Viridiflorol

Dimethyl sulfoxide (DMSO), N-formyl-Met-Leu-Phe (fMLF), phorbol 12-myristate 13-acetate (PMA), Trp-Lys-Tyr-Met-Val-Met (WKYMVM), Histopaque 1077, and viridiflorol were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). Germacrone and β-phellandrene were purchased from TargetMol (Boston, MA, USA). Curzerene was purchased from ChemNorm (Wuhan, China), and spathulenol was purchased from ChemFaces (Wuhan, China). n-Hexane was purchased from Merck (Darmstadt, Germany). Fluo-4AM was purchased from Invitrogen (Carlsbad, CA, USA), and FLIPR Calcium 5 was from Molecular Devices (Sunnyvale, CA, USA). Roswell Park Memorial Institute (RPMI) 1640 medium and Dulbecco’s Modified Eagle’s Medium (DMEM):F12 medium were purchased from HyClone Laboratories (Logan, UT, USA). Fetal calf serum and fetal bovine serum (FBS) were purchased from ATCC (Manassas, VA, USA). Hanks’ balanced salt solution was purchased from Life Technologies (Grand Island, NY, USA). HBSS without Ca²⁺ and Mg²⁺ is designated as HBSS^–; HBSS containing 1.3 mM CaCl₂ and 1.0 mM MgSO₄ is designated as HBSS⁺.

Tea tree oil was purchased from Essential Oil India—SAT Group, Kannauj, India. Solvents n-hexane and acetone of analytical grade were purchased from Sigma-Aldrich (St. Louis, MO, USA). Standards (α-pinene #80-56-8, sabinene #3387-41-5, camphene #79-92-5, β-pinene #127-91-3, myrcene #123-35-3, α-phellandrene #99-83-2, α-terpinene #99-86-5, p-cymene #99-87-6, limonene #5989-27-5, 1,8-cineole #470-82-6, γ-terpinene #99-85-4, terpinolene #586-62-9, (+)-terpinen-4-ol #2438-10-0, (-)-terpinen-4-ol #20126-75-5, (+)-α-terpineol #7785-53-7, (-)-α-terpineol #10482-56-1, β-caryophyllene #87-44-5, aromadendrene #489-39-4, α-humulene #6753-98-6, ledene #21747-46-6, globulol #489-41-8, and viridiflorol 552-02-3) were from Sigma-Aldrich (St. Louis, MO, USA) and α-copaene #3856-25-5 was purchased from Fluka Chemical Co., Buchs, SG, Switzerland.