Preparation of extracts brine shrimp lethality test
Powdered plant material was soaked sequentially in dichloromethane (99 and then ethanol (96 each for 48 h. However, extracts were obtained from some of the plants using ethanol only. The extracts were filtered and solvents removed using a rotary evaporator at a temperature of 40° C. he extracts were further dried in a freeze dryer to remove any residual water and then stored in a freezer at -200 C until the day of use.
Solutions of the extracts were made in DMso, at varying concentrations, and incubated in duplicate vials with the brine shrimp larvae in a total volume of 5 ml. Ten brine shrimp larvae were then placed in each of the duplicate vials. Others were placed in a
mixture of DMSO (30 ul and seawater to serve as a negative control. Cyclophosphamide, an anticancer drug, was used as a positive control. After 24 h the nauplii were examined against a lighted background, with a magnifying glass and the average number of survived larvae was determined. The mean percentage mortality was plotted against the logarithm of concentrations and the concentration killing fifty per of the larvae (LC50) was determined from the graph.