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Validated liquid chromatographic method and analysis of content of tilianin on several extracts obtained from Agastache mexicana and its correlation with vasorelaxant effect

Hernández-Abreu, Oswaldo, Durán-Gómez, Liliana, Best-Brown, Roberto, Villalobos-Molina, Rafael, Rivera-Leyva, Julio, Estrada-Soto, Samuel
Journal of ethnopharmacology 2011 v.138 no.2 pp. 487-491
Agastache, aerial parts, drying temperature, high performance liquid chromatography, hypertension, maceration, medicinal plants, methanol, plant extracts, quality control, rats
ETHNOPHARMACOLOGICAL RELEVANCE: To optimize the obtention of tilianin, an antihypertensive flavonoid isolated from Agastache mexicana (Lamiaceae), a medicinal plant used in Mexico for the treatment of hypertension. Also, a validated HPLC method to quantify tilianin from different extracts, obtained by several extraction methods, was developed. MATERIALS AND METHODS: The aerial parts of Agastache mexicana were dried at different temperatures (22, 40, 50, 90, 100 and 180°C) and the dry material was extracted with methanol by maceration to compare the content of the active constituent tilianin in the samples. Furthermore, EtOH:H₂O (7:3), infusion and decoction extracts were prepared from air-dried samples at room temperature to compare the content and composition of the different extraction methods. Moreover, an ex vivo vasorelaxant test on endothelium-intact aortic rat rings was conducted, in order to correlate the presence of tilianin with the activity of each extract. RESULTS: Higher concentration and amounts of tilianin were determined from chromatograms in the obtained methanolic extracts from plant material dried at 90, 50, 40 and 22°C, followed by 100°C; however, lower concentrations were observed in dried at 180°C and EtOH:H₂O (7:3). It is worth to notice that methanolic extracts with higher amount of tilianin were the most potent vasorelaxant extracts, even though these extracts were less potent than carbachol, a positive control used. Finally, decoction, infusion and EtOH:H₂O (7:3) extracts did not show any vasorelaxant effect. CONCLUSION: Results suggest that extracts with higher concentration of tilianin possess the best vasorelaxant activity, which allowed us to have a HPLC method for future quality control for this medicinal plant.