Consumption of Amaranth Induces the Accumulation of the Antioxidant Protein Paraoxonase/Arylesterase 1 and Modulates Dipeptidyl Peptidase IV Activity in Plasma of Streptozotocin-Induced Hyperglycemic Rats

Characteristics of Food Protein-Derived Antidiabetic Bioactive Peptides: A Literature Update

Diabetes, a glucose metabolic disorder, is considered one of the biggest challenges associated with a complex complication of health crises in the modern lifestyle. Inhibition or reduction of the dipeptidyl peptidase IV (DPP-IV), alpha-glucosidase, and protein-tyrosine phosphatase 1B (PTP-1B) enzyme activities or expressions are notably considered as the promising therapeutic strategies for the management of type 2 diabetes (T2D). Various food protein-derived antidiabetic bioactive peptides have been isolated and verified. This review provides an overview of the DPP-IV, PTP-1B, and α-glucosidase inhibitors, and updates on the methods for the discovery of DPP-IV inhibitory peptides released from food-protein hydrolysate. The finding of novel bioactive peptides involves studies about the strategy of separation fractionation, the identification of peptide sequences, and the evaluation of peptide characteristics in vitro, in silico, in situ, and in vivo. The potential of bioactive peptides suggests useful applications in the prevention and management of diabetes. Furthermore, evidence of clinical studies is necessary for the validation of these peptides’ efficiencies before commercial applications.

A Review of Recent Studies on the Antioxidant Activities of a Third-Millennium Food: Amaranthus spp

Amaranth (Amaranthus spp.) plant commonly refers to the sustainable food crop for the 21st century. The crop has witnessed significant attention in recent years due to its high nutritional value and agronomic advantages. It is a relatively well-balanced cosmopolitan food that is a protector against chronic diseases. Usually, the antioxidant activities of amaranth are held responsible for its defensive behavior. Antioxidant activity of plants, generally, is attributed to their phytochemical compounds. The current interest, however, lies in hydrolysates and bioactive peptides because of their numerous biological functions, including antioxidant effect. While the importance of bioactive peptides has been progressively recognized, an integrated review of recent studies on the antioxidant ability of amaranth species, especially their hydrolysates and peptides has not been generated. Hence, in this review, we summarize studies focused on the antioxidant capacity of amaranth renewal over the period 2015-2020. It starts with a background and overall image of the amaranth-related published reviews. The current research focusing on in vitro, in vivo, and chemical assays-based antioxidant activity of different amaranth species are addressed. Finally, the last segment includes the latest studies concerning free radical scavenging activity and metal chelation capacity of amaranth protein hydrolysates and bioactive peptides.

Amaranth as a Source of Antihypertensive Peptides

Amaranth is an ancestral crop used by pre-Columbian cultures for 6000 to 8000 years. Its grains have a relevant chemical composition not only from a nutritional point of view but also due to the contribution of components with good techno-functional properties and important potential as bioactive compounds. Numerous studies have shown that amaranth storage proteins possess encrypted sequences that, once released, exhibit different physiological activities. One of the most studied is antihypertensive activity. This review summarizes the progress made over the last years (2008-2020) related to this topic. Studies related to inhibition of different enzymes of the Renin-Angiotensin-Aldosterone system, in particular Angiotensin Converting Enzyme (ACE) and Renin, as well as those referring to potential modulation mechanisms of tissue or local Renin-Angiotensin-Aldosterone system, are analyzed, including in silico, in vitro, in vivo, and ex vivo assays. Furthermore, the potential use of these bioactive peptides or products containing them, in the elaboration of functional food matrices is discussed. Finally, the most relevant conclusions and future requirements in research and development of food products are presented.

Amaranth as a potential dietary adjunct of lifestyle modification to improve cardiovascular risk profile

The aim of this review was to summarize data regarding amaranth as a potential component of lifestyle modification to improve cardiovascular risk profiles by modifying cardiovascular risk factors such as cholesterol, diabetes, and hypertension. PubMed was searched for appropriate articles. The main inclusion criteria for articles were as follows: interventions with amaranth; conducted in humans or animals or in vitro; and reported serum lipids and lipoprotein levels, and antidiabetic, antihypertensive, and antioxidant abilities. The outcome measures were changes in serum lipids and the presence of antidiabetic, antihypertensive, and antioxidant activity. A total of 33 articles were included herein. Regarding hypolipidemic activity, most studies investigated the effect of intervention with amaranth in animals, and fewer studies were performed in humans. Most studies in animal models demonstrated the ability of amaranth to decrease total cholesterol and low-density lipoprotein cholesterol. Pilot studies in humans were not convincing regarding amaranth's lipid-lowering activity. Based on this search, it is not clear which constituents are potentially responsible for the hypocholesterolemic effect of amaranth. Some authors tend to think that squalene can play a role in this effect, whereas others suggest that different components of amaranth are of greater importance (eg, sterols, oil fractions rich in fatty acids, proteins, amino acids, or fiber) for its hypocholesterolemic effect. It is possible that several constituents are jointly responsible for this action. Regarding the antidiabetic, antihypertensive, and antioxidant activities, most studies were performed in vitro and showed good potential for all three biological effects. Future research should focus on clarifying the effect of amaranth on high-density lipoprotein cholesterol, identifying the constituents responsible for these beneficial effects, and providing more data regarding its use in humans, ideally using randomized controlled trials. The antidiabetic, antihypertensive, and antioxidant activities found in vitro should be confirmed further in animal or human models.