Alkaloids of Zanthoxylum monophyllum and Z. punctatum

The known alkaloids N-methylcorydine and magnoflorine were major constituents of stems and branches of Zanthoxylum punctatum (Rutaceae). Berberine was the major alkaloid of Z. monophyllum, which also contained a new pyrano-2-quinolone alkaloid, zanthophylline, and its desmethyl analog. Zanthophylline has an —NCH₂OAc functional group which is readily hydrolyzed by dilute acid. Methyl vanillate and the furocoumarin columbianetin were also found in Z. monophyllum.     

Alkaloids as inhibitors of photophosphorylation in spinach chloroplasts

A group of 12 alkaloids were tested as inhibitors of photophosphorylation in spinach chloroplasts. Ajmaline, a dihydroindole alkaloid, was found to be the strongest inhibitor of both cyclic and non-cyclic photophosphorylation. Low concentrations of ajmaline also inhibited the dark and light ATPases, and the coupled electron flow from water to ferricyanide, measured either as ferrocyanide formed or as oxygen evolved, but not the uncoupled electron transport or the pH rise of illuminated unbuffered suspensions of chloroplasts. Higher concentrations of ajmaline stimulated, instead of inhibiting, photosynthetic electron transport or oxygen evolution and decreased the pH rise, thus behaving as an uncoupler, such as ammonia.Photophosphorylation was partially inhibited by 100 μM dihydrosanguinarine, 100 μM dihydrochelerythrine (benzophenanthridine alkaloids); 500 μM O,O'-dimethylmagnoflorine, 500 μM N-methylcorydine (aporphine alkaloids) and 1 mM julocrotine. They also inhibited coupled oxygen evolution and only partially (dihydrosanguinarine and dihydrochelerythrine) or not at all (the other alkaloids) uncoupled oxygen evolution.Spegazzinine (dihydroindole alkaloid), magnoflorine, N-methylisocorydine, coryneine (aporphine alkaloids), candicine and ribalinium chloride were without effect on photophosphorylation at 500 μM.     

Pachyovatamine,a bisbenzylisoquinoline alkaloid,and other alkaloids from Pachygone ovata

A new dibenzo-p-dioxin biphenyl bisbenzylisoquinoline alkaloid, pachyovatamine, has been isolated from an extract of the leaves and stems of Pachygone ovata from Sri Lanka. The alkaloid was characterized by a consideration of its physicochemical data and conversion to O-acetyltiliacorinine. Pachygonamine, N-methylpachygonamine and tiliamosine were also isolated from the same extract.     

Cyclopeptide alkaloids from Melochia corchorifolia

Adouetine-y′ and a new cyclopeptide alkaloid, melofoline, have been isolated from melochia corchorifolia. The latter was characterized mainly from its mass spectrum and hydrolysis products. Melofoline has N,N-dimethyl-β-hydroxyleucine as the terminal amino acid and 2-aminobutyric acid as the ring amino acid, neither of which has been found in the positions before.     

Alkaloids and other constituents of Zanthoxylum williamsii,Z. monophyllum and Z. fagara

Zanthoxylum williamsii (Rutaceae) was found to contain (+)-asaranin, (+)-sesamin, esculetin dimethyl ether, nitidine, chelerythrine, magnoflorine, laurifoline, skimmianine and edulinine. The quaternary alkaloid fraction of Z. monophyllum contained berberine, magnoflorine, chelerythrine and a 1,2,9,10-substituted dihydroxydimethoxy-N,N-dimethylaporphinium salt. Leaves of Z. fagara were found to contain synephrine. Leaves of each species were examined for the presence of bishordeninyl terpene alkaloids, but none was found. Some chemotaxonomic relationships among Zanthoxylum species are discussed.     

Na-formylechitamidine,an alkaloid from Alstonia boonei

A known alkaloid, echitamidine, and a new alkaloid, N_a-formylechitamidine, have been isolated from the stem bark of Alstonia boonei. The structure of this new alkaloid was assigned on the basis of chemical and spectroscopic data.     

N-Formylcytisine: A new alkaloid from Thermopsis chinensis

A new base have been isolated from Thermopsis chinensis along with N-methylcytisine, cytisine, anagyrine and lupanine. The new alkaloid have been shown to be N-formylcytisine.     

Strictamine-N-oxide from rhazya stricta

A new alkaloid, strictamine-N-oxide has been isolated from the leaves of Rhazya stricta.     

1,2-dehydroaspidospermidine-N-oxide,an alkaloid from Rhazya stricta

A new alkaloid, 1,2-dehydroaspidospermidme-N-oxide, has been isolated from the roots of Rhazya stricta.     

(+)-5α,9α-dihydroxymatrine,a new lupin alkaloid from Euchresta horsfeldii

A new lupin alkaloid (+)-5α,9α-dihydroxymatrine has been isolated from the leaves of Euchresta horsfeldii (E. formosana cv riukiuensis) together with matrine, matrine N-oxide, sophoranol, sophoranol N-oxide, anagyrine, N-methylcytisine, N-formylcytisine and cytisine.     

