Bioactive Isoquinoline Alkaloids with Diverse Skeletons from Fissistigma polyanthum

Abstract

Six new isoquinoline alkaloids, including aporphine alkaloids (2, 3, 9, and 10), a benzylisoquinoline alkaloid (13), and a protoberberine alkaloid (17), were isolated from the roots of Fissistigma polyanthum, along with a new furanone (20) and 13 known isoquinoline alkaloids (1, 4−8, 11, 12, 14−16, 18, and 19). The structures of the new compounds were elucidated by the analysis of spectroscopic data. Compounds 1 and 2 are rare oxalylfused dehydroaporphine alkaloids. Compound 12 presented the most potent dual-target activities on AChE inhibition and Aβ aggregation inhibition, while compounds 13 and 19 simultaneously exhibited discernible AChE and BChE inhibitions with antioxidant activities. The activity results indicate that F. polyanthum alkaloids have a potential of inhibition and prevention of Alzheimer's disease mainly through both ChEs and β-amyloid pathways in addition to antioxidant activity.

Isatin-based spiro indolenine alkaloids from Isatis indigotica Fortune with anti-neuroinflammatory and acetylcholinesterase inhibitory effects

“…The percentage of anti-AChE activity was calculated as follows:Anti-AChE activity (%) = (( E − S )/ E ) × 100%where E is the activity of the enzyme without test isolates and S is the activity of the enzyme with the test isolates. 42…”

Alkaloids from Fritillaria przewalskii Bulbs and Their Anti‐Alzheimer's Disease Activities

“…The inhibitions on AChE and BChE were assessed as described previously. [14] Thioflavin T (ThÀ T) assay…”

“…[13] Nevertheless, until now, there are no explorations about the constituents in F. przewalskii and its biological activities. As part of our continuous studies on bioactive compounds from plants for AD treatment, [14] ten alkaloids were obtained from F. przewalskii, comprising three previously unreported isosteroidal alkaloids (1-3) and seven known alkaloids (4-10) (Figure 1). Compounds 1 and 2 both exist in the original plant by TLC detection, and represent the rare cevanine-type alkaloid N-oxides.…”