Camphor

High purity essential oil components carvacrol, geraniol, eugenol, methyl eugenol, trans-cinnamaldehyde, citronellic acid, (±)-citronellal, α-pinene, linalool, R (+)-limonene, eucalyptol, (−)-terpinen-4-ol, and menthone were obtained from Sigma-Aldrich (St. Louis, MO), whereas thymol and (±)-camphor were obtained from Alfa Aesar (Hill, MA) (Table S1). These active constituents are found in various aromatic plants (Table S1). All fifteen essential oil components (Table S1) were selected based upon the previous toxicity literature on different urban and agricultural pests^{22 (link)–31 (link)}. The positive controls dichlorvos (≤100% purity) and bifenthrin (98% purity) were obtained from Sigma Aldrich and Chem Service Inc. (West Chester, PA), respectively. Analytical grade solvents such as acetone, ethanol and dimethyl sulfoxide (DMSO) were purchased from Fisher Scientific (Pittsburgh, PA). Buffer salts and other reagents used for preparation of HEPES (4-(2-hydroxyethyl)−1-piperazineethanesulfonic acid)-buffered physiological saline were purchased from Sigma-Aldrich, Fisher Scientific and Avantor Performance Materials, LLC (Center Valley, PA).

Absolute ethanol was purchased from Daejung (South Korea). Trolox (6-hydroxy-2,5,7,8-tetramethyl-chromane-2-carboxylic acid), DPPH (2,2′-diphenyl-1-hydrazyl), ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, and potassium persulfate were supplied by Sigma-Aldrich (USA). ß-Caryophyllene was purchased from Tokyo Chemical Industry (Japan). Camphor and endo-borneol were provided by Alfa Aesar (USA). Thiophene was the internal standard for EO analysis (Sigma, USA). All chemicals and reagents were of analytical grade.

N-formyl-Met-Leu-Phe (fMLF), Trp-Lys-Tyr-Val-Met (WKYMVM), and farnesene (mixture of isomers) were from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). (±)-Bornyl acetate was from Cayman Chemical Company (Ann Arbor, MI, USA). Xanthoxylin was from TargetMol (Boston, MA, USA). Piperitone (mixture of isomers), (+)-camphor, and 1,8-cineole were from TCI America (Portland, OR, USA), and (−)-camphor was from Alfa Aesar (Ward Hill, MA, USA). Fluo-4AM was from Invitrogen (Carlsbad, CA, USA). Fetal bovine serum was from ATCC (Manassas, VA, USA). Hanks’ balanced salt solution without Ca²⁺ and Mg²⁺ (HBSS^–) was from Life Technologies (Grand Island, NY, USA). We prepared HBSS⁺ by adding 1.3 mM CaCl₂ and 1.0 mM MgSO₄. Human interleukin-8 (IL-8) was purchased from Peprotech (Rocky Hill, NJ, USA).