A new alkaloid from south african Conium species

Recent screening of South African Conium species for alkaloids as part of taxonomic studies has yielded γ-coniceine, coniine, methylconiine, conhydrine and a new alkaloid N-methylpseudoconhydrine. The relative stereochemistry of N-methylpseudoconhydrine was ascertained by ¹H NMR decoupling experiments. This latter alkaloid was found in significant amounts in the leaf and stem of some plants investigated and was the major alkaloid along with conhydrine in the leaf and stem of one group of high altitude plants. These plants also contained significant amounts of volatile oil, the major monoterpene being myrcene.     

(−)-N-ethylcytisine,a lupin alkaloid from the flowers of Echinosophora koreensis

A new lupin alkaloid, (?)-N-ethylcytisine, was isolated from the fresh flowers of Echinosophora koreensis. Its structure has been confirmed b     

Alkaloids and iridoids from Strychnos nux-vomica fruits

The alkaloid mixtures present in the fruit pericarp and fruit pulp of Strychnos nux-vomica L. are qualitatively very similar to that found in the seeds. In addition to alkaloids previously known to occur in this plant, small amounts of 4-hydroxystrychnine and the new base N-methyl- sec.-pseudo-β-colubrine have been isolated. Cantleyine, which is a non-indolic base and an artefact, has also been obtained. The iridoid mixture in the fruit pulp is predominantly loganin with small amounts of related compounds, including the biogenetically important secologanin.     

N-isobutyl-trans-2-trans-4-eicosadienamide and other alkaloids of fruits of Piper guineense

A novel alkaloid, N-isobutyl-trans-2-trans-4-eicosadienamide, has been isolated from the fruits of Piper guineense and fully characterized. The structure of the compound has been confirmed by an unambiguous synthesis of the tetrahydro derivative. The known alkaloid, δαβ-dihydropiperine has also been isolated and the position of the double bond in this compound confirmed by the use of an NMR shift reagent.     

Havanine—a steroidal alkaloid glycoside from Solanum havanense

A new steroidal alkaloid glycoside named havanine has been isolated from the leaves of Solanum havanense and its structure elucidated by spectral data as (25S)-O(3)-β-D-glucopyranosyl-16α-acetoxy-22,26-epiminocholesta-5,22(N)-dien-3β-ol.     

Alkaloid constituents from flower buds and leaves of sacred lotus (Nelumbo nucifera,Nymphaeaceae) with melanogenesis inhibitory activity in B16 melanoma cells

Methanolic extracts from the flower buds and leaves of sacred lotus (Nelumbo nucifera, Nymphaeaceae) were found to show inhibitory effects on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extracts, a new alkaloid, N-methylasimilobine N-oxide, was isolated together with eleven benzylisoquinoline alkaloids. The absolute stereostructure of the new alkaloid was determined from chemical and physicochemical evidence. Among the constituents isolated, nuciferine, N-methylasimilobine, (?)-lirinidine, and 2-hydroxy-1-methoxy-6a,7-dehydroaporphine showed potent inhibition of melanogenesis. Comparison of the inhibitory activities of synthetic related alkaloids facilitated characterization of the structure-activity relationships of aporphine- and benzylisoquinoline-type alkaloids. In addition, 3–30 μM nuciferine and N-methylasimilobine inhibited the expression of tyrosinase mRNA, 3–30 μM N-methylasimilobine inhibited the expression of TRP-1 mRNA, and 10–30 μM nuciferine inhibited the expression of TRP-2 mRNA.     

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.     

(+)-11-oxocytisine,a lupin alkaloid from leaves of sophora secundiflora

A new lupin alkaloid, (+)-11-oxocytisine (1), was isolated from the leaves of Sophora secundiflora together with (−)-anagyrine, (−)-N-methylcytisine, (−)-baptifoline, (−)-N-formylcytisine, (−)-N-acetylcytisine and (−)-cytisine. The structure of the new alkaloid (1) was presumed to be (+)-11--oxocytisine on the basis of its spectroscopic data.     

β-Phenethylamine,tetrahydroisoquinoline and indole Alkaloids of Desmodium tiliaefolium

Ten alkaloids (I-X), five β-phenethylamines, two tetrahydroisoquinolines, and three indole-3-alkylamines, have been isolated from Desmodium tiliaefolium. Chemical transformations, spectral (UV,IR, NMR, MS) evidence, and in most cases comparison with reference materials established their identity as tyramine (I), hordenine (II), 3,4-dimethoxy-β-phenethylamine (III), N,N- dimethyl-3,4-dimethoxyphenethylamine (IV), N-methyl-3,4-dimethoxy-β-hydroxyphenethylamine (V), salsoline (V1), salsolidine (VII), tryptamine (VIII), abrine (IX), and hypahorine (X). Alkaloid (V) is a new naturally occurring compound, while no tetrahydroisoquinoline alkaloid has been encountered before in this genus. This is the first time that three different types of alkaloids have been reported in a single legume species. In addition to the above alkaloids, four quaternary β-phenethylamines and tetrahydroisoquinoline alkaloids have been detected, and choline and betaine have been isolated from the water-soluble alkaloid fraction of the roots.     

Lupin alkaloids from sophora chrysophylla

A new lupin alkaloid, (?)-mamanine N-oxide, was isolated from Sophora chrysophylla together with 18 known alkaloids including some unusual lupin alkaloids such as kuraramine, lamprolobine, epilamprolobine, epilamprolobine N-oxide, (+)-mamanine and (?)-pohakuline. It was also shown that the alkaloid constituents of S. chrysophylla differed considerably in the leaves, stems and seeds.