Melissa officinalis, Labiateae has been used for the treatment of several disorders including diseases of the heart, liver, brain, insanity, giddiness, gripping, muscular pain, asthma, hydrophobia, tuberculous glands, headache, and scabies. In the present study immunomodulatory property of isolated compound obtained from ethanolic extract of whole plant of Melissa officinalis was investigated. The immunomodulatory activity of isolated compound was evaluated using various in vivo models including delayed type hypersensitivity (DTH) reaction, humoral antibody titer and carbon clearance test. Oral administration of isolated compound I (at 30 mg/kg) significantly inhibited sheep red blood cells induced delayed type hypersensitivity reactions and significantly increased the phagocyctic index. It also produced a significant dose related decrease in sheep erythrocyte specific haemagglutination antibody titer. The total leukocyte count (TLC), lymphocyte and neutrophil count increased significantly. These results clearly indicated that the isolated compound obtained from the whole plant ethanolic extract of Melissa officinalis presented a strong immunomodulatory potential.
