Application of Enzymatic Treatment on Bioactive Proteins and Peptides
Bioactivity of Proteins and Peptides
Bioactive proteins and peptides are considered valuable because of their reported biological functions including antioxidant, anti-hypertensive, anticancer, antimicrobial, anti-diabetic and antiproliferative activities. Application of naturally sourced bioactive peptides in cancer treatments is gaining popularity due to their decreased side effects compared to synthetic drugs. For instance, lunasin, a well-known bioactive peptide from plant sources (soy, barley, wheat, rye, etc.), has been reported to exhibit significant antineoplastic effects (Hernandez-Ledesma et al. 2013). Anticancer mechanisms of bioactive peptides occur primarily by inducing apoptosis, inhibiting cell migration, inhibiting gene proliferation, inhibiting tumour angiogenesis and antioxidant activity (Schweizer 2009; Tyagi et al. 2015). Several bioactive peptides with anticancer potentiality have been reported, such as in vitro antiproliferative activities of pentapeptide EQRPR (isolated from rice bran) against colon, breast, and liver cancer cells (Kannan et al. 2010). Food sourced bioactive peptides are also demanding in diabetic treatments. In vitro studies of peptides from fermented soybean have been reported to increase glucose uptake (Kwon et al. 2011). The anti-diabetic mechanism of food-based bioactive peptides involves reducing blood glucose, cholesterol, and triglyceride levels, improving glucose uptake, and inhibiting a-amylase activity. One study conducted by Mojica et al. (2017) isolated peptides, namely, FEELN, ATNPLF, AKSPLF, and LSVSVL, from black bean protein hydrolysate and checked their anti-diabetic potential. Results indicated that peptides were effective in reducing blood glucose levels by inhibiting glucose transporter 2 (GLUT2) and sodium-dependent glucose transporter 1 (SGLT1). Anti-hypertensive activity of two tripeptides, namely VPP and IPP from casein has been reported in a human study by Fekete et al. (2015). Thus, fermented milk was used to develop various functional food products such as Evolus®, Danaten®, Calpis®, and Ameal® based on the ability of bioactive peptides to treat hypertension (Ricci-Cabello et al. 2012). Reported physiological effects of bioactive compounds are given in Figure 7.3.
FIGURE 7.3 Reported health functionalities of bioactive metabolites extracted using enzymes.
Bioactive Peptides Modification
The enzymatic modification of proteins and peptides from waste or by-products of seafood, plants or animals has been reported (Guerard et al. 2001; Je et al. 2007; Wattanasiritham et al. 2016). To recover fish protein hydrolysate from fish meal/waste, Alcalase has been reported as one of the major enzymes. The fish protein hydrolysate is industrially utilized to prepare functional peptides which possess several beneficial effects (Guerard et al. 2001). The purified peptide hydrolysate had reported antioxidant potentials in in vivo study (Je et al. 2007).
Enzyme-Assisted Extraction of Proteins and Peptides
Proteins and peptide fractions are gaining research interest due to their considerable reported evidence on health benefits. To extract desired proteins from plant sources is relatively difficult due to the presence of rigid cell walls which make protein release difficult. Several other factors during protein extraction including isoelectric point (IP), hydrophobicity, molecular weight, temperature sensitivity and degradation properties have considerable effects on extraction quality (Nadar et al. 2017). Plant and animal sources are widely used to produce bioactive peptides (Suarez-Jimenez et al. 2012).
However, it is a sensitive task to extract protein without activity deterioration. Among several methods used for protein extraction, enzymatic application is a more efficient technique (Nadar et al. 2017). Pectinase usage improved the extraction rate of protein from soy without denaturation in pilot and laboratory scale studies (Jung et al. 2006). Alcalase®-assisted extraction increased rice bran protein yields (Jung et al. 2006). Successful extraction of plant-derived proteins depends on careful and clean cutting during sample preparation, sample freezing, use of fresh parts for samples, etc. (Ghaly and Alkoaik 2010). Protease-assisted extractions are also widely used to extract plant, animal, and marine proteins and peptides. Protease was proven efficient in increasing the yield of soy proteins (De Moura et al. 2011; De Almeida, De Moura Bell, and Johnson 2014). Bioactive peptides from pinto bean had the potentiality against a-amylase inhibition and had antioxidant properties (Ngoh and Gan 2016). The peptides were further fractioned based on molecular weight using ultrafiltration to separate those that exerted the highest antioxidant and a-amylase inhibiting activity. Enzyme-assisted extraction of proteins and peptides not only increased extraction quantity but also maintained quality enhancing bioactivity. Another example reported that Alcalase enzyme-assisted extraction increased potato and rapeseed protein-derived peptides, thereby increasing anti-hypertensive activity by inhibiting angiotensin converting enzyme (Sari et al. 2013). Similarly, another study reported that Alcalase-treated rapeseed demonstrated accelerated protein hydrolysis (Zhang et al. 2007).
Enzymatic application to extract proteins and peptides from different sample sources is a potential tool that could increase yield and quality to enhance compound bioactivity. Thus, the enzyme-assisted extraction of bioactive proteins/ peptides will be used by the food, pharmaceutical and nutraceutical industries to develop functional food and beverages as well as pharmaceutical and nutraceutical formulations.
Final Remarks with Future Perspectives
The demand for developing functional foods/products steadily increased with increasing population in the world which could be a challenge for the future decades. Therefore, the interest has been rising to find innovative techniques to extract or modify bioactive compounds from natural resources especially in developing functional and nutraceutical foodstuffs. To achieve the goal of developing functional foods, enzymatic application is widely used as a safe and simple green technology. Conventional extraction techniques or chemical modification methods have several limitations includes lower efficiency, time-consuming, costly and laborious. Enzyme- based methods are more efficient, environment-friendly and innovative for recovery of biomolecules from natural sources. Therefore, the enzymatic application could be used as a potential tool to develop functional food/products, which could be utilized by the food/nutraceutical/pharmaceutical industries. Further research is needed to provide more useful insight for scale-up of enzymatic methods on industrial scale especially focusing on industrial and economic feasibility and removal of barriers pertaining to operational performance.