Tween 80

Curcumin (95% total Curcuminoid content) was purchased from Alfa Aesar (Haverhill, MA, USA). Kolliphor RH40, Tween 80, and Neusilin US2 were purchased from BASF (Ludwigshafen, Germany), Sigma-Aldrich (St. Louis, MO, USA), and FUJI (Osaka, Japan), respectively. Other chemicals were purchased from Sigma-Aldrich. Cells used in this study were purchased from the American Type Culture Collection (ATCC), including Madin-Darby canine kidney (MDCK) cells (ATCC, ATCCPTA-7909), human A549 cells (ATCC, CCL-185™), and human embryonic kidney (HEK293T) cells (ATCC, CRL-3216™). Madin-Darby canine kidney (MDCK), human embryonic kidney 293T, and human adenocarcinoma lung A549 cells were cultured in Dulbecco’s modified Eagle’s medium (DMEM, HyClone, Logan, UT, USA) supplemented with 5% or 10% fetal bovine serum (FBS), 0.1 mM non-essential amino acids, 1.0 mM sodium pyruvate, 0.22% sodium bicarbonate, and antibiotics (penicillin-streptomycin (Gibco BRL, Life Technologies Corp., Carlsbad, CA, USA) at 37 °C in a humidified atmosphere of 95% air and 5% CO₂. IAV strain PR8 (A/Puerto Rico/8/1934, H1N1) was used (kindly provided by Dr. Laurence Tiley, Department of Veterinary Medicine, University of Cambridge, UK) in this study. Virus stocks were propagated in MDCK cells, and the titer was measured by a standard plaque assay.

CAT3 (purity > 99%), PF403 (purity > 99%), and (+)-Deoxytylophorinine (CAT) (purity > 99%) were prepared at our institute (Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China), and the structures were confirmed by infrared, two-dimensional nuclear magnetic resonance, and Fourier transform mass spectrometry. OA and Lipoid S75 (soy lecithin with 68% phosphatidylcholine) were both purchased from Lipoid KG (Ludwigshafen, Germany). Poloxamer188 (Pluronic F68) and Tween 80 were received as gifts from BASF (Ludwigshafen, Germany). Compritol 888 ATO was received as a gift from Gattefosse (Saint-Priest Cedex, France). The solvents for high-performance liquid chromatography (HPLC) were obtained from Thermo Fisher Scientific (Waltham, MA, USA). All other chemicals used were of analytical grade.