Pharmacology Original Paper	Planta Med 2007; 73: 1148-1155 DOI: 10.1055/s-2007-981593
© Georg Thieme Verlag KG Stuttgart · New York
Bioactivity-Guided isolation of β-Sitosterol and Some Fatty Acids as Active Compounds in the Anxiolytic and Sedative Effects of Tilia americana var. mexicana
Eva Aguirre-Hernández1, 2, Hortensia Rosas-Acevedo2, Marcos Soto-Hernández2, Ana Laura Martínez1, Julia Moreno1, Ma. Eva González-Trujano1
1 Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, México, D. F., México 2 Postgrado en Botánica, Colegio de Postgraduados, Estado de México, México

Abstract

Tilia species have been used as anxiolytics for many years. In a previous study anxiolytic-like effects of a hexane extract of Tilia americana var. mexicana inflorescences were observed in experimental models in mice. To get additional insights into the neuroactive actions of this particular Tilia species, in this study we report a bioactivity guided-fractionation of the extract and separation by column chromatographic methods to isolate three fatty acids and a triterpene identified as β-sitosterol as major constituents. Our results revealed that the crude extract at 10 and 30 mg/kg i. p. and some pooled fractions at the same dosages potentiated sodium pentobarbital-induced sleeping time and caused a significant increase in the time spent at the open-arm sides in the plus-maze test. A reduction in the exploratory behavioral pattern manifested as ambulatory activity, as well as head dipping and rearing tests was also observed. Further fractionation and purification yielded four major fractions containing fatty acids and β-sitosterol as the active compounds. A dose-response curve of β-sitosterol in the range 1 to 30 mg/kg doses indicated that this compound produced an anxiolytic-like action from 1 to 10 mg/kg and a sedative response when the dose was increased to 30 mg/kg, these effects resemble those produced by diazepam (0.1 mg/kg). Our results suggest that hexane extract of Tilia americana var. mexicana produces depressant actions on the central nervous system, at least in part, because of the presence of β-sitosterol and some fatty acids that remain to be identified.

Key words

Anxiety - β-sitosterol - central nervous system - sedative - Tilia americana var. mexicana - Tiliaceae