Cassiarins A and B, Novel Antiplasmodial Alkaloids from Cassia siamea

Abstract

Two novel alkaloids with an unprecedented tricyclic skeleton, cassiarins A (1) and B (2), have been isolated from the leaves of Cassia siamea, and the structures were elucidated on the basis of spectroscopic data. Cassiarin A (1) showed a potent antiplasmodial activity.

Investigation of Innovative Synthesis of Biologically Active Compounds on the Basis of Newly Developed Reactions

“…This synthetic strategy is applicable to the synthesis of other types of isoquinoline and indole alkaloids. 47) Annosqualine (71), isolated from the stems of Annona squamosa in 2004, 48) is a novel isoquinoline alkaloid with an unprecedented skeleton bearing a spirocyclohexadienone function. Although the structure of 71 was elucidated spectroscopically, its synthesis and its biological activity have not been reported yet.…”

“…3). 71) Due to the unique structural features and also the strong antiplasmodial activity of cassiarin A, we are interested in establishing a synthetic method for this alkaloid, which will hopefully be applicable to the synthesis of new potential antiplasmodial compounds. We envisaged that exploitation of sequential Sonogashira coupling for introducing alkyne groups to aromatic rings and subsequent 6-endo-dig cyclization of oxygen atoms to the resulting alkynes would be the most straightforward way to achieve the goal of constructing heteroaromatic skeletons.…”

New Tricyclic Alkaloids, Cassiarins G, H, J, and K from Leaves of Cassia siamea

“…(Leguminosae), has been widely used in traditional medicine, particularly for the treatment of periodic fever and malaria in Indonesia. 1,2) Cassiarin A, 3) an unprecedented tricyclic alkaloid exhibiting potent antimalarial activity against P. falciparum in vitro as well as P. berghei in vivo, 4) was isolated from the leaves of C. siamea and has attracted the attention of synthetic organic chemists [5][6][7] as well as pharmacologists. 8) Recently, we have also reported the synthesis of a series of a hydroxyl and a nitrogen-substituted derivatives of cassiarins A and B and their antimalarial activity against P. falciparum in vitro as well as a vasorelaxation activity.…”

Pseuduvarines A and B, Two New Cytotoxic Dioxoaporphine Alkaloids from Pseuduvaria rugosa

“…[1][2][3][4] Continuous research on phytochemical constituents of tropical plant Pseuduvaria rugosa led to the isolation of two new dioxoaporphine alkaloids, pseuduvarines A (1) and B (2). The genus Pseuduvaria belonging to the family Annonaceae has been known to contain particularly aporphine alkaloids with biological activities such as antituberculosis and cytotoxicity.…”