Lavandula angustifolia inflorescences (Fig. 1a) material was collected from agricultural planation near the town of Pomorie, Black Sea coast, Bulgaria (Fig. 1b) in third decade of June 2022. The plantation owner stated it was ‘Sevtopolis’ variety. Molecular markers test was not performed to confirm this. Steam extraction of the essential oil was performed using Clevenger apparatus for 4 h. GS/MS analysis of the composition of the essential oil was performed. Gas chromatography-mass spectroscopy (GC/MS) analysis was conducted according to European Pharmacopoeia (10^th edn.). The GC-MS analysis of diluted (1:1000) L. angustifolia essential oils was performed on Exactive Orbitrap GC-MS system (ThermoFisher Scientific) operating at 70 eV, ion source temperature 230 °C, interface temperature 280 °C with split injection (1 μL, ratio 20:1) at 270 °C injector temperature. A fused silica capillary column, 5% phenyl/95% methyl polysiloxane (TG5SILMS 30 m × 0.25 mm × 0.25 μm, Thermo) was used.

Figure 1. 

a. Agricultural planation – Lavandula angustifolia inflorescences; b. planation location.

We accessed the Scholar Google, Web of Science, and PubMed to identify publications for the period 1900–2023 with the search string: “Lavandula angustifolia + essential oil”, “linalool”, “linalyl acetate”, “Bulgaria”, “pharmacological effect/s”, etc. We selected 4 publications (Schmidt 2003; Prusinowska and Śmigielski 2014; Konaktchiev 2015; Zagorcheva et al. 2016) with totally 13 samples (Suppl. material 1) in which presented the full components’ lists in result of GC or GC-MS analyses of lavender (L. angustifolia) essential oil obtained by hydrodistillation form various varieties, under different cultivation regimes and extraction protocols (e.g. 40 min to 4 hours). We checked for synonyms in the compound names and eliminated the duplications (compounds were alphabetically sorted). Also, the records of isomers and coeluates were combined and generalized.

Linalool and linalyl acetate of the sample from Pomorie, which we characterized were compared to data set from the published research We used the data of linalool and linalyl acetate content from SE Bulgaria for a period of 5 years (Stanev and Angelova 2022). Average, Minimum and Maximum percent of the main components were calculated for Bulgarian samples and compared to the standards.

The yield of the lavender from Pomorie was 1.15 ml/100 g. We identified 44 components (Fig. 2, Table 1) with major constituents: linalyl acetate (27.52%), linalool (24.11%), E-β-ocimene (7.01%), terpinen-4-ol (5.11%), caryophyllene (4.46%), carvacrol (4.42%), lavandulyl acetate (3.52%), Z-β-farnesene (3.33%), Z-β-ocimene (3.15%).

Figure 2. 

GS/MS analysis of the composition of L. angustifolia essential oil – Origin Pomorie.

Linalool and linalyl acetate are the main ingredients based on which is evaluated the quality of the lavender essential oil. Our sample contained 26.84% linalool and 30.64% linalyl acetate (Table 1). We compared the contents of these two components to several samples from the 7 varieties from different origin and during different years (Fig. 3).

Figure 3. 

Linalool and linalyl acetate in our sample from Pomorie (Sevtopolis-BG-29) and ‘Sevtopolis’, ‘Hemus’, ‘Druzhba’, ‘Raya’, ‘Karlovo’, ‘Hebar’, and ‘Jubileina’, from different origin and during different years.

The content of linalool and linalyl acetate vary as between varieties so within the years and the locations of origin in Bulgaria. As is shown in previous research ‘Hemus’ and ‘Hebar’ varieties are characterized by a more stable ratio of linalool – linalyl acetate, compared to ‘Karlovo’, ‘Drujba’, ‘Raya’ and ‘Sevtopolis’ and the most stable one is ‘Jubileina’ (Stanev and Angelova 2022). The results of our descriptive statistics confirm the previously reported findings for the lavender essential oil samples from Bulgaria from various origins (Fig. 3), which fits the standards of ISO and/or European Pharmacopoeia (10^th edn., Table 2).

The main other components of our sample as well as the other examined Bulgarian samples fit the standards according to the requirements of ISO (2002) and the of European Pharmacopoeia (10^th edn., Council of Europe 2020) with few exceptions (Table 2).

Namely linalool and linalyl acetate are the precious constituents of lavender essential oil that possess anti-inflammatory activity (Peana et al. 2002) and sedative effect (Woronuk et al. 2011).

