R₁-barrigenol—a tea sapogenin—suppresses the lipopolysaccharide-induced inflammatory response in microglial cells

Abstract

Certain natural components are effective against inflammation, a hallmark of neurodegenerative disease progression. Although green tea contains sapogenins, their effects on brain function remain unknown. Herein, we focused on R1-barrigenol (R1B)—a major tea sapogenin—and evaluated its anti-inflammatory effects on mouse microglia. R1B treatment decreased mRNA and protein expression levels of inflammatory cytokines in lipopolysaccharide (LPS)-treated mouse microglia compared with those in LPS-treated control microglia. R1B reduced the mRNA expression of M1-type microglia markers and phosphorylation levels of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor-alpha. These results suggest that R1B suppresses LPS-induced nuclear factor κ-light-chain-enhancer of activated B signaling, a regulator of M1-type polarization. Therefore, it is suggested that R1B may reduce inflammatory responses by suppressing M1 polarization-type changes, and that R1B may exhibit preventive and therapeutic effects against neurodegenerative diseases.