Cyclombandakamines A₁ and A₂, Oxygen-Bridged Naphthylisoquinoline Dimers from a Congolese Ancistrocladus Liana

Abstract

Cyclombandakamines A (1) and A (2), both with an unprecedented pyrane-cyclohexenone-dihydrofuran sequence and six stereocenters and two chiral axes, are the first oxygen-bridged dimeric naphthylisoquinoline alkaloids. They were isolated from the leaves of an as yet unidentified Congolese Ancistrocladus species. Their stereostructures were established by spectroscopic, chemical, and chiroptical methods in combination with DFT and TDDFT calculations. They apparently originate from a cascade of oxidative cyclization reactions of "open-chain" naphthylisoquinoline dimers and exhibit significant antiprotozoal activities.

Ancistrolikokines E–H and related 5,8′-coupled naphthylisoquinoline alkaloids from the Congolese lianaAncistrocladus likokowith antiausterity activities against PANC-1 human pancreatic cancer cells

“…4,5,34 West African and some of the Central African Ancistrocladus plants produce both, typical Dioncophyllaceae-and Ancistrocladaceae-type alkaloids, and all possible hybrid forms thereof, 4,5,11,19 while 'Ancistrocladaceae/Dioncophyllaceae hybrid-type' alkaloids are frequently found in Central African species together with Ancistrocladaceae-type compounds. 4,5,20,[22][23][24][25][26][27][28]35,36 Thus, in view of the structures of the alkaloids found so far in A. likoko, this liana is a typical Central African species. Besides the hybrid-type alkaloids presented above, and the two 3S-congured metabolites ancistrolikokine D (6) and ancistroealaine A (7) ( Fig.…”

Michellamines A6 and A7, and further mono- and dimeric naphthylisoquinoline alkaloids from a Congolese Ancistrocladus liana and their antiausterity activities against pancreatic cancer cells

“…6 The latter is known to produce a drastically different metabolic pattern, including dimers with unsymmetric, 6 0 ,1 00 -coupled central axes, 17 with additional oxygen bridges 18 and/or acetal linkages, 21 but so far no symmetric, 6 0 ,6 00 -coupled ones, not even in traces.…”

Antiprotozoal dimeric naphthylisoquinolines, mbandakamines B3 and B4, and related 5,8′-coupled monomeric alkaloids, ikelacongolines A–D, from a Congolese Ancistrocladus liana

“…[1][2][3] Comprehensive data about the natural diversity of the genus Ancistrocladus within the Congo region, however, are still lacking. 1,3 Recent eld trips in combination with phylogenetic and phytochemical investigations clearly suggested the presence of further, hitherto unrecognized taxa, [3][4][5][6][7][8][9][10][11] along with the four botanically acknowledged Ancistrocladus species, 1,2,12,13 A. congolensis J. Léonard, A. likoko J. Léonard, A. ealaensis J. Léonard, and A. ileboensis Heubl, Mudogo & G. Bringmann. The latter species was discovered in the Southern Congo Basin, and described for the rst time in 2010, 12 whereas the three other Congolese taxa were botanically acknowledged for the rst time in 1949.…”

“…It is all the more remarkable that phytochemical investigations on Central African Ancistrocladus plants have picked up speed only quite recently, during the past decade, [4][5][6][7][8][9][10][11][14][15][16][17][18][19][20][21] considering that intense isolation work on Asian as well as West and East African taxa had started much earlier, leading to the discovery of structurally unique mono-and dimeric naphthylisoquinoline alkaloids with promising antiparasitic and antiviral activities. [22][23][24][25][26][27] More recent phytochemical studies on Ancistrocladus lianas from the Congo region, including all of the four valid taxa [14][15][16][17][18][19][20][21] mentioned above, but also botanically as yet unidentied plants, [4][5][6][7][8][9][10][11] furnished a whole series of further novel-type naphthylisoquinoline alkaloids, among them N,Ccoupled compounds 9,10 and, in particular, dimeric representatives with complex molecular architectures. [4][5][6]…”