抄録
White cypress (Callitris glaucophylla) belonging to Cupressaceae is distributed mainly in New South Wales State of Australia. Extracts of its heartwood are known to have anti-termite and anti-fungal activity. Previously we have found that inhalation or oral intake of cypress essential oil (CEO) exerted anti-obesity influence in mice and rats. Here we investigated which constituents included in CEO might be responsible for anti-obesity effect and how they could works.
CEO obtained by steam distillation from cypress heartwood was divided into acidic and neutral fractions in order to better characterize active constituents. Anti-obese effects in mice were assessed with reference to olfactory stimulation and reduction of body weight, tissue weights of the liver and epididymal adipose tissues. Moreover total cholesterol (TC) and triglyceride (TG) concentrations in the liver and plasma were analyzed quantitatively. As results, guaiol and α-,β-,γ-eudesmol fractions were found to be markedly decreased, along with TG and weights of epididymal adipose tissue.
In order to clarify the mechanisms of CEO on anti-obesity we examined whether olfactory stimulation excites sympathetic nerves innervating the interscapular brown adipose tissue using electrophysiological methods. (-)-Citronellic acid (CA), guaiol, α,β-,γ-eudesmol mixture fraction (GE), guaiol (G) and β-eudesmol fraction (E) were obtained by liquid-liquid partition, preparative HPLC and column chromatography from CEO and suspended in 100 volumes of water for administration to anesthetized rats. Sympathetic nerve activity on brown adipose tissue (BSNA) was significantly elevated with all except CA. These results show that olfactory stimulation with CEO enhances BSNA, with guaiol and β-eudesmol as the most active constituents.
A breeding experiment with mice fed CEO mixed into normal diet was also performed. No feeding disorder was observed throughout the experiment but body weights, and tissue weights of the liver and epididymal adipose were dramatically decreased, as well as TG concentrations in liver and plasma, resulting in anti-obesity effects. This phenomenon would suggest a potential for CEO use as an anti-obesity food flavoring agent in the future.
