1 8 cineole

The following synthetic compounds were purchased: 1,8-cineole (extra pure, Merck, Darmstadt, Germany), linalool (pure, Fluka, Steinheim, Germany), borneol (pure, Fluka, Steinheim, Germany) and α-terpineol (pure, Extrasynthese, Genay, France).

The LEO used in the present experiments (IT BIO 007 D86K, lot number MGL01/18) was a kind gift of Azienda Agricola Podere dell’Arco (Viterbo, Lazio, Italy) as a steam distilled sample obtained from a cultivar of lavandin (Lavandula x intermedia “Grosso”). Linalyl acetate (CAS 115-95-7), terpinen-4-ol (CAS 562-74-3), linalool (CAS 78-70-6), and 1,8-cineole (CAS 470-82-6) were purchased from Merck KGaA (Darmstadt, Germany).

Dimethyl sulfoxide (DMSO), acetylcholinesterase (AChE) from Electrophorus electricus and butyrylcholinesterase (BChE) from equine serum, acetylthiocholine iodide (ATCI), butyrylthiocholine iodide (BTCI), 5,5′-dithiobis-2-nitrobenzoic acid (DTNB), galanthamine hydrobromide, and all the buffer components (TWEEN20, bovine serum albumin, Trizma base, Trizma HCl, MgCl₂·6H₂O), cyclohexane, nonane, petroleum ether, ethyl acetate, 1,8-cineole, linalool, linalyl acetate, 4-terpineol, and α-terpineol were purchased from Merck Life Science S.r.l. (Milan, Italy).
Six batches of Elettaria cardamomum (L.) Maton EO were obtained via steam distillation from botanically identified plant material (dried fruits, geographical origin Guatemala) and supplied by Erboristeria Magentina (Poirino, Torino, Italy). The hydrodistilled EO was obtained by submitting 100 g of dried fruits (same geographical origin) purchased from a local herbal shop to hydrodistillation for 4 h in Clevenger apparatus (a pic of the plant used to obtain the hydrodistilled EO is reported in the Supplementary Material Figure S2). The EO was collected and stored in the dark at +4 °C until use.

Fresh rhizomes of A. galanga were collected from the medicinal plant garden of Chiang Mai University, Chiang Mai, Thailand in February 2018 according to the WHO Guidelines on Good Agricultural and Collection Practices (GACP) for Medicinal Plants. The plant was identified by Wannaree Charoensup (a botanist, Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai, Thailand), and the voucher specimen (no. 009245) was deposited at the Herbarium of the Northern Research Center for Medicinal Plants, Faculty of Pharmacy, Chiang Mai University, Thailand.
Fetal bovine serum (FBS), penicillin, streptomycin, L-glutamine, and RPMI 1640 were purchased from GIBCO InvitrogenTM (Waltham, MA, USA). Lymphoprep and 4-allylphenyl acetate were purchased from Axis-Shield PoC AS (Oslo, Norway) and ABCR GmbH (Karlsruhe, Germany). Methyl eugenol, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and DMSO were purchased from Sigma-Aldrich (St Louis, MO, USA). 1,8-cineole, polyoxyethylene sorbitan monooleate (Tween 80), phosphate buffer solution (PBS), and dichloromethane were of analytical grade and were supplied by Merck Millipore (Darmstadt, Germany). Diazepam and [³H]muscimol (36.6 Ci/mmol) were obtained from Nycomed Danmark A/S (Hobro, Denmark) and Perkin Elmer (Boston, MA, USA).

The GC–MS analysis was carried out with an Agilent 6890N–5973N GC–MS system (Santa Clara, CA, USA) on a sample of M. aquatica EO prepared by dilution to 1:100 with n-hexane. The instrument was operating in the EI mode at 70 eV and using a HP-5MS (5% phenylmethylpolysiloxane, 30 m, 0.25 mm i.d., film thickness 0.1 µm) (J&W Scientific, Folsom, CA, USA) capillary column.
The chromatographic parameters and chromatogram analysis were the same as those reported by Nkuimi Wandjou et al. [27 (link)]. Briefly, the analytical standards of α-pinene, sabinene, β-pinene, myrcene, α-terpinene, p-cymene, limonene, 1,8-cineole, (Z)-β-ocimene, (E)-β-ocimene, γ-terpinene, terpinolene, terpinene-4-ol, α-terpineol, (E)-caryophyllene, and α-humulene were purchased from Merck (Milan, Italy) and used for peak assignments based on retention time and mass spectrum (MS). Moreover, the combination of the calculated linear retention index (RI) and MS was used to confirm the identity of the other compounds. Semi-quantitative values (peak area percentages) were obtained by peak normalization without using correction factors.

The chemical solutions, acids, solvents, media, media chemicals, reagents, α-guaiene, and β-caryophyllene for biochemical studies were purchased from Sigma-Aldrich Co., St. Louis, MO, USA. Pure compounds of gallic acid, γ-terpinene, estragole, linalool, β-farnesene, 1,8-cineole, eugenol, β-terpineol, β-bergamotene, and nerol were supplied by Merck Co., St. Louis, MO, USA. Germacrene D was supplied by Aobious Inc., 9 Blackburn Drive, Gloucester, MA 01930, USA. α-Eudesmol was provided by BioCrick BioTech, 88 Keyuan Road, Hi-Tech Zone, Chengdu, Sichuan 610042, China.