Red Sea marine algae extracts-based silver nanoparticles as antibacterial-anticancer agents

Abstract

Algae extracts are usually embracing a variety of metabolites that are generally nontoxic and biodegradable. Eight seaweeds belong to red algae (Bostrychia tenella, Laurencia majuscula, L. obtusa, and L. Papillosa), green algae (Caulerpa racemose and Halimeda tuna), and brown algae (Cystoseira trinodis and Sargassum aquifolium) were collected from the Red Sea waters off Jeddah city, Saudi Arabia, and extracted with methanol. Silver nanoparticles were individually synthesized through eco-friendly benign chemistry approach using methanolic extracts of the collected algae. The identity and characterization of the prepared nanoparticles were confirmed by scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS). the antimicrobial activity of the total extract and isolated compounds was estimated against a set of Gram-negative and Gram-positive. S. aquifolium and L. obtusa extracts - based AgNPs showed the most remarkable antibacterial effects against all tested Gram-negative bacteria with diameter of inhibition ranging from 17±3.0 to 12±0.9 mm. Also, S. aquifolium and L. obtusa extracts - based AgNPs exhibited cytotoxicity against HepG2, PC-3, and HeLa cancer cells with IC₅₀ values (µg/mL) ranging between 20.6 ± 1.5and 52.9 ± 7.10. The obtained results indicated that Sargassum and Laurencia–based AgNPs showed remarkable cytotoxic and antibacterial activities.