Oil from African Basil (Ocimum gratissimum) to anaesthetise fish.

Clove oil (active ingredient eugenol) from the clove plant (Syzygium aromaticum). has been used for many years as an anaesthetic agent in a variety of fishes. However, the consistency of activity could vary depending on the batch. More recently, a company has refined the active ingredient and produced Aqui-S (iso-eugenol).

This paper describes another source of the eugenol – Clove Basil or African Basil (Ocimum gratissimum).

Aquaculture
Volume 353, Number 11 (June 2012)
	Essential oil of Ocimum gratissimumL.: Anesthetic effects, mechanism of action and tolerance in silver catfish, Rhamdia quelen
	Authors:	Lenise de Lima Silva, Thaylise Vey Parodi, Patrícia Reckziegel, Viviane de Oliveira Garcia, Marilise Escobar Bürger, Bernardo Baldisserotto, Carlos Augusto Malmann, Ana Maria Soares Pereira, Berta Maria Heinzmann
	Author Affiliations:	no affiliations available
	Source:	Aquaculture, Volume 353, Number 11 (June 2012)
	Page Numbers:	91 – 97
	Available Full Text:	Full Text: Subscription Required to view full text Format: PDF Size: Unknown Location: Publisher’s Site Authentication: Publisher’s Site
	Abstract:	The aim of this study was to determine the time until anesthetic induction and recovery in silver catfish (Rhamdia quelen) exposed to the essential oil of Ocimum gratissimumL. (EO), its potential mechanism of action via GABAergic transmission and the development of tolerance. The EO was obtained from the aerial parts of O. gratissimumL. by hydrodistillation and analyzed by gas chromatograph coupled to mass spectrometer (GC–MS). Eugenol (73.6%) and ß-bisabolene (18.3%) are the major compounds of the EO. Juvenile silver catfish were placed in aquaria containing different concentrations of the EO (10, 20, 30, 40, 50, 60, 70, 150 and 300mgL-1) to determine the point at which anesthesia was induced and the length of the recovery period. In the following experiments, the anesthetic effect of the EO (10, 20 and 40mgL-1) in association with benzodiazepine (BDZ) was determined. The GABAergic-like action and development of tolerance were assessed in fish exposed to BDZ (diazepam 150µM), EO (40mgL-1) or both EO and BDZ (EO+BDZ) at the same concentrations. After the induction of anesthesia, juveniles were transferred to an anesthetic-free aquarium containing either the classic BDZ antagonist flumazenil (5µM) or water to assess their recovery. The development of tolerance was evaluated in two experiments. In the first, juveniles were exposed to the EO twice in a 30-day interval, and in the second five exposures, weekly intervals were performed. Fish exposed to concentrations above 30mgL-1of the EO were effectively anesthetized without experiencing side effects or mortality. Fast anesthesia (<4min) could be obtained using 150 and 300mgL-1of the EO. Synergism was detected for EO+BDZ at the lower concentrations tested. Juveniles exposed to all tested drugs showed a faster recovery in flumazenil than those that recovered in water. The development of tolerance was observed in fish exposed to the EO or BDZ separately after the fifth exposure. Two exposures were sufficient to sensitize the fish to the action of these drugs. However, repeated exposure to EO+BDZ did not induce tolerance and/or sensitization. In conclusion, the EO of O. gratissimumis an effective and safe anesthetic for silver catfish, and its mechanism seems to be related to an interaction with the GABAA-benzodiazepine receptor.
	Citation:	Lenise de Lima Silva, Thaylise Vey Parodi, Patrícia Reckziegel, Viviane de Oliveira Garcia, Marilise Escobar Bürger, Bernardo Baldisserotto, Carlos Augusto Malmann, Ana Maria Soares Pereira, Berta Maria Heinzmann . Essential oil of Ocimum gratissimumL.: Anesthetic effects, mechanism of action and tolerance in silver catfish, Rhamdia quelen. Aquaculture, Volume 353, Number 11 (June 2012), pp. 91-97, <http://ejournals.ebsco.com/direct.asp?ArticleID=4BEE9E652C8106A7E1AC&gt;
	URL:	http://ejournals.ebsco.com/direct.asp?ArticleID=4BEE9E652C8106A7E1AC

 
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