Chemical constituents from leaves and cell cultures of pogostemon cablin and use of precursor feeding to improve patchouli alcohol level

Abstract

The study on the chemical constituents of an essential oil of Pogostemon cablin was carried out by hydrodistillation of leaf explants and the oil analysed by Gas Chromatography Mass Spectrometry (GC/MS). The oil yield was found to be 0.30 % (v/w) of fresh weight. Twenty two compounds were identified by GC/ MS as eighteen sesquiterpenes and three oxygenated sesquiterpenes. Among these, patchouli alcohol (60.30 %) was the major component, followed by germacrene A (11.73 %). In order to study the chemical constituents of the essential oil of plant cell cultures, leaves were surface sterilised and callus cultures initiated on MS media containing naphthaleneacetic acid (0.5 mg/l), and benzyladenine (1 mg/l), followed by incubation in suitable culture conditions. Cell suspension cultures were initiated by subculturing callus cultures into new liquid media and maintained in the same conditions. Chemical constituents of the essential oils produced by both callus and cell suspension cultures were extracted with dichloromethane and analysed by GC and GC/ MS. The results showed that essential oil obtained from these cultures contained the same major constituents, namely patchouli alcohol, as in the intact plant, but the level was low, and also contained a small amount of minor constituents. Feeding cis-farnesol, the precursor of patchouli alcohol, to cell suspension cultures resulted in the patchouli alcohol being increased from 19.5 mg/l to 25.5 mg/l.