Furoquinoline alkaloids from Teclea nobilis

Five new furoquinoline alkaloids, namely tecleabine (1), tecleoxine (2), isotecleoxine (3), methylnkolbisine (4) and chlorodesnkolbisine (5) were isolated from the aerial parts of Teclea nobilis, together with seven known furoquinoline derivatives; one acridone alkaloid, and one known flavanone. The structures of the alkaloids 1-5 were established by 1D and 2D NMR spectral data, including COSY, HMQC and HMBC experiments, as well as HRMS.     

Furoquinoline alkaloids from the southern African Rutaceae Teclea natalensis

The chloroform and ethyl acetate extracts of the leaves of Teclea natalensis have yielded two furoquinoline alkaloids, 6-[(2,3-epoxy-3-methylbutyl)oxy]-4,7-dimethoxyfuro[2,3-b]quinoline and 4,7-dimethoxy-6-[(3-methyl-2-butenyl)oxy]furo[2,3-b]quinoline, and the known alkaloids 4,7-dimethoxy-8-[(3-methyl-2-butenyl)oxy]furo[2,3-b]quinoline, flindersiamine and dictamnine.     

Alkaloids and limonoids from Bouchardatia neurococca: systematic significance

Five alkaloids, four beta-indoloquinazoline and one furoquinoline, and four terpenoids, three limonoids and one modified sesquiterpene, have been obtained from the aerial parts of Bouchardatia neurococca (Rutaceae). Two of the alkaloids, 1,2-dihydroxyrutaecarpine and 2-(2-[3-formylindolyl])-(3H)-quinazolin-4-one (bouchardatine), and two of the limonoids, 23-oxo-21xi-hydroxy-21,23-dihydroveprisone (veprisonic acid) and 21-oxo-23xi-hydroxy-21,23-dihydroveprisone (isoveprisonic acid) are new. The pattern of secondary metabolites isolated is rather unusual in the Rutaceae and is reminiscent of Tetradium, a genus with which Bouchardatia has not previously been associated.     

Mutagenic compounds in an extract from Rutae Herba (Ruta graveolens L.). II. UV-A mediated mutagenicity in the green alga Chlamydomonas reinhardtii by furoquinoline alkaloids and furocoumarins present in a commercial tincture from Rutae Herba

A commercial tincture prepared from Rutae Herba (Ruta graveolens L.) exhibited a moderate photomutagenicity in an arginine-requiring mutant strain of Chlamydomonas reinhardtii. In the tincture some furocoumarins, e.g., bergapten, psoralen, imperatorin, and 3 furoquinoline alkaloids (dictamnine, gamma-fagarine, skimmianine) were detected. All compounds revealed photomutagenic properties but their activities were quite different. Bergapten was the most potent furocoumarin. Dictamnine, the furoquinoline with the strongest effect, reached only about 10% of the activity of bergapten. Based on the amount of these compounds in the tincture and their activities we conclude that bergapten is mainly responsible for the photomutagenicity of the tincture. The lower phototoxicity and photomutagenicity of the furoquinoline alkaloids may be due to the fact that furoquinolines form only monoadducts with DNA in the presence of UV-A in contrast to furocoumarins which also form biadducts.     

Phytochemical and chemotaxonomic study on Dictamnus angustifolius G. Don ex Sweet (Rutaceae)

A phytochemical investigation of Dictamnus angustifolius led to the isolation of 14 compounds, including six furoquinoline alkaloids (1–6), two sesquiterpenoids (7, 8) and six flavonoids (9–14). The structures of these compounds were identified by spectroscopic methods and a comparison of their data with those reported in the literature. This is the first report of three furoquinoline alkaloids 1–3 and six flavonoids 9–14 from the genus Dictamnus and the first isolation of compounds 4–8 from D. angustifolius. The chemotaxonomic significance of furoquinoline alkaloids and sesquiterpenoids has also been summarized.     

New furanopyridine alkaloids from the leaves of Glycosmis pentaphylla

Three new furanopyridine alkaloids, namely glypenfurans A–C (1–3), were isolated from the leaves of Glycosmis pentaphylla together with six known furoquinoline alkaloids. Their structures were determined by extensive spectral analysis (UV, IR, MS, 1D and 2D NMR).     

Pyranocoumarins as chemotaxonomic markers in Eriostemon coccineus and Philotheca citrina

Examination of the aerial parts of Eriostemon coccineus and Philotheca citrina has shown both to contain the unusual pyranocoumarins avicennol, avicennin and cis-avicennol. Three minor coumarins isolated from P. citrina have been identified as avicennol methyl ether, cis-avicennol methyl ether and avicennol ethyl ether. Philotheca citrina also yielded another pyranocoumarin, dipetalolactone, and the common lignan sesamin. Eriostemon coccineus, in addition to coumarins, gave the furoquinoline alkaloids maculosidine and γ-fagarine and two dihydrocinnanic acid derivatives, eriostoic acid and a new compound with a substitution pattern comparable to cis-avicennin and which has been assigned the trivial name cis-avicennic acid. The co-occurrence of these rare pyranocoumarins supports the contention that Philotheca is closely allied to certain taxa currently placed in Eriostemon sect. Nigrostipulae.     

