Gallic acid

Acetonitrile (HPLC grade), 95% ethanol, 37% hydrochloric acid, sodium hydroxide, sulfuric acid, and dichloromethane were purchased from RCI Labscan, Bangkok, Thailand. Gallic acid, Folin–Ciocalteau phenol reagent, aluminum chloride, sodium acetate trihydrate, ferric chloride solution, ferrous sulfate heptahydrate, and potassium persulfate sodium carbonate were obtained from Loba Chemie, Mumbai, India. A549 (ATCC^® CCL-185TM) human lung adenocarcinoma cell line was purchased from the American Type Culture Collections (ATCC; Manassas, VA, USA). HaCaT cell line was purchased from Pacific Science, Co., Ltd. (Bangkok, Thailand). Dulbecco’s Modified Eagle Medium (DMEM), fetal bovine serum, 100 U/mL and 100 µg/mL streptomycin, and trypsin-EDTA were purchased from Invitrogen (Carlsbad, CA, USA). Dragendorff’s reagent, phosphotungstic acid, Gallic acid, DPPH (2,2-diphenyl-1-picrylhydrazyl), TPTZ (2,4,6-Tris(2-pyridyl)-s-triazine, ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), and sulforhodamine B (SRB) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Annexin V-FITC and PI solution were purchased from BD Biosciences, CA, USA). DCF-DA was purchased from Sigma Merck KGaA (Darmstadt, Germany).

The 1,1-diphenyl-2-picrylhydrazy (DPPH) assay’s scavenging activity was evaluated using the steps outlined in the previous study [28 (link)]. A total of 100 μL of 0.2 mM DPPH solution (Sigma-Aldrich, Darmstadt, Germany) dissolved in methanol (QRëC, Auckland, New Zealand) was mixed with 50 μL of the sample solution. The reaction was carried out in a 96-well microplate (SPL Lifesciences, Co., Ltd., Gyeonggi-Do, Republic of Korea) and incubated at room temperature for 30 min in the dark. The microplate reader, used to measure absorbance, was set to 517 nm. As positive controls, gallic acid and ascorbic acid (Loba Chemie Pvt. Ltd., Mumbai, India) were utilized. The amount of extract required to inhibit DPPH by 50%, or the IC₅₀ value (mg/mL), was used to express the scavenging activity.