Floral extracts-mediated green synthesis of NiO nanoparticles and their diverse pharmacological evaluations

Abstract

Biosynthesis has emerged as an exciting interface for assembling multifunctional metal oxide nanoparticles for diverse medicinal applications. Herein, biogenic nickel oxide (NiO-NPs) is synthesized by using floral extracts of Callistemon viminalis (C. viminalis) as a low cost, ecofriendly reducing and stabilizing agent. NiO-NPs were annealed at 300 °C, 400 °C and 500 °C while their physiochemical properties were established by HR-SEM/TEM, UV, XRD, FTIR, EDS, SAED and SQUID techniques. Particle size of NiO-NPs decreased with increase in annealing temperatures. Magnetization curves indicated superparamagnetic behavior of the biogenic NiO-NPs at 300 K. Highly crystalline NiO-NPs obtained after annealing at 500 °C were used for biomedical applications. The anti-leishmanial activity on Leishmania tropica promastigotes (KMH-23) and anticancer activity on HepG2 (RCB1648) revealed excellent inhibition potential with IC₅₀ of 37.21 µg/mL and 47 µg/mL, respectively. Significant antibacterial effect was observed against Klebsiella pneumonia and Proteus vulgaris with MIC’s of 12.5 µg/mL each. Acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and α-glucosidase inhibitory potential were comparable with positive control drugs. Moderate antioxidant activities were observed. NiO-NPs were observed to be hemolytic (30%) at higher dose (1000 µg/mL). Overall, NiO-NPs revealed a multifunctional nature that can be explored for diverse biomedical applications.

Communicated by Ramaswamy H. Sarma

Keywords:

• Biosynthesis
• Callistemon viminalis
• NiO-NPs
• antimicrobial
• anti-leishmanial
• anticancer
• cholinesterase inhibition
• hemolysis

Acknowledgements

Authors acknowledge the support of Prof. Dr. N.M Butt (PINSAT-Preston University, Islamabad), and Dr. Mlungisi nkosi (MRD-iThemba Labs) for their continuous support and encouragement. In addition, we acknowledge the kind Post-doc and PhD fellows at Material Research Department especially Dr. Ahmed Galmed, Dr. Saleh Khamlich, Dr. Sone. Many thanks to Siddiki, Nagla Numan, Hamza for their assistance. And a special thanks to Xanthine muller from Radio biology Lab, iThemba Labs for selfless cooperation. All authors contributed equally to this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was generously funded by National Research Foundation (NRF), South Africa and UNESCO-UNISA Africa Chair in Nanoscience and Nanotechnology (U2ACN2) South Africa