The challenge of developing medicine for twenty first century needs more systemic research on the branch of medicine for the welfare of human being. Toxicology is simply pharmacology at higher doses or pharmacology is simply toxicology at lower doses, which deals with the adverse effect of bioactive substances on living organisms along with their diagnosis and clinical use. Every drug has toxic effect. In order to develop and establish the safety levels of a new drug, toxicity studies are very essential. No drug is used clinically without its clinical trial as well as toxicity studies.
The production of antibiotic from genus Streptomyces species is well reputed (Atoni et al., 1997; Hamada et al., 1999). Following this concept, This study isolated the antagonistic strain of organism and later it was identified as Streptomyces species (Holt et al., 1994) from which two active metabolites 2-hydroxybenzoate-deoxoserine and 2-hydroxybenzoate-deoxo-dehydroxyserine having Rf value 0.311 and 0.482, respectively in the solvent system EtAc: pet ether (6.1) were isolated (Mondol, 2005).
All drugs are toxic at higher doses and even many drugs have unavoidable toxic effects at therapeutic doses. Therefore, it is important to assess the safety and efficacy of a new drug before clinically use. Therefore, keeping this objective in mind, sub-acute toxicity study of the compounds 2-hydroxybenzoate-deoxoserine and 2-hydroxybenzoate-deoxo-dehydroxyserine were carried out in Long Evans rats to assess its effects on morphological, gross behaviour, body weight changes as well as to find out histopathological, biochemical and hematological changes (Biswas et al., 1998). This experiment was done at Pharmacy Lab. of Rajshahi University, in 2002.
MATERIALS AND METHODS
Collection of rats: For toxicological study, Long Evans rats of same sex (male) and age (7 weeks) were collected from International Center for Diarrhoeal Disease Research (ICDDRB), Bangladesh.
Maintenance of the rats: The rats were kept in properly number iron cages individually in a clean animal house with an optimum room temperature and were given standard balance diet (Hawk et al., 1954). The rats were maintained in this way for 15 days before drug administration and continued up to end of the experiment.
Grouping of the rats: Weight of the individual rats were determined
and grouped into 3 groups as such A, B and C. Each group constrains 3 rats.
Group A (average body weight 78 g) received vehicle only and acts as control
group. Group B (average body weight 75 g) and Group C (average body weight 71
g) received the antimicrobial compounds 1 and 2, respectively.
Administration of the sample: The compound 1 and 2 were dissolved separately in distilled water with the help of Tween-20 in such a way that 3.5 mL contained 300 μg of the compound. The rats in group A, B and C were injected intraperitoneally with vehicle (300 μg) as well as compounds 1 (300 μg/rat/day) and 2 (300 μg/rat/day), respectively for 14 consecutive days.
Gross general observation: The body weights of each rat of both groups were measured before administration of the compounds and just prior to sacrifice them. During the whole experimental period their behaviors, CNA excitation, CNS depression, reflexes, muscular weakness, salivation and diarrhoea were monitored daily.
Experimental procedures: For hematological studies, blood was drawn from the tail vein of all the rats in groups A, B and C before administration of the compounds and blood smears were made on glass slides and stained with Leishmen reagents to perform TC, DC and platelet count (Ghai et al., 1990). With the use of capillary tubes, blood was drawn from each rat to estimate the hemoglobin percentage by Van Kampen-Zijlstra method (Ghai et al., 1990). The test was repeated on 7th and 14th day after administration of the compounds. The same procedure was followed for control rats.
Biochemical study: Blood was collected from the throat vein of each of the rats before sacrificing them at the end of 14 days of the administration of compounds and determined SGPT, SGOT, bilirubin, creatinine, urea by using procedure and reagents as described in Englehringer Mannheim GmbH Diagnostica.
Histopathological study: Histopathological studies of heart, kidney, liver and lung were performed by staining method using hematoxylin, eosin reagent and diphenylxylene mounting fluid. The tissues were observed under microscope at Rajshahi Medical College, Rajshahi, Bangladesh.
RESULTS AND DISCUSSION
The structure of the compounds 1 and 2 whose toxicological studies were performed are given below on the basis of spectral data (Mondol, 2002).
Gross general observation: The rats of group A, B and C showed no signs of tremor, convulsion and reflex abnormalities. No muscular numbness of hind, salivation and diarrheoa was observed. However, the body weight of all the rats were increased after compounds treatment was found to be statistically insignificant (Table 1).
Hematological profiles: No abnormalities were found in total counts of RBC and WBC, Platelet count, hemoglobin percentage and ESR of the compounds treated rats in comparison with that of control rats (Table 2).
Biochemical parameters of blood: The record of biochemical parameters in experimental groups of rats was insignificantly different in comparison with control group of rats (Table 3). These indicate that the compounds have no adverse effects on liver and kidney functioning.
Histopathological studies: Histopathological studies of the heart, kidney, liver and lung of both control and compounds treated rats showed no detectable abnormality among the 3 groups of rats, indicating that the compounds have no adverse effect on cellular structure of these organs (Table 4).
From the sub acute toxicity study, I conclude that the compounds 2-hydroxybenzoate-deoxoserine
and 2-hydroxybenzoate-deoxo-dehydroxyserine have no toxic effect in rats at
the dose and duration used in this study.
|| Effect of compounds on body weight of rats
|M1 and M2 sample mean value, SD1
and SD2 standard deviations; n numbers of rats; +, increase and
||Hematological profiles of Group A, B and C rats
|| Biochemical parameters of Group A, B and C rats
|M1, M2 and M3 = sample mean
value; SD1, SD2 and SD3 standard deviations;
n, number of rats; +, increase, and - decrease., Each parameter of the above
Table at 5% level of significance was non significant
|| Histopathology of Group A, B and C rats
|NAD = No abnormality detected
The results of this study may provide valuable information to researchers
for further clinical trial and chronic toxicity study.
This work was supported by a research grant from the department of Pharmacy, Rajshahi University, Bangladesh.