Computational and Experimental Progress on the Structure and Chemical Reactivity of Procyanidins: Their Potential as Metalloproteinases Inhibitors

Synthesis and experimental/computational characterization of sorghum procyanidins-gelatin nanoparticles

In this research, sorghum procyanidins (PCs) and procyanidin B1 (PB1) were encapsulated in gelatin (Gel) to form nanoparticles as a strategy to maintain their stability and bioactivity and for possible applications as inhibitors of metalloproteinases (MMPs) of the gelatinase type. Encapsulation was carried out by adding either PCs or PB1 to an aqueous solution of A- or B-type Gel (GelA or GelB) at different concentrations and pH. Under this procedure, the nanoparticles PCs-GelA, PCs-GelB, PB1-GelA, and PB1-GelB were synthesized and subsequently characterized by experimental and computational methods. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that all types of nanoparticles had sizes in the range of 22-138 nm and tended to adopt an approximately spherical morphology with a smooth surface, and they were immersed in a Gel matrix. Spectral analysis indicated that the nanoparticles were synthesized by establishing hydrogen bonds and hydrophobic interactions betweenGel and the PCs or PB1. Study of simulated gastrointestinal digestion suggested that PCs were not released from the Gel nanoparticles, and they maintained their morphology (SEM analysis) and antioxidant activity determined by Trolox-equivalent antioxidant capacity (TEAC) assay. Computational characterization carried out through molecular docking studies of PB1 with Gel or (pro-)metalloproteinase-2 [(pro-)MMP-2], as a model representative of the PCs, showed very favorable binding energies (around -5.0 kcal/mol) provided by hydrogen bonds, van der Waals interactions, and desolvation. Additionally, it was found that PB1 could act as a selective inhibitor of (pro-)MMP-2.