Truncation of Huia versabilis Bowman-Birk inhibitor increases its selectivity, matriptase-1 inhibitory activity and proteolytic stability

Novel Amphibian Bowman-Birk-Like Inhibitor with Antioxidant and Anticoagulant Effects Ameliorates Pancreatitis Symptoms in Mice

Acute pancreatitis (AP) is a serious inflammatory disorder and still lacks effective therapy globally. In this study, a novel Ranacyclin peptide, Ranacin, was identified from the skin of Pelophylax nigromaculatus frog. Ranacin adopted a compact β-hairpin conformation with a disulfide bond (Cys5-Cys15). Ranacin was also demonstrated effectively to inhibit trypsin and have anticoagulant and antioxidant activities in vitro. Furthermore, the severity of pancreatitis was significantly alleviated in l-Arg-induced AP mice after treatment with Ranacin. In addition, structure-activity studies of Ranacin analogues confirmed that the sequences outside the trypsin inhibitory loop (TIL), especially at the C-terminal side, might be closely associated with the efficacy of its trypsin inhibitory activity. In conclusion, our data suggest that Ranacin can improve pancreatic injury in mice with severe AP through its multi-activity. Therefore, Ranacin is considered a potential drug candidate in AP therapy.

Autophagy of Candida albicans cells after the action of earthworm Venetin-1 nanoparticle with protease inhibitor activity

The present studies show the effect of the Venetin-1 protein-polysaccharide complex obtained from the coelomic fluid of the earthworm Dendrobaena veneta on Candida albicans cells. They are a continuation of research on the mechanisms of action, cellular targets, and modes of cell death. After the action of Venetin-1, a reduced survival rate of the yeast cells was noted. The cells were observed to be enlarged compared to the controls and deformed. In addition, an increase in the number of cells with clearly enlarged vacuoles was noted. The detected autophagy process was confirmed using differential interference contrast, fluorescence microscopy, and transmission electron microscopy. Autophagic vesicles were best visible after incubation of fungus cells with the Venetin-1 complex at a concentration of 50 and 100 µg mL-1. The changes in the vacuoles were accompanied by changes in the size of mitochondria, which is probably related to the previously documented oxidative stress. The aggregation properties of Venetin-1 were characterized. Based on the results of the zeta potential at the Venetin-1/KCl interface, the pHiep = 4 point was determined, i.e. the zeta potential becomes positive above pH = 4 and is negative below this value, which may affect the electrostatic interactions with other particles surrounding Venetin-1.

Engineering and Structural Insights of a Novel BBI-like Protease Inhibitor Livisin from the Frog Skin Secretion

The Bowman–Birk protease inhibitor (BBI) family is a prototype group found mainly in plants, particularly grasses and legumes, which have been subjected to decades of study. Recently, the discovery of attenuated peptides containing the canonical Bowman–Birk protease inhibitory motif has been detected in the skin secretions of amphibians, mainly from Ranidae family members. The roles of these peptides in amphibian defense have been proposed to work cooperatively with antimicrobial peptides and reduce peptide degradation. A novel trypsin inhibitory peptide, named livisin, was found in the skin secretion of the green cascade frog, Odorrana livida. The cDNA encoding the precursor of livisin was cloned, and the predicted mature peptide was characterized. The mature peptide was found to act as a potent inhibitor against several serine proteases. A comparative activity study among the native peptide and its engineered analogs was performed, and the influence of the P₁ and P_2′ positions, as well as the C-terminal amidation on the structure–activity relationship for livisin, was illustrated. The findings demonstrated that livisin might serve as a potential drug discovery/development tool.

Fermentation of chickpea flour with selected lactic acid bacteria for improving its nutritional and functional properties

AIMS

To improve the nutri-functional quality of chickpea flour by fermentation with selected lactic acid bacteria (LAB) to formulate functional legume-derived products.

METHODS AND RESULTS

A Randomized Complete Block Design was carried out to assess the influence of experimental conditions (presence/absence of Lactiplantibacillus plantarum CRL2211 and/or Weissella paramesenteroides CRL2182, temperature, time and dough yield) on LAB population, acidification, antinutritional factors and total phenolic contents (TPCs) of chickpea flour. Fermentation with both strains for 24 h at 37°C produced an increase in LAB (up to 8.9 log CFU/g), acidity (final pH 4.06), TPC (525.00 mg GAE/100 g) and tannin and trypsin inhibitor removal (28.80 mg GAE/100 g and 1.60 mg/g, respectively) higher than the spontaneously fermented doughs. RAPD and Rep-PCR analysis revealed that fermentation was dominated by L. plantarum CRL2211. Molecular docking and dynamics simulations were useful to explain LAB enzyme behaviour during fermentation highlighting the chemical affinity of LAB tannases and proteinases to gallocatechin and trypsin inhibitors. Compared with other processing methods, fermentation was better than soaking, germination and cooking for increasing the techno-functional properties of chickpea flour. Fermented doughs were applied to the manufacture of crackers that contained 81% more TPC and 64% more antioxidant activity than controls.

CONCLUSIONS

Fermentation for 24 h at 37°C with selected autochthonous LAB was the best method for improving the quality of chickpea flour and derived crackers type cookies.

SIGNIFICANCE AND IMPACT OF STUDY

Chickpea is suitable for the development of novel functional foods. Fermentation with selected LAB would improve the final product quality and bioactivity. The combination of experimental and simulation approaches can lead to a better understanding of the fermentation processes to enhance the properties of a food matrix.

Bowman-Birk Inhibitors: Insights into Family of Multifunctional Proteins and Peptides with Potential Therapeutical Applications

Bowman-Birk inhibitors (BBIs) are found primarily in seeds of legumes and in cereal grains. These canonical inhibitors share a highly conserved nine-amino acids binding loop motif CTP1SXPPXC (where P1 is the inhibitory active site, while X stands for various amino acids). They are natural controllers of plants' endogenous proteases, but they are also inhibitors of exogenous proteases present in microbials and insects. They are considered as plants' protective agents, as their elevated levels are observed during injury, presence of pathogens, or abiotic stress, i.a. Similar properties are observed for peptides isolated from amphibians' skin containing 11-amino acids disulfide-bridged loop CWTP1SXPPXPC. They are classified as Bowman-Birk like trypsin inhibitors (BBLTIs). These inhibitors are resistant to proteolysis and not toxic, and they are reported to be beneficial in the treatment of various pathological states. In this review, we summarize up-to-date research results regarding BBIs' and BBLTIs' inhibitory activity, immunomodulatory and anti-inflammatory activity, antimicrobial and insecticidal strength, as well as chemopreventive properties.