Isolation and characterization of ACE-I inhibitory peptides from ribbonfish for a potential inhibitor of the main protease of SARS-CoV-2: An in silico analysis.

Recently, multifunctional fish peptides (FWPs) have gained a lot of attention because of their different biological activities. In the present study, three angiotensin-I converting enzyme (ACE-I) inhibitory peptides [Ala-Pro-Asp-Gly (APDG), Pro-Thr-Arg (PTR), and Ala-Asp (AD)] were isolated and characterized from ribbonfish protein hydrolysate (RFPH) and described their mechanism of action on ACE activity. As per the results, peptide PTR showed ≈ 2 and 2.5-fold higher enzyme inhibitory activity (IC50 = 0.643 ± 0.0011 µM) than APDG (IC50 = 1.061 ± 0.0127 µM) and AD (IC50 = 2.046 ± 0.0130 µM). Based on experimental evidence, peptides were used for in silico analysis to check the inhibitory activity of the main protease (PDB: 7BQY) of SARS-CoV-2. The results of the study reveal that PTR (-46.16 kcal/mol) showed higher binding affinity than APDG (-36.80 kcal/mol) and AD (-30.24 kcal/mol) compared with remdesivir (-30.64 kcal/mol). Additionally, physicochemical characteristics of all the isolated peptides exhibited appropriate pharmacological properties and were found to be nontoxic. Besides, 20 ns molecular dynamic simulation study confirms the rigid nature, fewer confirmation variations, and binding stiffness of the peptide PTR with the main protease of SARS-CoV-2. Therefore, the present study strongly suggested that PTR is the perfect substrate for inhibiting the main protease of SARS-CoV-2 through the in silico study, and this potential drug candidate may promote the researcher for future wet lab experiments.

The classical and potential novel healthy functions of rice bran protein and its hydrolysates.

Rice bran protein (RBP) is a plant protein obtained from rice bran, a byproduct produced during rice milling process. It has been proved to be a high quality protein due to containing all of the essential amino acids and the content closing to the FAO/WHO recommended ideal pattern. Recent studies indicated that RBP and rice bran protein hydrolysates (RBPH) served variety biological functions. In this review, we summarized the classical functions of RBP and RBPH mediating antioxidant activity, chronic diseases prevention (such as antihypertensive effect, anti-diabetic effect, cholesterol-lowering activity), and anti-cancer effect. We also proposed their potential novel functions on anti-obesity effect, attenuating sarcopenia, promoting wound healing. Furthermore, the potential benefit to coronavirus disease 2019 (COVID-19) patients was put forward, which might provide new strategy for development and utilization of RBP and RBPH.

Identification, protein antiglycation, antioxidant, antiproliferative, and molecular docking of novel bioactive peptides produced from hydrolysis of Lens culinaris.

Bioactive peptides produced from natural sources are considered as strategic target for drug discovery. Hyperglycemia caused protein glycation alters the structure of many tissues that impairs their functions and lead complications diseases in human body. This study investigated the bioactive peptides produced from red and brown Lens culinaris that might inhibit protein glycation to prevent diabetic complications. In this study, red and brown Lens culinaris protein hydrolysates were prepared by tryptic digestion, using an enzyme/substrate ratio of 1:20 (g/g), at 37°C, 12 hr then peptide fractions <3 kDa were filtered by using ultrafiltration membranes. Protective ability against protein glycation, DPPH radical scavenging, and anti-proliferative activities (on HepG2, MCF-7, and PC3 cell lines) of peptide fractions were assayed in vitro. Results showed that glycation was inhibited by peptides from 28.1% to 68.3% in different test model. PC3 cell line was more sensitive to the peptides which showed strong anticancer activity with lower IC50 (0.96 mg/ml). Peptide fractions were sequenced by HPLC-MS-MS. Twenty eight novel peptides sequences was identified. In silico study, two peptides could be developed as a potential bioactive peptides exhibited antiglycation, antioxidant, and antiproliferative activities. PRACTICAL APPLICATIONS: Peptides are becoming an emerging source of medications with the development of new technologies. We have selected Lens Culinaris as one of the rich sources of proteins to explore novel bioactive peptides encapsulated in its seeds. Peptides fractions demonstrated protective ability against protein glycation, strong antioxidant potential, and promising antiproliferative activity. We have identified 28 novel peptides and molecular docking study revealed that some peptides showed strong binding potential to insulin receptor and ACE. Thus, these peptides might be used to manage diabetes complication as well as COVID-19 disease due to their interaction with ACE. However, those peptides needs to be further studied as a potential new drug.