. 1. Essent. Oil Res., 15, 108-111 (MarcldApril 2003)

The Essential Oil Composition of (A. Gray) Rydb.

Mary E. Lucero,* Rick E. Estell and Ed L. Fredrickson USDA-ARSJornutlu Erperii~zentnlRange, Box 30003, MSC 3JER, Las Cruces, NM 88003-8003

Abstract Psorothamnus scoparius (broom ) was collected from the Jonrada Experimental Range in south central New Mexico. Current year's growth was collected from 10 , all found within an approximate 50 In radius of the GPS coordinates N32041.286' and \1'106"46.922' during June. 2000. Composite satnples were steain distilled, and the essential oil was analyzed using GC with FID and GC/MS. Mass spectra and retention indices were used to identify 64 compounds. Retention indices and EI mass spectra are also provided for 15 unknowns. y-Terpinene (22.3%),p- cynene (14.0%) and a-pinene (9.0%) were the major constituents of the oil.

Key Word Index Psorotl~anlnrtsscoparius, Fabacae. broom dalea, essential oil composition, p-cynene, y-terpinene

Introduction Experimental Psoru)thnin~~us.scopnrius (A. Gray) Rydb.,(syn. Dnbn material was collected from the Jonlada Experi- scopnr-in A. Gray; Pnroseln scopnrin (A. Gray) A. Heller) mental Range in southern New Mexico, at an altitude of 1,344 conlnlonly know11 as brooin dalea, is a woody dicot shrub of 111 above sea level. Ten plants were randomly selected from tlie family found in sandy soils of the Chihuahuan within an approximate 50 m radius of the GPS coordinates Desert Natural products chemistry of P. species has received N32'41.286' and\17106"46.922'. Coordinateswere determined little attention. Raffauf (1)included P. frei~iontii(referred to usinga Garinin GPSl2 personal navigator. Samples coilsisted therein as Dolea frei~~or~tii)in his survey of plant alkaloids, as of 10 15-cm leaders of current year's growth froin each of 10 one of less than 22% of legumes analyzed which tested plants. These samples were placed on dry ice immediately positive for alkaloids. Raffauf's assays were qualitative, based after clipping, and were stored at 20°C until steain distilla- on colorimetric changes following spotting with Dragendorffs tions and dry matter analyses were performed. A voucher reagent. Two antimutagenic isoflavones isolated froill P. speciillen, identified as P scopnrius (Gray) Rydb, was placed fre~ilontii(2), a protein kinase C inhibitor from P. jur~ceus(3), in the Jornada Experimental Range Herbarium located in Las and counlarin, dalrubone, and their methoxy- derivatives (4) Cruces, NM. are the only specific compounds we found in the literature Collected tissue was ground in liquid nitrogen and 20 g pertaining to Psorothoini~us.Although the plant releases a were steain distilled for 6 h as described by Tellez et. al. (8), pleasant aroma, making it popular among southu~esterngar- using a 500 inL flask and 250 111L water. The resulting oil was deners, we found no descriptions of the volatile oil coinposi- dissolved in 100% ethanol. Both batches were a~idyzedby tion of any plant within the Psorothn~~~nusgenus. No ob~ious GUMS using a Varian model 3400 GC \\it11 a DB-5 coluinn physical barriers, such as thorns, are present in P. scopnrius, (30 in x 0.25 mm fused silica capillary column, film thickness yet it is unpalatable to livestock. Previous studies with other 0.25 ~111)coupled to a Finnigan ion trap mass spectrometer plant species have demonstrated that leaf surface volatiles (EI, 70 eV). Helium at 1inVmin was used as a camer gas, and may deter herbivory (5-7). In this report, we examine the oil injector and transfer line temperatures were set at 220°C and present in P. scopnrius. 260°C, respectively. The initial colunln temperature was 60°C,

'Address for correspondence Received: August 2001 Revised: October 2001 1041-2905/03/0002-0108$6.00/0-@ 2003 Allured Publishing Cop. Accepted: October 2001

10S/Joumal of Essential Oil Research Vol. 15, MarchIApril 2003 Psorothamnus scoparius -

