1.   Introduction

A major ecoregion in the intermountain western United States is the sagebrush steppe (sagebrush-dominated semiarid high desert), which covers about 62.7 million hectares of the Great Basin and Colorado Plateau [1]. The region is characterized by cold winters, relatively low annual precipitation, and dominance of sagebrush (Artemisia species) cover and perennial grasses [2]. Common sagebrush species include Artemisia tridentata Nutt., Artemisia tripartita Rydb., Artemisia arbuscula Nutt., and Artemisia cana Pursh. Other common plant species in this ecoregion include shrubs, such as rabbitbrush (Ericameria nauseosa (Pursch) G.L. Nesom & G.I. Baird, Chrysothamnus viscidiflorus Nutt.) and bitterbrush (Purshia tridentata (Pursh) DC.) and forbs, such as balsamroot (Balsamorhiza sagittata (Pursh) Nutt.), yarrow (Achillea millefolium L.), Lomatium species, and Eriogonum species [1].

There are four subspecies of Artemisia tridentata Nutt. (big sagebrush, Asteraceae) currently recognized by World Flora Online (WFO): A. tridentata subsp. tridentata (Great Basin sagebrush), A. tridentata subsp. vaseyana (Rydb.) Beetle (mountain big sagebrush), A. tridentata subsp. wyomingensis Beetle & A.L. Young (Wyoming sagebrush), and A. tridentata subsp. parishii (A. Gray) H.M. Hall & Clem. (Parish sagebrush, Mojave sagebrush) [3]. Each A. tridentata subspecies occupies a distinct environment; however, hybridization can occur in intermediate zones [4, 5].

Mountain big sagebrush (A. tridentata subsp. vaseyana) ranges from British Columbia, Canada, south through Washington, Idaho, Montana, Oregon, Wyoming, California, Nevada, Utah, and Colorado, and into northern Arizona and New Mexico [6]. The plant is generally found in montane meadows and forests at elevations of 2000-2800 m. It is a medium-sized shrub, around 0.4-0.8 m tall. The leaves are 12-35 mm long, 2-3 mm wide, with three shallow lobes; the flower stalks are prominent paniculiform arrays, 10-15 cm long [6] (Fig. 1).

Figure 1. Artemisia tridentata subsp. vaseyana (Rydb.) Beetle.

A: Photograph of the plant taken at the time of collection.

B: Scan of a pressed sample.

Volatiles from A. tridentata subsp. vaseyana have been previously studied in southwestern Montana (major components α-pinene, 1,8-cineole, camphor, and two unidentified monoterpenoids) [7], central Utah (major components 1,8-cineole, trans-3-(1-oxo-2-methyl-2-propenyl)-2,2- dimethylcyclopropylmethanol, 2,2-dimethyl-6-isopropenyl-2H-pyran, 2,3-dimethyl-6-isopropyl-4H-pyran, thujone, sabinol, chrysanthemol, chrysanthemyl acetate, fragranyl acetate, fragranol, and 2-isopropenyl-5-methylhexa-(E)-3,5-dien-1-ol) [8], north-central Wyoming (major components, α-pinene, camphene, 1,8-cineole, camphor, fragranol, and grandisol) [9], and southwestern Idaho (major components 1,8-cineole, α-thujone, and camphor) [10]. The present study represents the first collection and analysis of A. tridentata subsp. vaseyana from the Sawtooth Valley of central Idaho. We hypothesized that the geographical remoteness of this collection from those from Utah or Montana likely exhibited a different chemical profile from previous reports.

Artemisia cana Pursh (silver sagebrush, Asteraceae) is an aromatic shrub found in the grasslands, floodplains, and montane forests of the western United States and Canada [6, 11, 12]. There are three subspecies of A. cana: A. cana subsp. cana (plains silver sagebrush), A. cana subsp. bolanderi (A. Gray) G.H. Ward (Bolander’s silver sagebrush), and A. cana subsp. viscidula (Osterh.) Beetles (mountain silver sagebrush) [3]. Plains silver sagebrush is generally found east of the Continental Divide, including western Canada (Manitoba, Saskatchewan, Nebraska, Alberta and British Columbia) and the northwestern United States (North Dakota, South Dakota, Nebraska, Montana, Wyoming, Colorado). The range of Bolander’s silver sagebrush is generally restricted to the enclosed basins of central Oregon and eastern California. Mountain silver sagebrush inhabits mountainous regions (approximately 1,800 m or higher) of southern Idaho, southwestern Wyoming, eastern Nevada, south along the Continental Divide, northern New Mexico and northern Arizona [13]. The plant generally grows 0.1-0.3 m tall, with linear-oblanceolate, entire leaves measuring 1-5 mm wide and up to 7 cm long, and covered with a silvery-white pubescence. The flower heads are arranged into congested, leafy panicles, sometimes reduced to a raceme or spike-like inflorescence [6, 11, 12] (Fig. 2).

