Antioxidant, Antibacterial, and Antiparasitary Activities of Green Nanoparticles Synthesized Using Water-Soluble Melanins of Fruits

• Published in: BioNanoScience 2022-03, Vol.12 (1), p.228-240
• Main Authors: Montes-Avila, Julio, López-Angulo, Gabriela, Duarte-de-la-Peña, Gisela, Díaz-Camacho, Sylvia Páz, Osuna-Galindo, Velia Carolina, López-Valenzuela, José Ángel, Delgado-Vargas, Francisco
• Format: Article
• Language: English
• Subjects: Antioxidants; Artemia; Biological and Medical Physics; Biomaterials; Biophysics; Circuits and Systems; Engineering; Fruits; Gold; Infrared radiation; Infrared spectroscopy; Light scattering; Minimum inhibitory concentration; Nanoparticles; Nanotechnology; Paralysis; Pathogens; Photon correlation spectroscopy; Silver; Synthesis; Toxicity; Transmission electron microscopy
• ISSN: 2191-1630; 2191-1649
• DOI: 10.1007/s12668-022-00940-y

Up to date, fruit melanins have not been employed to synthesize nanoparticles (NPs). Crescentia alata , Randia echinocarpa , and Vitex mollis fruit are used in traditional medicine, and their soluble melanins (SMes) have high antioxidant activity. These SMes were used to prepare silver (green-AgNPs) and gold (green-AuNPs) NPs and evaluate their antioxidant capacity (DPPH and FRAP), activity against human pathogens (bacteria and the parasite Hymenolepis nana ), and toxicity ( Artemia salina assay). All SMes were useful to synthesize green-AgNPs but only V. mollis SMe for green-AuNPs. Infrared spectroscopy, dynamic light scattering, and transmission electron microscopy (TEM) showed that SMe is on the green-NPs surface. TEM showed 13–31-nm spherical green-AgNPs and 2–16-nm spherical and cylindrical green-AuNPs. Green-AgNPs showed higher antioxidant (FRAP = 3.4–725.4 µmol TE g −1 ; DPPH = 10.9–748.2 µmol TE g −1 ) and antibacterial (MIC = 1.85–15 µg mL −1 ; MBC = 3.7–30 µg mL −1 ) activities than the chemical-NPs. Moreover, the green-NPs (25 mg mL −1 ) were active against H. nana with the following times (min) (paralysis, death): green-AgNPs (10–40, 15–90) and V. mollis AuNPs (28, 40). The toxicity of the green-NPs (LC 50  = 61.6 to > 1000 μg mL −1 ) depended on the SMe employed in the preparation. V. mollis NPs were the less toxic: minimal toxicity for the AgNPs (LC 50  = 826.91 μg mL −1 ) and non-toxic for the AuNPs (LC 50  > 1000 µg mL −1 ). Thus, the SMes are useful to obtain green-NPs of high stability that showed activities against human pathogens, suggesting their potential to be used as alternative health treatments.