Biosynthesis, Characterization, and Biological Activities of Procyanidin Capped Silver Nanoparticles

Abstract

In this study, procyanidin dimers and Leucosidea sericea total extract (LSTE) were employed in the synthesis of silver nanoparticles (AgNPs) and characterized by ultraviolet-visible (UV-Visible) spectroscopy, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), and dynamic light scattering (DLS) techniques. AgNPs of about 2–7 nm were obtained. DLS and stability evaluations confirmed that the AgNPs/procyanidins conjugates were stable. The formed nanoparticles exhibited good inhibitory activities against the two enzymes studied. The IC50 values against the amylase enzyme were 14.92 ± 1.0, 13.24 ± 0.2, and 19.13 ± 0.8 µg/mL for AgNPs coordinated with LSTE, F1, and F2, respectively. The corresponding values for the glucosidase enzyme were 21.48 ± 0.9, 18.76 ± 1.0, and 8.75 ± 0.7 µg/mL. The antioxidant activities were comparable to those of the intact fractions. The AgNPs also demonstrated bacterial inhibitory activities against six bacterial species. While the minimum inhibitory concentrations (MIC) of F1-AgNPs against Pseudomonas aeruginosa and Staphylococcus aureus were 31.25 and 15.63 µg/mL respectively, those of LSTE-AgNPs and F2-AgNPs against these organisms were both 62.50 µg/mL. The F1-AgNPs demonstrated a better bactericidal effect and may be useful in food packaging. This research also showed the involvement of the procyanidins as reducing and capping agents in the formation of stable AgNPs with potential biological applications.

Cytotoxic Effects of Phytomediated Silver and Gold Nanoparticles Synthesised from Rooibos (Aspalathus linearis), and Aspalathin

“…It is interesting to note that the GR NPs showed smaller particle sizes by two to three-fold than their corresponding ASP in each of the AuNPs and AgNPs. This observation is complementary to the several reports of the synergistic effects of the other compounds in GR during synthesis despite ASP being the major compound [17][18][19]24]. Remarkably, smaller sizes of GR and ASP-AgNPs were formed relative to the AuNP counterparts, even though both Au and Ag belong to the same family of d-block in the periodic table.…”

“…In continuation of the previous studies to probe the involvement of isolated compounds from plant extracts in the phytomediated synthesis of metallic nanoparticles [17][18][19], green rooibos (GR) and ASP have been selected as reducing and stabilising agents in this study because of their wide spectrum of biological activities and antioxidant potential. The isolation procedures of pure ASP (Figure 1) and its spectroscopic data has been reported recently [20].…”

“…Still, limited information exists in the literature on the application of ASP for the synthesis of gold (Au) and silver (Ag) nanoparticles and the toxicity of the synthesised NPs on cancer cell lines. Although, the use of natural pure compounds such as hypoxoside, the proanthocyanidin dimer, and chalcones from different plant species in the preparation of Au-and AgNPs have been reported [17][18][19]. The current study presents a complimentary report on the synthesis of metal NPs using a single natural compound with a well-defined pharmacological profile, such as ASP.…”

A review of alpha-glucosidase inhibitors from plants as potential candidates for the treatment of type-2 diabetes

“…In addition, carbohydrates intake was found to enhance the uptake of procyanidin monomers. The encapsulation of procyanidin fractions from Leucosidea sericea in silver nanoparticles was found to further enhance the stability of these compounds without altering their inhibitory effect against alpha-glucosidase and alpha-amylase enzymes (Badeggi et al 2020 ). The stability of the nanoformulation of procyanidins is encouraging for the development of new alpha-glucosidase inhibitor as such drug needs to resist degradation by digestive juices and intereactions with intestinal microorganisms.…”

Recent advances on therapeutic potentials of gold and silver nanobiomaterials for human viral diseases

“…The extract of several plants parts such as leaves, roots, stem bark, flowers and seeds have been used in the fabrication of both metal NPs. For instance, Citrus limetta peels [ 8 ], aqueous extract of Cinnamon cassia [ 37 ], Allium sativum [ 38 ], Pelargonium sidoides [ 39 ], Leucosidea sericea (procyanidins) [ 40 , 41 ] have been used for the biological synthesis of both Au and Ag NPs. Additionally, the green synthesis entails the use of microorganisms such as bacteria, fungi, and viruses for producing metal NPs of immense biological functions.…”