Toxicology of Asparagus laricinus in rats

Abstract

Traditional medicine has been a fertile source of revealing lead novel molecules which are then subjected to investigations using the techniques of the modern drug discovery. There are a number of conventional drugs that originate from plants, such as aspirin (from willow bark), digoxin (from foxglove), quinine (from cinchona bark), and morphine (from the opium poppy). The aim of the present work was to evaluate the possible toxic effects of the dried roots of Asparagus laricinus extracts using Sprague Dawley rats as animal models. In this study we investigated the use of Asparagus laricinus roots extracts for novel anticancer drug development, specifically looking at the safety and toxicology. Previous in vitro studies on Asparagus laricinus extracts have demonstrated anticancer activity against three human cell lines, namely, breast MCF7, renal TK10 and melanoma UACC62. These necessitated further studies on Asparagus laricinus extracts, such as toxicity, adverse effects investigations as well as in vivo biological studies using animal models. The objectives of the study was to evaluate variations in serum biochemical parameters, investigate possible deviations in haematological parameters, and also to assess histopathological variations on the liver, kidneys and spleen tissues of animals exposed to aqueous and ethanolic extracts of Asparagus laricinus roots. The study was conducted at the Animal Research Unit at the University of the Free State, Bloemfontein, South Africa.Written approval for the final version of the protocol was obtained from the Interfaculty Animal Ethics Committee of the Faculty of Health Sciences at the University of the Free State. The dried plant roots were pulverized, 10g soaked in ethanol or distilled water and agitated for 72 hours at 120 rpms. The supernatant was filtered and the ethanol removed completely under vacuum. The aqueous sample was lyophilized to obtain dried powdered material. The powdered plant material was dissolved in distilled water to prepare 2%, 10% and 20% concentration. The material was also dissolved in ethanol and different concentrations were obtained by varying the volumes of the solution administered. The study population consisted of a total of 54 Sprague Dawley rats (weighing between 180g and 250g), both male and female, obtained from the above research unit. The animals were divided into two groups of 24 and 30 rats for aqueous and ethanolic extracts, respectively. The aqueous group was further divided into four subgroups of 6 rats which were exposed to 2%, 10% and 20% extracts and the control group (unexposed). The ethanolic group was divided into five subgroups of 6 rats which were exposed to increasing doses of 50, 100, 200 and 400mg/kg/day extracts and the last group served as controls (unexposed). The aqueous extracts were administered to the three subgroups for eight weeks ad libitum while the control group was exposed to tap water. Ethanol extracts were administered daily over a period of two weeks through gavage and the control group was administered water through gavage as well. Blood samples were collected, animals were sacrificed and organs/tissues excised for histological assessment. Biochemical and haematological tests were selected as indicators of the damage to the tissue of organs, including the liver, kidney and spleen. A significant difference (p<0.05) was observed for platelets with the ethanol extract at a dose of 50g/kg/day. There were no statistical differences between the treatment groups and controls with regard to the rest of haematological variables and selected biochemical tests. Comparison of the controls (n=6) and treatment groups (n=6) revealed an average median change in weight of slightly above 50g over the entire eight-week period of experimentation with aqueous extracts. A significant difference (p<0.05) was observed for both haemoglobin and blood urea nitrogen results with the 20% water extract. There were no statistical differences between the treatment and control groups with regard to the rest of haematological variables and selected biochemical tests. Histological evaluation could not reveal any pathological changes in both the aqueous and ethanolic extracts across all levels of dosage. The main purpose of the study was to establish whether Asparagus laricinus has any toxic or adverse effects on the tissue and organs of animal models. This was done by evaluating hepatotoxicity, nephrotoxicity, spleen and vascular damage to the animals. Dose-response assessment of the effect of the extract was done by analysis of the blood and tissue samples collected at the end of the research. Biochemical and haematological results could not show any patterns in abnormalities although we observed statistically significant results on few parameters. Histologically, no pathological changes were observed. In conclusion, we summarize that the toxicological evaluation of Asparagus laricinus extracts may be considered relatively free of toxicity when given orally, as it did not cause death, damage or inflammation to the tissues, nor produced any remarkable biochemical and haematological adverse effects in both the male and female Sprague Dawley rats.