Effect of Cymbopogon citratus Essential Oil (EO) on Handling Stress in Giant Freshwater Prawn (Macrobrachium rosenbergii).

BACKGROUND AND OBJECTIVE: Effects of Cymbopogon citratus essential oil (EO) was tested on minimizing handling stress in Macrobrachium rosenbergii through the evaluation of their metabolite responses [glucose, lactate, glycogen, protein, Lactate Dehydrogenase (LDH), Malate Dehydrogenase (MDH), Acetylcholinesterase (AChE) and Alanine Aminotransferase (ALT)]. This study aimed to investigate the efficacy of C. citratus extract in the anaesthetization of M. rosenbergii. MATERIALS AND METHODS: Three treatments including control, prawn exposed to stress alone (T1) and prawn exposed to stress in the presence of C. citratus EO (T2) were tested. A C. citratus EO at 500 µL L-1 had been determined in a previous study and was selected as the critical dose to be applied as an anesthetic agent. Handling stress was induced into prawns by netting, at 2 min interval for 30 min and their hemolymph were collected to determine the metabolite responses. RESULTS: The increase of glucose, lactate and LDH of M. rosenbergii when exposed to handling stress alone (T1) in comparison to T2 (stress with anesthetic C. citratus EO) were identified. Further, a low glycogen level in parallel with low AChE activity was observed which indicates the involvement of secondary metabolites to cope with the energy demand in T1 over T2. CONCLUSION: This study indicates the efficiency of C. citratus EO to reduce stress during handling in M. rosenbergii.

Efficiency of essential oils of Ocimum basilicum and Cymbopogum flexuosus in the sedation and anaesthesia of Nile tilapia juveniles

ABSTRACT This study aimed to verify the sedative and anaesthetic effect of the essential oils of basil (Ocimum basilicum) (EOOB) and lemongrass (Cymbopogum flexuosus) (EOCF) in Nile tilapia juveniles. The fish were transferred to aquaria containing different concentrations of each essential oil: 10, 25, 50, 100, 200, 400 and 600 μL L-1. The time of sedation ranged from 7 to 31 seconds and the recommended concentration was 10 or 25 μL L-1 for both essential oils. The best times for anaesthesia and recovery were found for the concentrations of 400 μL L-1 for EOOB (135.2 and 199.1 seconds, respectively) and 600 μL L-1 for EOCF (327.1 and 374.8 seconds, respectively). In conclusion, we recommend the use of EOOB and EOCF for the sedation and anaesthesia of Nile tilapia at concentrations of 10-25 (for both), 400 and 600 μL L-1, respectively.

Rapid detection of five anesthetics in tilapias by in vivo solid phase microextraction coupling with gas chromatography-mass spectrometry.

The concentration of five rapidly metabolized anesthetics in living tilapias was determined in this study, by the presented method coupling in vivo solid phase microextraction (SPME) to gas chromatography-mass spectrometry (GC-MS), which was the first time that in vivo sampling method was adapted in detecting the anesthetic residue in the living aquatic product. The analytical performance of the developed method was evaluated in homogenized tilapia dorsal muscle, and the results demonstrated that the present method possessed low detection limits 1.7-9.4ngg-1), wide linear ranges (10 or 30-5000ngg-1), and satisfactory reproducibility (relative standard deviations no more than 8.1% and 10.8% for inter-fiber and intra-fiber assays, respectively). Standard curves were established in homogenized tilapia dorsal muscle for calibrating in vivo SPME in living tilapias. And the concentrations determined by in vivo SPME were close to those determined by the liquid extraction. By using the present method, one anesthetic residue was detected above the detection limit in tilapias from the local markets. Comparing to traditional methods, the present one exhibited superior time-efficiency and cost performance, as the extraction time was only ten minutes, which was short to successfully avoid the possible loss of analytes caused by elimination and sample storage. In addition, owing to the time-efficiency of the present method, the elimination of the anesthetics in tilapias was traced successfully in the laboratory.

Liquid-phase microextraction based on two immiscible organic solvents followed by gas chromatography with mass spectrometry as an efficient method for the preconcentration and determination of cocaine, ketamine, and lidocaine in human urine samples.

