Biogenic silver nanoparticles from Abutilon indicum: their antioxidant, antibacterial and cytotoxic effects in vitro

Green synthesis of silver nanoparticles using biological entities is gaining interest because of their potential applications in nano-medicine. Herein, we report the biological synthesis of Abutilon indicum silver nanoparticles (AIAgNPs) using aqueous Abutilon indicum leaf extract (AILE) and evaluation of their biological applications. TEM analysis revealed that the spherical biogenic AIAgNPs were found to be between 5 and 25 nm in size. The bioactive phyto-constituents such are condensed tannins of AILE were found to play a key role in the reduction and capping of AIAgNPs. The biological properties of AIAgNPs were premeditated as free radical scavenging activity, antibacterial effect and anti-proliferative activity. AIAgNPs were found to exhibit good free radical scavenging activities and the intense zone of inhibition displayed by them in six different pathogenic species indicate the potential antibacterial effect. Further, AIAgNPs showed a dose dependant anti-proliferative effect against COLO 205 (human colon cancer) and MDCK (normal) cells with an IC50 of 3 and 4 μg/mL and 100 and 75 μg/mL, respectively after 24 and 48 h. The morphological changes, chromatin condensation and membrane potential loss induced by AIAgNPs were evidenced by AO/EB and AnnexinV-Cy3 staining. The mitochondrial membrane potential (MMP) loss and G1/S transition cell cycle arrest in COLO 205 cells was evidenced in rhodamine123 staining and FACS analysis. The high levels of ROS as shown in DCF-DA staining could have played a major role in DNA fragmentation and eventually lead to apoptosis. The mode of action through the induction apoptosis by AIAgNPs in COLO 205 cells is exciting with promising application of nano-materials in biomedical research.