Table I. Compounds identified in the oil of Psorothamnus scoparius

Component Identification Percent of Total Percent of Total Peak Area (FID) Peak Area (TIC)

tricyclene a-pinene camphene P-pinene 6-methyl-5-hepten-2-one myrcene a-phellandrene a-terpinene p-cymene limonene (Z)-p-ocimene phenylacetaldehyde (E)-p-ocimene y-terpinene terpinolene a-fenchol cis-p-menth-2-en-1-01 a-campholenal trans-pinoca~eol camphene hydrate borneol ethyl benzoate terpinen-4-01 4-methyl-acetophenone p-cymen-8-01 a-terpineol ascaridole geranial p-cymen-7-01 ca~acrol a-ylangene a-copaene (E)-P-damascenone P-bourbonene (Z)-jasmone italicene a-gurjunene a-cedrene P-caryophyllene trans-a-bergamotene aromadendrene a-humulene allo-aromadendrene y-gurjunene y-muurolene p-selinene cis-P-guaiene epi-zonarene p-curcumene y-cadinene 6cadinene cadina-1,4-dienel a-cadinene a-calacorene P-calacorene spathulenol globulol humulene epoxide II 1-epi-cubenol epi-a-cadinol a-muurolol P-eudesmol P-bisabolol cadalene

'[I] 2,3-dioxabicyclo(2.2.2)oct-5-ene, 1-methyl-4-(1-methylethyl)-, (1-a, 4-8); t = trace (~0.1%)

Vol. 15, MarchlApril 2003 Journal of Essential Oil Research1109 Lucero et al.

Table II. Mass Spectra and Retention Indices of unknowns from the essential oil of Psorothamnus scoparius

RI Percent of Percent of MS of Unknowns at 70 eV Total Total Peak Area Peak Area (FID) (TIC)

and a lineartemperature increase of3OC/rnin was programmed Table 11, along wiith their EI mass spectra. Since soft ioniza- into each run. A series of 40-, 400-, and 600-ng injections was tion was not available to verify the inolecular ions, no molecu- used to validate retention times for both low- and high- lar ions have been designated. Mass spectra of the unknowns concentration coinponents. Compounds were identified by bore no resemblance to the spectra reported for the previ- coinparing mass spectra and retention indices (9)wiith litera- ously isolated compounds (2-4), nor would any of these ture data (10, 11) and with our own MS library, wi~hichwas compounds be expected to partition with the oil fraction. developed using authentic standards. y-Terpinene was by far the most abundant compound in To validate the peak area percentages revealed on the total thevolatile fractioii, constitutingover22% ofthe oil. y-Terpiiiene ion chromatogram, the oil was also analyzed using a Shiinadzu is a biosynthetic precursor to cavacrol (12), which was also GC8APF equipped with a flame ionization detector and fitted present, albeit at trace levels. Cavacrol is antimicrobial (l2),as for use with capillav columns. A split/splitless injector was is thymol, which is synthesized from p-cymene. The large used, and the coluinn and temperature gradient were identical stores of y-terpinene and p-cyinene seen in I? scopnrius could to those described above forthe GUMS. The injectorteinpera- perhaps serve as a biochemical reserve, enabling the plant to ture was 250°C. Dry inatter percent was determined by d~ng rapidly respond response to microbial attack or other stress. triplicate, 2 g samples of ground tissue at 100°C for 24 11. The other inajor volatile, a-pinene, has been demonstrated to deter feedlng by sheep when applied to alfalfa pellets (13). Results and Discussion In suininay, y-terpinene dominated the oil profile of P. scopnrius. a-Pinene and p-cyinene were also present in sig- D1-y inatter accounted for 55% ofthe tissue fresh weight. nificant proportions. Roughly 10% of the total peak area The volatile fraction accounted for 0.03% of the dl? matter. within the FID chroinatograins of the oil profile was ac- Table I shows the identity, retention indices, and percent counted for by 15 coinpotinds whose mass spectra did not composition of the oil components identified by GUMS in correlate well with spectra contained in Adams (11)or NIST l? 400-ng injections of scopnrius oil. Larger injections were (10) libraries, and may belong to novel compounds. The required to detect the same peaks by FID. Peak areapercent- remainder ofthe profile was composed ofveiy small peaks for ages varied slightly between the two types of chromatograin. which clear mass spectra could not be obtained dtie to the low Both values are shou~n.Identified peaks comprising less than signal to noise ratio. 0.1% of the total peak area are marked "t" (trace). Sixty-five compounds were positively identified, accounting for 80% of the coinposition of the oil. Unknowns accounted for the Acknowledgements remainder of the total detected peak area. Unknowns corn- The alrthorr extend tl?nnks and appreciation to Yllnn Feng 1Vnng prising at least 0.1% of the oil detected by FID are listed in for a.rsista~lcercith GCIAIS arlalysis.

