Volatile Constituents of Leaf Oils from the Genus Baccharis. Part I: B. racemosa (Ruiz et Pav.) DC and B. linearis (Ruiz et Pav.) Pers. Species from Argentina**

Journal of Essential Oil Research: JEOR, Jan/Feb 2005 by Malizia, Rubén A, Cardell, Daniel A, Molli, José S, González, Silvia, Et al

Abstract

Volatile compounds from Baccharis racemosa (Ruiz et Pav.) DC and two samples of B. linearis (Ruiz et Pav.) Pers. leaves collected in the Argentinean Patagonia were isolated by steam distillation. Yields on the oils were 2.50% for B. racemosa; 0.92% for B. linearis (sample A) and 1.91% for B. linearis (sample B). The leaf oils were analyzed by GC and GC/MS. The main constituents of each oil were: (i) B. racemosa oil: sabinene (13.6%), β-pinene (2.8%), myrcene (2.0%), limonene (13.3%), δ-cadinene (5.3%), (E)-nerolidol (5.0%), viridiflorol (2.6%), α-muurolol (9.7%) and α-cadinol (3.1%); (ii) B. linearis (sample A) oil: α-pinene (6.5%), β-pinene (14.9%), myrcene (2.2%), limonene (27.6%), bicyclogermacrene (2.7%), δ-cadinene (3.9%), caryophyllene oxide (3.1%), cubenol (4.7%) and α-cadinol (4.7%); and (iii) B. linearis (sample B) oil: α-pinene (2.5%), β-pinene (6.5%), limonene (27.7%), β-caryophyllene (2.0%), germacrene D (4.7%), bicyclogermacrene (5.4%), δ-cadinene (6.7%), cubenol (6.0%) and α-cadinol (3.0%).

Key Word Index

Baccharis racemosa, Baccharis linearis, Asteraceae, essential oil composition, sabinene, β-pinene, limonene, α-muurolol.

Introduction

The genus Baccharts L. belongs to Asteraceae family, Tubulifloroideae subfamily, Astereae tribe, comprising more than 400 species of useful aromatic and medicinal plants, widely distributed in central and South America. In Argentina, about 100 species are known and are widely distributed. Baccharis racemosa and B. linearis (Ruiz et Pav.) Pers. [syn. B. rosmarinifolia Hook, et Arn.] (n.v. huencu, romerillo) (Spanish) are distributed in the woods of central and southern Chile, and on the western side of Argentinean Patagonia. They grow in mountainous zones, in sandy soils with gravel, neutral pH and good drainage, mainly along the roads (1-6).

Apparently, there are no previous investigations on the composition of B. racemosa. Some results have been reported focusing on the secondary metabolites of B. linearis including alkaloids, waxes and diterpenes (7-11). The hybridization of B. linearis with B. macraei yielded B. intermedia, the chemical composition of which has been reported (12). The oleanolic acid content in B. linearis and its effects on Heliothis zea larvae has also been reported (13). However, few studies on the composition of the volatile oils from these species have been published. In this regard, only one study described the composition of the leaf oil of B. linearis by TLC (14). Moreover, there seems to be no previous study on the composition of Argentinean B. linearis leaf oil. The present study reports on the oil yields and the compositions of the leaf oils from B. racemosa and B. linearis growing in Argentinean Patagonia.

Experimental

Sampling: Specimens were collected in spring from the following places: B. racemosa: Presa Futaleufú, Futaleufú Department, Chubut Province, Argentina. Baccharis linearls (sample A): Ruta 259, aproximately 3 km from Esquel city, Futaleufú Department, Chubut Province, Argentina. Baccharis linearis (sample B): Route 258 - La Burrada (at 15 km of Leleque cross). Voucher speciinens have been deposited at the Herbarium of the Department of Forestal Botanies, Faculty of Engineering, National University of Patagonia, Chubut Province, Argentina.

Essential oil: The oil was obtained by hydrodistillation for 3 h using a Clevenger-type apparatus. The samples were subjected to five replications giving an average yield (mL of oil per 100 g of leaves) of2.50% (standard deviation 0.03%) for B. racemosa; 0.92% (standard deviation 0.04%) for B. linearis (A); and 1.91% (standard deviation 0.02%) for the second sample of B. linearis (B).

Components identification: The constituents of the leaf oils were identified by gas chromatography, using retention indices and Chromatographie standards. The retention indices of each file of data were calculated with respect to a set of hydrocarbons of C^sub 7^ to C^sub 23^. The identity of each constituent was checked with the retention time of a pure standard compound on two columns of different polarity. Peak area percentages were calculated from FID area percentages without using either correction factors or an internal standard. The mass spectra were compared to spectra already reported in the literature (15,16) and to those obtained with authentic samples.

Analytical GC: The GC analysis of the oils was performed on a Hewlett Packard 584OA gas Chromatograph. Column: DB-5 (30 in × 0.25 mm, film thickness: 0.25 µm). Detector: FID (flame ionization detector). Carrier gas: nitrogen. Split relation: 1:100. Temperature program: initial temperature: 60°C (O min); incremental increase 4°C/min; final temperature: 300°C (15 min); injector temperature: 250×C; detector temperature: 350×C; injection volume: 0.2 µL.

GC/MS: The GC/MS analysis was performed with a Shimadzu QP-5000 GC/MS equipped with an electronic impact source at 260×C, operating with an emission current of 0.7 mA and 70 eV electron energy. The Chromatograph was equipped with columns identical to those used for the GC analysis. A temperature program from 50°-240°C at 6°C/min was used. Carrier gas: helium.