Optimization of Sorghum Kafirin Extraction Conditions and Identification of Potential Bioactive Peptides

Abstract

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.

Effect of Protease Type and Peptide Size on the In Vitro Antioxidant, Antihypertensive and Anti-Diabetic Activities of Eggplant Leaf Protein Hydrolysates

“…For instance, the dipeptides identified in alcalase hydrolysate (MS, AF and FA) were found to exhibit antioxidant, ACE-inhibitory and dipeptidyl peptidase IV-inhibitory activities. In fact, MS and FA peptides were identified to be present in egg white and bean protein hydrolysates, respectively (BIOPEP-UWM database) while AF was found to be an ACE-inhibitor in Sorghum Kafirin hydrolysate [ 51 ]. Some of the identified peptides in the CH have been found to exhibit various bioactive properties such as ACE-inhibitory, antioxidant, α-amylase and α-glucosidase inhibitory activities as reported in the BIOPEP-UWM database.…”

“…This is reflected in the identified peptide sequences, whereby only the AH contained dipeptides. Earlier studies also reported that alcalase was most potent protease in producing smaller size peptides during hydrolysis of rice dreg [ 51 ] and pea [ 3 ] proteins.…”

In situthermal modification of kafirin using infrared radiations and microwaves

“…Several studies on kafirin reported the presence of major bands between 15 and 30 kDa with dimers and oligomers 4,11,19,23,38,39 . According to Emmambux and Taylor, 5 heat treatment of kafirin showed a decrease in all band intensities.…”

“…Several methods have been tried to improve the yield and purity of the kafirin so that it can be efficiently utilized as a gluten substitute. Castro‐Jácome et al 23 . reported that amyloglucosidase pretreatment increased the yield of the kafirin.…”

Precooked sorghum flour as proper vehicle of ACE‐I and DPP‐IV inhibitory sorghum peptides

“…Various studies have shown the role of sorghum in the non‐transmissible disease prevention such as hypertension or hyperglycaemia (Ortíz‐Cruz et al ., 2015). This effect has been attributed mainly to the angiotensin‐converting enzyme (ACE‐I) and dipeptidyl peptidase‐4 (DPP‐IV) inhibitory peptides released from α‐kafirin, the main storage protein in sorghum (Castro‐Jácome et al ., 2020). Moreover, a novel ACE‐I inhibitory peptide (TLS) with IC 50 value of 102.1 μmol L −1 was successfully purified from sweet sorghum grain protein hydrolysate (Wu et al ., 2016).…”