A new type of liquid-phase microextraction based on two immiscible organic solvents was optimized and validated for the quantification of lidocaine, ketamine, and cocaine in human urine samples. A hollow-fiber based microextraction technique followed by gas chromatography coupled with mass spectrometry detection was used to reduce matrix interferences and improve limits of detection. The analytes were extracted from aqueous sample with pH 11.0, into a thin layer of organic solvent (n-dodecane) sustained in the pores of a hollow fiber, and then into a second organic acceptor (acetonitrile) located inside the lumen of the hollow fiber. With the application of optimized values, good linearity was obtained in the range of 1-500 µg/L for lidocaine and ketamine and 2-500 µg/L for cocaine with the determination coefficient values (r(2) ) >0.9943. The preconcentration factors and limits of detection (S/N > 3) were 250-350 and 0.01-0.05 µg/L, respectively. Intra and interassay precision values were <7.3 and 9.3%, respectively. The method was successfully applied for the determination and quantification of target analytes in human urine samples.

Sedative and anesthetic activities of the essential oils of Hyptis mutabilis (Rich.) Briq. and their isolated components in silver catfish (Rhamdia quelen)

This study evaluated the sedative and anesthetic effects of the essential oils (EO) of Hyptis mutabilis (Rich.) Briq. and their isolated components on silver catfish (Rhamdia quelen). Quantitative chemical differences between the EOs obtained from leaves and inflorescences were verified, and a new chemotype rich in globulol was described. Although there were no significant differences in the time of induction for sedation and anesthesia between the EOs, only the leaf EO at 344 mg/L anesthetized all fish without side effects. Fractionation of the leaf EO was carried out by column chromatography. The isolated compounds [(+)-1-terpinen-4-ol and (-)-globulol] showed different activity from that detected for the leaf EO in proportional concentrations and similar sedation to a eugenol control at 10 mg/L. However, fish exposed to 1-terpinen-4-ol (3 and 10 mg/L) did not remain sedated for 30 min. Anesthesia was obtained with 83-190 mg/L globulol, but animals showed loss of mucus during induction and mortality at these concentrations. Synergism of the depressor effects was detected with the association of globulol and benzodiazepine (BDZ), compared with either drug alone. Fish exposed to BDZ or globulol+BDZ association showed faster recovery from anesthesia in water containing flumazenil, but the same did not occur with globulol. In conclusion, the use of globulol in aquaculture procedures should be considered only at sedative concentrations of 10 and 20 mg/L, and its mechanism of action seems not to involve the GABAA-BDZ system.

Assessing the local anesthetic effect of five essential oil constituents.

We studied the effects of five monoterpenoids, viz. 1,8-cineole, fenchone, linalool, p-cymene and α-pinene, on the sciatic nerve fibers of the frog Rana ridibunda (Pallas, 1771) and compared them to that of lidocaine, a standard local anesthetic. The isolated sciatic nerve, with its perineurium intact, was placed in a three-chambered recording bath, which allowed us to monitor the compound action potentials (CAP), stable in amplitude, for over 2 days. The half-vitality time (IT(50)), which is the time required for the amplitude of the CAP to decrease to 50% of its control value, was 53.5 ± 0.9 h for a nerve incubated in normal saline at 26.0 °C. The IT(50) values for nerves incubated in saline with p-cymene, 1,8-cineole, or α-pinene, at 30.0 mM, were 19.9 ± 0.4, 32.9 ± 0.5, and 31.0 ± 0.3 hours, respectively. As the IT(50) value for 30.0 mM lidocaine, a standard local anesthetic, was 1.6 ± 0.3 min under the same conditions, these three compounds cannot be considered as having a local anesthetic effect. The IT(50) values for 30.0 mM linalool and fenchone were 5.7 ± 0.6 and 15.4 ± 1.1 min, respectively; they were significantly, but not markedly different from the respective value for lidocaine. These results combined with the fast inhibition of the CAP and its fast recovery after the removal of either linalool or fenchone indicate a local anesthetic activity of the two compounds. Linalool retained this activity even at lower concentrations of 15.0 and 7.5 mM. The local anesthetic effects of lidocaine and linalool were concentration-dependent; this was not the case for fenchone, which had a relatively strong local anesthetic activity at 30.0 mM, but was entirely inactive at 25.0 mM. On the basis of the effects of the five monoterpenoids on the electrophysiological properties of the sciatic nerve fibers of the frog, we conclude that, whereas 1,8-cineole, p-cymene and α-pinene cause only minor effects, linalool and fenchone exhibit acute local anesthetic activity.