Protein Hydrolysates from Citrullus lanatus Seed: Antiradical and Hydrogen Peroxide-scavenging properties and kinetics of Angiotensin-I converting enzyme inhibition

Abstract

This study investigated the in vitro antihypertensive, antiradical and hydrogen peroxidescavenging properties of protein hydrolysates from Citrullus lanatus (watermelon) seed (CSPHs) obtained through enzymatic digestion. Proteins from watermelon seeds were isolated and enzymatically hydrolyzed with non-specific (alcalase), moderately specific (pepsin) and highly specific (trypsin) proteases, mimicking human gastrointestinal digestion. The hydrolysates were investigated for inhibitory property against angiotensin-I-converting enzyme (ACE) activity. Using N-[3-(2furyl)acryloyl]-L-phenylalanyl-glycyl-glycine as the substrate, CSPHs showed concentration-dependent ACE inhibition (IC 50 1.377-1.757 mg/mL) with peptic CSPH having the strongest ACE-inhibition followed by tryptic CSPH. Kinetic analysis revealed that peptic CSPH inhibited ACE activity in a mixedtype inhibition pattern while alcalase and tryptic CSPHs exhibited non-competitive inhibition mode. Peptic CSPH demonstrated the strongest DPPH radical-scavenging activity while tryptic CSPH showed the highest H 2 O 2-scavenging property. These results show that protein hydrolysates from watermelon seed possess bioactivities that could be exploited in the management of hypertension.

Extraction and Characterization of Antioxidant Peptides from Fruit Residues

“…Molecular weights between 0.5 and 1.5 kDa are also a common feature within antioxidant peptides [22]. Antioxidant peptides have been obtained from rapeseed residues (Brassica napus) [23,24], peels of pomegranate (Punica granatum) [3,25] and mango (Mangifera indica) [26], and seeds of apricot (Prunus armeniaca) [11,27], peach (Prunus persica L.) [11,16,28,29], bottle gourd (Lagenaria sciceraria) [30][31][32], cherry (Prunus cerasus L.) [11,33], olive (Olea europaea) [11,16,17,34], plum (Prunus domestica L.) [11,14,29,35], tomato (Solanum lycopersicum) [21,[36][37][38][39][40][41][42][43], wax gourd (Benincasa hispida) [44], jujube (Ziziphus jujube) [45,46], muskmelon (Cucumis melo) [47], watermelon (Citrullus lanatus) [32,[48][49][50][51][52][53], papaya (Carica papaya)…”

“…Incubation temperatures of 40-50 • C have been employed to promote protein solubilization. This strategy has been used in the extraction of proteins from the seeds of tomato, jujube, watermelon, Chinese cherry, African breadfruit, and pumpkin, as well as in pumpkin oil cake [21,37,[41][42][43]45,48,50,52,[55][56][57][58][59][60][61][62]. Despite the popularity and industrial applicability of this procedure, its selectivity and extraction yield, in general, are very low.…”

“…Table 3 groups the assays employed for the evaluation of antioxidant activity in hydrolysates obtained from fruit residues. [20,31,48] Scavenging effect on ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals ABTS radicals that absorb at 734 nm are produced by the reaction of ABTS with potassium persulfate. The method evaluates the reduction in the absorbance of ABTS radicals due to the presence of potential antioxidants.…”

Improving the Silk Industry by Studying the Effect of Several Aqueous Extracts to Enhance the Efficiency of Silkworm Bombyx mori L. Production

“…Peptides from plant sources have attention due to their ability to use it as food additives. (Arise et al, 2016b). One plant that has been extensively studied for its numerous bioactivities is Moringa oleifera.…”

Kinetic characteristics of partially purified invertase from <em>Citrullus lanatus</em> Rind

“…It comprises of about 6% sugar, 91% water and the residual portion consisting of vitamins and minerals. Water melon has been reported in several studies to have therapeutic properties, including antihypertensive, anti-diabetic, antioxidant, anti-inflammatory and antimicrobial effects (Arise et al, 2016a;Arise et al, 2016b;Erhirhie and Ekene, 2013). The rind of watermelon rind is usually discarded as waste, although it is edible (Al-Sayed and Ahmed, 2013).…”