Sonia Barberis

Bioactive Peptides as Functional Food Ingredients

Abstract Bioactive peptides are protein-specific portions from 2 up to some dozens of amino acid residues with desirable biological activities, based on their composition and sequence. Databases report about 3000 peptide sequences with potential activities (antioxidant, antihypertensive, antithrombotic, antiadipogenic, antimicrobial, antiinflammatory, and antitumoral). It is assumed that peptides have high specificity in target tissues; no or little toxicity, do not accumulation in the organism, and easily degrade in the environment. However, their usefulness as nutraceuticals is limited by the low bioavailability due to the gastrointestinal digestion, poor transportability through the membranes, and rapid plasma clearance. This chapter reviews the different technologies for the production of bioactive peptides. Although the size of the molecule will determine the technology most suitable for its production, this chapter emphasizes the chemical and enzymatic synthesis. Finally, some strategies to enhance absorption, effectiveness, and bioavailability, and to study molecular mechanisms of activity and safety of these functional ingredients are discussed.

Behavior of Araujiain, a new cysteine phytoprotease, in organic media with low water content

In this paper we studied the effect of different organic solvents (1-octanol, trichloroethylene, ethanol, ethyl acetate, tetrahydrofuran, cyclohexane, propanone, acetonitrile, dichloromethane, chlorobenzene, N,N-dimethylformamide, acetophenone, diethyl ether, methanol, ethylene glycol and toluene) with low and constant water content on substrate preferences, thermostability and stability (caseinolytic activity retention after 4 h) of proteases of Araujia hortorum Fourn. ( Asclepiadaceae ). The stability of araujiain was high in N,N-dimethylformamide and ethanol at 40oC, but decreased at higher temperature. Araujiain substrates preferences in buffer Tris-HCl (pH 8), ethylene glycol and N,N-dimethylformamide exhibited different patterns, but the enzyme showed a high preference by glutamine derivative in all cases. According to FTIR spectroscopy studies, araujiain changed its secondary structure and as a consequence, it also changed its substrate preferences. This enzyme showed lower α-helical character and greater β-sheet folding in buffer than in organic media. A larger amount of antiparallel β-sheet residues indicates the formation of tighter intermolecular hydrogen bonds and enzymatic aggregates. These facts could explain the higher esterolytic activities, the greater stability and good hydrolytic potential of araujiain in some organic media such as N,N-dimethylformamide.

Enzymatic and chemical synthesis of new anticoagulant peptides

In this study we report the enzymatic synthesis of N‐α‐[Carbobenzyloxy]‐Tyr‐Gln‐Gln (Z‐YQQ), a new anticoagulant tripeptide. It was obtained using phytoproteases from the stems and petioles of Asclepias curassavica L. as catalyst in an aqueous–organic biphasic system formed by 50% (v/v) ethyl acetate and 0.1 M Tris–HCl buffer pH 8. The resulting peptide was compared with the analogous peptide Tyr‐Gln‐Gln (YQQ) produced by solid‐phase chemical synthesis. The in vitro anticoagulant activity of the aforementioned peptides was determined using Wiener Lab Test (Wiener, Argentina). The toxicological activity of the peptides was also determined. The enzymatically synthesized Z‐YQQ peptide acted on the extrinsic pathway of the coagulation cascade, delaying the conversion time of prothrombin to thrombin and fibrinogen to fibrin by 136 and 50%, respectively, with respect to the controls. The chemically synthesized YQQ peptide acted specifically on the intrinsic pathway of the coagulation cascade, affecting factors VIII, IX, XI, and XII from such cascade, and increasing the coagulation time by 105% with respect to the control. The results suggest that two new anticoagulant peptides (Z‐YQQ and YQQ) can be useful for safe pharmaceutical applications. Nevertheless, some aspects related to peptide production should be optimized.

Functional properties of goat cheese protein hydrolysed Evaluation by artificial neural network

The aim of this work is to study key functional parameters of the goat cheese protein hydrolysates. A Plackett-Burman Statistical Design, Response Surface Methodologies and Artificial Neural Network are applied to describe the effects of different factors (pH, Temperature, Time of hydrolysis, Amount of added buffer and Enzyme : Substrate ratio) on the following functional parameters of goat cheese proteins, which are hydrolysed by papain: Free Amine Nitrogen (NA), Total Soluble Nitrogen (NT), Solubility (PSI), Water Holding Capacity (WHC), Emulsifying Activity Index (EAI), Emulsifying Stability Index (ESI), Viscosity ( ), Held Water (HW), Surface Hydrophobicity (So), Foaming Capacity (FC) and Foam Stability (FS). According to our results, the release of soluble proteins from goat cheese to the supernatant (NT) and the hydrolysis degree of proteins into the supernatant (NA) increased until 443% and 273%, respectively. PSI, WHC, EAI, ESI and HW increased until 443%, 159%, 0.88%, 324% and 64% respectively.  decreased until 33% and So (bitter peptides indicator) was reduced until 98.8 %, regard to the original protein isolates. FC and FS were extremely low or null. Predicted values were experimentally confirmed and compared with those of original protein isolates.

Acacia caven pollen from South America. An useful bio-indicator of environmental pollution. A healthy food supplement?

The aim of this work is to evaluate the mineral and heavy metal contents of Acacia caven (Mol.) Molina pollen, a South American plant which grows in the Northwest of Argentina, for studying its behavior as bio-indicator of environmental pollution and their consequences as dietary supplement. Mineral and heavy metal contents were determined by flame atomic absorption / emission spectrometry (FAAS and FAES, respectively), inductively coupled plasma optical emission spectrometry (ICP-OES) and hydride generation atomic absorption spectrometry (HG-AAS). The obtained results demonstrated that some mineral contents (K, Ca, P, Fe, Mg, Na, Zn and Se) of Acacia caven pollen met the requirements of both, the Food and Nutritional Board (FNB) and the Argentinean Alimentarius Codex (AAC) to be used as a dietary supplement. Nevertheless, some heavy metals analyzed such as Al, Cu, Ni, V, Cr and Cd, exceeded the upper levels (UL) established by FNB and AAC, probably due to environmental contamination. Beyond the high level of some heavy metals found in the Acacia caven pollen, this could be an important dietary supplement by their high Fe and low Na contents. Considering that the suggested doses of commercial pollen by pharmacists and companies advice is 13.5 g/day, an only doses of Acacia caven pollen would satisfy the recommended daily intake (RDI) of Fe given by FNB for an adult individual. In spite of this promising date, further studies on the Fe bioavailability and heavy metal toxicity from Acacia caven pollen should be carried out for being used this pollen as dietary supplement.