Synthesis of gold nanoparticles using Lippia scaberrima Sond. and the biological activity in combination with Aspalathus linearis (Burm.f.) R. Dahlgren
Anna-Mari Reid (1) Carel B. Oosthuizen (1), Ray S. Suprakas (2), Kattesh V. Katti (3) and Namrita Lall (1)
(1) Department of Plant and Soil Sciences, University of Pretoria, Pretoria, 0002, South Africa.
(2) DST/CSIR National Centre for Nano-Structured Materials, CSIR, Pretoria 0002, South Africa.
(3) Department of Radiology, University of Missouri, Missouri 65211, United States of America.
Tuberculosis (TB), as an epidemic, has had devastating consequences across the globe. Many plant extracts have been studied for their ability to treat tuberculosis or its associated symptoms. Both Lippia scaberrima Sond. (LS) and Aspalathus linearis (Burm.f.) R. Dahlgren (AL), are popular forms of health teas in South Africa. This study focused on the ability of the extracts, alone and in combination, together with the essential oil of Lippia scaberrima (LIPESS) to aid in the symptomatic relief of TB associated side-effects. Furthermore, the study evaluated the mechanistic activity by the binding affinity to enzymes Glutathion reductase (Gtr) and Mycothione reductase (Mtr). LS was found to have a MIC-value of 125 µg/ml against Mycobacterium tuberculosis H37Rv (M. tb) whereas, in combination with (AL) fermented (LSRB) and (AL) unfermented (LSRBG); the MIC values were found to be 500 µg/mL for both. The antiproliferative activities were obtained on HepG2 cells and ranged between 109.20 ± 8.05 mg/mL and 244.90 ± 4.97 mg/mL for LS, LSRB, LSRBG and LIPESS. LIPESS had an IC50 value of 244.90 ± 4.97 µg/mL and showed the lowest levels of toxicity. Initial studies on acetaminophen-induced hepatotoxicity indicated that LIPESS had hepatoprotective activity. LIPESS showed the most promising results with noteworthy hepatoprotective activity and moderate antimycobacterial activity. This study further investigated the synthesis and characterization of gold nanoparticles from LS. The absorption of the gold nanoparticles showed an intense peak at a wavelength of 540 nm. Transmission Electron Microscopy (TEM) images confirmed most of the formed gold nanoparticles were spherical in shape. The possible functional groups were identified by Fourier Transform Infrared Spectroscopy (FTIR). Finally, the cytotoxic potential was reduced by 2-fold when compared with the ethanolic extract. All the samples can be considered as adjuvants for the alleviation of side-effects experienced during TB infection.