Figure 2. Artemisia cana subsp. viscidula (Osterh.) Beetle.

A: Photograph of the plant taken at the time of collection.

B: Scan of a pressed sample.

Previous investigations of Artemisia cana subsp. cana have shown that the essential oils are dominated by 1,8-cineole and camphor [9,14,15]. Gundawardena and co-workers isolated and identified santolina triene, artemisia triene, artemiseole, 1,8-cineole, camphor, α-pinene, lyratal, isolyratol, lyratol, chrysanthemol, trans-chrysanthemal, chrysanthemyl acetate, fragranyl acetate, fragranol, 2-isopropenyl-5-methyl-(E)-hexa-3,5-dien-1-ol, 2,2-dimethyl-6-isopropenyl-2H-pyran, 2,3-dimethyl-6-isopropyl-4H-pyran, 2,4-diisopropenyl-5H-furan, and rothrockene from a pentane extract of A. cana subsp. viscidula [8]. However, the volatile chemical composition was not quantified. To the best of our knowledge this is the first report on the essential oil composition of A. cana subsp. viscidula growing in the Sawtooth Valley of central Idaho. We hypothesized that the chemical composition would differ from that of A. cana subsp. cana. As part of our interest in the volatile phytochemistry of aromatic and medicinal plants, we obtained and analyzed the essential oils from Artemisia tridentata subsp. vaseyana and Artemisia cana subsp. viscidula, which were growing in the Sawtooth Valley of central Idaho, and compared and contrasted the essential oil compositions with previous reports on these sagebrush species.

2.   Materials and methods

2.1. Plant Material

The aerial parts of A. tridentata subsp. vaseyana and A. cana subsp. viscidula were collected from several plants growing in the Sawtooth Valley of Idaho on 11 October, 2025, in the early afternoon (Table 1). Artemisia tridentata vaseyana samples #1-3 were collected at 1:50, 1:55, and 1:58 pm, respectively. Artemisia cana viscidula samples #1-4 were collected at 1:53, 2:03, 2:12, and 2:53 pm, respectively. The plants were identified in the field by W.N. Setzer and verified by comparison with herbarium samples from the New York Botanical Garden [16]. Voucher specimens (WNS-Atv-2544 and WNS-Acv-5680) were deposited in the University of Alabama in Huntsville Herbarium. The fresh plant material was frozen after collection and stored frozen (‒20 °C) until processed. For each plant sample, the fresh/frozen plant material was chopped and then hydrodistilled using a Likens-Nickerson apparatus for four hours with continuous extraction of the distillate with dichloromethane. The solvent was evaporated from the distillate using a stream of warm air to obtain the essential oils (Table 1).

Table 1. Collection and hydrodistillation details of Artemisia tridentata subsp. vaseyana and Artemisia cana subsp. viscidula.

Sample	Location	Mass plant material (g)	Mass essential oil (g)	Essential oil color	Yield (%, w/w)
Artemisia tridentata subsp. vaseyana
#1	44°2’46” N, 114°51’12” W, 2054 m asl	52.80	2.40	pale yellow	4.55
#2	44°2’48” N, 114°51’13” W, 2050 m asl	93.17	3.81	pale yellow	4.09
#3	44°2’48” N, 114°51’14” W, 2050 m asl	39.53	2.07	greenish-yellow	5.24
Artemisia cana subsp. viscidula
#1	44°2’47” N, 114°51’13” W, 2053 m asl	44.33	1.69	pale yellow	3.81
#2	44°2’48” N, 114°51’11” W, 2050 m asl	71.03	2.82	yellow	3.98
#3	44°2’33” N, 114°50’28” W, 2057 m asl	79.14	3.69	yellow	4.67
#4	44°2’33” N, 114°50’29” W, 2057 m asl	82.01	3.14	yellow	3.83

