Isolation of Novel ACE-Inhibitory and Antioxidant Peptides from Quinoa Bran Albumin Assisted with an In Silico Approach: Characterization, In Vivo Antihypertension, and Molecular Docking

Abstract

Albumin is the major fraction of quinoa protein that is characterized as having high nutritional value. However, until now, scant information is available on the bioactivity of quinoa albumin or its hydrolysates. To promote its usage, we extracted albumin in this study from quinoa bran assisted with cellulase and hemicellulose, and hydrolyzed it by alcalase and trypsin to produce bioactive peptides. The hydrolysates (QBAH) were purified by gel filtration and reversed-phase high-performance liquid chromatography (RP-HPLC), followed by identification using liquid chromatography-mass spectrometry (LC-MS/MS). Furthermore, based on in silico analysis, one angiotensin-I converting enzyme (ACE)-inhibitory and antioxidant peptide, RGQVIYVL (946.6 Da), and two antioxidant peptides, ASPKPSSA (743.8 Da), and QFLLAGR (803.5 Da), from QBAH were synthesized. RGQVIYVL showed a high ACE-inhibitory activity (IC 50 = 38.16 µM) with competitive mode of inhibition, and showed significant antihypertensive effect in spontaneously hypertensive rats at a concentration of 100-150 mg/kg body weight (bw). Molecular docking simulation showed that it could interact with the active ACE site via hydrogen bonds with high binding power. Moreover, RGQVIYVL, ASPKPSSA, and QFLLAGR all demonstrated high ·OH scavenging activity (IC 50 = 61.69-117.46 µM), ABTS + scavenging activity (58.29-74.28%) and Fe 2+ chelating ability (32.54-82.48% at 0.5 mg/mL). They could also retain activity after gastrointestinal enzyme digestion. These results indicate that quinoa albumin is a potential source of bioactive peptides possessing antioxidant and ACE-inhibitory activities.

Administration with Quinoa Protein Reduces the Blood Pressure in Spontaneously Hypertensive Rats and Modifies the Fecal Microbiota

“…Much research has focused on the antihypertension characteristics of protein from the quinoa and its enzymolysis products. For example, RGQVIYVL, a peptide from quinoa bran albumin, showed a significant antihypertensive effect in SHRs at a concentration of 100 or 150 mg/kg BW [ 22 ]. As reported in our previous study [ 23 ], quinoa protein hydrolysate produced by simulated gastrointestinal digestion showed a potent ACE inhibitory activity, and induced a significant decrease in blood pressure of SHRs between 2 and 10 h after oral administration at the dose of 200 or 400 mg/kg BW.…”

“…), a pseudocereal that originated in South America, has been recognized as an excellent source of dietary protein due to its high level of protein and well-balanced amino acids composition. Several quinoa protein hydrolysates that prepared by Alcalase, pepsin, trypsin, bromelain, etc., have been reported to possess in vitro ACE inhibitory activity [ 19 , 20 , 21 , 22 , 23 ], and some of them have demonstrated excellent antihypertensive activity in SHRs [ 22 , 23 ]. However, the in vivo antihypertensive effect of intact quinoa protein remains unclear.…”

The functional ingredients of quinoa (Chenopodium quinoa) and physiological effects of consuming quinoa: A review

“…Strong 2,2′‐azino‐bis (3‐ethyl‐benzthiazoline‐6‐sulfonic acid) cation (ABTS + ) and oxygen radical scavenging activity were observed, along with inhibitory effect on nitric oxide (NO) production, tumor necrosis factor‐α (TNF‐α), and interleukin‐6 (IL‐6) in lipopolysaccharide (LPS)‐stimulated RAW264.7 macrophages, implicating the antioxidant and immunomodulatory potential of this peptide (Ren et al., 2017). Some other peptides in quinoa like ASPKPSSA and QFLLAGR also demonstrated high free radical scavenging and iron chelating activity, whereas peptide RGQVIYVL in quinoa was found to inhibit angiotensin‐I converting enzyme (ACE) through competitive inhibition, which means that it may benefit blood pressure control (Zheng et al., 2019).…”

“…Evidence has demonstrated that increased oxidative stress is associated with many adverse health conditions, including Alzheimer disease, CSD, depression, and cancer (Al‐Qabba et al., 2020; Alvarez‐Jubete, Wijngaard, et al., 2010; Zheng et al., 2019). Reducing oxidative stress may help maintain a healthy state.…”

Antioxidant Peptides from Sepia esculenta Hydrolyzate Attenuate Oxidative Stress and Fat Accumulation in Caenorhabditis elegans

“…There is growing interest in the therapeutic applications of food-derived bioactive substances as safer alternatives, either as nutraceuticals or functional foods [ 11 , 12 , 13 ]. Bioactive peptides are a class of multifunctional compounds derived from food proteins, which have been reported to possess a variety of important physiologically related biological activities such as antioxidant, antihypertensive, and anti-inflammatory actions [ 14 , 15 , 16 ]. As a result, they have the potential to provide better alternatives to synthetic drugs to prevent and treat chronic diseases that affect a growing number people [ 15 , 17 ].…”