Wednesday, 29 June 2016

Re: Comparison of True and Spike (Spanish) Lavender Essential Oils from Spain

  • Lavender (Lavandula angustifolia, Lamiaceae)
  • Spike (Spanish) Lavender (Lavandula latifolia, Lamiaceae)
  • Aromatic Profiles/Bioactivity
Date: 06-15-2016HC# 111563-546

Carrasco A, Martinez-Gutierrez R, Tomas V, Tudela J. Lavandula angustifolia and Lavandula latifolia essential oils from Spain: aromatic profiles and bioactivities. Planta Med. 2016;82(1-2):163-170. doi: 10.1055/s-0035-1558095.

Lavender (Lavandula angustifolia, Lamiaceae) grows throughout the world and is widely used medicinally and for cosmetic and beauty products. Spike (Spanish) lavender (L. latifolia) also has medicinal and cosmetic uses. The essential oils of both of these plants may have varying antioxidant or anti-inflammatory properties. Studies investigating compounds in lavender and spike lavender essential oils and their bioactivity from plants grown in the Spanish Mediterranean Coast are lacking. This research study used gas chromatography and assays to determine the composition of essential oils and gauge their antioxidant and anti-inflammatory bioactivity.

Four samples each of the essential oils of lavender (Ang1-4) and spike lavender (Lat1-4), representing three climate zones, were officially identified, vouchered, and analyzed. Essential oils were produced using triple steam distillation and dried over anhydrous sodium sulphate resulting in a "strong smelling pale yellow oil" which was stored at −4°F until used. Essential oils were analyzed using fast gas chromatography-mass spectrometry; retention time, retention index, and mass spectra were used for identification by comparing against standards or spectral databases.

To measure antioxidant activity, several assays were used. The oxygen radical absorbance capacity (ORAC) assay works by measuring a compound's efficiency in reducing a peroxyl radical. The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assay reports the percentage of scavenging activity, and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay works by assessing the percentage of DPPH scavenged by the compound of interest. Data from all antioxidant assays were reported as equivalents of the vitamin E analog, Trolox. Chelating power (ChP) on ferrous ions, reducing power (RdP), and the lipoxygenase (LOX) inhibition activity also were measured. Compounds of the essential oils were analyzed according to their mM concentration and peak area.

Ang1 and Ang4, samples from the same climate zone, showed a 78.88% similarity; this was also seen from Lat1 and Lat3 (70.94% similarity), grown in the same climate zone. It is reported that samples from lavender and spike lavender had a 30.75% similarity, suggesting that essential oil composition may be unique to both region and species. While linalool, α-terpineol, and (E)-β-caryophyllene are prevalent in both lavender and spike lavender, lavender had greater amounts of linalyl acetate, eucalyptol (1,8-cineole), and camphor, which may have a bearing on aroma and bioactivity differences among the plants. The most common class of compounds was monoterpenes (85%), with alcohol as the most common functional group (40%).

The ORAC values for the essential oils measured significantly differed among samples, with the most potent being Ang3 (1.65 ± 0.07 µmol TE/µl essential oil) versus the least potent, Lat2 (1.10 ± 0.05 µmol TE/µl essential oil, P<0.05). Lesser ORAC values were found to correspond with increased monoterpene concentration. The ABTS activity also ranged from Lat2 (4.2 ± 0.1 µmol TE/µl essential oil; most potent) to Ang2 (0.6 ± 0.1 µmol TE/µl essential oil, P<0.05; least potent). DPPH activity also ranged from Ang2 (0.9 ± 0.04 µmol TE/µl essential oil) to Lat2 (0.22 ± 0.02 µmol TE/µl essential oil, P<0.05). The differential DPPH activity may be due to differences in (E)-β-ocimene or lavandulol compounds, among others. ChP values, expressed in mg of the common chelator ethylenediaminetetraacetic acid (EDTA) equivalents (EDTAE), ranged from the best chelator (Ang4, 2.6 ± 0.2 mg EDTAE/ml essential oil, P<0.05) to the worst (Ang1, 0.1 ± 0.0 mg EDTAE/ml essential oil); RdP, expressed in mg of ascorbic acid equivalents (AAE), ranged from Lat3 (7.5 ± 0.4 mg AAE/L essential oil) to Ang3 (2.7 ± 0.2 mg AAE/L essential oil, P<0.05). This activity may be due to the presence of terpene compounds. LOX inhibition ranged from 38.0 ± 0.4% (Lat4) to 23.6 ± 2.3% (Lat2).

In summary, this study suggests that bioactivity variability in samples from different climate zones may be explained by the different compound content. This has implications for the use of these essential oils for medicinal and economic purposes.

—Amy C. Keller, PhD