2.2. Gas Chromatographic Analysis

The A. tridentata subsp. vaseyana and A. cana subsp. viscidula essential oils were analyzed by GC-MS using a Shimadzu GC-MS-QP2010 Ultra (Shimadzu Scientific Instruments, Columbia, MD, USA), fitted with a Zebron ZB-5ms fused silica capillary column (60 m ´ 0.25 mm ´ 0.25 μm film thickness) (Phenomenex, Torrance, CA, USA). The MS detector was operated in the electron impact (EI) mode with an electron energy of 70 eV, scan range of 40–400 atomic mass units, and scan rate of 3.0 scans/s. The injector, interface, and ion source temperatures were 260 °C. The GC oven was programed with an initial temperature of 50 °C, ramped at 2 °C/min to 260 °C, and held at 260 °C for 5 min. Each sample (0.1 μL of a 5% solution of essential oil in dichloromethane) was injected using a split mode (24.5:1). Retention indices were determined based on a series of homologous C8-C26 n-alkanes (Sigma-Aldrich, St. Louis, MO, USA) using the arithmetic method described by van den Dool and Kratz [17]. The identification of the essential oil components were determined by comparison of retention indices (within 5 RI units) and mass spectral fragmentation (similarity index > 80%) with those in the databases of Adams [18], Satyal [19], Mondello [20], NIST20 [21],and W23N23 [22]. The percentages of the essential oil components were calculated based on peak integration without standardization.

2.3. Multivariate Analyses

Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were performed using XLSTAT v. 2018.1.1.62926 (Addinsoft, Paris, France). For the HCA, 18 A. tridentata subsp. vaseyana essential oil compositions from this study and previous publications [9,10] were treated as operational taxonomic units, and the percentages of the 14 most abundant essential oil components (α-pinene, camphene, artemiseole, 1,8-cineole, α-thujone, β-thujone, grandisol, chrysanthenone, trans-pinocarveol, camphor, trans-chrysanthemol, fragranol, ethyl trans-chrysanthemumate, and fragranyl acetate) were used to define the chemical associations between the A. tridentata subsp. vaseyana essential oil samples. Dissimilarity was used to determine clusters, considering the Euclidean distance, and Ward’s method was used to define agglomeration. PCA was performed for the visual verification of the essential oil interrelationships of the different A. tridentata subsp. vaseyana samples using 14 major components as variables with a Pearson correlation matrix. Both HCA and PCA for A. cana subspecies cana [9, 14, 15] and viscidula (this work) were carried out as described above using 10 major components (α-pinene, camphene, artemiseole, 1,8-cineole, santolina alcohol, cis-chrysanthemal, camphor, trans-chrysanthemol, ethyl trans-chrysanthemumate, and (2E)-1,3,7-trimethyl-2,6-octadienyl acetate).

3.   Results and discussion

3.1. Chemical Composition of Artemisia tridentata subsp. vaseyana

The essential oils of A. tridentata subsp. vaseyana were obtained by hydrodistillation using a Likens-Nickerson apparatus, with yields of 4.09 5.24% (w/w). The Likens-Nickerson simultaneous distillation extraction method generally gives higher essential oil yields [23–26] and higher yields of volatile monoterpene hydrocarbons [23] that are prone to escape due to the high temperatures of boiling water [27] and water-soluble components [24, 28, 29] that would otherwise partition into the hydrosol [29]. Thus, the Likens-Nickerson method is appropriate for small amounts of plant material [26] and is often the best method to obtain the most representative oil with the highest overall recovery  [29]. Gas chromatographic analysis of the essential oils identified 76 components, which accounted for 98.0-98.4% of the total composition. The essential oil compositions are compiled in Table 2. The essential oils were dominated by oxygenated monoterpenoids, predominantly fragranol (55.8-70.0%) and fragranyl esters (25.0-31.6%). A representative chromatogram of A. tridentata subsp. vaseyana is shown in Supplementary Fig. S1. Oxygenated monoterpenoids have generally dominated the essential oils of Artemisia tridentata [10, 30], including A. tridentata subsp. vaseyana [9,10], although the individual compositions are highly variable. Other sagebrush species, e.g., Artemisia ludoviciana Nutt [9, 14, 31–34], Artemisia frigida Willd [14, 35–40], and Artemisia longifolia Nutt. [9] are also rich in oxygenated monoterpenoids (Table 2).

