Lipoxygenase (LO) is a biological target for many diseases such as asthma, atherosclerosis, and cancer. Our labs have synthesized and investigated nordihydroguaiaretic acid (NDGA) derivatives and have established that the reductive inhibition of soybean and 15-human LO can be affected by the strength of the electron-withdrawing substituents on the phenyl rings of NDGA. In addition, we have determined that hydrophobic NDGA derivatives activate 15-HLO, suggesting a hydrophobic allosteric site.

Pyridines and pyrazines substituted with 1,2,4-oxadiazole-5-ones, 1,2,4-oxadiazole-5-thiones, and 1,3,4-oxathiazoline-2-ones were synthesized and tested against Mycobacterium tuberculosis. The two former ring systems were documented in the literature to act as carboxylic acid isosteres. The latter series was synthesized as possible synthetic intermediates to 1,2,4-thiadiazole-3-ones and was included in this study due to their interesting activity. Pivaloyloxymethyl derivatives of the isosteres were also prepared in order to increase their lipophilicity and therefore improve their cellular permeability. The derivatized isosteres were expected to be biotransformed by esterases to the active species after penetration of the mycobacterial cell wall. Biological properties of the compounds were compared with the unmodified polar isosteres of pyrazinoic and nicotinic acids. The majority of the compounds exhibited activities ranging from 0.5 to 16 times the potency of pyrazinamide.

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