Green Biogenic of Silver Nanoparticles Using Polyphenolic Extract of Olive Leaf Wastes with Focus on Their Anticancer and Antimicrobial Activities

Abstract

Agro-industrial wastes are rich in polyphenols and other bioactive compounds, and valorizing these wastes is a crucial worldwide concern for saving health and the environment. In this work, olive leaf waste was valorized by silver nitrate to produce silver nanoparticles (OLAgNPs), which exhibited various biological, antioxidant, anticancer activities against three cancer cell lines, and antimicrobial activity against multi-drug resistant (MDR) bacteria and fungi. The obtained OLAgNPs were spherical, with an average size of 28 nm, negatively charged at −21 mV, and surrounded by various active groups more than the parent extract based on FTIR spectra. The total phenolic and total flavonoid contents significantly increased in OLAgNPs by 42 and 50% over the olive leaf waste extract (OLWE); consequently, the antioxidant activity of OLAgNPs increased by 12% over OLWE, recording an SC50 of OLAgNPs of 5 µg/mL compared to 30 µg/mL in the extract. The phenolic compound profile detected by HPLC showed that gallic acid, chlorogenic acid, rutin, naringenin, catechin, and propyl gallate were the main compounds in the HPLC profile of OLAgNPs and OLWE; the content of these compounds was higher in OLAgNPs than OLWE by 16-fold. The higher phenolic compounds in OLAgNPs are attributable to the significant increase in biological activities of OLAgNPs than that of OLWE. OLAgNPs successfully inhibited the proliferation of three cancer cell lines, MCF-7, HeLa, and HT-29, by 79–82% compared to 55–67% in OLWE and 75–79% in doxorubicin (DOX). The preliminary worldwide problem is multi-drug resistant microorganisms (MDR) because of the random use of antibiotics. Therefore, in this study, we may find the solution in OLAgNPs with concentrations of 2.5–20 µg/mL, which significantly inhibited the growth of six MDR bacteria L. monocytogenes, B. cereus, S. aureus, Y. enterocolitica, C. jejuni, and E. coli with inhibition zone diameters of 25–37 mm and six pathogenic fungi in the range of 26–35 mm compared to antibiotics. OLAgNPs in this study may be applied safely in new medicine to mitigate free radicals, cancer, and MDR pathogens.

Comparative analysis of silver-nanoparticles and whey-encapsulated particles from olive leaf water extracts: Characteristics and biological activity

“…Moreover, the C = O stretching shifted to 2359.68 cm -1 and 2285.73 cm -1 with a lower intensity. The significant shift of O–H and C = O stretching vibrations indicates their binding with silver ions [ 55 , 60 ]. Besides, amide II or N-H vibrations shifted to 1636.03 cm -1 (Tofahy) and 1634.15 cm -1 (Shemlali), indicating the involvement of the protein functional groups of OLE as capping agents for the Ag ions, stabilizing Ag-NPs and preventing their agglomeration [ 22 , 61 ].…”

Potential Therapeutic Properties of Olea europaea Leaves from Selected Cultivars Based on Their Mineral and Organic Profiles

“…Moreover, the inhibitory activity against MDR bacteria by composite OLE AgNPs was superior to that of the standard antibiotic. The authors explain that OLE bioactive groups surrounded the surface of the AgNPs, leading to superior antioxidant, antimicrobial, and anticancer activities [ 82 ]. These studies did not identify the type of cultivar they employed to synthetize the NPs, but from our work, it is possible to propose all of the tested cultivars to create AgNPs against Gram(+) B. cereus (ATCC 14579), while O. europaea Verdeal’s leaves show the most adequate matrix for producing green AgNPs against Gram(+) S. aureus (ATCC 25923).…”

Green Synthesis of Uncoated and Olive Leaf Extract-Coated Silver Nanoparticles: Sunlight Photocatalytic, Antiparasitic, and Antifungal Activities

“…Whatman No. 1 filter paper was used to filter the solution, and the filtrate was then employed in the following tests [ 28 ].…”

“…Silver nitrate reacts with an extract of olive leaf waste to produce Ag-NPs, which have shown a range of biological, antioxidant, and antibacterial properties against multi-drug-resistant (MDR) bacteria and fungi, as well as anticancer activity against cancer cell lines [ 28 , 29 ]. Ag-NPs were produced using a green synthetic method that used olive leaf extract.…”