Aloysia hatschbachii

Fortes, Carlos Herminio Magalhães, Ferrari, Fabiola Tonelli, Baldisserotto, Bernardo, Schmidt, Denise, Sutili, Fabrício Jaques & Heiznmann, Berta Maria, 2024, Anesthetic potential of essential oils from Brazilian native plants in Rhamdia quelen juveniles (silver catfish), Neotropical Ichthyology 22 (3), pp. e 240034-e 240034 : e240034-240034

Aloysia hatschbachii leaves essential oil (AHOl).

The 100 mg L- 1 concentration took longer to reach S2 than the 300 mg L- 1 concentration, but did not differ from 50 mg L- 1. To reach stages S3a and S3b, the concentration of 300 mg L- 1 took the least time. However, to achieve deep anesthesia the concentration that took the longest was 100 mg L- 1, but this did not differ from 50 mg L- 1. The concentrations of 50 and 100 mg L- 1 were those that achieved anesthetic recovery the fastest ( Tab. 4 ).

Essential oil from leaves of Aloysia hatschbachii (AHOl).

At 20 mg L- 1, fish were in the S2 stage from 10 min to 3 h after the start of the experiment. From 3 to 6 h, 87.5% of the fish exposed to this concentration remained sedated (S2), and 12 h after the start of the experiment, they showed normal behavior. After 10 min at 50 mg L- 1, 75% of the fish were in the S4 stage and the remaining fish in the S3b stage. After 20 min, 87.5% of the fish were in the S4 stage and the remaining ones in the stage S3b. All fish were in the S4 stage after 30 min and from this time onwards, the central depressant effect gradually regressed and after 12 h, most fish showed normal behavior. The concentration of 100 mg L- 1 induced the S4 stage in all fish from 10 min to 2 h, and a 3 h, all fish were at S5 ( Fig. 1C ).

Essential oil from leaves of Aloysia hastschbachii (AHOl).

Regarding the signs of anesthesia induction/ CNS depression, the concentration-response curves for AHOl show a constant pattern ( Fig. 2C ). Furthermore, the lowest concentrations showed a similar pattern between them, such as concentrations of 50 mg L- 1 (log = 1.69) and 100 mg L- 1 (log = 2.00), with a decrease in induction time for the highest concentration (300 mg L- 1; log = 2.47). However, the recovery time at this concentration increased and, in addition, the animals presented adverse effects. Thus, among the concentrations applied, the lowest may be indicated for silver catfish juvenile, as they have shorter recovery time and times to reach anesthetic induction stages similar to 100 mg L- 1.

Figures

FIGURE 1 | Stages of anesthesia observed over time in Rhamdia quelen (silver catfish) exposed to essential oil of inflorescences (A) and leaves (B) of Acmella oleracea, leaves (C) of Aloysia hatscbachii and leaves (D) of Cordia verbenacea. N - Normal behavior, S2 - sedation, S3a - partial loss of balance, S3b - total loss of balance, S4 - anesthesia, and S5 - bulbar collapse (n = 8).

FIGURE 2 | Graphic representation for the studied concentrations of the essential oils of Acmella oleracea inflorescences (A) and leaves (B), Aloysia hatschbachii leaves (C), and Cordia verbenacea leaves (D). The graphs were constructed from the equation described in item 2.7. The concentrations are represented in log form, being 20 mg L-1 (log = 1.3); 30 mg L-1 (log = 1.47); 50 mg L-1 (log = 1.69); 80 mg L-1 (log = 1.9); 100 mg L-1 (log = 2.00); 200 mg L-1 (log = 2.3); 300 mg L-1 (log = 2.47), and 400 mg L-1 (log = 2.6).