Kanjang (Korean soy sauce) is a byproduct of the production of the Korean fermented
soybean. In the present study, seven indole alkaloid derivatives were isolated from
methanol extract of kanjang. Their structures were identified as 1-propyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic
acid (1), 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (2), 1-methyl-1,2,3,4-tetrahydro-β-carboline-1-carboxylic
acid (3), 3-indoleacetic acid (4), Nb-acetyltryptamine (5), 1-methyl-3,4-dihydro-β-carboline
(6), and flazine (7) by NMR and MS analyses. Preliminary screening for anti-neuroinflammatory
effects of isolated indole alkaloids in lipopolysaccharide (LPS)-stimulated BV2 cells
revealed that these compounds inhibited the production of nitric oxide and prostaglandin
E2. For the subsequent investigation of anti-neuroinflammatory action of these metabolites,
compounds 4 and 7 were selected, and the results revealed that these inhibitory effects
correlated with the suppressive effect of 4 and 7 on inducible nitric oxide synthase
and cyclooxygenase-2 expression in LPS-stimulated BV2 cells. In regards to the mechanism
of the anti-inflammatory effect, 4 and 7 significantly inhibited the nuclear factor-kappa
B pathway.