Table 2. Essential oil compositions (percent of total composition) of Artemisia tridentata subsp. vaseyana from Sawtooth Valley, Idaho.

RIcalc	RIdb	Compounds	Area %
			#1	#2	#3
766	774	Isobutyric acid	tr	tr	tr
829	830	Isovaleric acid	tr	tr	tr
840	840	2-Methylbutanoic acid	tr	tr	tr
848	846	(Z)-Salvene	tr	tr	-
850	850	Propyl isobutyrate	-	-	tr
850	850	(2E)-Hexenal	tr	tr	tr
880	878	3-Methyl-3-buten-1-yl acetate	tr	tr	tr
914	913	Isobutyl isobutyrate	tr	tr	tr
920	920	Prenyl acetate	tr	tr	tr
923	923	Tricyclene	-	tr	tr
926	927	α-Thujene	tr	tr	tr
933	932	α-Pinene	tr	0.1	0.1
949	953	Butyl isobutyrate	-	-	tr
949	950	Camphene	tr	0.1	tr
961	960	Benzaldehyde	tr	tr	tr
972	972	Sabinene	0.1	0.2	tr
978	978	β-Pinene	tr	0.1	tr
989	989	Myrcene	-	tr	tr
990	990	Dehydro-1,8-cineole	tr	0.1	tr
1017	1018	α-Terpinene	tr	tr	tr
1022	1022	Ethyl 3-methylbut-3-enyl carbonate	tr	tr	tr
1025	1025	p-Cymene	tr	tr	tr
1029	1030	Limonene	tr	tr	tr
1031	1031	2-sec-Butylthiazole	tr	-	tr
1032	1032	1,8-Cineole	2.1	3.2	1.9
1043	1043	Phenylacetaldehyde	0.1	tr	tr
1052	1055	Prenyl isobutyrate	-	tr	tr
1058	1058	γ-Terpinene	tr	0.1	tr
1070	1069	cis-Sabinene hydrate	tr	tr	tr
1085	1086	Terpinolene	tr	tr	tr
1105	1104	Nonanal	tr	-	tr
1107	1105	α-Thujone	2.9	4.4	0.1
1111	1112	cis-Rose oxide	tr	0.1	0.1
1111	1113	Phenethyl alcohol	tr	-	-
1118	1118	β-Thujone	0.3	0.4	-
1119	1118	Dehydrosabina ketone	tr	tr	-
1126	1127	trans-Rose oxide	tr	tr	0.1
1127	1123	Grandisol	tr	tr	0.1
1137	1138	Benzeneacetonitrile	tr	tr	tr
1138	1140	3-Methylbutenyl 2-methylbutyrate	-	tr	-
1138	1139	Nopinone	tr	-	-
1140	1140	trans-Sabinol	tr	0.1	-
1141	1141	trans-Pinocarveol	tr	0.1	-
1147	1145	Camphor	-	0.3	tr
1151	1152	Nerol oxide	tr	-	-
1162	1164	Pinocarvone	tr	tr	tr
1170	1170	δ-Terpineol	tr	tr	tr
1172	1173	Borneol	-	0.2	-
1180	1180	Terpinen-4-ol	0.1	0.2	0.1
1194	1199	3,9-Epoxy-p-mentha-1,8(10)-diene	tr	-	-
1195	1195	α-Terpineol	-	0.1	tr
1220	1212	Fragranol	64.3	55.8	70.0
1284	1285	Bornyl acetate	-	0.2	tr
1288	1286	trans-Sabinyl acetate	tr	0.1	-
1320	1325	Dihydrocarvyl acetate	tr	0.1	tr
1346	1345	Fragranyl acetate	26.7	30.0	24.1
1354	1361	Neryl acetate	0.1	0.2	0.1
1380	1375	α-Copaene	0.1	tr	0.1
1388	1391	β-Bourbonene	-	-	tr
1423	1424	(E)-β-Caryophyllene	0.3	0.1	tr
1441	1441	Fragranyl propionate	0.3	1.0	0.4
1445	1448	Neryl propionate	-	tr	tr
1481	1482	γ-Curcumene	0.1	0.1	0.1
1484	1484	Fragranyl isobutyrate	0.2	0.2	0.4
1484	1480	Germacrene D	0.2	0.2	0.2
1499	1497	Bicyclogermacrene	tr	0.1	0.1
1499	1497	α-Selinene	-	-	tr
1507	1507	Geranyl isobutyrate	-	0.1	0.1
1521	1518	δ-Cadinene	tr	0.1	tr
1574	1575	Fragranyl 2-methylbutyrate	0.2	0.3	0.1
1578	---	Fragranyl isovaleratea	tr	0.1	tr
1580	1576	Spathulenol	0.1	0.1	0.1
1584	1587	Caryophyllene oxide	0.1	tr	tr
1628	1632	Muurola-4,10(14)-dien-1β-ol	0.1	0.1	-
1658	1655	α-Cadinol	tr	tr	tr
1951	1960	(E)-Tibetin spiroether	tr	-	-
		Compound classes
		Monoterpene hydrocarbons	0.1	0.6	0.1
		Oxygenated monoterpenoids	97.1	97.2	97.5
		Sesquiterpene hydrocarbons	0.6	0.5	0.4
		Oxygenated sesquiterpenoids	0.2	0.1	0.1
		Benzenoid aromatics	0.1	0.0	0.0
		Aliphatic esters	tr	tr	tr
		Others	tr	tr	tr
		Total identified	98.2	98.4	98.0

