Damiao Pergentino de Sousaa,*, Ellen Raphaelb, Ursula Brocksomb, ˜ and Timothy John Brocksomb
Departamento de Fisiologia, Universidade Federal de Sergipe, CEP 49100-900 ´ ˜ Sao Cristovao-SE, Brazil. E-mail: email@example.com ˜ ´ Departamento de Quımica, Universidade Federal de Sao Carlos, CEP 13565-905 ˜ Sao Carlos-SP,Brazil ˜
* Author for correspondence and reprint requests Z. Naturforsch. 62 c, 563Ð566 (2007); received January 17/March 12, 2007 Many essential oils and monoterpenes are used therapeutically as relaxing drugs and tranquilizers. In this study, ten structurally related monoterpene alcohols, present in many essential oils, were evaluated in mice to investigate their pharmacological potential inthe central nervous system. Isopulegol (1), neoisopulegol (2), (ð)-isopinocampheol (3), (Ð)-myrtenol (4), (Ð)-cis-myrtanol (5), (+)-p-menth-1-en-9-ol (6) and (ð)-neomenthol (8) exhibited a depressant effect in the pentobarbital-induced sleep test, indicating a sedative property. (Ð)Menthol (7), (+)-dihydrocarveol (9), and (ð)-isoborneol (10) were ineffective in this test. The results show thatthese psychoactive monoterpenes have the profile of sedative drugs, and this pharmacological effect is influenced by the structural characteristics of the molecules. Key words: Sedative Effect, p-Menthane, Monoterpenes
Introduction Essential oils are natural products with many different applications, especially in the medical and cosmetic areas. The use of essential oils in the flavour andfragrance industry is well known, and their fragrances have been used in aromatherapy to induce mental tranquility or relaxation and to aid sleep in humans (Lavabre, 2001). In addition, many of them are found to exhibit varied biological properties, such as spasmolytic (Lis-Balchin and Hart, 1999) and anticonvulsant (Almeida et al., 2003) activities. These effects are probably due to the structuraldiversity of the essential oil constituents. This notion is supported by previous studies which showed that some monoterpenes present in many essential oils possess sedative activity in animal experiments, such as linalool (Elisabetsky et al., 1995), 1,8-cineole (Santos and Rao, 2000) and α-terpineol (Buchbauer et al., 1993). Some derivatives of monoterpenes also showed a sedative effect (De Sousa etal., 2004, 2006). These facts led us to evaluate ten structurally related monoterpene alcohols through a preliminary screening to verify their potential as sedative drugs. The investigated monoterpenes are present in the volatile oils of many plant species such as Mentha piperita (Galeotti et al., 2002), Zanthoxylum schinifolium (Paik et al., 2005) and Mentha x villosa (Arruda et al., 2006).0939Ð5075/2007/0700Ð0563 $ 06.00
Materials and Methods Chemicals The following compounds were used (purity higher than 95%): Isopulegol (1) and neoisopulegol (2) [separated by column chromatography of technical grade isopulegol (Dierberger S. A., Barra Bonita, Brazil)]; (ð)-isopinocampheol (3), (Ð)-myrtenol (4), (Ð)-cis-myrtanol (5), (+)-pmenth-1-en-9-ol (6), and (ð)-isoborneol (10) (Aldrich, USA);(Ð)-menthol (7) (Usina Colombina S. A., Bebedouro, Brazil); (ð)-neomenthol (8) and (+)-dihydrocarveol (9) (SCM Glidden Organics, Jacksonville, USA). All were dissolved in 5% Tween 80 as an emulsion. Pentobarbital and polyoxyethylene-sorbitane monolate (Tween 80) were purchased from Sigma (USA). Animals Male Swiss mice (26Ð36 g; 6Ð8 weeks old) were obtained from the Biology Department ofUniversidade Federal de Sao Carlos. The animals were ˜ maintained at constant room temperature [(23 ð 1) ∞C] and on a 12 h/12 h light-dark cycle (light from 07:00 to 19:00 h), with free access to food and water, for a minimum of 7 d before performing the experiments. All behavioural observations were conducted between 13:00 and 19:00 h.
” 2007 Verlag der Zeitschrift für Naturforschung, Tübingen ·...