Novel dna polymerase inhibitors, mikanolide and dihydromikanolide

Process for obtaining a dry extract of Mikania micrantha, Mikania scandens and Mikania cordata leaves, comprising at least 50% by weight of mikanolide and dihydromikanolide and at least 20% dihydromikanolide, the said process being characterised in that it comprises the following successive stages:

• grinding and drying Mikania micrantha, Mikania scandens and Mikania cordata leaves;
• addition, to the ground leaves of Mikania micrantha, Mikania scandens and Mikania cordata leaves, of a solvent chosen from toluene, ethyl acetate, toluene and ethyl acetate mixtures, toluene and acetone mixtures, ethyl acetate and heptane mixtures, and heptane and acetone of the mixtures in proportions of 7:3 to 3:7;
• filtration and recovery of the filtrate;
• concentration of the extract of the primary extract solution in order to obtain a concentration of 2.5 to 10% dry extract;
• dividing of the concentrated extract obtained in the preceding stage between the extraction solvent and a mixture comprising from 10% to 50% methanol or ethanol in water;
• washing of the alcohol-water phase with n-hexane or heptane;
• elimination of the alcohol of the alcohol-water phase;
• extraction of the aqueous phase obtained with ethyl acetate;
• drying of the ethyl acetate phase with a drying agent;
• evaporation of the solvents and recovery of the dry extract;
• purification of the dry extract obtained by a physico-chemical separation method;
• and
• obtaining, after elimination of the solvents, the desired extract.