The Essential Oil of Eucalyptus tereticornis and its Constituents, α- and β-Pinene, Show Accelerative Properties on Rat Gastrointestinal Transit

The essential oil of EUCALYPTUS TERETICORNIS (EOET) has pharmacological activities but their effects on the gastrointestinal tract are yet unknown. It possesses α- and β-pinene as minor constituents, isomers largely used as food or drink additives. In this work, we studied their actions on gut motility. After feeding with a liquid test meal, conscious rats received perorally EOET, α-, or β-pinene, and the fractional dye retention was determined. EOET and its constituents decreased the gastric retention. In anesthetized rats, pinenes increased gastric tonus, while enhancing the meal progression in the small intestine of conscious rats. Both α- and β-pinene contracted gastric strips IN VITRO but relaxed the duodenum. Conversely, EOET relaxed both the gastric and duodenal strips. In conclusion, EOET accelerates the gastric emptying of liquid, and part of its action is attributed to the contrasting effects induced by α- and β-pinene on the gut.