The phenothiazine nucleus is known for their inhibitory activity towards the regulatory enzymes that are contributing to diseases such as asthma, autoimmune diseases including allergic rheumatoid and encephalomyelitis. In this study a number of substituted phenothiazines were synthesized and screened for their biological activity against the regulatory enzymes involved in inflammatory diseases. Our results show that the newly synthesized compounds 4a-c and 5a-c exhibited promising target specific enzyme inhibition against phosphodiesterase, prostaglandin dehydrogenase and superoxide dismutase activity depending on steric factors of the molecules.