The present invention relates to a synergistic pharmaceutical composition comprising Compound C2 (Neo-isopulegol), C3 (Iso-pulegol) and C4 (Citronellol) derived from herbal seed extract of Litsea cubeba useful for the treatment of lung cancer. The present invention also relates to the activity of compounds C2 or C3 or C4 either alone or in combination in killing of A549 lung cancer cells.