Linalool is a monoterpene compound, which can be found in the essential oil of different aromatic plant species. Naturally occurring is its (–)-enantiomer, or (–)-linalool. Inhalation of linalool has been shown to impart positive psychopharmacological effects in humans (Woronuk et al. 2011). Linalool is the major pharmacologically active constituent involved in the anti-anxiety effect of lavender oil (Umezu et al. 2006). Linalool acts on the somatic sensory system with local anesthetic properties, since it blocks the action potential by acting on voltage-dependent Na+ channels (Leal-Cardoso et al. 2010). A study of Paena et al. (2003) show that (–)-linalool inhibits the inflammatory pain in mice, as determined by a significant reduction in acetic acid-induced abdominal constrictions, whereas higher dose is effective in the hot plate test, which is a model of supraspinal analgesia. Later Paena et al. (2006) explain possible mechanism of the antinociceptive effect as reduction of nitric oxide (NO) production/release, where cholinergic and glutamatergic systems are involved. In vitro studies of linalool show dose-dependent sedative effects at the central nervous system, including hypnotic, anticonvulsant and hypothermic properties. Re et al. (2000) report inhibitory effect of linalool on the acetylcholine (ACh) release and on the channel open time in the mouse neuromuscular junction. Camargo et al. (2016) suggest that linalool possesses antihypertensive potential. Their study show that linalool is able to reduce cardiac hypertrophy, decrease vascular reactivity to a vasoconstrictor agent phenylephrine and to increase pharmacological potency to the vasodilator agent sodium nitroprusside, which is an example of its synergetic properties (Camargo et al. 2016). Dias et al. (2017) analyze the antifungal activity of linalool against Candida species. The result show that the best antifungal activity of linalool is on Candida tropicalis (MIC = 500 mg/mL), followed by Candida albicans (MIC = 1.000 mg/mL), and Candida krusei (MIC = 2.000 mg/mL). Linalool can also be a potential antifungal agent against Microsporum canis and Microsporum gypseum (Silva et al. 2017). The influence of (R)-(–)-linalool on airborne microbes when vaporized with an air washer has been reported and the average reduction in germ count was above 40% (Sato et al. 2007). Linalool has high antioxidant properties that can be used in treating different diseases, including cancer (Jabir et al. 2018). Iwasaki et al. (2016) show that linalool induces apoptosis of human colon cancer cells via cancer-specific oxidative stress. In prostate cancer cells, linalool treatment result in the appearance of cell shrinkage and membrane blebbing, which are characteristic features of cell apoptosis (Sun et al. 2015). Repellent activity of linalool was evaluated by Müller et al. (2009). Linalool diffusers provided a 93% repellency rate indoors and a 58% repellency rate outdoors, which shows that linalool can be used as an alternative to toxic insecticides. (Müller et al. 2009). Linalool is rated as only a mild irritant to man and in vivo studies on mousse and rats, show low acute toxicity, orally and through the skin (Kamatou and Viljoen 2008).

Linalyl acetate is the acetate ester of linalool, and because of that, the two often occur in conjunction. The two compounds possess similar pharmacological activity. Linalyl acetate, as well as linalool play a major role in the anti-inflammatory activity displayed by the essential oils containing them. This statement is evaluated by reduction of the edema in Carrageenin-induced edema in rats (Peana et al. 2002). Moon et al. (2018) suggests that linalyl acetate would be beneficial to treatment of atopic and inflammatory diseases by reducing Thymic stromal lymphopoietin (Moon et al. 2018). A study by Seo et al. (2021) suggests that lavender oil and in particular, linalyl acetate may have preventive role in rheumatoid arthritis against muscle wasting in rats, which are chronically exposed to nicotine. Linalyl acetate prevents olmesartan-induced intestinal hypermotility mediated by interference of the sympathetic inhibitory pathway in hypertensive rats (Kwon et al. 2018). Also, linalyl acetate acts as a muscle relaxant on the vascular smooth muscle tissue in rabbits (Koto et al. 2006). Linalyl acetate can suppress the production of melanin and thus exhibits anti-hyperpigmentation properties (Peng et al. 2014). |It has anti-hypertensive properties that can prevent hypertension-related ischemic injury (Hsieh et al. 2018). Linalyl acetate can prevent the development of Type 2 diabetes mellitus by reducing insulin resistance and stress levels and by improving mitochondrial dysfunction in male rats exposed to high fat diet and chronic stress (Shin et al. 2020).

Although particular components have certain pharmacological effects the essential oil as a whole often possess higher efficiency due to the synergism of the components. There are many studies, confirming the synergistic effect of lavender essential oil in the antimicrobial therapy. The combination of lavender oil with piperacillin significantly alters the outer membrane permeabilization of Escherichia coli compared to a control (Yap et al. 2014). The combination of essential oil and conventional antibiotics could reduce the beta-lactam antibiotic resistance (Yap et al. 2013). The combination of gentamicin and linalool towards Methicillin-resistant Staphylococcus aureus shows a strong bactericidal action (Adaszyńska-Skwirzyńska et al. 2019). Lavender oil can be combined not only with antibiotics, but also with other essential oils. A synergistic action between lavender and tea tree essential oil results in enhanced antifungal activity (Cassella et al. 2002). The combination of Artemisia herba alba, Lavandula angustifolia and Rosmarinus officinalis essential oils showes synergism at very low concentrations compared to MICs (Moussii et al. 2020).