Synthesis and evaluation of the antioxidant and antiinflammatory activities of some benzo[l]khellactone derivatives and analogues

Treatment of 3-hydroxy-β-lapachone 4 with ylide 5 gave the coumarin derivative 7a, which was transformed to compounds 10–14. Compound 14 was then transformed to benzo[f]seselin 15 as well as to benzo[l]khellactones 16, 18 from which the title compounds 17, 19 I, 19 II, 20, 21 I and 21 II were prepared. All the tested compounds were found to interact with DPPH in a concentration and time dependent manner. All the tested compounds highly inhibited the soybean lipoxygenase, whereas compounds 12, 17 and 19 II highly compete with DMSO for •OH. Compounds 7a, 7b, 12 and 17 induced at 48.7–58.9% protection against carrageenin induced rat paw edema.