Green synthesis of gold nanoparticles (Au NPs) using Tribulus terrestris extract: Investigation of its catalytic activity in the oxidation of sulfides to sulfoxides and study of its anti-acute leukemia activity

With regards to applied, facile, green chemical research, a bio-inspired approach is being reported for the synthesis of Au NPs by using Tribulus terrestris extract. The innate oxygenated phytochemicals facilitated the green reduction of Au3+ ions to corresponding NPs and also stabilized them by encapsulating them. This modification prevented the as-synthesized Au NPs towards agglomeration and tiny NPs were obtained in uniformly spherical in shape and in the range of 10-15 nm dimension. Physicochemical characteristics of the green synthesized Au NPs were evaluated by advanced physicochemical techniques like UV-Vis and FT-IR spectroscopy, SEM, TEM, EDX and XRD study. Catalytic performance of the biomolecule functionalized Au NPs was investigated in the controlled and selective oxidation of sulfides to sulfoxides using hydrogen peroxide as green oxidant at room temperature. Aromatic, aliphatic and heterocyclic sulfides were oxidized to their corresponding sulfoxides with high yields without formation of over oxidized sulfones. The catalyst was easily recovered and recycled for 8 successive times without noticeable decrease in catalytic activity. In addition, the biosynthesized Au NPs indicated suitable antioxidant and anti-acute leukemia properties against THP-1 cell line. Tribulus terrestris extract and the green synthesized Au NPs exhibited a maximum DPPH scavenging activity of 78% and 29.37%, respectively. Again, in the anticancer studies over THP-1 cell line following MTT assay, the Au NP exhibited gradual reduced % cell viability with increase in its concentration. At an Au NPs concentration of 2000 mu g/mL, the % toxicity became maximum suggesting efficient inhibition of cancer invasion. Based on the above results, Au NPs-Tribulus could be administered as a potential anti-leukemia drug for the treatment of acute leukemia following the clinical trial studies in humans.

Automated summary

A bio-inspired approach using Tribulus terrestris extract was utilized to synthesize Au NPs, which showed efficient catalytic performance in the oxidation of sulfides and exhibited potential anti-leukemia properties. Physicochemical characterization was carried out using advanced techniques, showcasing promising applications of the biosynthesized Au NPs.