Tangeretin

Analytical grade standards (at least 95% purity) were used for quantification. 7-Methoxycoumarin, hesperidin, neohesperidin, scoparone were obtained from J&K Scientific Ltd. (Beijing, China). Bergamotine, bergapten, citropten, didymin, eriocitrin, hyperoside, isomangiferin, isoquercetin, isovitexin, limonin, luteolin-6-glucoside, mangiferin, narirutin, nobiletin, nomilin, orientin, rhoifolin, rutin, sinensetin, tangeretin, vicenin-1, vicenin-2 and vitexin were obtained from Wuhan ChemFaces Biochemical Co., Ltd. (Hubei, China). Chrysoeriol-7-glucoside, homoeriodictyol-7-glucoside, isorhamnetin, isorhamnetin-3-glucoside, isorhamnetin-3-neohesperidoside, isorhamnetin-3-rutinoside, isorhoifolin, isoscoparin, kaempferol-3-neohesperidoside, kaempferol-3-rutinoside, obacunone, prunin and quercetin-3-neohesperidoside were obtained from FineTech Industry Ltd. (Hubei, China).

Plant compounds skullcapflavone II (1), nobiletin (2), and tangeretin (3) were purchased from ChemFaces Biochemical Co., Wuhan, China. Baicalein (4) and wogonin (5) were obtained from Sigma Aldrich. Purities of the compounds were ≥98%. Chlorpromazine, verapamil, rifampicin, ethidium bromide, isoniazid, and phosphate-buffered saline (PBS) in tablets (0.01 M phosphate buffer, 0.0027 M KCl, 0.14 M NaCl and 0,05% Tween 80, pH = 7.4) were purchased from Sigma Aldrich (Poole, UK).
All compounds were dissolved either in dimethyl sulfoxide (DMSO) or in sterile deionized water.