High-Performance Liquid Chromatographic Analysis of Flavones from the Anti-inflammatory Fraction of Orthosiphon stamineus Chloroform Extract

Abstract: Orthosiphon (O.) stamineus is a popular medicinal herb which has gained its popularity by the name of Misai Kucing (Cat s Whiskers) in Malaysia. It has been used traditionally as diuretic and for the treatment of rheumatism, diabetes, hypertension and inflammation. Studies have been carried out to screen the anti-inflammatory activity of O. stamineus extract on animals. Sub-fraction Cf2B from the crude chloroform extract of O. stamineus was found to be most active in inhibiting carrageenan-induced hind paw oedema in mice thus indicating the most active anti-inflammatory fraction of the extract to be sub-fraction Cf2B. Two compounds were isolated and identified from this active sub-fraction, namely 5,3 -dihydroxy-6,7,4 -trimethoxyflavone 1 and 5,6,7,3 ,4 - pentamethoxyflavone 2. Compounds I and 2 are flavones commonly known as eupatorin (EU) and sinensetin (SI) respectively. Both compounds were identified and elucidated through spectroscopic methods. A simple, rapid and accurate high-performance liquid chromatographic (HPLC) method was developed for the assessment of these two flavones. In the quantitative determination, the concentrations of EU and SI are found to be 0.0505 mg/ml (5.05%) and 0.0286 mg/ml (2.86%) respectively in 1 mg/ml of Cf2B active sub-fraction. The method is precise with relative standard deviations for these two constituents ranging between 1.27-4.52%) (intra-day) and 2.17-4.52%) (inter-day).