Cytotoxic Effects of Phytomediated Silver and Gold Nanoparticles Synthesised from Rooibos (Aspalathus linearis), and Aspalathin.

Akeem O Akinfenwa,Robbie C Luckay,Naeem S Abdul,Jeanine L Marnewick,Fathima T Docrat,Ahmed A Hussein

doi:10.3390/plants10112460

Akeem O Akinfenwa, Robbie C Luckay + Show 4 more

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https://doi.org/10.3390/plants10112460

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Abstract

The green chemistry approach has continuously been applied for the synthesis of functional nanomaterials to reduce waste, environmental hazards, and the use of toxic chemicals among other reasons. Bioactive natural compounds have been found great potential in this regard and are used to improve the stability, activity, and biodistribution of metal nanoparticles (MNPs). Aspalathin (ASP) from Aspalathus linearis (rooibos) has a well-defined pharmacological profile and functional groups capable of both reducing and capping agents in the synthesis of metallic nanoparticles (NP). This study provides the first report of the phytomediated synthesis of gold and silver nanoparticles (AuNPs/AgNPs) via ASP and the green rooibos (GR) extract. The study demonstrated a green chemistry approach to the biosynthesis of nanoparticles of GR-AuNPs, ASP-AuNPs, GR-AgNPs, and ASP-AgNPs. The results showed that GR and ASP could act both as reducing and stabilising agents in the formation of crystalline, with different shapes and dispersity of NPs in the ranges of 1.6–6.7 nm for AgNPs and 7.5–12.5 nm for the AuNPs. However, the ASP NPs were less stable in selected biogenic media compared to GR NPs and were later stabilised with polyethene glycol. The cytotoxicity studies showed that GR-AgNPs were the most cytotoxic against SH-SY5Y and HepG2 with IC50 108.8 and 183.4 μg/mL, respectively. The cellular uptake analysis showed a high uptake of AuNPs and indicated that AgNPs of rooibos at a lower dose (1.3–1.5 μg/mL) is favourable for its anticancer potential. This study is a contribution to plant-mediated metallic nanoparticles using a pure single compound that can be further developed for targeted drug delivery for cancer cells treatments in the coming years.

Highlights

Cancer, a multistep disease involving rapid and uncontrol cell multiplication, is among the world-leading health challenges that have attracted global concern
Considering the importance of surface functionalisation with a well-defined pharmacologically natural compound is crucial to the bioactivity, biodistribution, and biocompatibility of different metal nanoparticles (MNPs) in the medical field; this study aims to biosynthesise Au- and AgNPs capped with rooibos extract and pure ASP compound using a green chemistry approach to evaluate their cytotoxic activity against liver cancer and neuroblastoma human cell lines and determine the cellular uptake of the nanoparticles
In continuation of the previous studies to probe the involvement of isolated compounds from plant extracts in the phytomediated synthesis of metallic nanoparticles [17,18,19], green rooibos (GR) and ASP have been selected as reducing and stabilising agents in this study because of their wide spectrum of biological activities and antioxidant potential

Summary

Introduction

A multistep disease involving rapid and uncontrol cell multiplication, is among the world-leading health challenges that have attracted global concern. Huge concerns have been raised about the serious side effects, including kidney and liver toxicity and hearing impairment associated with these drugs. Other biocompatible metal-based drugs such as gold and silver have been reported as promising anticancer agents [2,3]. Strategies to reduce the side effects while improving the potencies of metal-based anticancer drugs have been ongoing. Among such strategies is the development of nanosystems for gold and silver as nanoparticles capped with antioxidant-rich plant sources for anticancer studies [4]

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