Lipophilic naphthols and 1,4-naphthoquinones as inhibitors of prostaglandin synthesis. 6. Study of 1,4-naphthoquinones

A number of plumgagin homologues (2-alkyl-1,4-naphthoquinones) and their 3-methyl derivatives are synthesized to enhance the inhibition of the prostaglandin synthetase (PGS)-activity by the natural compound plumbagin and to minimize its toxicity. The inhibition of the enzyme activity by the new naphthoquinones is only weak but their naphthol precursors are strong PGS-inhibitors. The mechanism of this enzyme interaction by the lipophilic naphthol derivatives is discussed in context with their singlet oxygen (1O2) reactive properties.