The invention refers to an isolated extract of walnuts of high efficiency andstability over time useful for the manufacture of a medicament for the treatmentof viral, fungal and bacterial diseases, which is characterized in that it isobtained from a process comprising: i) Collecting unripe walnut fruits as rawmaterial； ii) Preparing the raw material for the extraction； iii) Freezing theraw material prepared in the previous step； iv) Drying； v) Extracting in a timelower than 10 minutes； vi) Filtration； and vii) Final packaging. The inventionalso refers to its use for manufacturing a medicament for the treatment of bacterial,fungal and viral diseases and to a composition comprising it.
