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Purpose: To develop a reverse phase high performance liquid chromatography (RP-HPLC) method for the analysis of the crude extracts of Orthosiphon stamineus.
Methods: A simple and facile analytical method was developed using RP- HPLC with UV detection for the identification and quantitation of bioactive markers present in O. stamineus extracts. Four different bioactive markers were used for the analysis, namely, rosmarinic acid, orthosiphol-A, 3’-hydroxy-5, 6, 7,4’-tetramethoxyflavone (TMF) and 5, 6, 7, 3’, 4’-pentamethoxyflavone (sinensetin), using an isocratic mobile phase methanol: tetrahydrofuran: water (0.1% H3PO4) (55:5:40) on Nucleosil C-18 column (250 mm x 4.6 mm i.d., 5 ìm particle size) at a flow rate of 0.7 ml/min and detection at 330 nm with 30 min separation time.
Results: The bioactive marker orthosiphol A was identified and isolated from the water extract of O. stamineus leaves. The standard calibration curves for the marker were linear in the range 0.01 - 500 ìg/ml with a regression coefficient (r2) > 0.9996. The recoveries of the four markers were in the range 83.2 to 106.4 % at relative standard deviation (RSD) values < 5 %. The limit of detection (LOD) and of quantification (LOQ) were 2 and 20 ng/ml, respectively.
Conclusion: The developed method is simple, sensitive and specific for simultaneous determination of the indicated marker compounds either qualitatively or quantitatively, and may be used as a fingerprint
profile for the standardization of extractives or herbal medicines from O. stamineus.