ANTIOXIDANT ACTIVITY OF SOLANUM NIGRUM EXTRACTS

Plants have been the basis of many traditional medicine systems throughout the world for thousands of years and continue to offer new remedies. Modern medicine has gradually developed over the years of scientific and observational efforts of scientists, however, a part of its development remains in the roots of traditional medicine. In the plant family Solanaceae (night shadow plants) the genus Solanum is a very large group of about 1400 species found throughout in the temperate and tropical regions of the world. Solanum nigrum L. (SNL) (black night shades) is a species of Solanum genus, and this herbal plant is best adapted to soils of high fertility, especially those high in nitrogen and phosphorus. SNL is considered as a medicinal plant and source of food in many countries. Human consumption of their leaves and fruits as food is widespread, particularly in Africa and SE Asia(1). Most pharmacological studies reported on SNL focused on the antitumor activity with several reports on the hepatoprotective, antimicrobial, antinociceptive, anti-inflammatory and anti-pyretic properties(2). The present study was designed to investigate the antioxidant activites of two SNL polar extracts with different in vitro antioxidant testing systems. In order to verify whether examined extracts were able to restore the oxidative status modified by glutamate in primary cultures of astrocytes, the GSH levels and the intracellular ROS production were evaluated. We also investigated the cytotoxicity of extracts by MTT test. Results SNL leaves were collected around Catania (Sicily, Italy). The dried and powdered leaves were extracted in methanol/water solution (80:20 v/v) and water,respectively. The water extract was freeze-dried. The methanol was removed under reduced pressure below 40° C and the aqueous phase remaining after evaporation of organic phase was freeze-dried. On the basis of DPPH assay it was showed that both SNL extracts to exhibit interesting antioxidant activity. By Folin–Ciocalteu method we found that the total phenolic content is greater on water extract than hydro-alcoholic one. In our experimental models, it was demonstrated that the pre-incubation with SNL extracts were able to counteract the glutamate toxicity. They possessed antioxidant activity in a cellular free system. Furthermore, the extracts were able to restore the levels of GSH and ROS modified by glutamate to control values.