Authentication of Fennel, Star Anise, and Anise Essential Oils by Gas Chromatography (GC/MS) and Stable Isotope Ratio (GC/IRMS) Analyses.

The aromatic compound (E)-anethol is widely used in the flavor, fragrance, and medicinal industries. This compound is commonly produced through steam distillation of fennel, star anise, and anise seed. Given the cost of production, these natural and authentic essential oils are commonly adulterated with lower-cost natural materials or synthetic alternatives. The current study investigates essential oil profiles (gas chromatography/mass spectrometry) and stable isotope ratios (gas chromatography/isotope ratio mass spectrometry) of the abundant compound (E)-anethol in both authentic reference standards (n = 15) and commercially available samples (n = 30). This multifaceted analytical approach establishes techniques for ensuring the authenticity of essential oil sources of (E)-anethol and was then used to evaluate the current essential oil market sources of (E)-anethol. These findings report that adulteration of (E)-anethol-containing natural products takes various forms, and a multifaceted analytical approach is recommended for authentication. Of the commercial samples analyzed for this report, 27% were adulterated.

Essential Oil Composition and Enantioselective Profile of Agastache urticifolia (Lamiaceae) and Monardella odoratissima (Lamiaceae) from Utah.

Two species within the Lamiaceae (mint) family, Agastache urticifolia and Monardella odoratissima, are aromatic plants that are native to the Intermountain Region (USA). Essential oil produced through steam distillation was examined to establish the essential oil yield and both the achiral and chiral aromatic profiles of both plant species. The resulting essential oils were analyzed by GC/MS, GC/FID, and MRR (molecular rotational resonance). For A. urticifolia and M. odoratissima, achiral essential oil profiles were largely composed of limonene (71.0%, 27.7%), trans-ß-ocimene (3.6%, 6.9%), and pulegone (15.9%, 4.3%), respectively. Between the two species, eight chiral pairs were analyzed and, interestingly, the dominant enantiomer (calculated as ee%) of limonene and pulegone switched between the two species. Where enantiopure standards were not commercially available, MRR was used as a reliable analytical technique for chiral analysis. This study verifies the achiral profile for A. urticifolia and, for the first time to the authors' knowledge, establishes the achiral profile for M. odoratissima and chiral profile for both species. Additionally, this study confirms the utility and practicality of using MRR for determining chiral profiles in essential oils.

Essential Oil Composition and Stable Isotope Profile of Osmorhiza occidentalis Torr. (Apiaceae) from Utah.

Osmorhiza occidentalis Torr. is an essential-oil-bearing plant in the Apiaceae family. Volatile oil was produced through steam distillation (n = 3) of the above ground plant parts and was analyzed by gas chromatography (GC/FID, GC/MS), and gas chromatography/isotope ratio mass spectrometry (GC/IRMS) to establish the essential oil composition and stable isotope profile. The resulting essential oils were found to be comprised of 33 volatile compounds. Prominent volatile compounds include methyl chavicol (avg. 61.6%), (Z)-ß-ocimene (avg. 14.7%), sabinene (avg. 10.5%), and γ-terpinene (avg. 2.8%). Stable isotope values were determined for prominent volatile compounds, including methyl chavicol, (Z)-ß-ocimene, sabinene, and γ-terpinene. Values for δ2H range from -393.479 (avg. sabinene) to -171.516 (avg. methyl chavicol). Those for δ13C range from -35.957 (avg. methyl chavicol) to -30.820 (avg. (Z)-ß-ocimene). The essential oil yield was 0.12% (w/w). The current study establishes for the first time, to the best knowledge of the authors, the essential oil yield, essential oil composition, and stable isotope profile of prominent volatile compounds extracted from the above-ground portions of O. occidentalis. These results provide insight into the volatile chemical composition produced by the plant and provide fundamental data for substantiation of ethnobotanical applications.

Essential Oil Composition and Stable Isotope Profile of Cultivated Ocimum campechianum Mill. (Lamiaceae) from Peru.

Ocimum campechianum Mill. (Peruvian basil) is an essential oil-bearing plant of the Lamiaceae family. Volatile oil produced through steam distillation of Peruvian basil was examined to establish the aromatic and stable isotope profiles of samples (n = 9) from three different cultivated plots in Peru. The resulting essential oils were analyzed by GC/FID, GC/MS, and GC/IRMS. In accordance with findings from other researchers, multiple chemotypes, defined by the most abundant aromatic compounds, exist within these populations. Overall, 55% of samples are the eugenol chemotype (values ranging 15.4-30.2%), 33% are the methyl eugenol chemotype (values ranging 68.1-68.7%), and a single sample is a mixture of both chemotypes, containing high levels of both eugenol (38.1%) and methyl eugenol (8.6%). Stable isotope ratios, δ2H and δ13C, performed on prominent compounds provide supporting data for distinguishing chemotypes. Complete aromatic profiles, stable isotope ratios, and essential oil yield are established for each sample. This study confirms the existence of multiple chemotypes and, for the first time, to the author's best knowledge, establishes stable isotope ratios for O. campechianum essential oil, which proves a useful tool in further investigating plant metabolism and determining essential oil authenticity.

Essential Oil Profile and Yield of Corolla, Calyx, Leaf, and Whole Flowering Top of Cultivated Lavandula angustifolia Mill. (Lamiaceae) from Utah.

Lavandula angustifolia Mill. (lavender) is an essential-oil-bearing plant in the Lamiaceae family. Volatile oil produced through the steam distillation of lavender was examined to establish the essential oil yield and aromatic profile from each portion of the plant-namely, the corolla, calyx, leaf, and whole flowering top. The resulting essential oils were analyzed by GC-FID and GC-MS. The different plant parts generally shared similar compounds but in varying relative percentages. Aromatic profiles of the whole flowering top and calyx were similar, with prominent compounds being linalool acetate (34.3%, 32.0%), linalool (26.5%, 32.9%), lavandulyl acetate (5.6%, 4.9%), terpinen-4-ol (5.3%, 7.0%), and (Z)-ß-ocimene (4.5%, 5.4%), respectively. Aromatic profiles for the corolla and leaf were unique. Prominent aromatic compounds of the corolla included linalool acetate (18.4%), linalool (10.8%), epi-α-cadinol (10.0%), borneol (7.3%), and lavandulyl acetate (6.3%). Prominent aromatic compounds of the leaf included epi-α-cadinol (19.8%), γ-cadinene (11.0%), borneol (6.0%), caryophyllene oxide (4.9%), and bornyl acetate (4.8%). Complete profiles and essential oil yields of corolla, calyx, leaf, and whole flowering top were established. This study establishes the influence the corolla, calyx, and leaf exert on the aromatic profile of the whole flowering top and provides insight into authentication of lavender essential oil.