The present invention relates to a novel pharmaceutical composition for serotonin reuptake inhibition, wherein the composition comprises pentacyclic terpenoid glycosides, preferably asiaticoside and madecassoside optionally along with excipients. Also the present invention relates to a process of preparation of novel pharmaceutical composition for serotonin reuptake inhibition, wherein the process comprising steps of: (a) obtaining extract from the plant Centella asiatica; (b) treating the extract with the solvents to remove fatty substances, chlorophyll and other colorants; (c) purifying the extract through HPLC to obtain the eluted solvent; and (d) concentrating the eluted solvent to arrive at the composition. The invention also relates to the use of a composition comprising pentacyclic terpenoid glycosides, preferably asiaticoside and madecassoside optionally along with excipients to manufacture a medicament for serotonin reuptake inhibition in a subject in need thereof.