Anesthetic activity of the essential oil of Ocimum americanum in Rhamdia quelen (Quoy & Gaimard, 1824) and its effects on stress parameters

The aim of this study was to evaluate the anesthetic activity of the essential oil (EO) of Ocimum americanum L. in silver catfish (Rhamdia quelen ). In the first experiment, the depressor effects and chemical composition of the leaf EO (LEO) and inflorescence EO (IEO) were compared. Juveniles (n = 10) were placed in aquaria containing different concentrations of EO (25 - 500 mg L-1) to determine the point at which anesthesia was induced and the length of the recovery period. In the following experiment, the effects of 300 and 500 mg L-1 LEO exposure on stress parameters (plasma cortisol, glucose and sodium levels) after air exposure for 1 min were assayed. Fish (n = 10 per sampling time) were sampled immediately or transferred to anesthetic-free aquaria until sampling (15, 30, 60 or 240 min). LEO was composed mainly of β-linalool and 1,8-cineole in similar proportions, whereas IEO showed β-linalool as major compound. Anesthesia was obtained in silver catfish with 200-500 mg L-1 between 4-8 min for LEO and 6-16 min for IEO. Lower EO concentrations did not reach anesthetic stage up to 30 min. LEO used as anesthetic prevented the cortisol increase and sodium loss induced by aerial exposure. Glucose levels were raised in catfish exposed to LEO compared to basal group (not air exposed) in almost all observation times. EO of O. americanum obtained from leaves was considered suitable to anesthetic procedures due to its fast induction and handling-induced stress prevention.

O objetivo deste trabalho foi avaliar a atividade anestésica do óleo essencial (EO) de Ocimum americanum L. em jundiás (Rhamdia quelen ). No primeiro experimento, os efeitos depressores e a composição química dos óleos obtidos a partir das folhas (LEO) e das inflorescências (IEO) desta espécie vegetal foram comparados. Para isto, juvenis de jundiás (n = 10) foram transferidos para aquários contendo diferentes concentrações de EO (25 - 500 mg L-1) a fim de determinar os tempos de indução aos estágios de anestesia e de recuperação. No experimento seguinte foram determinados os efeitos da exposição a 300 e 500 mg L-1 de LEO em parâmetros de estresse (cortisol, glicose e níveis de sódio plasmáticos) após os animais serem expostos durante 1 min ao ar. Os peixes (n = 10 por tempo de amostragem) foram coletados imediatamente ou transferidos para aquários livres de anestésico até amostragem (15, 30, 60 ou 240 min). LEO demonstrou ser composto majoritariamente por β-linalol e 1,8-cineol em proporções similares, enquanto que IEO apresentou β-linalol como constituinte majoritário. O estágio de anestesia foi verificado em jundiás com 200-500 mg L-1 entre 4-8 min para LEO e 6-16 min para IEO. Menores concentrações de ambos os EO não promoveram anesthesia até 30 min. O uso de LEO como anestésico preveniu o aumento de cortisol e a perda de sódio induzida pela exposição aérea. Já a glicemia encontrava-se aumentada em peixes expostos ao LEO em comparação ao grupo basal (não exposto ao ar) na maioria dos tempos de observação. Assim, EO de O. americanum obtido a partir das folhas foi considerado adequado para procedimentos anestésicos devido a sua rápida indução e capacidade de prevenir o estresse decorrente do manuseio.

Biological activities of Ocimum sanctum L. fixed oil--an overview.

Seeds of Ocimum sanctum L. (Labiatae; popularly known as 'Tulsi' in Hindi and 'Holy Basil' in English) contain a pale yellow colored fixed oil. The oil possesses antiinflammatory activity due to dual inhibition of arachidonate metabolism supplemented by antihistaminic activity. The antiinflammatory activity is not dependent on the pituitary adrenal axis. The oil possesses antipyretic activity due to prostaglandin inhibition and peripherally acting analgesic activity. The oil has been found to be effective against formaldehyde or adjuvant induced arthritis and turpentine oil induced joint edema in animals. Lipoxygenase inhibitory, histamine antagonistic and antisecretory activities of the oil contribute towards antiulcer activity. The oil can inhibit enhancement of vascular capillary permeability and leucocyte migration following inflammatory stimulus. The LD50 of the oil is 42.5 ml/kg and long-term use of oil at 3 ml/kg dose does not produce any untoward effects in rats. The oil contains a-linolenic acid, an omega-3 fatty acid, which on metabolism produces eicosapentaenoic acid and the same appears to be responsible for the biological activity. The oil has hypotensive, anticoagulant and immunomodulatory activities. Antioxidant property of the oil renders metabolic inhibition, chemoprevention and hypolipidaemic activity. Presence of linolenic acid in the oil imparts antibacterial activity against Staphylococcus aureus. The oil alone or in combination with cloxacillin, a beta-lactamase resistant penicillin, has been found to be beneficial in bovine mastitis, an inflammatory disorder resulting from staphylococcal infection. Existence of anti-inflammatory, analgesic and antibacterial activities in single entity i.e. fixed oil appears to be unique.