RIcalc = Experimentally determined retention index using the arithmetic formula of van den Dool and Kratz [17].

RIdb = Reference retention index from the databases [18–22]. tr = trace (< 0.05%).

a A reference RI for fragranyl isovalerate was not available, but by homology with fragranyl isobutyrate, it should be around 1580.

Fragranol, (1S,2S)-1-(2-hydroxyethyl)-2-isopropenyl-1-methylcyclobutane, was first isolated from Artemisia fragrans Willd. [41]. The compound has also been found in the essential oils of other members of the Asteraceae, including Achillea nobilis subsp. neilreichii (A. Kern.) Velen. [42], Achillea lingulata Waldst. & Kit. (syn. Aspilia cachimboensis H. Rob.) [43], Achillea wilhelmsii K. Koch (syn. Achillea santolinoides subsp. wilhelmsii (K. Koch) Greuter) [44], Pentzia incana (Thunb.) Kuntze [45], Artemisia pontica L. [46], and Artemisia cana Pursh [47], in addition to Artemisia tridentata subsp. vaseyana [9]. Fragranol is also the sex pheromone of the papaya mealybug, Paracoccus marginatus Williams & Granara de Willink [48]. The epimer of fragranol, grandisol, (1R,2S)-1-(2-hydroxyethyl)-2-isopropenyl-1-methylcyclobutane, is the sex pheromone of the boll weevil, Anthonomus grandis Boheman [49] and the aggregation pheromone of the deodar weevil, Pissodes nemorensis Germar [50]. Grandisol has also been reported in the essential oils of Artemisia chamaemelifolia Vill. [51] and A. tridentata subsp. vaseyana [9].

The presence of both fragranol and grandisol in A. tridentata subsp. vaseyana from the Sawtooth Valley of Idaho (this study) indicates a qualitative similarity to several accessions of A. tridentata subsp. vaseyana from the Bighorn Mountains, Wyoming [9]. However, there are major quantitative differences between the two. Grandisol was only detected in small amounts in the present study, while some accessions from Wyoming showed high concentrations (8.8-36.2%), while other accessions showed none. Conversely, fragranyl esters were abundant in the Idaho samples, but were not detected in the samples from Wyoming. Interestingly, Zheljazkov and co-workers [9] observed profound differences in grandisol and fragranol concentrations in A. tridentata subsp. vaseyana, which were collected from different locations in the Bighorn Mountains of Wyoming, as well as in different months of the year. Likewise, there were substantial differences in the essential oil compositions of two sites in the Boise National Forest, Idaho [10]. The essential oil from one site was dominated by 1,8-cineole and α-thujone, whereas that from the other site was rich in artemiseole and camphor. Neither fragranol nor fragranyl acetate was detected in these essential oils. These differences, coupled with the differences observed in the Sawtooth Valley, Idaho, collection, suggest that the phytochemical composition of this plant species and subspecies might be affected by geographical location and seasonality, resulting in different chemotypes [52]. Other factors that may contribute to the ecological plasticity include herbivory [53], co-dominant plant associations, soil texture [54, 55], and disturbance (e.g., fire, grazing) [56, 57].

