Structure-activity relationship study of hydroxyethylamine isostere and P1' site structure of peptide mimetic BACE1 inhibitors.

An aromatic substituent has been introduced into a known hydroxyethylamine (HEA)-type BACE1 inhibitor containing the superior substrate sequence to enhance inhibitory activity. The HEA-type isosteres bearing different hydroxyl group and methyl group configurations were prepared through a branched synthesis approach using intra- and inter-molecular epoxide opening reactions. The effect of their configuration was evaluated, showing that an R-configuration improved the inhibitory activity, while introduction of a methyl group on the isostere decreased the activity. Based on the non-substituted isostere with an R-configuration, 21 derivatives containing various substituents at the P1' site were synthesized. Our evaluation of the derivatives showed that the structure of the P1' site had a clear effect on activity, and highly potent inhibitor 40g, which showed sub-micromolar activity against recombinant BACE1 (rBACE1), was identified. The docking simulation of 40g with rBACE1 suggested that a carboxymethyl group at the para-position of the P1' benzene ring interacted with Lys285 in the S1' pocket.

Novel mutation in splicing donor of dystrophin gene first exon in a patient with dilated cardiomyopathy but no clinical signs of skeletal myopathy.

One cause of X-linked dilated cardiomyopathies is mutation of the dystrophin gene. We report the case of a young boy who suffered from dilated cardiomyopathy caused only by dystrophin-deficient cardiac muscle, but who did not present with any clinical signs of skeletal myopathy. Sequence analysis of the patient's dystrophin gene revealed the presence of a novel single point mutation at the first exon-intron boundary, inactivating the 5' splice site consensus sequence of the first intron. The lack of muscle weakness observed clinically can be explained by expression of the brain and Purkinje dystrophin isoforms in skeletal muscle.