Synthesis, Characterization and Assessment of Lapachol as Metal Nanoparticles for Selected Biological Activities

This study was conducted to isolate Lapachol (1, 4- naphthoquinone) from heterophragma adenophyllum seem and to synthesize its copper and silver nanoparticles followed by their antibacterial assessment. Lapachol was isolated from stem heartwood of heterophragma adenophyllum seem through column chromatographic technique. Characterization of Lapachol was carried through melting point assessment and running its comparative TLC against standard, added with structure elucidation by FT-IR spectrum. Silver nanoparticles of Lapachol were synthesized by treating 1 mM silver nitrate (AgNO3) solution with 1 mM solution of Lapachol in the presence of sodium hydroxide (0.1 N) in double distilled water at pH of 7.6 having temperature 40 °C for 3 hours. Whereas, copper-Lapachol nanoparticle synthesis was performed by treating 1 mM copper acetate tetrahydrate (Cu (CH3COO)2. 4H2O) with 1 mM solution of Lapachol at pH of 7.8 having temperature 40°C for 5 hours. Both newly formulated silver and copper nanoparticles were characterized using UV-visible, FT-IR spectroscopic techniques followed by SEM evaluation. The UV spectrum confirmed peaks at 415 nm and 560 nm for silver and copper nanoparticles, respectively. FTIR spectrum also positively identified the nanoparticle synthesis. Assessment by SEM revealed that the size of silver and copper nanoparticle were 6 nm and 30 nm, respectively using ImageJ software. Lapachol, copper and silver salts along with their synthesized nanoparticles were evaluated for their antibacterial study against Staphylococcus. aureas, Escherichia. coli and Bacillus. subtilis. The results obtained for their comparative evaluation revealed that silver-Lapachol and copper-Lapachol nanoparticles have greater antibacterial efficacy against all three aforementioned strains of bacteria at 5 μg/ml, 40 μg/ml and 80 μg/ml concentrations versus their counterparts of Lapachol and above mentioned metallic salts.