Phytosynthesis of gold nanoparticles using hydrolysable tannins from <i>R. palmeri</i> as reductant and capping agent and their cytotoxic activity

Background: In recent years, the usage of metabolites obtained from plants in the synthesis of noble metal nanoparticles as reducing and stabilizing agents has been investigated, being polyphenols, such as anthocyanins and tannins highlighted due to the variety of beneficial effects that these compounds present in the human health. Objective: This study reports the use of hydrolysable tannins (HT) obtained from Rubus palmeri as a reducing and capping agent in the gold nanoparticles syntheses (AuNPs), as well as their cytotoxic effect on HeLa cell lines. Results: The obtained HT were identified as derivates of ellagic acid (Sanguiin H-6/Lambertianin A, Lambertianin C, and Lambertianin D). Furthermore, a successful synthesis occurred in a 1 mg/mL:1 mM (HT:HAuCl 4 ) proportion rate at 30 °C, generating a single surface plasmon resonance (SPR) signal at 530 nm. The Fourier-transform infrared spectroscopy (FTIR) proved the interaction between the HT over the AuNPs surface. Additionally, the transmission electron microscopy (TEM) analysis set an average particle size of 22.2 nm and a prevalence of spheres. Moreover, the antioxidant assays showed a variation of two folds between the HT and the AuNPs-HT. Finally, the cytotoxic assay allowed us to establish an IC 50 value at 16.52 µg/mL, indicating an cytotoxic effect in HeLa cells. Conclusion: The results reported herein demonstrate the function of HT in the photosynthesis of AuNPs, producing a colloid with cytotoxic effects on HeLa cells.