2.7. Toxicity test on Drosophila melanogaster

The toxicity test was carried out by exposing flies to the HEPrB in two tests: Mortality test, according to the model proposed by Cunha et al. [19], and the negative geotaxis test, proposed by Coulom & Birman (2004).

In the mortality test, twenty adult flies, four days old, were isolated in pots containing filter paper soaked in a solution of sucrose, extract and distilled water. Concentrations of 50, 25, 10 μg / mL and a 20 % sucrose control were used. This test was repeated in six times for each concentration. Then, mortality readings were taken at time intervals of 3, 6, 9, 12, 24, 36 and 48 h. 12 h light / dark cycle and temperature controlled at 25 °C were respected during the tests.

For the negative geotaxis test, the glass tube in which the flies were contained was tapped so that the flies were positioned at the bottom of the tube. Then the number of flies that were able to climb up to the edges to a height of 4 cm was counted. The reading was performed twice for each tube, following the same time intervals as the mortality test.