*3.1. Chemicals and Reagents*

Lipopolysaccharide (LPS from *Salmonella enterica* serotype Typhimurium), indomethacin, and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Dulbecco's Modified Eagle Medium (DMEM), 0.25% trypsin-EDTA solution, penicillin/streptomycin (P/S) solution, and fetal bovine serum (FBS) were purchased from Gibco (Grand Island, NY, USA). Dimethyl sulfoxide (DMSO) was purchased from Merck (Darmstadt, Germany). PGE2 ELISA assay kit was obtained from R&D Systems (Minneapolis, MN, USA). TNF-α ELISA assay kit (ab100747) and nitric oxide assay kit (ab65328) were purchased from Abcam (Waltham, MA, USA). The specific primers were obtained from Integrated DNA Technologies (Coralville, IA, USA). KAPA SYBR FAST One-step RT-qPCR kit was purchased from KAPA biosystems (Wilmington, MA, USA). RNeasy kit was obtained from Qiagen (Hilden, Germany).

#### *3.2. Plant Materials and Isolated Lignans*

The *M. sirikitiae* leaves were collected from Mae Surin Waterfall National Park, Mae Hong Sorn Province, Thailand (Latitude 18.94271; Longtitude 98.07122). A voucher specimen (BKF144972) of the plant has been deposited at the Forest Herbarium, Royal Forestry Department, Bangkok, Thailand. The methanol extract of *M. sirikitiae* leaves together with its lignans **1**–**6**, including (−)-epieudesmin (**1**), (−)-phylligenin (**2**), 2-(3,4-dimethoxyphenyl)- 6-(3,5-dimethoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane (**3**), magnone A (**4**), mitrephoran (**5**), 3 ,4-*O*-dimethylcedrusin (**6**) were prepared as described in our previous study [10]. Briefly, 1 kg of ground dried *M. sirikitiae* leaves was extracted by maceration with methanol. After the solvent was evaporated, 102.0 g of methanol leaf extract was obtained. Solvent– solvent partitioning of the methanol extract (90.0 g) resulted in four subfractions, including hexane (20.7 g), ethyl acetate (21.1 g), butanol (47.6 g), and aqueous (24.2 g) subfractions. Separation of the mixture of hexane and ethyl acetate subfractions by column chromatography using silica gel P60 40–63 μm (SiliaFlash®; Silicycle) and Sephadex™ LH-20 (GE Healthcare Life Sciences) as stationary phases afforded six isolated lignans, **1**–**6**. The colorless crystals of (−)-epieudesmin (**1**) (197.5 mg), (−)-phylligenin (**2**) (717.4 mg), magnone A (**4**) (24.0 mg), and mitrephoran (**5**) (12.4 mg) were obtained after recrystallization from mixed solvent of methylene chloride and methanol. Moreover, 2-(3,4-dimethoxyphenyl)-6-(3,5 dimethoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane (**3**) (9.6 mg) and 3 ,4-*O*-dimethylcedrusin (**6**) (141.2 mg) were isolated as pale-yellow semisolids. The chemical structures of the isolated lignans were elucidated by their spectroscopic and physical characteristic data (see Supplementary Materials).