Methyl chanofruticosinate alkaloids from Kopsia arborea

Six alkaloids belonging to the methyl chanofruticosinate group, viz., prunifolines A-F, in addition to six other known methyl chanofruticosinate alkaloids, were isolated from the leaf extract of Kopsia arborea. The structures were determined using NMR and MS analysis and comparison with known related compounds.     

Alcaloïdes de Zanthoxylum tsihanimposa

From the bark of Zanthoxylum tsihanimposa (Rutaceae) 5 furoquinoline and benzophenanthridine alkaloids were isolated. Three are known compounds: γ-fagarine, skimmianine and dihydrochelerythrinylacetone. The other two, dihydrochelerythrinylacetaldehyde and O-methyldihydrochelerythrinyl-acetone, are probably artefacts.     

棕色扁海绵中的吡咯生物碱

从中国南海棕色扁海绵Phakellia fusca Schimidt的乙醇浸提物中,分离得到3个吡咯生物碱,结合理化性质,波谱分析,文献检索,确定其结构分别为4,5-二溴-1H-吡咯-2-甲酸甲酯(1)、4,5-二溴-3-氰-1H-吡咯-2-甲酸甲酯(2)、4,5-二溴-1H-吡咯-2-甲酰氨(3)。其中化合物(2)未见文献报道。     

Formation of edulinine and furoquinoline alkaloids from quinoline derivatives by cell suspension cultures of Ruta graveolens

The formation of furoquinoline alkaloids and of edulinine, elaborated by cell suspension cultures of Ruta graveolens, was found to occur by way of 4-hydroxy-2-quinolone. Other substrates transformed to furoquinolines included 4-hydroxy- and 4-methoxy-3-(3-methyl-2-butenyl)-2-quinolone, known earlier as natural precursors in studies with whole plants. Involvement of dictamnine as a natural precursor of 8-methoxydictamnine (γ-fagarine) and skimmianine was proved using ¹⁴C-labelled compounds. Edulinine in the cell suspensions was formed from such substrates as 4-hydroxy-N-methyl-2-quinolone, 4-hydroxy-3-(3-methyl-2-butenyl)-N-methyl-2-quinolone and its 4- methyl ether; this is probably the natural biosynthetic sequence. Changes in alkaloid yields were noted upon prolonged subculturing.     

Ring A-seco limonoids and flavonoids from the Kenyan Vepris uguenensis Engl. and their antioxidant activity

Two A-seco-limonoids, accorded the trivial names, uguenensene and uguenensone and a C-7 prenylated flavonoid, uguenenprenol were isolated from Vepris uguenensis (Rutaceae). In addition, 11 known compounds, niloticin, chisocheton A, kihadalactone A, limonyl acetate, methyl uguenenoate, 7-O-methylaromadenrin, flindersiamine, 8α,11-elemodiol, tricoccin S₁₃ acetate, skimmianine, and lupeol were isolated. The structures of the compounds were elucidated and characterized by spectroscopic analyses (NMR, GC–MS and IR). Antioxidant activity of the isolated compounds showed that uguenenprenol and 7-O-methylaromadenrin are good antioxidant agents. Significantly high antioxidant activity was also exhibited by 8α,11-elemodiol, which was 72% at 250 μg mL⁻¹ and 57% at 15.62 μg mL⁻¹ when tested with the deoxyribose method. The two liminoids fit nicely into the biosynthetic pathway from niloticin to methyl uguenenoate.     

Secondary metabolites produced by callus cultures of various Ruta species

Callus cultures were established from hypocotyl explants of R. bracteosa, R. chalepensis and R. macrophylla. Calli were maintained for more than three years on MS-medium supplemented with 1 mg l^-1 of each 2,4-D and kinetin. Acridone and furoquinoline alkaloids and coumarins have been isolated from four week old calli grown on a hormone containing and hormone-free medium. A new chlorinated acridone alkaloid has been detected.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - MS medium after Murashige & Skoog [6]     

Chemical constituents of Sigmatanthus trifoliatus Huber ex Emmerich (Rutaceae)

The phytochemical investigation of Sigmatanthus trifoliatus Huber ex Emmerich (Rutaceae) allowed the isolation and identification of the coumarins seselin, osthol, coumurrayin and braylin, besides the furoquinoline alkaloids evolitrine, dictamnine, γ-fagarine and skimmianine. Their chemical structures were determined based on MS, NMR analyses, and supported by comparison with those reported in the literature. The essential oils composition of leaves, roots, and trunk were also analyzed, showing the compounds b-Caryophyllene (33.2%), germacrene-D (28.1%) and bornyl acetate (14.7%) as main components, respectively. The chemotaxonomic significance of the isolated compounds was discussed.     

