Table 2.

The novel candidate agents under investigation for regulating the secretion of pulmonary mucus

Classification of novel candidate agents	Compounds
Novel compounds and/or repositioned drugs targeting for regulating the secretion of pulmonary mucus under investigation	11,12- epoxyeicosatrienoic acids (EET) (Lasker et al., 2000)
	FK224 and CP99994 (Bertrand and Geppetti, 1996; Advenier et al., 1997)
	Sildenafil (Wang et al., 2009)
	Niflumic acid (Nakanishi et al., 2001; Zhou et al., 2002; Hauber et al., 2005b, 2007b)
	Blockers of P2Y2 purinoceptor (Davis, 2002)
	Peptides related to myristoylated alanine-rich C kinase substrate (MARCKS) (Singer et al., 2004; Green et al., 2011)
	Blockers of retinoic acid receptor (RAR)-α (Koo et al., 1999; Aggarwal et al., 2006)
Natural products targeting for regulating the secretion of pulmonary mucus under investigation	4′,7-dihydroxyflavone (Zhou et al., 2015)
	Apigenin (Seo et al., 2014; Sikder et al., 2014b)
	Baicalein (Lee et al., 2003, 2004a, 2004b; Heo et al., 2007a)
	Baicalin (Heo et al., 2007a)
	Berberine (Sikder et al., 2011)
	Carbenoxolone (Heo et al., 2007b; Lee et al., 2011a)
	Chrysin (Shin et al., 2012)
	Coixol (Lee et al., 2015b)
	Curcumin (Heo et al., 2009)
	Daidzein (Lee et al., 2011c)
	Dioscin (Lee et al., 2015a)
	Ebeiedine (Kim et al., 2016)
	Genistein (Heo et al., 2009)
	Gingerol (Kim et al., 2009; Chang et al., 2010)
	Glyceryl trilinoleate (Lee et al., 2015b)
	Glycyrrhizin (Heo et al., 2007b; Nishimoto et al., 2010; Lee et al., 2011a)
	Hesperidin (Lee et al., 2003, 2004a, 2004b)
	Kaempferol (Kwon et al., 2009)
	Lobetyol (Yoon et al., 2014)
	Lobetyolin (Yoon et al., 2014)
	Lupenone (Yoon et al., 2015)
	Lupeol (Yoon et al., 2015)
	Luteolin (Lee et al., 2015c)
	Methyl linoleate (Yoon et al., 2014)
	Methylprotodioscin (Lee et al., 2015a)
	Morusin (Lee et al., 2014)
	Naringin (Nie et al., 2012)
	Obtusifolin (Choi et al., 2019)
	Oleanolic acid (Cho et al., 2011)
	Ophiopogonin D (Park et al., 2014)
	Platycodins (Shin et al., 2002; Choi et al., 2011; Ryu et al., 2014)
	Prunetin (Lee et al., 2011b; Ryu et al., 2013)
	Quercetin (Kwon et al., 2009; Yang et al., 2012)
	Resveratrol (Lee et al., 2012)
	Scutellarin (Jiang et al., 2011)
	Silibinin (Kim et al., 2012b)
	Spicatoside A (Park et al., 2014)
	Suchengbeisine (Kim et al., 2016)
	Taraxerol (Yoon et al., 2015)
	Tilianin (Song et al., 2017)
	Tussilagone (Choi et al., 2018)
	Ursolic acid (Cho et al., 2011)
	Verproside (Lee et al., 2015d)
	Verticine (Kim et al., 2016)
	Wogonin (Sikder et al., 2014a, 2014b)