The most note worthy feature of the hetrocyclic ring is the asymmetry of the exocyclic
angles at N(1A) [i30.
malondialdehyde and aromatic DNA adducts in larynx tissues.
N, and =0 groups either in the ring or exocyclic
2] units (especially exocyclic
methylene group) and having three rings in its chemical structure.
The Ser158 residue encoded by exon 4 is hydrogen bonded via a side-chain hydroxyl group to the exocyclic
hydroxyl 03 of the pyridoxal ring of the pyridoxine 5'-phosphate cofactor; hence, the Ser158Leu mutation is likely to disrupt cofactor binding.
A typical HPLC chromatogram showing co-migration of the exocyclic
acrolein--dG adduct peak (UV and radioactivity) from the synthetic standards and from cockerel aorta DNA is shown in Figure 2.
We were expecting the five-membered C-ring formation of steroidal structure of 1 since exocyclic
free radical is more stable than endocyclic  The Pd-assisted intermolecular cascade cyclization of reduced derivative of acetal 6 also favoured five-membered C-ring in a separate study in our group  The dihydroxylation of the steroidal precursor 5 followed by C-ring cleavage with Pb(OAc)4 and condensation of resulting trione would furnish the complete synthesis of steroidal backbone 4 of 1 (scheme-1).
Lipid peroxidation as a potential endogenous source for the formation of exocyclic
Based on these results, metabolite M2 was generated by oxidation of the exocyclic
methyl group of emodin, and could be identified as o-hydroxyemodin.