76 point of discussion is the relev

76 point of discussion is the relevance of pro-oxidant compounds in living cells that exerted a 77 relevant role in some cell signaling pathways and a beneficial effect associated to oxidative 78 stress. Another point in this context is the contrasting results reported in several studies 79 suggesting either no effect or potential negative effects in certain diseases. The influence of 80 experimentation level (in vitro, in vivo, and clinical trials) is believed to have a significant 81 impact on results. In addition, natural antioxidants can exert pro-oxidant activity, which 82 induces oxidative stress, and few is known about the interaction with medication and 83 supplements (Pham-Huy, He, & Pham-Huy, 2008; Carocho & Ferreira, 2013). 84 The importance of such characteristics of peptides has been discussed in several reviews 85 available in the scientific literature. For instance, Sarmadi and Ismail (2010), in an overview 86 perspective, discussed several aspects related to antioxidant peptides. Authors highlighted 87 the importance of bioactive peptides, particularly for allergic reactions, that may preserve part 88 of its precursor protein allergenic activity. Liu et al. (2016) reviewed the free peptide 89 composition in meat and meat products, along with its biological and potential role in 90 pharmacological applications. Halim, Yusof, and Sarbon (2016), evaluated the releasing, 91 technological application such as water and fat holding capacity, and intended health 92 benefits of antioxidant activity and other biological activities of peptides extracted from fish 93 proteins. In a similar way, Mohanty et al. (2016) reviewed how digestion, fermentation and 94 enzymatic activity affected the releasing of bioactive peptides from milk proteins. The authors 95 also reported important findings related to biological activity, particularly as potential 96 therapeutic agents against non-communicable diseases (e.g. hypertension and 97 immunological diseases). 98 In all reviews, meat, fish, and milk proteins were shown as important sources of bioactive 99 peptides. In a similar way, Sila and Bougatef (2016) supported the exploration of marine by-100 products as potential sources of antioxidant peptides and suggested the potential and 101 significant application of these compounds in complex food systems. The production of