Multivariate analyses (HCA, and, PCA) were carried out in order to visualize the differences in volatile chemical profiles of A. tridentata subsp. vaseyana (Figs. 3 and 4). The HCA shows five groupings: (1) a camphor-rich group, (2) an α-pinene/trans-pinocarveol group, (3) an α-thujone type with only one sample, (4) an ethyl trans-chrysanthemumate/grandisol group, and (5) a fragranol/fragranyl acetate group (samples from this study). The PCA corroborated the HCA and indicated correlations between the individual samples and their major components (Fig 3).

Figure 3. Dendrogram based on hierarchical cluster analysis of chemical compositions of Artemisia tridentata subsp. vaseyana.

Zheljazkov [9], Swor [10].

Figure 4. Biplot based on principal component analysis of Artemisia tridentata subsp. vaseyana chemical compositions.

Zheljazkov [9], Swor [10].

3.2. Chemical Composition of Artemisia cana subsp. viscidula

Hydrodistillation of the fresh/frozen aerial parts of A. cana subsp. viscidula yielded pale-yellow to yellow essential oils with yields of 3.81-4.67% (w/w). Gas chromatographic analysis led to identification of a total of 56 components in the essential oils, which accounted for only 67.4-79.1% of the total composition. Five unidentified components had concentrations greater than 1% (Table 3).

Table 3. Essential oil compositions (percent of total composition) of Artemisia cana subsp. viscidula from Sawtooth Valley, Idaho.

