Anti-inflammatory effect of alkaloids extracted from Dendrobium aphyllum on macrophage RAW 264.7 cells through NO production and reduced IL-1, IL-6, TNF-α and PGE2 expression

Dendrobium aphyllum is an edible plant that is used as a functional food to improve health. We previously examined peptides and polysaccharides extracted from Dendrobium aphyllum; however, we did not investigate D. aphyllum's alkaloid compounds and their functions. In this study, we detail the composition of alkaloids from Dendrobium aphyllum (DAA), including 2 alpha, 3 beta-dihydroxy nortropane, 1-methyl-2-[(4Z,7Z)-4,7-tridecadienyl]-4(1H)-quinolone and maokonine, which were first identified by UPLC-MS analysis. Furthermore, the anti-inflammatory activity of DAA on LPS-induced RAW 264.7 macrophages was examined. DAA treatment inhibited LPS-induced NO production and decreased (P < 0.05) IL-1, IL-6, TNF-alpha and PGE2 secretion in the RAW 264.7 macrophages. DAA treatment also inhibited COX-2 and iNOS mRNA expression in a dose-dependent manner, indicating that these compounds can attenuate the synthesis of the above-mentioned molecules at the transcriptional level, tentatively confirming their anti-inflammatory effect.