatic adducts formed in the electrospray process. ... 

Richard, C. and Boule, R, Is the oxidation of salicylic add to 2,5-dihydroxybenzoic acid a spedfic reaction of singlet oxygen , /. Photochem. Photobiol. A Chem., 84, 151,1994. 

Convert benzoic acid to 3,5-dihydroxybenzoic acid (alpha-resorcyclic acid) (I). 50 g (I), 134 g dimethylsulfate, 60 g NaOH, 300 ml water add 35 g NaOH and reflux to obtain about 50 g 3,5-dimethoxybenzoic acid (II) which is converted to dimethoxybenzoyl chloride (HI) with PCI5. Extract the (HI) with ether and filter. Saturate the ether with NH3 at 0° C and filter. Wash with ether and water and reciystallize from hot water to get 3,5-dimethoxy-benzamide (IV). To a solution of 1 M of n-hexyl bromide (or 1,2-dimethylheptyl bromide, etc.) add 24.3 g Mg in 200 ml ether to... 

---