RIcalc	RIdb	Compounds	Area %
			#1	#2	#3	#4
756	740	3-Methyl-3-buten-1-ol	tr	tr	0.1	tr
803	802	Hexanal	tr	tr	tr	0.1
850	850	(2E)-Hexenal	tr	tr	tr	0.1
879	878	3-Methyl-3-buten-1-ol acetate	0.1	0.1	0.2	0.1
932	932	α-Pinene	0.4	0.4	0.9	0.6
990	992	(3E)-2,6-Dimethyl-3,5-heptadien-2-ol	0.2	0.2	0.3	0.5
994	994	Yomogi alcohol	0.8	0.5	0.7	0.3
1021	1022	Ethyl 3-methylbut-3-enyl carbonate	0.1	-	0.1	tr
1031	1032	1,8-Cineole	0.8	0.6	1.5	0.9
1037	---	(2E,4E)-Hexadienyl acetate	0.2	0.1	0.2	0.1
1057	1057	γ-Terpinene	tr	tr	tr	0.1
1078	1079	Artemisia alcohol	0.1	tr	0.1	tr
1100	1098	Perillene	0.5	0.7	0.7	1.0
1105	1104	Nonanal	-	-	-	0.1
1139	---	cis-Chrysanthemal	4.3	5.8	6.1	1.8
1153	1153	trans-Chrysanthemal	0.3	0.4	0.4	0.1
1157	1155	trans-Chrysenthemol	4.6	1.6	2.3	0.5
1162	1164	Pinocarvone	0.1	0.1	0.3	0.4
1164	1165	Lavandulol	0.1	-	0.1	-
1180	1180	Terpinen-4-ol	0.3	0.2	0.5	0.5
1195	1195	α-Terpineol	0.1	-	0.2	-
1212	---	Unidentifieda	4.8	12.1	11.0	11.4
1228	---	Unidentifiedb	1.3	1.2	0.9	1.3
1278	1280	Ethyl trans-chrysanthemumate	26.3	15.3	17.6	7.8
1284	1284	Lavandulyl acetate	0.9	0.6	0.6	0.2
1290	1289	trans-Verbenyl acetate	0.5	0.5	0.5	0.6
1303	---	Unidentifiedc	2.9	3.5	3.1	5.3
1375	1375	α-Copaene	0.1	0.3	0.1	0.3
1382	1382	β-Bourbonene	-	tr	-	0.1
1398	1396	(2E)-1,3,7-Trimethyl-2,6-octadienyl acetated	37.0	37.7	33.7	38.2
1412	---	Unidentifiede	1.8	1.9	1.7	1.9
1417	---	Unidentifiedf	7.6	8.7	6.1	8.5
1432	1432	trans-α-Bergamotene	0.1	0.1	0.1	0.3
1439	1439	(Z)-β-Farnesene	-	-	tr	0.1
1452	1452	(E)-β-Farnesene	-	tr	0.1	0.2
1477	1482	γ-Curcumene	0.5	0.7	0.8	2.8
1479	1480	Germacrene D	0.3	0.9	1.4	2.6
1482	1483	trans-β-Bergamotene	-	-	-	0.3
1494	1497	Bicyclogermacrene	tr	0.1	0.1	0.2
1497	1500	trans-Chrysanthemyl 2-methylbutanoate	tr	0.1	0.2	0.3
1508	1509	β-Curcumene	-	-	-	0.1
1516	1518	δ-Cadinene	tr	0.2	0.1	0.3
1540	1541	α-Calacorene	-	0.1	tr	0.1
1559	1560	(E)-Nerolidol	-	-	-	0.1
1575	1576	Spathulenol	tr	0.1	0.1	0.2
1581	1587	Caryophyllene oxide	tr	0.1	0.1	0.1
1622	1623	Humulane-1,6-dien-3-ol	tr	0.2	0.1	0.3
1625	1624	Muurola-4,10(14)-dien-1β-ol	-	0.3	0.1	0.4
1627	1631	1-epi-Cubenol	tr	0.1	tr	tr
1639	1642	Methyl (Z)-jasmonate	0.2	0.1	0.3	-
1643	1644	τ-Muurolol	-	0.1	0.1	0.1
1650	1651	α-Muurolol	-	-	-	0.2
1655	1655	α-Cadinol	-	0.1	0.1	0.2
1670	1671	β-Bisabolol	-	-	-	0.2
1670	1669	Methyl epi-(Z)-jasmonate	0.1	-	0.1	-
1683	1686	epi-α-Bisabolol	-	-	-	0.1
1917	1925	(Z)-Tibetin spiroether	-	-	0.2	0.3
1950	1960	(E)-Tibetin spiroether	0.2	0.6	2.9	3.6
2300	2300	Tricosane	tr	tr	tr	tr
2500	2500	Pentacosane	tr	tr	tr	0.1
2700	2700	Heptacosane	tr	tr	tr	0.1
		Compound classes
		Monoterpene hydrocarbons	0.4	0.4	0.9	0.7
		Oxygenated monoterpenoids	39.7	26.5	31.8	14.5
		Sesquiterpene hydrocarbons	1.0	2.3	2.7	7.3
		Oxygenated sesquiterpenoids	tr	0.9	0.6	1.8
		Others	38.0	39.0	38.1	43.2
		Total identified	79.1	69.1	74.0	67.4

RIcalc = Retention index calculated with respect to a homologous series of n-alkanes on a ZB-5ms column.

RIdb = Reference retention index from the databases. tr = trace (< 0.05%).

a MS(EI): 137(29%), 123(8%), 97(46%), 69(77%), 43(34%), 41(100%).

b MS(EI): 110(27%), 97(18%), 95(34%), 81(13%), 67(16%), 55(11%), 43(100%), 41(24%).

c MS(EI): 137(100%), 123(12%), 109(13%), 95(20%), 81(22%), 79(14%), 69(33%), 67(31%), 55(22%), 43(81%), 41(67%).

d Tentatively identified based on MS and RI.

e MS(EI): 150(4%), 135(6%), 122(14%), 107(39%), 69(100%), 43(69%), 41(56%).

f MS(EI): 154(2%), 137(5%), 94(70%), 79(100%), 59(64%), 43(65%), 41(12%).

