Evaluation of the bioactive properties of peptides obtained from the enzymatic hydrolysis of mesquite (Prosopis laevigata) cotyledon flour proteins

Abstract

For several decades, Mexico has faced a series of health problems that reduce the quality of life of its inhabitants. Diseases such as diabetes, hypertension, respiratory infections, and cancer are responsible for the primary mortality rates in the country and require immediate attention. Fortunately, Mexico also has privileged plant biodiversity, with a cultural meaning firmly rooted in Mexican society reflected in its traditions, customs, gastronomy, and increasingly frequent in the research of molecules with bioactive properties. In this sense, it is especially relevant to study those species with inherent value to the communities where they are endemic but that have remained outside of scientific scrutiny as potential sources of molecules that help solve current health challenges. The species Prosopis laevigata, commonly known as mesquite, is a clear example of a plant with economic, medicinal, and nutritional importance, but that has been little studied, which is why it represents an area of opportunity in contributing to the literature. Bioactive peptides have been positioned as attractive study molecules due to a series of properties, including potent biological activity, relative safety compared to other small molecules, diversity of target molecules, and ease of production. The objective of this work was to evaluate the bioactive peptides derived from the enzymatic hydrolysis of the proteins present in the seed of Prosopis laevigata in order to determine their antioxidant potential, as well as their antimicrobial, cytotoxic, and enzymatic inhibitory capacity. The peptides presented SC50 values of 81 and 89 µg/mL for the fractions smaller and larger than 5 kDa, respectively, demonstrating strong antioxidant capacity in the ABTS assay. Similarly, a reducing power of 0.250 and 0.156 was obtained in the FRAP test, reaching similar conclusions. The cell viability assay against the HepG2 cell line showed a cytotoxic effect at high concentrations of the peptides (8 mg/mL). On the other hand, the antimicrobial assay demonstrated an inhibition in the growth of S. aureus but was inefficient in inhibiting the growth of E. coli, suggesting a selective inhibition mechanism. Finally, it was demonstrated that the peptides have the ability to inhibit the activity of α-amylase. In addition, it was evident that the type of inhibition depends on the fraction used as an inhibitor, resulting in a competitive type of inhibition for those peptides with a size less than 5 kDa and mixed for peptides greater than 5 kDa. Altogether, the results revealed the great potential of P. laevigata peptides as bioactive molecules and justified the importance of continuing to study them to implement them in a functional product in response to the prevention or treatment of health challenges in Mexico.