110/Journal of Essential Oil Research Vol. 15, MarchIApril 2003 Psorothamnus scoparius

References 7. R.E. Estell, E.L. Fredrickson, D.M. Anderson, Havstad, K.M. and Remmenga, M.D. Relationship of tarbush leaf surface terpene profile 1. R.F Raffauf, Plant alkaloids: A guide to their discovery. Food Products with livestock herbivory. J. Chem. Ecol., 24, 1-11 (1998). Press, New York (1996). 8. M.R. Tellez, R.E. Estell, E.L. Fredrickson, and K.M. Havstad, Essential 2. G. Manikumar, K. Gaetano, M.C.Wani, H.Taylor, T.J.Hughes, J.Warner, Oil of Chrysothamnus pulchellus (Gray) Greene ssp. pulchellus. J. R. McGivney, and M.E.Wall, Plant antimutagenic agents, 5. Isolation Essent. Oil Res., 10, 201-204 (1998). and structure of two new isoflavones, fremontin and fremontone from 9. E. KovAts, Gas-chromatographische charakterisierung organischer , J. Nat. Prod., 52,769-773 (1989). verbindugen. Teil 1: Retentionsindicesaliphatischerhalogenide, alkohole, 3. X. Li, H.Zhang, C. Ashendel, P. Fanwick, andC. Chang, Psorothamnone aldehyde, und ketone. Helv. Chim. Acta, 41, 1915-1932 (1958). A: a novel heterocyclic compound from Psorothamnus junceus. 10. Finnigan Standard FormatNlSTMS Library. National Institute of Science Tetrahedron Lett., 39, 3417-3420, (1998). and Technology. (1990), Maryland. 4. D.L. Dreyer. K.P. Munderloh, ,and W.E. Thiessen, Extractives of Dalea 11. R.P. Adams, Identification of Essential Oil Components by Gas species (Leguminosae). Tetrahedron, 31,287-293. ChromatographyIMassSpectroscopy. Allured Publishing Corporation, 5. R.E. Estell, D.M. Anderson, and K.M. Havstad, Effects of organic Carol Stream, Illinois (1 995). solvents on use of tarbush by sheep. J. Chem. Ecol., 20, 1137-1141 12. A. Sivropoulou, E. Papanikolaou, C. Nikolaou, S. Kokkini, T. Lanaras, (1994). and M. Arsenakis, Antimicrobial and Cytotoxic Activities of Origanum 6. R. E. Estell, E. L. Fredrickson, D. M. Anderson, K. M. Havstad, and M. Essential Oils. J. Agric. Food Chem., 44, 1202-1205. 96. D. Remmenga, Tarbush Leaf Surface Terpene Profile in Relation to 13. R. E. Estell, , E. L. Fredrickson, M. R. Tellez, K. M. Havstad, W. L. Shupe, Mammalian Herbivory. Proceedings: Shrubland Ecosystem Dynamics D. M. Anderson, and M.D. Remmenga, Effectsof volatile compoundson in a Changing Environment. General Technical Report INT-GTR-338, consumption of alfalfa pellets by sheep. J. Animal Sci., 76, 228-233 United States Department of Agriculture, 237-241, (1996). (1998).

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