Synthesis of isonicotinoylhydrazones from anacardic acid and their in vitro activity against Mycobacterium smegmatis.

Isonicotinoylhydrazones were synthesized from a natural product anacardic acid, a major constituent of cashew nut shell liquid. The unsaturated side chain in anacardic acid and its 5-nitro derivative were converted into C(8')-aldehydes by oxidative cleavage. C(8')-aldehydes are then coupled with isoniazid (an anti-TB drug) to obtain N-isonicotinoyl-N'-8-[(2'-carbohydroxy-3'-hydroxy) phenyl] octanal hydrazone (5) and N-isonicotinoyl-N'-8-[(2'-carbohydroxy-3'-hydroxy-6-nitro) phenyl] octanal hydrazone (6). These isonicotinoylhydrazones of anacardic aldehydes showed potent antimycobacterial activity against Mycobacterium smegmatis mc(2)155. The synergistic studies of 5 and 6 with isoniazid showed more inhibitory activities than isoniazid alone. Compounds 5 and 6 also showed activity against Mycobacterium tuberculosis H(37)Rv.