Simultaneous Determination of Two Isomers of Asarone in Piper sarmentosum   Roxburgh (Piperaceae) Extracts using Different Chromatographic Columns

Purpose: To develop a rapid and reliable reverse phase high performance liquid chromatography (RPHPLC) method to quantify the two isomers of asarones in P. sarmentosum extracts using two different columns under similar analytical conditions.
Methods: Two isomers, α- and β-asarone, were analyzed using two types of C-18 columns with 0.1 % orthophosphoric acid: acetonitrile: methanol (50: 40: 10) as mobile phase. The developed method was applied to determine the contents of α- and β-asarone in extracts of different parts of P. sarmentosum.
Results: Column A retention times for the elution of α- and β-asarone were 11.890 ± 0.008 and 10.80 ± 0.004 min, respectively, and were significantly shorter than those of column B (15.110 ± 0.024 and 13.290 ± 0.018, respectively, p < 0.001). Column B showed better resolution (1.82 ± 0.025 of the isomers than column A (1.10 ± 0.01, p < 0.001). Both columns showed comparable sensitivity, precision and selectivity of the compounds investigated. α-Asarone level was in the range 0.36 - 5.14 % in ethanol and 50 % ethanol extracts, but absent in all water extracts. β-Asarone occurred in the range of 0.01 - 0.15 % in ethanol and 50 % ethanol extracts but was absent in all water extracts of P. sarmentosum.
Conclusion: The results indicate that the developed method is a suitable quality assurance method for determining α- and β-asarone isomers in herbal extracts and food preparations.

Keywords
α- Asarone; Isomers; Piper sarmentosum; Herbal extracts; Retention time