A Multifunctional Trypsin Protease Inhibitor from Yellow Bell Pepper Seeds: Uncovering Its Dual Antifungal and Hypoglycemic Properties.

Fungal infections are a growing public health concern worldwide and the emergence of antifungal resistance has limited the number of therapeutic options. Therefore, developing novel strategies for identifying and developing new antifungal compounds is an active area of research in the pharmaceutical industry. In this study, we purified and characterized a trypsin protease inhibitor obtained from Yellow Bell Pepper (Capsicum annuum L.) seeds. The inhibitor not only showed potent and specific activity against the pathogenic fungus Candida albicans, but was also found to be non-toxic against human cells. Furthermore, this inhibitor is unique in that it also inhibits α-1,4-glucosidase, positioning it as one of the first plant-derived protease inhibitors with dual biological activity. This exciting discovery opens new avenues for the development of this inhibitor as a promising antifungal agent and highlights the potential of plant-derived protease inhibitors as a rich source for the discovery of novel multifunctional bioactive molecules.

Purification and Characterization of a Novel Thermostable Papain Inhibitor from Moringa oleifera with Antimicrobial and Anticoagulant Properties.

Plant cystatins (or phytocystatins) comprise a large superfamily of natural bioactive small proteins that typically act as protein inhibitors of papain-like cysteine proteases. In this report, we present the purification and characterization of the first phytocystatin isolated from Moringa oleifera (MoPI). MoPI has a molecular mass of 19 kDa and showed an extraordinary physicochemical stability against acidic pHs and high temperatures. Our findings also revealed that MoPI is one of the most potent cysteine protease inhibitors reported to date, with Ki and IC50 values of 2.1 nM and 5.7 nM, respectively. More interestingly, MoPI presents a strong antimicrobial activity against human pathogens such as Enterococcus faecalis and Staphylococcus aureus. In addition, MoPI also showed important anticoagulant activity, which is an unprecedented property for this family of protease inhibitors. These results highlight the pharmaceutical potential of this plant and its derived bioactive molecules.

Purification and Identification of Novel Antioxidant Peptides Isolated from Geoffroea decorticans Seeds with Anticoagulant Activity.

Geoffroea decorticans is a xerophilous deciduous tree present in most arid forests of southern South America, which is commonly used in traditional medicine. The seeds of this tree have been previously investigated for their singular chemical composition, but their protein content has been poorly investigated. Herein, we report the isolation, purification, and characterization of a set of thermostable peptides derived from Geoffroea decorticans seeds (GdAPs) with strong antioxidant and anticoagulant activities. The most potent antioxidant peptides showed a half maximal inhibitory concentration (IC50) of 35.5 ± 0.3 µg/mL determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH). They also caused a dose-dependent prolongation of the aPTT clotting time with an IC50 value of ~82 µg/mL. Interestingly, MALDI-TOF/MS analysis showed the presence of three major peptides with low molecular weights of 2257.199 Da, 2717.165 Da, and 5422.002 Da. The derived amino-acid sequence of GdAPs revealed their unique structural features, exhibiting homology with various proteins present in the genome of Arachis hypogaea. All in all, our data suggest a direct applicability of GdAPs for pharmaceutical purposes.

Extraction and partial characterization of a coagulant preparation from Silybum marianum flowers. Its action on bovine caseinate.

An outstanding parameter in cheese making is the type of coagulant, which greatly influences the characteristics of the final products. Proteolysis is the most important set of biochemical changes during ripening of most cheeses, and is carried out, in different magnitude, by proteolytic agents originated in milk, rennet (or rennet substitute), and starter and non-starter micro-organisms (Silva & Malcata, 2000). The demand for alternative sources of milk coagulants, to replace the expensive and limited natural rennet supplies, has increased (Esteves et al. 2001). All commercial enzymes employed as milk coagulant are aspartic proteinases, which are most active at acidic pH and preferentially cleave peptide bonds between residues with hydrophobic side-chains (Silva & Malcata, 1999). Because of the presence of aspartic proteinases, aqueous crude extracts from flowers of Cynara cardunculus (Veríssimo et al. 1995, 1996), Cynara humilis, and/or Cynara scolymus are traditionally employed in the Iberian Peninsula as vegetable rennet for cheesemaking (Reis et al. 2000). Milk clotting activity was also proved in flowers of Centaurea calcitrapa and Onopordum turcicum (Tamer, 1993; Domingos et al. 1998). All these species are included within the Asteraceae family and furthermore in the same tribe: Cardueae Cass.= Cynareae Less. (Ariza Espinar & Delucchi, 1998). When a potential rennet substitute is studied, it is particularly important to evaluate adequately the degradation patterns of the caseins because of their effects on yield, consistency, and flavour of the final cheese (Fox, 1989). It is important to guarantee a well-balanced breakdown of curd proteins (caseins) in order to avoid formation of undesired attributes in cheese such as low viscosity and high bitterness (Visser, 1993). One of the most frequently used methods to monitor proteolytic processes on caseins is urea-polyacrylamide gel electrophoresis. On the other hand, tricine-SDS polyacrylamide gel electrophoresis improves the separation, identification and quantification of casein hydrolysates because it allows the visualization of large and small peptides (Pardo & Natalucci, 2001), with the additional advantage of allowing the estimation of molecular masses. Both methods are then suitable to characterize the performance of vegetable rennet in different ways. This preliminary study had the following objectives: the partial characterization of (i) the aspartic proteolytic activity present in flowers of Silybum marianum (L.) Gaertn. (Asteraceae); and (ii) the hydrolytic profile of bovine caseins.