The invention relates to a process for the isolation of compound scopoletin which is used as nitric oxide synthesis inhibitor from Artemisia annua and other plant families, said process comprising extraction of dried powdered material of different plant parts with an aqueous acetonitrite solvent in the ratio of 1:5 for 6 to 8 hrs., concentration of the extracted solvent upto 30% of its original extract under vacuum, partitioning the concentrated extract with halogenated solvent to transfer scopoletin in the non-polar halogenated solvent, drying halogenated solvent over anhydrous sodium sulphate and evaporating the solvent, crystallizing the residues in methanol and filtering the crystals, concentrating the filtrate and chromatographed on silica gel, eluting scopoletin in chloroform methanol mixture; and crystallization of the fractions containing the scopoletin to get the pure scopoletin compound.