In vitro antiplasmodial and antioxidant activities of bisbenzylisoquinoline alkaloids from Alseodaphne corneri Kosterm

Objective:To study antiplasmodial and antioxidant activities of the isolation of alkaloids from the active dichloromcthanc extract of Alseodaphne corneri.Methods:Phytochemical studies of the crude extract led to the isolation of six alkaloids using recycle high performance liquid chromatography and preparative thin layer chromatography.The antiplasmodial activity of the isolated compounds was evaluated usingthe histidinc-rich protein II assay.The isolated alkaloids were also tested for their antioxidant activity using three different assays:DPPH.ferric reducing ability of plasma and metal chelating assays.Results:Malaria infection caused the formation of free radicals which subsequently led to oxidative stress and apoplosis.The antioxidant properties of the alkaloids under investigation revealed that in addition to the aniiplasmodial activity,the alkaloids could also prevent oxidative stress.(+)-laurotetanine and(+)-norstephasubine exhibited strong antiplamodial activities with IC_(50) values of 0.189 and 0.116 μM.respectively.Conclusions:Interestingly,the two most potent compounds that exhibit aniiplasmodial activity also exhibit good antioxidant activities.The crude dichloromcthanc extract and the isolated compounds exert substantial aniiplasmodial and antioxidative activities which in turn suppress oxidative stress and cause less damage to the host.

AN ARTIFACT BISBENZYLISOQUINOLINE ALKALOID FROM THE ROOT OF STEPHANIA TETRANDRA

A new artifact bisbenzylisoquinoline,2,2′-N,N-dichloromethyltetrandrine(1),has been ob- tained from the root of Stephania tetrandra and its structure has been advanced on the basis of spectroscopic and chemical evidence.

A new bisbenzylisoquinoline alkaloid from Plumulanelumbinis

One new bisbenzylisoquinoline alkaloid, neferine N-oxide （1）, along with three known compounds, neferine （2）, liensinine （3）, and isoliensinine （4）, were isolated from Plumulanelumbinis - the embryo of the seed of Nelumbonucifera. Their structures were elucidated by extensive spectroscopic analysis （MS, UV, IR, NMR）, and the absolute configurations were determined by experimental circulardichroism （CD） spectra. Compound 1 is a new naturally occurring bisbenzylisoquinoline alkaloid with an N-oxide functionality, and the CD spectrum of （1R, 1＇R） neferine is first reported. The antioxidant activities of compounds 1-4 were evaluated using the ORAC assay, which illustrated that all these compounds showed the different levels of oxygen radical absorbance capacity.

Circular dichroism of tail-to-tail bisbenzylisoquinoline and the absolute configuration of daurisoline isolated from Menispermum dauricum

Since two asymmetric centres are usually present in the bisbenzylisoquinolines,the circular dichroism is known to be an important method to elucidate their stereochemistry.We studied the relationships of the CD spectra with the stereochemistry of synthetic RR-(1),SS-(2),RS-daurisoline(3) and SR-daurisoline(4).By comparision of the CD spectrum of natural daurisoline(1)from Menis- permum dauricum(Menispermaceae)with those of synthetic enantiomers,the absolute configuration was established as RR-daurisoline(1).

(+)/(-)-Yanhusuosines A and B, two dimeric benzylisoquinoline-protoberberine alkaloid atropo-enantiomers featuring polycyclic skeletons from Corydalis yanhusuo

(+)/(-)-Yanhusuosines A(1) and B(2), two pairs of trace benzylisoquinoline-protoberberine atropoenantiomeric homodimers featuring an unprecedented 6/7/6/6/6/6 hexacyclic skeleton, were isolated from the tubers of Corydalis yanhusuo. The structures of(+)/(-)-1 and(+)/(-)-2 were elucidated using spectroscopic and quantum-chemical calculation approaches.(+)/(-)-Yanhusuosines A(1) and B(2)represent a new class of alkaloid dimers biogenetically constructed by a molecule of benzylisoquinoline with a unit of protoberberine via an intermolecular [4 + 3] cycloaddition. Their plausible biosynthetic pathways are discussed, and compound 2 exerted moderate inhibitory activity of NO formation in LPS induced RAW264.7 macrophages.