Chemical Composition of the Essential oil of Chromolaena odorata (L.) R. M. King & H. Rob. Roots from India

The hydrodistilled essential oil of the roots of Chromolaena odorata (L.) R. M. King & H. Rob. was analysed by gas chromatography equipped with flame ionization detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC/MS). A total of twenty-nine compounds have been identified, accounting 97.6% of the total oil. The main constituents were himachalol (24.2%), 7-isopropyl-1,4-dimethyl-2-azulenol (17.6%), androencecalinol (14.1%), and 2-methoxy-6-(1-methoxy-2-propenyl) naphthalene (5.6%). The essential oil consists mainly of phenyl derivatives (41.6%), followed by oxygenated sesquiterpenes ((26.6%), long-chain hydrocarbons (18.9%), sesquiterpene hydrocarbons (6.8%), oxygenated monoterpenes (2.8%), and monoterpene hydrocarbons (0.9%). This study revealed that the roots of C. odorata produced different chemotypes other than leaves oil. This is the first report on the essential oil composition of the roots of C. odorata. 1. Introduction Chromolaena odorata (L.) R. M. King & H. Rob. (Syn: Eupatorium odoratum L.) (Asteraceae) is a perennial herb and distributed throughout India, tropical Asia, and Mexico [1, 2]. In traditional medicine this plant is used in the treatment of coughs, colds, and skin diseases [3], wound healing, and as a local antiseptic agent [4]. C. odorata is a medicinal plant having diverse pharmacological properties, namely, anti-inflammatory [5, 6], antimicrobial [7, 8], antigonorrhoeal [9], antipyretic, antispasmodic [6], diuretic [10], analgesic [11], and wound healing [12] activities. The chemical compositions of the essential oils of C. odorata that have been reported from different countries [13–20] are summarized in Table 1. The essential oil constituents of the leaves of C. odorata from Benin reported as α-pinene, pregeijerene, geijerene, β-pinene, and germacrene D [13] as the major compounds. In a report from Cameroon and Congo, α-pinene and p-cymene [14], while, from India, pregeijerene, epi-cubebol, cubebol, cis-sabinene hydrate, 10-epi-γ-eudesmol, germacrene-D-4-ol, δ-cadinene, germacrene D, geijerene, cyperene, 10-epi-γ-eudesmol, α-muurolol and khusimone [15] have been identified as the major constituents. The major compounds such as α-pinene, geijerene, and pregeijerene from Ivory Coast [16, 17] and α-pinene, β-pinene, germacrene D, β-copaen-4α-ol, β-caryophyllene, geijerene, pregeijerene [18], α-pinene, cadinene, camphor, limonene, β-caryophyllene and cadinol isomer [8] from Nigeria have been identified. In another report from Thailand, pregeijerene, germacrene D, α-pinene, β-caryophyllene, vestitenone,