Synthesis of amino acid analogues of 10-methoxy dibenz and evaluation of their radical scavenging activity

A method for the synthesis of L-aminoacid (L-tyrosine, L-phenylalanine, L-hydroxyproline and L-threonine) analogues of l0-methoxy-dibenz[b,f]azepine is proposed. l0-methoxy-dibenz[b,f]azepine as a basic molecule was prepared by a known method. The key intermediate 3-chloro-1-(10-methoxy-5H-dibenz[b,f]azepine- 5-yl)propan-1-one was obtained by N-acylation of 10-methoxy-dibenz[b,f]azepine with 3-chloro-propionylchloride. Further coupling of the respective L-aminoacids was accomplished to produce 3-(4-hydroxyphenyl)-2-(3-(10-methoxy-5H-dibenz[b,f] azepine-5-yl)-3-oxopropylamino)propanoic acid 2-(3-(10-methoxy-5H-dibenz[b,f] azepine-5-yl)-3-oxopropylamino)-3-propanoic acid, 2-(3-(l0-methoxy-5H-dibenz phenyl-propanoic acid, 3-hydroxy- 1-(3-(l0-methoxy-5Hdibenz[b,f]azepin-5-yl)-3- oxopropyl)pyrrolidine-2-carboxylic acid, and 3-hydroxy-2-(3-( 10-methoxy-5H-dibenz acid, respectively. The synthesized compounds were evaluated in regard to their potential over the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity. Butyihydroxy anisole (BHA) and ascorbic acid (AA) were used as reference antioxidant compounds and also a comparative study with the newly synthesized compounds was done. Under the present experimental conditions, the analogues containing L-tyrosine, L-hydroxyproline and L-threonine, possess a direct scavenging effect by trapping the stable DPPH free radical. L-Hydroxyproline analogues showed a significant radical scavenging activity among the synthesized analogues. DPPH activity of the pure L-aminoacids was also determined and a comparative study with the newly synthesized products was done. The DPPH activity of products was found to be greater than that of the L-aminoacids.