Amphibian host-defense peptides with potential for Type 2 diabetes therapy - an updated review

Exploring alternative sources of protein in food: Trends in nutrient and functional features

Proteins are essential biomolecules that perform critical roles in various biological processes, such as building and repairing tissues, transporting substances, signaling hormones, and providing protection. Traditional methods of meeting human protein needs, primarily through animal farming, have significant negative impacts on the environment. In many low-income countries, protein requirements often go unmet due to the high costs associated with animal farming. Additionally, the rise in food allergies has become a serious health concern, highlighting the need for alternative protein sources that cater to individuals sensitive to traditional proteins. As the world's population is projected to reach around nine billion by 2050, there are growing concerns that conventional protein sources may not be sufficient to meet the increasing demand. This situation has led to heightened interest in alternative protein sources that can fulfill nutritional needs without the drawbacks associated with traditional meat consumption. This systematic review aims to explore non-traditional dietary protein sources, focusing on their nutritional and some techno-functional characteristics reported. These sources may include a variety of options such as animals (both vertebrates and invertebrates), plants (like leaves, seeds, and legumes), algae, fungi, and by-products from the food industry.

Novel tryptophyllin peptides from Physalaemus centralis inhibit oxidative stress-induced endothelial dysfunction in rat aorta preparation

Amphibian skin is a rich source of molecules with biotechnological potential, including the tryptophyllin family of peptides. Here, we report the identification and characterization of two tryptophyllin peptides, FPPEWISR and FPWLLS-NH2, from the skin of the Central Dwarf Frog, Physalaemus centralis. These peptides were identified through cDNA cloning and sequence comparison. FPWLLS-NH2 shares its primary structure with a previously identified peptide from the skin of Pelophylax perezi, named PpT-2. Another peptide, FPPEWISR, is novel and was named PcT-1. After solid-phase peptide synthesis, both peptides exhibited significant antioxidant activity, with PcT-1 and PpT-2 demonstrating ABTS radical scavenging capacities of 0.305 and 0.269 mg Trolox equivalents/mg peptide, respectively, and ORAC values of 0.319 and 0.248 mg Trolox equivalents/mg peptide. Additionally, PcT-1 and PpT-2 inhibited AAPH-induced hemolysis in human red blood cells, achieving a protection level comparable to Trolox at 0.2 mg/mL. In rat aorta preparations, both peptides partially restored acetylcholine-induced vasorelaxation following pyrogallol-induced oxidative stress, with a greater protective effect of PpT-2. Hemolytic activity assay indicated no cytotoxicity in human red blood cells, and tests on Galleria mellonella larvae confirmed their low toxicity in vivo. These findings highlight the biotechnological potential of PcT-1 and PpT-2 as antioxidant agents, paving the way for new therapeutic applications in combating oxidative stress-related diseases.

Magainin-AM2 inhibits sucrose-induced hyperglycaemia, oxidative stress, and cognitive dysfunction in Drosophila melanogaster

Hyperglycaemia-induced oxidative stress plays significant roles in the development of type 2 diabetes and its complications. This study investigates effects of magainin-AM2 on high-sucrose diet induced redox imbalance and cognitive impairment in Drosophila melanogaster. Effects of various concentrations of sucrose, magainin-AM2 or a combination of both agents on mortality, eclosion rate, generation of reactive oxygen and nitrogen species, activities of antioxidant enzymes, thiol system, and markers of cognitive functions in control and treated flies were examined. Results showed that the exposure of flies to high sucrose (30 %-60 % w/w) diet increased mortality rate (38-67 %, P < 0.001) and levels of glucose (1.8-1.9-fold, P < 0.001), hydrogen peroxide (1.4-1.5-fold, P < 0.01) and nitrite/nitrate (1.2-fold, P < 0.01). Decreased levels of total thiol (53-59 %, P < 0.01), non-protein thiols (59-63 %, P < 0.01), catalase activities (39-47 %, P < 0.01-0.05) and glutathione-s-transferase activities (31-43 %, P < 0.01-0.05) were also observed. Magainin-AM2 (0-10 μM/kg diet) did not affect fly mortality rate, levels of hydrogen peroxide and nitrite/nitrate, and activities of catalase and glutathione-s-transferase. However, the peptide produced a dose-dependent increase in total thiol 1.2-1.6-fold, P < 0.001-0.01)and increases non-protein thiol levels at 10 μM/kg diet (2.0-fold, P < 0.01). Magainin-AM2 inhibited sucrose-induced elevation of glucose (55-70 %, P < 0.001), hydrogen peroxide (11-12 %, P < 0.01) and nitrite/nitrate (20-34 %, P < 0.01-0.05). The peptide prevented sucrose-induced reduction in total and non-protein thiols (1.9-2.0-fold, P < 0.05) levels and activities of catalase (2.3-3.1-fold, P < 0.001) and glutathione-s-transferase (1.8-2.8-fold, P < 0.001-0.05). Magainin-AM2 inhibited sucrose-induced reduction in acetylcholinesterase activities (3.6-4.0-fold, P < 0.001), eclosion rate (18 %, P < 0.001) and negative geotaxis (1.3-14-fold, P < 0.001). These results indicate that beneficial actions of magainin-AM2 may also involve the prevention of hyperglycaemia-induced oxidative damage and encourage its further development as an anti-diabetic agent.

Multifunctional host-defense peptides isolated from skin secretions of the banana tree dwelling frog Boana platanera (Hylidae; Hylinae)

Five host-defense peptides (figainin 2PL, hylin PL, raniseptin PL, plasticin PL, and peptide YL) were isolated from norepinephrine-stimulated skin secretions of the banana tree dwelling frog Boana platanera (Hylidae; Hylinae) collected in Trinidad. Raniseptin PL (GVFDTVKKIGKAVGKFALGVAKNYLNS.NH2) and figainin 2PL (FLGTVLKLGKAIAKTVVPMLTNAMQPKQ. NH2) showed potent and rapid bactericidal activity against a range of clinically relevant Gram-positive and Gram-negative ESKAPE + pathogens and Clostridioides difficile. The peptides also showed potent cytotoxic activity (LC50 values < 30 μM) against A549, MDA-MB-231 and HT29 human tumor-derived cell lines but appreciably lower hemolytic activity against mouse erythrocytes (LC50 = 262 ± 14 μM for raniseptin PL and 157 ± 16 μM for figainin 2PL). Hylin PL (FLGLIPALAGAIGNLIK.NH2) showed relatively weak activity against microorganisms but was more hemolytic. The glycine-leucine-rich peptide with structural similarity to the plasticins (GLLSTVGGLVGGLLNNLGL.NH2) and the non-cytotoxic peptide YL (YVPGVIESLL.NH2) lacked antimicrobial and cytotoxic activities. Hylin PL, raniseptinPL and peptide YL stimulated the rate of release of insulin from BRIN-BD11 clonal β-cells at concentrations ≥100 nM. Peptide YL was the most effective (2.3-fold increase compared with basal rate at 1 μM concentration) and may represent a template for the design of a new class of incretin-based anti-diabetic drugs.