Borneol

The standard compounds used for the GC analysis were thymol, trans-anethol, (+)-borneol, (−)-borneol, α-terpineol, L-carvone, (R)-(+)-limonene, eucalyptol, farnesol, neryl acetate, (±)-citronellal, citral, γ-terpinene, nerol, α-pinene, p-cymene, (−)-trans-caryophyllene, geraniol, geranyl acetate, carvacrol, eugenol, sabinene hydrate, bornyl acetate, linalyl acetate, myrcene and (±)-camphor and were purchased from Sigma-Aldrich (St. Louis, MO, USA). In addition, 1,1-Diphenyl-2-picryl-hydrazyl-hydrate (DPPH∙) was obtained from Sigma-Aldrich GmbH (Germany). All chemicals and solvents were analytical reagent grade.

(-)-Menthol, (-)-borneol, S-(+)-3-octanol, S-(-)-2-methylbutanol-1, the 2nd generation Grubbs catalysts, dicyclopentadiene, 1,2,4-trichlorbenzene, maleic anhydride, Et₃N, SOCl₂, and cis-5-norbornene-endo-2,3-dicarboxylic anhydride (endo-NDA) were purchased from commercial suppliers (Sigma-Aldrich, ABCR GmbH, and TCI) and used as received unless otherwise noted. Methylene chloride and 1,2-dichloroethane were distilled over CaH₂ under argon atmosphere and stored over molecular sieves (4 Å). Toluene was distilled in argon atmosphere and stored over molecular sieves (4 Å). ((1R,2S,5R)-6,6-Dimethylbicyclo[3.1.1]heptan-2-yl)methanol (pinanol) was prepared according to the procedure described earlier [36 (link)].

For positive identification of the compounds in P. maliformis flowers, β-pinene, borneol, indole, terpin, raspberry ketone (4-(4-hydroxyphenyl)-2-butanone), cuelure (4-(4-acetoxyphenyl)-2-butanone), zingerone (4-(4-hydroxy-3-methoxyphenyl)-2-butanone), farnesol, palmitic acid, ethyl palmitate, phytol, linolenic acid, ethyl linoleate, ethyl linolenate, stearic acid, ethyl stearate, and squalene were purchased from Sigma-Aldrich (Merck KGaA, Darmstadt, Germany). Nonanoic acid was purchased from Acros Organics (Thermo Fisher Scientific, Geel, Belgium). Propyl laurate was purchased from AbovChem (AbovChem LLC, San Diego, CA, USA). Farnesyl acetate (a mixture of isomers) was purchased from TCI (Tokyo Chemical Industry Co., Ltd. Tokyo, Japan). Linoleic acid was purchased from Alfa-Aesar (Thermo Fisher Scientific, Lancashire, UK). The chemicals were analytical or reagent grade with 98% or higher purity and used without further purifications. Zingerol (4-(4-hydroxy-3-methoxyphenyl)-2-butanol) was synthesized by the reduction of zingerone with sodium borohydride in methanol (See Supplementary Materials for synthetic details).

Medical Borneol was obtained from Shanghai Hongqiao Traditional Chinese Medicine Co., Ltd. (+)‐Borneol (simply called Borneol in this study), (±)‐menthol (simply called menthol in this study), complete Freund's adjuvant, and capsaicin were purchased from Sigma‐Aldrich. Formalin was purchased from Xilong Chemical Co. AMTB, naloxone, and LY341495 were obtained from TOCRIS. Bicuculline was obtained from Tokyo Chemical Industry. Muscimol was obtained from Enzo Life Sciences. ATP disodium salt was obtained from Sangon Biotech. Ionomycin was purchased from Cayman Chemical. Morphine hydrochloride was obtained from Northeast Pharm.

Reference standards (+) -β-Pinene (≥98.5%), 1-Octen-3-ol, borneol (≥95%), butyric acid (≥99.5%), citral (≥95%), cis-3-hexen-1-ol (≥98%), diacetyl, dimethyl sulphide, dimethyl trisulphide (≥98.5%), 3-methylbutanal (≥97%), 2-methylbutanal (≥95%), ethyl 2-methylbutanoate (99%), ethyl 2-methylpentanoate (internal standard, ≥99%), ethyl-3-methylbutanoate (≥98%), 3-methylbutyl-2-methylpropanoate (≥98%), 2-methylbutyl-2-methylpropanoate (≥95%), and ethyl cinnamate (99%), ethyl 2-methylpropanoate (≥99%), ethyl 3-methylbutanoate (≥98%), ethyl 4-methylpentanoate (≥97%), ethyl butanoate (≥99,5%), ethyl hexanoate (≥99.5%), eugenol (99.6%), furaneol (≥99%), geraniol (≥99%), hexanol (≥99%), 3-methylbutyl acetate (≥97%), linalool (97%), menthol (99%), methyl nonanoate (≥99.8%), myrcene (≥90%), geranyl acetate (≥97%), dimethyl disulphide (≥90%), limonene (97%), hexanal (≥98%), 3-hexenol (≥95%), 2-phenyl ethanol (≥99%), β-caryophyllene (≥80%), α-humulene (≥96%), humulene oxide, S-methyl 5-methylpentanthioate S-methyl hexanthioate, S-methyl 4-methylpentanoate and theaspirane (≥90%) were purchased from Sigma Aldrich (St. Louis, MO, USA).

Stock solutions of phytochemicals were prepared as 10 mg ml^–1 concentration and stored at 4^oC for further use. Myrtenol, α-bisabolol, carvacrol, phytic acid and ethyl linoleate were procured from Sigma-Aldrich, India. Cineole, theophyline, borneol, oleic acid and α-pinene were procured from Alfa Aeser, India. MEthanol (Sigma-Aldrich, India) was used to dissolve Myrtenol, ethyl linoleate and theophyline. Ethanol (Sigma-Aldrich, India) was used to dissolve α-bisabolol, phytic acid, Cineole, theophyline, borneol, oleic acid and α-pinene.