Limonene

All reagents and solvents were purchased from commercial sources and used as received without further purification. Melamine (C₃H₆N₆, 99%), potassium ferricyanide (K₃[Fe(CN)₆], AR), (1R)-(−)-10-CSA (99%), (1S)-(−)-10-CSA (99%), L-phenylalanine (99%), D-phenylalanine (98%), L(+)-glutamic acid (99%), D-glutamic acid (98%), L(−)-carvone (99%), S-(+)-carvone (97%), +CAM, 99% and TAD, 98% were purchased from Shanghai Macklin Biochemical Co. Ltd. (China). (+)-limonene (>95%), (−)-limonene (>95%) were purchased from Tokyo Chemical Industry (TCI) Co. Ltd (Japan). NDA, 98% was purchased from ARK Pharm, Inc., USA. Ethanol (AR, ≥99.7%), concentrated sulfuric acid (AR, 95–98%), sodium chloride (NaCl, AR) and magnesium chloride hexahydrate (MgCl₂·6H₂O, AR) were purchased from Sinopharm Chemical Reagent Co., Ltd. (China). Sucrose (AR), Rhodamine B (RhB, AR), methyl orange (MO, 96%), alizarin yellow R (AYR, AR), L-tryptophan (99%) and D-tryptophan (98%) were purchased from Aladdin Industrial Corporation (China). Fe(phen)₃Cl₂ was synthesized according to previous report ^{28 (link)}.

Miconazole, diflucan (fluconazole), and 5-fluorocytosine were purchased from Combi-Blocks Inc. (San Diego, CA, USA). Itraconazole and voriconazole were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). 2-(4-Thiazolyl) benzimidazole (thiabendazole, TBZ) was obtained from San-ai Oil Co., Ltd. (Tokyo, Japan). Amphotericin B and terpinen-4-ol were purchased from FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan), and α-pinene, camphene, 3-carene, limonene, γ-terpinene, 1,8-cineole, and p-cymene were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan).

All the essential oils were provided by Bio-Jourdeness International Groups Co. Ltd. (Taichung Taiwan). Citronellol, geraniol, neryl acetate, and limonene were obtained from Tokyo Chemical Industry Co., Ltd. (Tokya, Japan). Purity of these compounds were above 99%, according to the GC and ¹H-NMR analysis. McCoy’s medium, fetal bovine serum (FBS), sodium pyruvate, penicillin, and streptomycin were obtained from Invitrogen (Carlsbad, CA, USA). 3-(4,5-Dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and dimethylsulfoxide (DMSO) were purchased from Sigma-Aldrich. Antibody against ACE2 was obtained from Arigo Biolaboratories (Hsinchu, Taiwan). Antibody against GAPDH was obtained from Cell Signaling Technology Inc. All other chemicals were reagent grade or HPLC grade and were supplied by either Merck or Sigma-Aldrich.