The alkaloids of Abuta imene and Abuta rufescens

The alkaloid fraction of either Abuta imene or Abuta rufescens was found to contain the oxoaporphines imenine, homomoschatoline, and imerubrine, as well as the azafluoranthenes imeluteine, rufescine and norrufescine. Structures are proposed for the new alkaloids imerubrine and norrufescine, and a synthesis of homomoschatoline is described.     

New Balfourodendron 4-quinolone alkaloids

New tertiary alkaloids with a 4-quinolone skeleton, (±)-ribalinine (3b), (?)-ribalinidine (3c), (±) and (+)-ribaline (2b), have been obtained from Balfourodendron riedelianum. During isolation, 3c and 3b were found together with the quaternary alkaloidal fraction. The structure elucidations were in part based on spectrometric data. Furthermore, 2b and 3c were chemically correlated with the known ribalinium whilst the structure of 3b was confirmed by total synthesis. The configuration of 3c is S as determined by the Korean's method.     

Indole alkaloids from Kopsia jasminiflora

Seven new indole alkaloids (aspidofractinine type 1–3, kopsine type 5, strychnos type 6, and vincamine type 7, 8) were isolated from Kopsia jasminiflora (Apocynaceae) collected in Thailand. 5-Oxokopsinic acid (4) was isolated from nature for the first time. The structures of the new alkaloids were determined by spectroscopic analyses and chemical transformation of a known alkaloid. 5,6-Secokopsinine (1) possesses a dialdehyde function that is formed by oxidative cleavage of the C-5–C-6 bond of kopsinine (9). New vincamine-type alkaloid 8 showed potent inhibitory activity toward human cancer cell lines (A549, HT29, HCT116).     

Three new Lycopodium alkaloids from Huperzia carinata and Huperzia squarrosa

Eleven Lycopodium alkaloids with lycodine-type, lycopodine-type, and fawcettimine-related skeletons were isolated from the whole plants of Huperzia carinata (Desv. Ex. Poir.) Trevis and Huperzia squarrosa (G. Forst) Trevis (Huperziaceae). Among them, 8,15-dihydrohuperzine A (2), lycocarinatine A (3), and lycoposerramine U N-oxide (11) are new compounds. The structures of these new alkaloids were elucidated on the basis of 2D NMR correlations. Some of these isolated alkaloids were assayed for acetylcholinesterase (AChE) inhibitory activity.     

Daphtenidines A-D, new Daphniphyllum alkaloids from Daphniphyllum teijsmannii

Daphtenidines A-D (1-4), four new alkaloids were isolated from the leaves of Daphniphyllum teijsmannii, and the structures including relative stereochemistry were elucidated on the basis of spectroscopic data. Daphtenidines A (1) and B (2) were possessing daphnilactone A-type skeleton. This is the second isolation of daphnilactone A-type alkaloids from natural sources. Daphtenidine C (3) was 4-acetoxy form of daphmanidin A, while daphtenidine D (4) was 14-dehydro form of yuzurimine.     

The alkaloids from the fruits of the plant Daphniphyllaceae

Six alkaloids have been isolated from the fruits of the plant Daphniphyllaceae. Two of them are new alkaloids, namely methyl homodaphniphyllate (1) and daphnilactone-B (2). The structure of the former was deduced by chemical transformation from daphniphylline (3). The structure of daphnilactone-B was estimated by the exhaustive spectral analysis as well as by chemical evidences, and finally determined by an X-ray crystallographic analysis of the free base.     

Calyciphyllines H-M, new Daphniphyllum alkaloids from Daphniphyllum calycinum

Six new Daphniphyllum alkaloids, calyciphyllines H-M (1-6), were isolated from the leaves and stems of Daphniphyllum calycinum (Daphniphyllaceae). The structures and relative stereochemistry of 1-6 were elucidated on the basis of spectroscopic data, and the absolute stereochemistry of 3 was assigned by PGME method.     

Athrotaxis alkaloids. Part II. Alkaloids of a. selaginoides and a. laxifolia

The taxodeaceous plant A. Selaginoides contains six known homoerythrina-type alkaloids and selaginoidine, which has a furan ring replacing the benzene ring of the latter type. Selaginoidine and five of the six above-mentioned alkaloids also occur in A. laxifolia.     

Indole alkaloids from cultivated Vinca major

Nine new indole alkaloids, vinmajines A–I (1–9), and 43 known indole alkaloids were isolated from cultivated Vinca major in Kunming. The new structures were elucidated by extensive spectroscopic and quantum theory analysis. In addition, the results also supported that types of indole alkaloids from V. major might be influenced significantly by the ecological environment.     

