in research and development of herbal formulae , intra - laboratory verification of the effectiveness is an important method to establish evidence based korean medicine . despite the frequent use of medicinal plants , few scientific studies have been undertaken to determine the safety of traditional medicinal herbs . if the safety of medicines and plant products intended for human consumption is to be determined , systematic toxicological studies must be performed using various experimental models to predict the toxicity and to set the criteria for selecting a safe dose in humans . through long practice theories and techniques have been developed to eliminate or reduce the toxicity , as well as the drastic actions and side effects , of some drugs . sulfur is the third most abundant mineral in the body and is essential for life . sulfur makes up the vital amino acids used to create proteins for cells and tissues and for hormones , enzymes , and antibodies . however , direct administered of sulfur to the human body will generally results in strong toxic side effects . therefore , super key ( processed sulfur ) , the product remaining after sulfur has been processed to remove the poison , was developed for medicinal use . this study was performed to examine the oral toxicity and the lethal dose of super key . the testing methods were visual observation of the general symptoms , body weight changes and necropsy findings in 8-weeks - old sprague - dawley ( sd ) rats . the current research trend for oral toxicity testing of extracts is to study acute and subacute toxicity through good laboratory practice ( glp ) regulations . all the experiments for this research were conducted at medvill , an institution authorized to perform non - clinical studies , under the glp regulations . the super key was prepared in a sterile room at wonkwang university gwangju korean medical hospital . after having been weighed by using an electronic scale and mixed with corn oil , it was prepared at normal potency . the reason sd rats were chosen is that they have been widely used in safety tests in the field of medicine , so the results can be easily compared with many other databases . the mean weights of the rats were 285.3  314.5 g and 200.5  222.9 g , respectively , for the male and the female rats at the time of super key administration . for all animals , a visual inspection was conducted , and all animals were weighed at the beginning of the experiment . during the seven days of acclimatization , the general symptoms of the rats were observed once a day . the temperature of the lab was 19.7  22.6c , and the humidity was 48.1%  75.6% . however , an aberration occurred on july 19 , 2014 , from 17:30 pm to 18:00 pm when the humidity was 75.6% . the above temporary aberration occurred due to a malfuncion of the air conditioning equipment and the reinstallation of a temperature and humidity sensor . in spite of this , no abnormalities of the general symptoms were observed . enough food ( lab diet 5053 ) and ultra violet ( uv)-filtered water were provided . animals were selected if their weights and general symptoms were normal . in total , 20 male rats and 20 female rats were selected . the animals were randomly distributed into 4 groups ( 5 male and 5 female rats per group ) as shown in ( table 1 ) . in this study , 2,000 mg / kg was set as the high dose , and 1,000 mg / kg and 500 mg / kg were set as the mid and the low doses , respectively . in the control group , a dose of 10 ml / kg of normal saline solution was administered . super key and normal saline were administered into the mouths of the rats in all groups by using disposable syringes . this study was conducted under the approval of the institutional animal ethics committee of medvill co. , ltd . from the 1 day to the 14 day after treatment , the general symptoms were examined once a day . on the day of dosing ( day 0 ) , the general symptoms ( side effects , revealing time , recovery time , etc . ) , as well as the mortality , were examined at 30 minutes and at 1 , 2 , 4 , and 6 hours after oral administration . the weights were measured immediately before treatment and at 1 , 3 , 7 and 14 days after treatment . after observations had been terminated , necropsies were conducted on the rats after their abdominal aorta and vein had been cut under co2 anesthesia , and the organs of all surviving animals were visually inspected and microscopically examined . the weight data from the experiments were analyzed by using the statistical package for social science ( spss ) program ( spss 16.0 ) . a levene test was conducted to evaluate the homogeneity of the variance and the significance . the one - way analysis of variance ( anova ) test was conducted when the homogeneity of the variance was recognized ( significance level : 0.05 on both sides ) . also , the kruskal - wallis test was conducted when heterogeneity of the variance was recognized ( significance level : 0.05 on both sides ) . the weight examinations showed slight decreases in the weights of four female rats ( two female rats in the 1,000 mg / kg group and two female rats in the 2,000 mg / kg group ) . finally , in both the control and the experimental groups , no meaningful differences in the necropsy findings were noted . since then , sulfur has been used for various reasons , such as to treat skin diseases , and as an intestinal drug sulfur is a bright yellow crystalline solid or powder . sulfur is the seventh most abundant mineral in the body , and the body of a human weighing approximately 70 kg contains roughly 140 g of sulfur . sulfur is acquired through the consumption of food primarily in the form of sulfur - containing amino acids ( saas ) , such as methionine , cysteine , cystine , and taurine , and in its glucosinolate form , which is found in cruciferous vegetables , such as cabbage and cauliflower . in dongui bogam , sulfur is mainly used for the treatments of an abdominal mass and pathogenic qi in the pit of the stomach , stagnation of cold qi , chronic cold syndrome in the back and the kidneys , loss of sensation due to cold wind , and coldness , pain , and loss of power in the legs . it fortifies the sinews and bones , tonifies yang qi , removes balding , malignant furuncles , infantile malnutrition affecting the nose and other conditions in the external genitals , and kills scabies parasites . sulfur is widely used to detoxify the body , treat scabies [ 6 , 7 ] , heal sores and eliminate itching . kong et al   showed that the treatment of human gastric adenocarcinoma cells ( ags ) with extracts from young radishes that had a high organic sulfur glucosinolate content inhibited cancer cell growth . in addition , bak et al   reported that treating ht-29 human colon cancer cells with kimchi extract made with sulfur treated radishes also inhibited the growth of cancer cells . choi and kim   reported that , when diverse cancer cells were treated with extracts from a hot water extraction from regular ducks or organic - sulfur - fed ducks , a noticeable effect in proliferation inhibition was seen in the cells treated with the extract from organic - sulfur - fed ducks . in previous studies , inorganic sulfur has been demonstrated to inhibit the proliferation of breast cancer cells . the study showed that inorganic sulfur reduced cell proliferation by inhibiting the expression and the activation of epidermal growth factor receptor ( egfr ) and by increasing the expression of bcl-2-associated x ( bax ) in estrogen - independent breast cancer ( mda - mb-231 ) human breast cancer cells . another study investigated the inhibitory effect of sulfur on prostate cancer ( pca ) in vivo . in that research , prostate tumors were developed by injecting 22 rv1 or du 145 pca cells into sulfur treated and untreated nude mice . the results showed that sulfur inhibited the growth of androgen independent prostate cancer in vivo . furthermore , the intake of refined inorganic sulfur has been reported to reduce the clinical side effects of radiotherapy in cancer patients . however , the direct administration of sulfur to the human body will generally results in a strong toxic side effect . therefore , super key , processed sulfur with the poison removed , was developed for medicinal use . although super key has been used in clinics , safety studies on super key are insufficient . toxicity tests provide important data and are essential for evaluating the safety of test substances in medications . doses of 500 mg / kg , 1,000 mg / kg , and 2,000 mg / kg of super key were administered to the experimental groups , and a dose of 10 ml / kg of normal saline solution was administered to the control group . in all four groups , no deaths occurred , and no significant differences in the clinical signs or weights were noted between the control group and the experimental groups . the necropsy results to check for abnormalities in organs showed no significant findings . animal testing is the most fundamental and basic way to assess the safety of materials to be used for medical purposes . for that reason , the korea food & drug administration of korea has testing protocol guidelines for the study of toxicity , and all experiments should be conducted following glp regulations . the results of our study , which followed that protocol and those regulations , showed that the administration of 2,000 mg / kg of super key did not cause any changes in the weights of sd rats or in the results of necropsy examinations . it also did not result in any mortalities , which indicates that super key is safe to use as a treatment . however , the acute and the chronic side effects of super key need to be studied more in order to assess its oral toxicity , and more hematology and blood chemistry studies are required . the results of this reseach showed that administration of 500  2,000 mg / kg of super key did not cause any changes in the weights of sd rats or in the results of necropsy examinations . neither did it result in any mortalities , which indicates that the lethal dose of super key is higher than 2,000 mg / kg . the results obtained in this study suggest that administration of super key as treatment may be safe . s.d . , standard deviation ; n , number of animals .
objectives : this study was performed to analyze the single - dose oral toxicity of the super key ( processed sulfur).methods : all experiments were conducted at medvill , an institution authorized to perform non - clinical studies , under the good laboratory practice ( glp ) regulations . in order to investigate the oral toxicity of super keywe administered it orally to sprague - dawley ( sd ) rats . 
 the sd rats were divided into four groups of five male and five female animals per group : group 1 being the control group and groups 2 , 3 , and 4 being the experimental groups . 
 doses of super key 500 mg / kg , 1,000 mg / kg and 2,000 mg / kg were administered to the experimental groups , and a dose of normal saline solution , 10 ml / kg , was administered to the control group . 
 we examined the survival rates , weights , clinical signs , gross findings and necropsy findings . 
 this study was conducted under the approval of the institutional animal ethics committee . 
 ( approval number : a01 - 14018).results : no deaths or abnormalities occurred in any of the four groups . although slight decreases in the weights of some female rats were noted , no significant changes in weights or differences in the gross findings between the control group and the experimental groups were observed . to check for abnormalities in organs , 
 we used microscopy to examine representative histological sections of each specified organ ; the results showed no significant differences in any of the organs.conclusion:the results of this research showed that administration of 500  2,000 mg / kg of super key did not cause any changes in the weights or in the results of necropsy examinations . neither did it result in any mortalities . 
 the above findings suggest that treatment with super key is relatively safe . 
 further studies on this subject are needed to yield more concrete evidence .