In the present work, we investigated the synthesis of stable ZnO nanoparticles with the biological method using three kinds of extracts, one from mesocarp of fruit and another from mesocarp and seed of the fruit of avocado (Persea Americana Mill) which belongs to the family Lauraceae. Flavonoids in fruits of P.americana could be behind the anti-inflammatory, anti-cancer and anti-hypertensive properties of the plant.