The interest in extracting kafirins (KAF), the main storage protein from sorghum grain has recently increased due to its gluten-free content and the significant scientific evidence showing the health benefits of the bioactive peptides from cereal grains in human diets. The objectives were to obtain the highest percentage of KAF extraction using amyloglucosidase as pretreatment to increase the extraction yield and predict the bioactive peptides in the KAF. In this study, pretreatments with amyloglucosidase increased the extraction yield of KAF compared with extraction methods using only ethanol and sodium metabisulfite. Two protein fragment sequences were identified from KAF extract and were evaluated for potential bioactive peptide using the BIOPEP-UWM database, which suggest that KAF proteins from white sorghum may be considered as good precursors of dipeptidyl peptidase-inhibitor, angiotensin-converting enzyme inhibitor, antioxidant and hypotensive peptides following chymotrypsin, thermolysin, and subtilisin and their combination. Average scores aligned using PeptideRanker confirmed KAF proteins' potential sources of bioactive peptides with over 5 peptides scored over 0.8. In addition, 31 unexplored peptide sequences that could have biological activity were identified. Our results suggest that KAF can be used in the peptide productions with potential biological activity and beyond.

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Background: Ultraviolet B (UVB) causes photoaging of the skin, the appearance of wrinkles, spots, and alteration of the skin barrier. The main cells in the most superficial layer of the skin are the keratinocytes; these cells play an important role in protecting this organ.Objective: The present study aimed to investigate the antioxidant activity of the hydrolysates from kafirin to inhibit UVB-induced responses in human keratinocytes cells (HaCaT).Methods: Kafirin hydrolysates were produced by enzymatic hydrolysis with alcalase.The activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), in the HaCaT cell line in the presence of UVB and the effects of the hydrolysates against the UVB-induced response were evaluated. Furthermore, the peptides that were generated by hydrolysis were identified in silico using the BIOPEP database.Results: Two protein sequences were identified (α-kafirin and the precursor protein of α-kafirin), in the kafirin extract. A degree of hydrolysis of 18.8% was obtained by hydrolyzing the kafirin extract with alcalase. The kafirin hydrolysates avoided the decrease in endogenous antioxidant enzymes such as SOD, CAT, and GPx reducing the oxidative stress generated by UVB. Using the BIOPEP-UWM database, we found 102 peptide sequences, and it has shown that the peptides have a large amount of hydrophobic amino acids such as proline, alanine, and glutamine, and amino acids with high antioxidant capacity. Conclusion:These results suggest that the kafirin hydrolysates can be used as antioxidant agents to ameliorate UVB-induced skin keratinocytes cells' response in vitro, providing an alternative against UVB-induced photoaging.

Sorghum (Sorghum bicolor L. Moench) is an important staple food crop grown worldwide, easy to grow and drought tolerant. In recent years, sorghum grain has been increasingly regarded as a promising feedstock for the production of bioactive compounds. In particular, its main protein (kafirins fraction) has been used for the generation of biologically active peptides due to its high hydrophobic amino acid content and its hypoallergenicity. Several studies have shown that sorghum-derived peptides have antioxidant, anticancer, antimicrobial and anti-inflammatory activities, among others. These beneficial health effects could be attributed to the fact that in general, peptides derived from kafirins present glutamic acid and non-polar amino acids: proline, leucine and alanine. It has been reported that the presence of these hydrophobic amino acids in peptides facilitates their interaction with free radicals by neutralizing them, in addition to their low molecular weight and the position of the amino acids in the peptide sequence. Therefore, sorghum is a cereal with high potential for the production of biologically active peptides with benefits for human health.