John’s wort), Passiflora incarnate L. (maypop), Valeriana officinalis L. (Valerian) and Melissa officinalis L. (Lemon balm)) revealed that primary metabolites in the tricarboxylic acid (TCA) cycle as well as secondary metabolites belong to flavonoids and terpenoids positively correlated with BDNF (i.e., brain-derived neurotrophic factor; an important indicator of neurodegenerative diseases) expression level in vitro (Gonulalan et al., 2020). Here, BDNF is linked to neurodegenerative disease.