The present study investigated the anthocyanins and total polyphenols contents. Nalca (Gunnera tinctoria) is a plant of recognized importance in southern Chile, since it has an edible petiole which provides incomes to rural groups that are engaged in their commercialization. Nevertheless, no background exists about his secondary metabolites. The antioxidant capacity was determined by DPPH method, and its biological activity was evaluated against Cladophialophora and Cryptococcus laurentii. The results indicated that the Nalca petiole has high crude fiber content (11.57%). Also, it presented a high concentration of total polyphenols (7291.1 ± 224 mg GAE/100 g dry weight) and a high antioxidant capacity ((105735 ± 3008.14 µmoles TEAC/100 g dry weight). On the other hand, the extract showed a fungicide effect against the microorganisms assayed. The results suggest that Nalca is promissory source of bioactive compounds and a potential fungicide alternative in development.