Green Synthesis of Gold Nanoparticles Using Different Leaf Extracts of Ocimum gratissimum Linn for Anti-tubercular Activity

Abstract

Background: Tuberculosis is a greatest threat to human health. It requires urgent need to seek new devise alternate strategies and ant-tubercular compounds. In the present scenario, Nonmaterias, have opened new avenues in medicine, diagnosis and therapeutics. Objective: In view of this, the current study aims to synthesize gold nanoparticles and determine its efficacy to inhibit Mycobacterium tuberculosis. Methods: Gold nanoparticles (GNPs) synthesized from medicinal plant, such as Ocimum gratissimum linn, were tested against Mycobacterium tuberculosis (H37RV strain). Gold nanoparticles were characterized by UV-Vis spectrophotometer, FTIR, SEM and TEM. TEM results revealed that the GNPs were found spherical in structure and around 10-25 nm in diameter. UV-Vis spectroscopy exhibited an absorption peak at 348 nm. Fourier transform infra-red spectroscopy showed the GNPs have coated with phytoconstituents (terpenoids) that indicate the role of bio-molecules responsible for efficient stabilization and capping of the gold nanoparticles. In vitro model was designed to determine minimum inhibitory concentration (MIC) of each sample by Lowenstein Jensen (LJ) slope method. Results: The results showed that the presence of ursolic acid in ethanolic and hydroalcoholic extracts was found to be 2.89% and 1.97%, respectively. GNPs of ethanolic and hydroalcoholic exhibited anti-tubercular activity, with MIC 2.5 µg/ml and 20 µg/ml, respectively. While ethanolic and hydroalcoholic extracts showed such activity at concentrations 50 µg/ml and 75 µg/ml, respectively. Conclusion: GNPs synthesized from ethanolic extract showed profound efficiency to kill mycobacteria. As in this method no chemical reagents were used, the synthesized gold nanoparticles have potential for biological applications. There is an urgent need to further development of nano-antibiotic for tuberculosis.