The major components in the essential oils of A. cana subsp. viscidula were cis-chrysanthemal 1.8-5.8%), trans-chrysanthemol (0.5-4.6%), ethyl trans-chrysanthemumate (7.8-26.3%), and (2E)-1,3,7-trimethyl-2,6-octadienyl acetate (33.7-38.2%), along with the major unidentified components RI 1212 (4.8-12.1%), RI 1303 (2.9-5.3%), and RI 1417 (6.1-8.5%). A representative chromatogram of A. cana subsp. viscidula is shown in Supplementary Fig. S2.

The chemical composition of A. cana subsp. viscidula is remarkably different from that of A. cana subsp. cana [9, 14, 15], which was dominated by camphene (as high as 11.3% [9]), 1,8-cineole (up to 30.5% [9]), and camphor (as much as 55.2% [15]). Multivariate analyses (HCA and PCA) illustrated the striking differences in the essential oil compositions between the two subspecies of A. cana. The major component in A. cana subsp. viscidula, (2E)-1,3,7-trimethyl-2,6-octadienyl acetate, was previously observed, albeit in small quantities, in Artemisia ludoviciana (4.4%) [31], A. tridentata subsp. tridentata (0.1%) [30], A. tridentata subsp. wyomingensis (0.2%) [10], and Achillea millefolium var. occidentalis (0.4%) [58]. Because (2E)-1,3,7-trimethyl-2,6-octadienyl acetate is rarely observed in essential oils and its identification was not confirmed using an authentic standard or an orthogonal technique, its identification is only tentative at this time (Figs. 5 and 6).

Figure 5. Dendrogram based on hierarchical cluster analysis of chemical compositions of Artemisia cana.

Lopes-Lutz #1 [15], Lopes-Lutz #2 [14], Zheljazkov [9].

Figure 6. Biplot based on principal component analysis of Artemisia cana subsp. viscidula and subsp. cana chemical compositions.

4.   Conclusions

This project has provided evidence for a new chemotype of A. tridentata subsp. vaseyana. Based on the results of this study, samples of A. tridentata subsp. vaseyana from the Sawtooth Valley of Idaho represent a fragranol/fragranyl acetate chemotype (63.4 ± 7.1% fragranol; 26.9 ± 3.0% fragranyl acetate), which is remarkably different from previously reported samples. The essential oil of A. cana subsp. viscidula from the Sawtooth Valley of central Idaho can be described as a chemotype dominated by (2E)-1,3,7-trimethyl-2,6-octadienyl acetate (36.7 ± 2.0%) and ethyl trans-chrysanthemumate (16.7 ± 7.6%), which is significantly different from the camphor / 1,8-cineole chemotype found for A. cana subsp. cana. The remarkable differences in the essential oil compositions of these samples compared to previously published essential oil compositions likely reflect the effects of geographical location and other abiotic and biotic factors. Additional research on these Artemisia species as well as other sagebrush species from other geographical locations in western North America is needed to fully appreciate the phytochemical diversity of members of this genus.

Disclaimer (artificial intelligence)

Authors hereby state that no generative AI tools such as Large Language Models (ChatGPT, Copilot, etc.) and text-to-image generators were utilized in the preparation or editing of this manuscript.

Supplementary materials

Figure S1. Chromatogram of A. tridentata subsp. Vaseyana.
Figure S2. Chromatogram of A. cana subsp. viscidula.
Supplementary material to this article can be found online at
https://currentsci.com/images/articlesFile/supplementary.1785418208.pdf

 

Authors’ contributions

Conceptualization, W.N.S.; methodology, P.S., W.N.S.; software, P.S.; validation, P.S., W.N.S.; formal analysis, A.P., P.S., W.N.S.; investigation, K.S., A.P., P.S., W.N.S.; resources, P.S., W.N.S.; data curation, W.N.S.; writing—original draft preparation, W.N.S.; writing—review and editing, K.S., A.P., P.S.; visualization, W.N.S.; supervision, P.S., W.N.S.; project administration, W.N.S.

Acknowledgements

This work was carried out as part of the activities of the Aromatic Plant Research Center (APRC, https://aromaticplant.org/).

Funding

This research received no specific grant from any funding agency.

Availability of data and materials

All data will be made available on request according to the journal policy.

Conflicts of interest

The authors declare no conflict of interest.

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