Antioxidant and anti-inflammatory activity of aryl-acetic and hydroxamic acids as novel lipoxygenase inhibitors

Lipoxygenase plays an essential role in the biosynthesis of the leukotrienes. Leukotrienes, as LO metabolites of arachidonic acid (AA), have been implicated as mediators in the pathophysiology of inflammatory diseases, host defense reactions and to play important role in the propagation of the diseases states, exacerbating the local events and ultimately leading to tissue damage. Simple stable molecules containing the hydroxamic acid functionality have been shown to inhibit 5-lipoxygenase. In fact, several hydroxamates are orally active inhibitors of the enzyme as determined by their ability to block the biosynthesis of leukotriene in vivo. In order to establish the inhibitory utility of simple hydroxamates several omega-phenylalkyl and omega-naphthylalkyl hydroxamic acids were synthesized. In an attempt to expand and delineate these results we tried to synthesize some more for a further pharmacochemical study. Since lipophilicity is a significant physicochemical property determining distribution, bioavailability, metabolic activity and elimination, we tried to determine experimentally their lipophilicity from RPTLC method. The compounds are tested in vitro on: a) soybean lipoxygenase inhibition, b) interaction with 1,1-diphenyl-2-picryl-hydrazyl (DPPH) stable free radical, c) the HO* radical mediated oxidation of DMSO, d) inhibition of lipid peroxidation, e) scavenging of superoxide anion radicals f) interaction with glutathione and g) in vivo for the inhibition of carrageenin induced rat paw edema. The compounds have shown important antioxidant activity, medium anti-inflammatory activity and potent inhibition of soybean lipoxygenase as a result of their physichochemical features.