Isoindolinone-type alkaloids from the sponge-derived fungus Stachybotrys chartarum

Eight new isoindolinone-type alkaloids named chartarutines A–H (1–8) and a known analogue (9) were isolated from the sponge-associated fungus Stachybotrys chartarum. Their structures were elucidated by extensive spectroscopic (IR, MS, 1D, and 2D NMR) data analyses, in addition to the Mosher method and CD effects for the assignment of their absolute configurations. All compounds were evaluated for the inhibition against HIV-1 virus, while chartarutines B, G, and H exhibited significant inhibitory effects. Primary structure–activity relationship was discussed.     

Fate of the benzene hydrogens in ergot alkaloids biosynthesis

Feeding experiments with specifically labelled precursors showed that in ergot alkaloids biosynthesis, the isoprenylation of tryptophan occurs without intermediate hydroxylation.     

Caldaphnidines A-F, six new Daphniphyllum alkaloids from Daphniphyllum calycinum

Six new Daphniphyllum alkaloids, namely caldaphnidines A-F (1-6), together with eight known ones, deoxycalyciphylline B, deoxyisocalyciphylline B, bukittiggine, calycicine A, methyl homosecodaphniphyllate, daphnilactone B, and daphnezomines L-M, were isolated from the leaves and the seeds of Daphniphyllum calycinum. The structure of 1 was determined by a single-crystal X-ray diffraction study, and the structures of 2-6 were established by spectral methods, especially two-dimensional NMR techniques (¹H-¹H COSY, HMQC, HMBC, and NOESY).     

The biosynthesis of the alkaloids of Goebelia pachycarpa

Summary 1. Qualitative and quantitative compositions of the main alkaloids in five development phases of theGoebelia pachycarpa C. A. Mey. have been determined.2. The radioactivities of the alkaloids isolated after feeding the plant with assumed precursors -[2-¹⁴C] lysine and [1,5-¹⁴C] cadaverine — show that vigorous synthesis of alkaloids takes place in the flowering and budding periods.3. The results of an investigation of the oxidation products and of the alkaloids introduced and isolated after the feeding of plants with labelled matrine and labelled sophocarpine show that the alkaloids undergo interconversion without intramolecular changes.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh, Soedinenii, No. 4, pp. 549–552, July–August, 1977.     

Seven new alkaloids from the roots of Stemona tuberosa

Seven new alkaloids, named as 1,9-epoxy-9a-hydroxystenine (1), tuberostemoline A (2), tuberostemoline B (3), tuberostemoninol C (4), oxotuberostemonine A (5), the mixture of bisdehydrotuberostemonine D (6), and bisdehydrotuberostemonine E (7), together with four known alkaloids neotuberostemonine (8), sessilifoline B (9), stemoxazolidinone F (10), and tuberostemoninol A (11), were isolated from the roots of Stemona tuberosa. The structures of 1–7 were elucidated through extensive spectroscopic analysis, and the relative configurations of 1–6 and 8 were further confirmed by X-ray crystallographic data. Compounds 8, 9 and the mixture of 6 & 7 exhibited potential acetylcholinesterase (AChE) inhibitory activities.     

Two new quinolone alkaloids from Dianthus superbus var. superbus

Two new quinolone alkaloids, superbusines A (1) and B (2), were obtained from the whole plants of a Chinese medicinal plant, Dianthus superbus var. superbus. Their structures, featuring a glucosyl moiety linked with a rare 2-(hydroxymethyl)-5-(2-hydroxypropan-2-yl)phenol fragment, were determined on the basis of detailed spectroscopic analyses, and the absolute configurations were assigned by time-dependent density functional theory (TD-DFT)-based electronic circular dichroism (ECD) calculations. The two alkaloids were evaluated in a series of bioassays without showing antimicrobial, anti-inflammatory, antioxidant, cytotoxic and α-glucosidase inhibitory properties, while they exhibited slight protection against amyloid-β(Aβ)-induced injury on neuron SH-SY5Y cells.     

New pyrrolidine alkaloids from the roots of Pandanus amaryllifolius

Four new alkaloids, pandamarilactonines-E, -F, and -F-N-oxide consisting of a pyrrolidine moiety and two α-methyl-γ-lactone residues, and pandamarilactonine-G, possessing a pyrrolidinone function, were isolated from the roots of Pandanus amaryllifolius. Their structures were determined based on spectroscopic analyses and chemical syntheses.