Anti-plasmodial activity of aqueous neem leaf extract mediated green synthesis-based silver nitrate nanoparticles

Abstract

The objective of this study is to synthesize neem-silver nitrate nanoparticles (neem-AgNPs) using aqueous extracts of Azadirachta indica A. Juss for malaria therapy. Neem leaves collected from FRIM Malaysia were authenticated and extracted using Soxhlet extraction method. The extract was introduced to 1 mM of silver nitrate solution for neem-AgNPs synthesis. Synthesized AgNPs were further characterized by ultraviolet-visible spectroscopy and the electron-scanning microscopy. Meanwhile, for the anti-plasmodial activity of the neem-AgNPs, two lab-adapted Plasmodium falciparum strains, 3D7 (chloroquine-sensitive), and W2 (chloroquine-resistant) were tested. Red blood cells hemolysis was monitored to observe the effects of neem-AgNPs on normal and parasitized red blood cells. The synthesized neem-AgNPs were spherical in shape and showed a diameter range from 31−43 nm. When compared to aqueous neem leaves extract, the half inhibitory concentration (IC₅₀) of the synthesized neem-AgNPs showed a four-fold IC₅₀ decrease against both parasite strains with IC₅₀ value of 40.920 µg/mL to 8.815 µg/mL for 3D7, and IC₅₀ value of 98.770 µg/mL to 23.110 µg/mL on W2 strain. The hemolysis assay indicates that the synthesized neem-AgNPs and aqueous extract alone do not have hemolysis activity against normal and parasitized red blood cells. Therefore, this study shows the synthesized neem-AgNPs has a great potential to be used for malaria therapy.

Keywords:

• Anti-plasmodial
• Azadirachta indica A. Juss
• green synthesis
• nanoparticles
• silver nitrate

Acknowledgment

We would also like to thank the Natural Products Division, Forest Research Institute Malaysia, (FRIM) for the technical support. A high appreciation to the School of Health Science, Universiti Sains Malaysia (USM) for helping us to perform scanning electron microscopy (SEM) and also the Institute for Research in Molecular Medicine (INFORMM) for providing us facilities to culture and maintain the malaria parasite and SpectraMax M5e microplate reader to collect the data.

Disclosure statement

The authors declare that there is no conflict of interest regarding the publication of this article

Additional information

Funding

Authors would like to acknowledge Universiti Sains Malaysia, USM [Individual Grant; 1001/CIPPM/812150], and the Higher Institution Centre of Excellent (HICoE) Fund provided by the Ministry of Education, Malaysia [311/CIPPM/4401005] for the financial support.