Chem. Pharm. Bull. 53(7) 856—860 (2005)

cablin (BLANCO) BENTH. (Family Labiatae), commonly known as “Guang-Huo-Xiang” or Cablin Patchouli. It is a Chinese Materia Medica traditionally used for the treatment of common cold, nausea and diarrhea. Patchouli oil, the volatile oil of P. cablin, has been widely used in the cosmetic and oral hygiene industries to scent perfumes, flavor toothpaste, etc. Modern researches have repeatedly demonstrated various pharmacological activities of this oil including anti-emetic properties, trypanocidal activities, anti-bacterial, anti-fungal and Ca antagonist activities. It was reported that P. cablin contains sesquiterpenes cytotoxic chalcones, antimutagenic flavones. Patchoulic alcohol (Chart 1) is a major active ingredient of Herba Pogostemonis and is the most odor-intensive component of patchoulic oil. Therefore, the patchoulic alcohol content has been widely used as an indicator for the quality assessment of Herba Pogostemonis or dried P. cablin. Determination of patchoulic alcohol content, however, is not straightforward owing to the inherent chemical complexity of Herba Pogostemonis. Conventional methods always failed to give reliable results. For example, GC equipped with packed column may encounter difficulties in achieving satisfactory resolution. Capillary GC interfaced with Flame Ionization Detector (GC/FID) did not give steady outputs as a result of interfering GC peaks. To overcome these difficulties, we have developed a GC/MS/MS method to determine the patchoulic alcohol content in the whole herbs, stems and leaves of Herba Pogostemonis. All samples were freeze-dried in advance and then extracted with liquid carbon dioxide by supercritical fluid extraction to minimize the loss or decomposition of the active ingredient in the herbs. Supercritical fluid extraction is particularly useful for the extraction of volatile oils and thermally liable compounds. It has the advantage of extraction at a relatively low temperature, negligible solvent residue and relatively high extraction efficiency. Quantitative analysis was conducted by measuring the abundance of product ions of patchoulic alcohol in the MSMS spectrum. The identity of target compound was confirmed by full-scan mode and MS/MS scan mode by matching the retention time with an authentic standard. The enhanced selectivity of GC/MS/MS can eliminate the possible chromatographic interference occurred in GC/FID analysis. The minimized chromatographic interferences observed in the present study indicated suitability of the developed method for quality evaluation and quality control of Herba Pogostemonis.