This study was conducted during the period from January, 2001 to April, 2002 in the laboratory of the Department Qf Parasitology, Bangladesh Agricultural University (BAU), Mymensingh.
The test parasites Gastrointestinal (g/i) nematodes used as the test parasites in this study were collected from the viscera of goats slaughtered in local K.R. market of Bangladesh Agricultural University, Mymensingh. The selected g/i nematodes of goats are Haemonchus contortus, Trichostrongylus spp., Trichuris spp., Strongyloides papillosus, Oesophagostomum columbianum, Cooperia spp. and Bunostomum trigonocephalum.
Preparation of plant extract The plant and plant materials used in this experiment were procured from BAU campus and its surrounding rural areas, and identified by a botanist. The common names and scientific names of the used plants and the portion of the plants extracted for the present experiment are given in Table 1. The plant materials were dried at 55-60°C for 48-72 hours and prepared dust by pulverising with manual grinder. Ten gram of each category of dust was taken in a 500 ml beaker and separately mixed with 100 ml of either ethanol or distilled water. Then the mixture was stirred for 30 minutes by a magnetic stirrer (6000 rpm) and left stand for next 24 hrs. The mixture was then filtered through a fine cloth and again through filter paper (Whatman No. 1). The filtered materials were taken into a round bottom flask and then condensed by evaporation of solvent from filtrate in a water bath at 50°C and 60° C for ethanol and water respectively up to final volume of 10 ml. After the evaporation of solvent from filtrate, the condensed extracts were preserved in tightly corked labelled bottle and stored in a refrigerator until their screening for anthelmintic property.
The test drugs Two patent drugs Deminte; Morantel citrate (Reneta Bangladesh Limited) and Helmee; Albendazole, (Reneta Bangladesh Limited) were used as positive control. Solution of different extract Aqueous solutions of 25, 50 and 100 mg/m1 and ethanol solution of 10, 25 and 50 mg/ml were prepared by adding distilled water to the stock solutions. All the solutions were prepared at the day of experiment.
In vitro culture of infective larvae Adult nematodes were collected from the abomasi of goats according to the procedure described by Taylor (1934), Bell (1957) and Rahrnan (1969). An in vitro culture system has already been established in our laboratory for harvesting the infective third stage larvae (L3) of gastrointestinal nematodes (Islam and Begum, 2001). Briefly, the collected worms were washed for several times with phosphate buffer saline (PBS). Then uteri of gravid females were dissected out, crushed gently in a petri dish to release eggs. A known volume of PBS was added to eggs and incubated at room temperature (25-30 C)for about 72 hrs and then transferred to a 100 ml beaker and incubated further until development of L3 had occurred. During cultivation the culture media were monitored every morning for observing the development of larvae towards L3 stage. The L3 were washed several times in PBS through centrifugation at 2000 rpm for 7 minutes and finally counted and suspended in a 100 ml beaker. The L3 were maintained in the laboratory by incubating them at 37°C in sterile condition.
In vitro screening of plant extracts Aqueous and ethanol plant extracts at various concentrations (10, 25, 50, 100 mg/ml) levels were screened by using both adult worms and L3 stage larvae. A 200 pl PBS containing 25 adult worms (both male and female) and 100 L3 was pipetted on to separate petri-dishes and a 800 pl of extracts of each concentration was then added. Following a 3 hrs treatment period at room temperature, the percent non- motile (dead) L3 was calculated from the dead adult and larvae killed by adding a drop of Lugol's iodine.
Statistical analysis Data were analyzed by Student t-test to determine the significant differences among the variables (Steel and Torrie, 1980).