Fragrant Lactones in the Steam Distillation Residue of Aeollanthus suaveolens Mart. ex Spreng and Analysis by HS – SPME
Lupe, Fernanda A
The volatiles found in the headspace of Aeollanthus suaveolens were analyzed by solid phase microextraction coupled with GC/MS. This led to the identification of the 23 compounds. During steam distillation of the oil of A. Suaveolens, the very fragrant lactones, massoia lactone and δ- decalactone, were concentrated in the residue from which they can easily be extracted for perfumery purposes.
Key Word Index
Aeollanthus suaveolens, Lamiaceae, headspace analysis, massoia lactone, linalool, (E)- β- farnesene, linalyl acetate, neothujyl acetate, β- bisabolene, geranyl acetate and epi-β- santalene.
Catinga de mulata (Aeollanthus suaveolens Mart ex- Spreng) belongs to the Lamiaceae family and is a native annual herb from the Amazon region. It is used by the population in a fragrant bath made by infusion of the aromatic plants that possess religious or folkloric motivation, and in home-made perfumes. In ethnomedicine it is used to combat fever, weakness and migraine (1). The leaf is the most used part of the plant as tea or juice (1). The essential oils of the leaves and flowers obtained by hydrodistillation have been found to contain (-) linalool, farnesene and (-) massoialactone as main components (1). The highest yields of linalool occurred in the leaf (31.5%), while for farnesene it was observed at a higher concentration in the flower (55.3%), leaf (21.9%) and in the stalk (42.2%) (1). With regard to massoia lactone, its major concentration occurred in the leaf (25.2%), while in the other parts of the herb, the content was not significant (1). The antimicrobial activity of the oil was reported, with massoia lactone being strongly active against the S. setubal microorganisms and Bacillus subtilis (2). The MIC (Minimum Inhibition Concentration) of the oil sample showed more activity against Escherichia colt and Cryptococcus neoformans (2). Phytochemicals studies have been pharmacologically monitored revealing that the oil is responsible for the blockade of induced convulsions for Metrazol (PTZ) in mice (3).
Solid Phase Microextraction (SPME) has become a very popular technique for the extraction and pre-concentration of organic analytes. SPME uses a fused silica fiber coated by thin films of pure polymeric or dispersions of solid adsorbents in polymers extracting phases such as polydimethylsiloxane (PDMS) and PDMS/divinylbenzene (PDMS/DVB), respectively as both are able to ad sorb analytes from different matrixes. SPME is normally preferred over other techniques because it’s simple, relatively inexpensive and solventless technique (4). Headspace-SPME, HS-SPME, has been widely applied to aroma related analytical problems and its suitability and convenience for the isolation of volatile compounds of plants.
In this work, we adopted HS-SPME coupled to GC/MS for the identification of volatile compounds from A. suaveolens to compare the volatile composition in the essential oil, fresh plant, dried plant and residue of steam distillation.
The Natural Products Chemistry Laboratory studies extracts and essential oils, aiming the use of natural products for the industry of perfume and cosmetics.
Plant material and oil isolation: The samples were obtained in the municipal market Ver-o-Peso in Amazon (Belém, Para) January 2005. Tl.The equipment was a Marconi 2OL steam distillation unit made of 306 inox steel mad in Brazil. Fresh aerial parts of A. suaveolens (3kg) were subjected to steam distillation for 2.5 h, resulting in the isolation of 306 mg of oil extracted from the distillate water by methylene chloride. The extraction residue (CM4) was dried at ambient temperature. SPME analyses were performed using four different samples: fresh plant (CMl), dried plant (CM2), the isolated oil of fresh aerial plants through vapor steam distillation (yield 0.02%) (CMS), and the isolation residue by steam distillation (CM4), Table I.
HS-SPME: A suspension of 200 mg of sample mashed and ISmL of saturated aqueous NaCl in a 25mL septum-sealed was magnetically stirred at 1200 rpm for 15 min at 55°C for sample/headspace pre-equilibration. After this time, a PDMS (100 µm) fiber was exposed to the vial headspace for 20 min. The extracted analytes were immediately desorbed and analyzed using GC/MS.
Gas chromatography/masa epectrometry: The samples were analyzed on a HP5890-II GC equipped with an HP-5 fused silica column (30 m x 0.25 mm, film thickness 0.25µm) and interfaced with a quadrupole detector HP-5870-B. Column temperature programmed from 60°0 -240°C at 3°C/min; injector was operated at splitless mode at 220°C. Helium was used as carrier gas at the flow rate of 1.0 mL/min, the mass spectrometer was operated at 7OeV.
Identification of components: The identification of the constituents was assigned on the basis of comparison of their retention indices and their spectra in the Wiley Library and those given in the literature (5).
Results and Discussion
Table 1 shows the results of the analyses.
About 99% of the substances present in the different samples were identified. They were 13 monoterpenes, eight sesquiterpenes and two lactones. Linalool was the most abundant substance common to all samples. Besides linalool, massoia lactone and δ-decalactone, the substances present in prominence were: in the fresh plant: neothujyl acetate and β-bisabolene; in the dry plant: (E)-β- farnesene and linalyl acetate; in the oil: geranyl formate, linalyl acetate and epi -β-santalene. It was found that the yield of oil through steam distillation was 0.02% concentrating, both massoia lactone and δ- decalactone in the residue. Massoia lactone was abundant either in the dry or in the fresh plant and seems to be the substance giving the characteristic aroma of Catinga de Mulata. It is important to observe that steam distillation did not lead to the isolation of the two lactones. δ-decalactone, however, is little abundant in the two materials. Massoia lactone is extremely abundant in the residue of the essential oil extraction through steam distillation using fresh plant material and can be regarded as an important component of this fragrance.
We would like to thank Rosa Maria Barata HoUandafor acquisition of the fresh samples ofAeolanthus suaveolens.
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4. J. Pawliszyn, Applications of Solid Phase Mlcroextractton. Edit., J. Pawliszyn, pp. 3-21, Royal Soc. Chem., Cambridge (1999).
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Fernanda A. Lupe, Ana C. Lemes, Fabio Augusto and Lauro E. S. Barata*
Organic Chemistry Dept., Chemistry Institute, University of Campinas, Campinas, Brazil
* Address for correspondence
Received: August 2005
Revised: February 2006
Accepted: March 2006
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