<i>Tribulus terrestris</i> fruit’s potential for synthesizing gold nanoparticles with remarkable biological prospects

Tribulus terrestris is a member of the family Zygophyllaceae commonly known as “puncture vine”. The plant has been used traditionally as an analgesic and to relieve rheumatic pain, eye problems, sexual dysfunction and edema. The aim of this work was to test the use of T. terrestris fruit extract as a reducing agent in synthesizing gold nanoparticles (AuNPs), test their biological activities, and assess their suitability as a therapeutic agent by testing them for potential adverse effects on human cells. Indeed, we have performed the most comprehensive biological testing of AuNPs produced using T. terrestris extracts to date. The aqueous extract of dried powdered T. terrestris fruits was used for the reduction of hydrogen tetrachloroaurate (III) trihydrate (AuCl4·3H2O). The fruit extract's phytochemical components effectively served as reducing, capping and stabilizing agents, resulting in the production of consistent and round-shaped AuNPs with a size range of less than 100 nm. The synthesized AuNPs were subjected to various physicochemical analyses, then evaluated for antibacterial, antifungal and antileishmanial activity, and subjected to hemagglutination, cytotoxicity and antioxidant bioassays. The AuNPs showed inhibition zones against several bacterial and fungal strains, and exhibited antileishmanial activity at high doses. The AuNPs demonstrated positive hemagglutination activity against human Red Blood Cells (RBCs) of blood groups A and B at 10 and 20 µg/mL, but no hemagglutination activity against groups AB and O at up to 40 µg/mL. The AuNPs showed no cytotoxicity against human RBCs at up to 40 µg/mL, suggesting that they may be suitable for use in a clinical setting. The antioxidant activity of the AuNPs was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and the results indicated a high antioxidant potential.