Dihydrochalcones, coumarins and alkaloids from Metrodorea nigra

Two novel dihydrochalcones, 2′,3,4′,6′-tetrahydroxy-4-methoxy-3′,5-di-(3,3-dimethylallyl)-dihydrochalcone and 2′,.3,6′-trihydroxy-4-methoxy-5-(3,3-dimethylallyl)-3′,4′-(2″,2″-dimethyldihydropyran)-dihydrochalcone, have been isolated from fresh fruits of Metrodorea nigra. Stems and leaves showed a similar composition and we have isolated common steroids, simple coumarins, several furocoumarins, furoquinoline alkaloids and a furofuran lignan. From stems, we have also isolated the pentacyclic 6-C-monoterpenyl-5,7-dioxycoumarin, deoxybruceol. Structures of the isolated compounds were elucidated on the basis of spectral data.     

Isolation and Antimacrofouling Activity of Indole and Furoquinoline Alkaloids from ‘Guatambú’ Trees (Aspidosperma australe and Balfourodendron riedelianum)

In this work, the antifouling activity of five alkaloids, isolated from trees of the Atlantic rainforest, was studied. The tested alkaloids were olivacine ( 1 ), uleine ( 2 ) and N‐methyltetrahydroellipticine ( 3 ) from Aspidosperma australe (‘yellow guatambú’) and the furoquinoline alkaloids kokusaginine ( 4 ) and flindersiamine ( 5 ) from Balfourodendron riedelianum (‘white guatambú’). All these compounds can be isolated from their natural sources in high yields in a sustainable way. The five compounds were subjected to laboratory tests (attachment test of the mussel Mytilus edulis platensis) and field trials, by incorporation into soluble matrix paints, and 45 days of exposure of the painted panels in the sea. The results show that compound 3 is a very potent antifoulant, and that compounds 4 and 5 are also very active, while compounds 1 and 2 did not show any significant antifouling activity. These results open the way for the development of environmentally friendly antifouling agents, based on abundant and easy‐to‐purify compounds that can be obtained in a sustainable way.     

Alkaloids,limonoids and furocoumarins from three Mexican Esenbeckia species

The chemical constituents of three Mexican Esenbeckia species have been determined. Rutaevin was the main limonoid present in the seeds of all three species, E. litoralis, E. flava and E. berlandieri. The husks, leaves, wood and bark contained a wide array of known furocoumarins and furoquinoline alkaloids. In addition, 1-hydroxy-3-methoxy-N-methylacridone was obtained from E. litoralis bark and a new natural 2-quinolone alkaloid, formulated as 3,3-diisopropyl-N-methyl-2,4-quinoldione, was obtained from E. flava wood. The structure was assigned from spectroscopic considerations and conversion to N-methylhaplofoline.     

Cholinesterase inhibitory pregnane-type steroidal alkaloids from Sarcococca hookeriana

The bioassay-guided phytochemical investigation on Sarcococca hookeriana have resulted in the isolation of four new pregnane-type steriodal alkaloids: hookerianamide-D [(2'E,20S)-20-(N,N-formyl(methyl)amino)-3beta-(3',4'-dimethyl-2'-pentenamido)-5alpha-pregnane] (1), hookerianamide-E [(2'E,20S)-20-(N,N-dimethylamino)-3beta-(senecioylamino)-5alpha-pregn-14-en-2beta-O-acetate] (2), hookerianamide-F [(2'E,20S)-20-(N-methylamino)-3beta-(tigloylamino)-5alpha-pregn-2,14-dien-4-one] (3), and hookerianamide-G [(20S)-20-(N,N-dimethylamino)-3beta-(N-methylbenzamido)-5alpha-pregn-4beta-O-acetate] (4), along with five known alkaloids 5-9. Their structures were determined by spectroscopic analysis. These steroidal alkaloids and chemically derived derivatives of compound 5 have displayed varying degree of inhibitory activities against acetylcholinesterase and butyrylcholinesterase enzymes in a concentration-dependent fashion, with the IC(50) values ranging from 1.5 to 148.2 and 0.6 to 100.2 microM, respectively.     

First stereoselective total synthesis and anticancer activity of new amide alkaloids of roots of pepper

The first stereoselective total synthesis of new natural amide alkaloids 1–3 have been achieved from commercially available starting materials. Wittig olefination, Sharpless asymmetric dihydroxylation, epoxidation, a trans regioselective opening of 2,3-epoxy alcohol, Horner–Wadsworth–Emmons (HWE) olefination and amide coupling are the key steps. The amide alkaloids 1–3 are evaluated for their anticancer activity against colon (HT-29), breast (MCF-7) and lung (A-549) human cancer cell lines for the first time.     

Methyl chanofruticosinates from leaves of Kopsia flavida Blume

Three new indole alkaloids with methyl chanofruticosinates skeletal system, viz., methyl 12-methoxy-N1-decarbomethoxychanofruticosinate, methyl 12-methoxychanofruticosinate and methyl 11,12-dimethoxychanofruticosinate, in addition to methyl 11,12-methylenedioxy-N1-decarbomethoxychanofruticosinate, have been isolated from the leaves of Kopsia flavida Blume. The structures of these three new indole alkaloids were assigned by NMR spectral data using various 2D-techniques.