Avenanthramides (AVNs) means a unique secondary metabolites category, produced exclusively by genus Avena sp. Till nowadays it was described more than eighty. AVNs are amides of anthranilic acid and various polyphenolic acids with one or more double bonds. AVNs as single molecules express strong antioxidant, anti-inflammatory and antineoplastic effect. Taking in account limited largest of the AVNs molecules (to 300 g/M) it is possible to expect increase of biological activity by dimerization or derivatization, where we could categorize too preparation of nanoparticles by green synthesis techniques, what is significant subject of current research. For green synthesis it is necessary the selection of the oat extracts with maximal AVNs content, ideally AVNs with predicted optimal pharmacological parameters and significant activity. The optimal varieties were selected from bulky collection with n> 100, the dynamic of the secondary metabolites synthesis during germination process was detailly monitored in case of variety TATRAN during ten days by HPLC techniques. The maximal content of AVNs was archived on the 8-th day of germination for variety TATRAN, 610.13 mg/g of dried material. For major AVNs (2c, 2p, 2f) was realized quantification by external calibration, other AVNs were analyzed semi- quantitively. Selected water-methanolic extracts with perspective AVNs content were subjected to preparation of green synthesis products by reaction with AgNO₃. For synthetized products were realized basic, spectral analysis and compared was antioxidant and pro-oxidant activity towards basic extracts. The archived results show statistically significant increase of pro-oxidant activity, what is one of the mechanisms of antimicrobial and cytostatic effect.