Analysis of Heavy Metals in Pleurotus Tuberregium Sclerotia,Toxicity in Blood, Bonemarrow and Some Selected Organs of Albino Rats

Abstract

Pleurotus Tuberregium is a common mushroom which is used as food or medicine, more commonly as a vegetable soup thickener. This study investigated the presence of heavy metals in wild samples of pleurotus tuberregium sclerotia consumed within our localities, compared the degree of heavy metal contamination of the samples, investigated the presence of heavy metals in the serum of albino rats due to its consumption and the effects of its consumption on blood, bone marrow, liver and kidney of the rats. Two wild samples of pleurotus tuberregium sclerotia were collected from Bomu village in Gokana Local Government Area of Rivers State a part of Nigeria rich in oil and mining activities and Agbudu in Orumba South Local Government Area of Anambra State a part of Nigeria relatively low in oil and oil mining activities. The samples were authenticated at the Department of Plants and biotechnological Sciences, University of Nigeria, Nsukka. A phytochemical screening of the samples was carried out as described by Trease and Evans. Samples were analyzed for the presence of heavy metals using an Atomic Absorption Spectrophotometer (AAS 240FS Varian) at the Springboard Research Laboratories, Awka, Anambra State. A crude aqueous extract of the samples was prepared. A total of 37 male albino rats 6-7 weeks old weighing 200g + 20g were used for a protocol involving the oral acute toxicity and sub-chronic toxicity of the crude aqueous extract of the samples. The oral acute toxicity of the extract was determined using 12 of the rats according to the procedure for the two phases testing as described by Lorke. A repeated 14-days dosing oral toxicity was then applied for the sub-chronic study. The remaining 25 out of the 37 rats were divided into five groups (A – E) of five rats each. After a previous 14days period of acclimatization, Group A were fed with water and feed only and served as the control, Group B received 1500mg/kg of the sample extract from Rivers State, Group C received 1000mg/kg of the same sample extract while Groups D and E received 1500mg/kg and 1000mg/kg respectively of sample extract from Anambra State. Whole blood samples were analyzed for haematological profile using the fully automated analyser Mind Ray, Japan while serum was analyzed for biochemical parameters involving the liver and kidney indices using Boehringer knoll chemistry semi-automated analyzer 4010 system. The liver and kidney tissues were examined for histological changes and the bone marrow aspirates examined for effects of metal toxicity as well. Data was analyzed using SPSS version 17.0 and results expressed as mean + standard error of the mean. Results were considered significant at P<0.05. Phytochemical screening of the samples revealed low presence of oils, tannins, moderate presence of glycosides, flavonoids, an abundance of proteins, alkaloids and saponnins. The crude aqueous extract was found to be non-toxic up to 5000mg/kg. Lead, mercury, aluminum, platinium, cadmium, arsenic and nickel were detected in both samples but there were no statistically significant differences (P > 0.05) between concentrations of metals. These metals were also detected in the serum of some of the test rats. There were no statistically significant difference (P > 0.05) in the serum concentrations of metals in test rats treated with the same doses of the different sample extracts except for the test Group B in which cadmium recorded high concentrations of (0.057 + 0.006) as compared to Group D (0.010 + 0.010) and test Group E in which Nickel recorded (0.055 + 0.021) as compared to Group C (0.000 + 0.000). There were no statistically significance differences (p>0.05) in the haematological parameters in all the groups and as compared to the controls . There were no statistically significant differences (p>0.05) in the biochemical parameters of the liver and kidneys in all the groups and as compared to the controls. The bone marrow aspirate revealed normal micrograph in all the groups while the liver and kidneys maintained their normal histoarchitectures. These result patterns are in accordance with the safety claims on the use of p. tuberregium sclerotia as food or medicine.