Anti-microbial and anti-cancer activity of gold nanoparticles phytofabricated using clerodin enriched clerodendrum ethanolic leaf extract

Abstract

Background: Search for options that can overcome microorganism’s resistance to traditional drugs, has shifted the focus towards plant-based molecules and extracts. Latest developments in plant-based nanomaterials have further expanded the role of plant extracts since nano particle - plant extract combinations are shown to possess enhanced biological activity and reduced toxicity to human cells. In the present study, facile, one-pot synthesis of nearly monodispersed gold nanoparticles was developed using Clerodin enriched Clerodendrum infortunatum ethanolic leaf extract under ambient conditions. The synthesized gold nanoparticles were evaluated for broad spectrum anti-microbial activity as well as compatibility with human peripheral blood mononuclear cells. Methods: Clerodin enriched fraction from C. infortunatum leaves ethanol extract was used to synthesize gold nanoparticle from chloroauric acid. Synthesized gold nanoparticles were characterized and tested for broad spectrum anti-microbial activity against Staphylococcus aureus, Bacillus cereus, Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa using the standard broth dilution method. Cytotoxicity of the gold nanoparticles was evaluated against human monocyte leukemic cells (THP-I) and healthy peripheral blood mononuclear cells. MTT and FACS based Annexin V/FITC-PI assays were used to study its cytotoxic effect. Results: TEM analysis showed an average diameter of 33 ± 5 nm for the synthesized nanoparticles. EDX validated the presence of elemental Au (98.8%) and confirmed its nano form. Antimicrobial assay of gold nanoparticles showed significant inhibitory effect in all the tested pathogens. Additionally, MTT and Annexin-V/ PI assay demonstrated the cytotoxic activity of the nanoparticles against THP-I cells. Interestingly, nanoparticles did not show cytotoxicity against healthy human peripheral blood mononuclear cells. Conclusion: Gold nanoparticles generated in an eco-friendly process using Clerodin enriched fractions showed promising broad spectrum antibacterial activity. Simultaneously, they proved themselves to be benign against healthy human cells indicating potential therapeutic applications. Added benefit for the nanoparticles was, they had anti-proliferative effects against human leukemic monocyte cancer (THP-I) cells.

Keywords

• Clerodin
• Clerodendrum infortunatum
• Gold nanoparticles
• Antimicrobial activity
• Cytotoxicity