Cocktail of three isoquinoline alkaloids derived from Glaucium grandiflorum Boiss. & A. Huet subsp. refractum (Nábelek) Mory inhibits the production of LPS-induced ROS, pro-inflammatory cytokines, and mediators through the down-regulation of p38 MAPK in BV-2 cells

Abstract

Glaucium grandiflorum extracts have traditionally been used to treat brain-related disorders. G. grandiflorum extracts also exhibited inhibitory effects on cholinesterase enzymes, as well as antigenotoxic activity. However, no research has been done on the effect of G. grandiflorum alkaloid extracts on the anti-oxidative and anti-inflammatory mechanisms. In this study we aimed to evaluate the anti-oxidative and anti-inflammatory activities of the alkaloid extract obtained from G. grandiflorum as well as the mechanisms responsible for their neuroprotective effects in neuronal damage caused by LPS in BV2 cells. We used LC-MS/MS and 1H, 13C NMR analysis to determine the presence of major alkaloids (allocryptopine, tetrahydropalmatine, and tetrahydroberberine N-oxide (trans-cannadine-N-oxide) in the alkaloid extracts. We used flow cytometry to study the alkaloid extracts' effects on ROS production; we also employed qRT-PCR and Western Blot to analyze the effects of oxidative stress and inflammation-related genes and proteins. ROS production within the cell was inhibited by chloroform alkaloid extract (CAE). There occurred marked CAE-induced reductions in IL-1β, Cox-2, and iNOS mRNA expressions. We also observed marked reductions in IL-6 and TNF-α mRNA expressions with methanol alkaloid extract (MAE). CAE effectively suppressed IL-1β and iNOS protein levels, especially as in qRT-PCR studies, while MAE effectively reduced IL-6 and TNF-α protein levels. Additionally, MAE was found to be prominent in suppressing the levels of Cox-2 protein, unlike qRT-PCR studies. According to our study findings, oxidative stress brought about by inflammation was suppressed by alkaloid extracts from G. grandiflorum which can be attributed to their suppressor effects on the pro-inflammatory cytokines-mediators, and p38 MAPK. As a result, a drug active substance that suppresses oxidative stress and inflammation has been brought to the neuropharmacological field.