60 research outputs found
Chemoselective labeling and site-specific mapping of 5-formylcytosine as a cellular nucleic acid modification
No full textAncistrolikokines E-H and related 5,8-coupled naphthylisoquinoline alkaloids from the Congolese liana with antiausterity activities against PANC-1 human pancreatic cancer cells
No full textA striking feature of the metabolite profile of (Ancistrocladaceae) is the exclusive production of 5,8-linked naphthylisoquinoline alkaloids varying in their OMe/OH substitution patterns and in the hydrogenation degree in their isoquinoline portions. Here we present nine new compounds of this coupling type isolated from the twigs of this remarkable Central African liana. Three of them, the ancistrolikokines E (9), E (10), and F (11), are the first 5,8-linked naphthyldihydroisoquinolines found in nature with -configuration at C-3. The fourth new metabolite, ancistrolikokine G (12), is so far the only representative of the 5,8-coupling type that belongs to the very rare group of alkaloids with a fully dehydrogenated isoquinoline portion. Moreover, five new -methylated naphthyltetrahydroisoquinolines, named ancistrolikokines A (13), A (14), C (5), H (15), and H (16) are presented, along with six known 5,8-linked alkaloids, previously identified in related African species, now found for the first time in . The structural elucidation was achieved by spectroscopic analysis (HRESIMS, 1D and 2D NMR) and by chemical (oxidative degradation) and chiroptical (electronic circular dichroism) methods. The new ancistrolikokines showed moderate to good preferential cytotoxic activities towards pancreatic PANC-1 cells in nutrient-deprived medium (NDM), without causing toxicity under normal, nutrient-rich conditions, with ancistrolikokine H (16) being the most potent compound
Gardenifolins A–H, Scalemic Neolignans from <i>Gardenia ternifolia</i>: Chiral Resolution, Configurational Assignment, and Cytotoxic Activities against the HeLa Cancer Cell Line
No full textCyclombandakamines A1 and A2, oxygen-bridged naphthylisoquinoline dimers from a congolese Ancistrocladus liana
No full textCyclombandakamines A1 (1) and A2 (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
Antiplasmodial ealapasamines A-C,'mixed' naphthylisoquinoline dimers from the Central African liana Ancistrocladus ealaensis
No full textThree unusual heterodimeric naphthylisoquinoline alkaloids, named ealapasamines A-C (1-3), were isolated from the leaves of the tropical plant Ancistrocladus ealaensis J. Léonard. These 'mixed', constitutionally unsymmetric dimers are the first stereochemically fully assigned cross-coupling products of a 5,8'- and a 7,8'-coupled naphthylisoquinoline linked via C-6' in both naphthalene portions. So far, only two other West and Central Ancistrocladus species were known to produce dimers with a central 6,6″-axis, yet, in contrast to the ealapasamines, usually consisting of two 5,8'-coupled monomers, like e.g., in michellamine B. The new dimers 1-3 contain six elements of chirality, four stereogenic centers and the two outer axes, while the central biaryl axis is configurationally unstable. The elucidation of the complete stereostructures of the ealapasamines was achieved by the interplay of spectroscopic methods including HRESIMS, 1D and 2D NMR (in particular ROESY measurements), in combination with chemical (oxidative degradation) and chiroptical (electronic circular dichroism) investigations. The ealapasamines A-C display high antiplasmodial activities with excellent half-maximum inhibition concentration values in the low nanomolar range
Antiprotozoal spirombandakamines A1 and A2, fused naphthylisoquinoline dimers from a congolese Ancistrocladus plant
No full textFrom the leaves of a yet undescribed Congolese Ancistrocladus species, two novel naphthylisoquinoline dimers, spirombandakamines A1 (1) and A2 (2), were isolated, together with a new, but "classical" dimer, mbandakamine B2 (3). The cage-like stereostructures of 1 and 2 were established by combining spectroscopic, chemical, and chiroptical methods with quantum-chemical ECD calculations. Their unique molecular frameworks may originate from "open-chain" dimers, such as 3, by an oxidation-induced cascade of reactions. They possess strong antiprotozoal properties
Michellamines A6 and A7, and further mono- and dimeric naphthylisoquinoline alkaloids from a Congolese Ancistrocladus liana and their antiausterity activities against pancreatic cancer cells
No full textMichellamines A6 (1) and A7 (2) are the first dimers of 5,8′-coupled naphthylisoquinoline alkaloids with cis-configured stereocenters in both tetrahydroisoquinoline subunits. They were isolated from the leaves of a recently discovered, yet unidentified Congolese Ancistrocladus liana that shares some morphological characteristics with Ancistrocladus likoko. Two further new dimeric analogs, michellamines B4 (3) and B5 (4), were obtained, along with two previously likewise unknown monomers, ancistrobonsolines A1 (5) and A2 (6), which, besides one single known other example, are the only naphthyldihydroisoquinolines with an M-configured biaryl axis and R-configuration at C-3. Moreover, five compounds earlier reported from other Ancistrocladus species were identified, ancistroealaine C (7), korupensamines A (8a) and B (8b), and michellamines A2 (9) and E (10). Their complete structural elucidation succeeded due to the fruitful interplay of spectroscopic, chemical, and chiroptical methods. Chemotaxonomically, the stereostructures of the metabolites clearly delineate this Congolese Ancistrocladus liana from all known related species, showing that it might be a new taxon. Ancistrobonsolines A1 (5) and A2 (6) exhibited strong preferential cytotoxicities against human PANC-1 pancreatic cancer cells under nutrient-deprived conditions, without displaying toxicity in normal, nutrient-rich medium. Against cervical HeLa cancer cells, the dimeric alkaloids michellamines A6 (1) and E (10) displayed the highest cytotoxic activities, comparable to that of the standard agent, 5-fluorouracil. Furthermore, ancistrobonsolines A1 (5) and A2 (6) showed weak-to-moderate antiprotozoal activities
Biochemical lesions of the nigrostriatal system by TaClo (1-trichloromethyl, 1,2,3,4,-tetrahydro-ß-carboline) and derivatives
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