Evaluation of the biological activity of Moringa oleifera leaves extract after incorporating silver nanoparticles, in vitro study

Abstract

Moringa oleifera is rich in various active phyto-constituents (tannins, sterols, terpenoids, flavonoids, saponins, anthraquinones, alkaloids, and vitamins) in addition to different minerals in its leaves and seeds. Presence of these constituents is responsible for the antioxidant activity and the ability to protect against oxidative damage. Based on measurements of the cytotoxic activities, M. oleifera leaves were found to be more effective than the plant seeds. Therefore, the plant leaves were selected for preparation of silver plant nano-extract during the present study. The silver nanoparticles (Ag-NPs) were synthesized then characterized by transmission electron microscope (TEM), ultraviolet-visible (UV-VIS) spectroscopy and dynamic light scattering (DLS) measurements. Moreover, the in vitro antioxidants were assayed in M. oleifera leaves extract before and after incorporating Ag-NPs through measurement of total polyphenolic compounds and scavenging activities against free radicals in addition to the cytotoxic activity against growth of human colon carcinoma. Furthermore, the phenolic compounds were detected by gas chromatography coupled with a mass spectrometer (GC/MS) and fourier transform infrared (FT-IR) spectroscopy. Also, the median lethal dose (LD50) of the extract and nano-extract was evaluated. It was showed that incorporation of Ag-NPs into the M. oleifera leaves extract enhanced the total antioxidant capacity, concentration of total polyphenolic compounds, reducing power and scavenging activity against attack of free radicals in addition to increasing the cytotoxicity against growth of colon cancer cells. This might be related to increasing the phenolic compounds as a result of incorporation of Ag-NPs and detected by the GC/MS and FT-IR analysis. It was found that there was no wide gap in the LD50 between M. oleifera leaves extract and silver nano-extract. The LD50 values of the M. oleifera leaves extract and silver nano-extract were about 14,250 and 13,750 mg/Kg, respectively. The study revealed that incorporation of Ag-NPs into the M. oleifera extract enhanced the in vitro antioxidative efficiency and might be related to increasing the phenolic compounds.