Essential oil profiling of <em>Alpinia </em> species from southern India

Abstract

<em>Alpinia galanga </em> Willd. (Greater galangal) and <em>Alpinia calcarata </em> Rosc. (Lesser galangal) are the two most important medicinal plant species of the genus <em>Alpinia</em> (Fam. Zingiberacae) widely found in South India. Plant rhizomes are used as flavours in native dishes and ingredients in many traditional medicines to treat various ailments such as rheumatism, headache, sore throat, chest pain, skin diseases and stomach disorders. Diverse germplasm of <em>A. galanga </em> (12) and <em>A. calcarata </em> (16) collected from different parts of South India was evaluated for essential oil content and composition. The essential oil content isolated from rhizomes was relatively higher in <em>A. calcarata </em> (0.29-0.96 %) as compared to <em>A. galanga </em> (0.21-0.41 %) germplasm. Chemical profiles of volatile oils isolated from rhizomes of <em>A. galanga </em> and <em>A</em>. <em> calcarata </em> germplasm were investigated by gas chromatography-flame ionization detection (GC/FID) and gas chromatography-mass spectrometry (GC/MS). Essential oil profiling of <em>Alpinia </em> species revealed fifty-six volatile compounds of which oxygenated monoterpenoids were the most predominant in both the plant species. Out of these, 1,8-cineole was the major oxygenated monoterpenoid compound present in both the species, which was much higher in <em>A. galanga </em> (47.5-67.3 %) as compared to <em>A. calcarata </em> (13.0-30.2%). These two species differed significantly in oil composition as <em>A. calcarata </em> contained substantially high content of ɑ-fenchyl acetate (26.3-38.7%), camphor (3.3-4.7%), camphene (0.7-6.6%), α-terpineol (4.8-8.0%), borneol (3.4-5.0%) and (E)-methyl cinnamate (2.1-6.0%). The aroma compounds identified in <em>A. galanga</em> oil were ɑ-pinene (0.7-3.7 %), ɑ-terpineol (1.0- 2.7%), chavicol (0.2-0.7 %), methyl eugenol (0.7-1.2 %), ß-farnesene (7.0-14.6%), eugenol (0.8-2.6%) and ß-sesquiphellandrene (2.4-10.8%). Volatile compounds chavicol, ß-farnesene, eugenol and <em>ß</em>-sesquiphellandrene were present only in <em>A. galanga </em> oil. Compound 1,8-cineole is an important aroma chemical used widely in pharmaceutical preparations due to its expectorant, antiseptic and anesthetic properties. Findings of this study may encourage utilization of these two species of <em>Alpinia </em> for pharmaceutical and industrial purpose.