Acridone alkaloids from Severinia buxifolia

Two new acridone alkaloids, severifoline and N-methylseverifoline along with the known alkaloids, N-methylatalaphylline, atalaphyllinine and 5-hydroxy-N-methylseverifoline, were isolated from the root bark of Severinia buxifolia. The structures of severifoline and N-methylseverifoline were established by chemical and spectroscopic methods.     

Cytotoxic 7S-oxindole alkaloids from Gardneria multiflora

Seven new oxindole alkaloids, gardmutines A–F (1–6) and 18-hydroxy-chitosenine (7), along with 15 known alkaloids, were isolated from the aerial parts of Gardneria multiflora Makino. The structures of the alkaloids were established by spectroscopic methods. Alkaloids 1–6 are the first Gardneria alkaloids possessing a 7S configuration. Gardmutines D and E were cytotoxic to HeLa, MCF-7 breast, and SW-480 colon cancer cell lines.     

Steroidal alkaloids of Marsdenia rostrata

Some of the main constituents of Marsdenia rostrata, originating from two localities, were isolated and identified. The sample from the Toonumbar State Forest in northern New South Wales contains the known alkaloid anabasine and two new steroidal ester alkaloids, rostratine and dihydrorostratine. They were identified as O-acetyl-O-nicotinoylsarcostin and O-acetyl-O-nicotinoyldihydrosarcostin. The sample from the South Coast of N.S.W. yielded the two new ester alkaloids and a number of neutral polyhydroxy pregnane aglycones, one of which has been identified as metaplexigenin, but there was no anabasine.     

Antimicrobially active alkaloids from Tabernaemontana pachysiphon

Twenty-three alkaloids and five steroids and triterpenes have been isolated and identified from the root bark and stem bark of a Nigerian Tabernaemontana pachysiphon. The following bases have not previously been obtained from this species: isositsirikine, 16-epiisositsirikine, normacusine B, 16-epiaffinine, anhydrovobasindiol, tubotaiwine, ibogaline, isovoacangine, voacamine, lochnericine, 3R-hydroxyconopharyngine, 3S-hydroxyconopharyngine and 11-demethylconoduramine, the last three being new alkaloids. The dimeric indole alkaloids and 3R/S-hydroxyconopharyngine were shown to possess strong antibacterial activity against Gram-positive bacteria and the dimers against Gram-negative bacteria also.     

Hasubanan alkaloids of Stephania japonica

Two new hasubanan alkaloids, 16-oxoprometaphanine and 16-oxohasubanonine, were obtained from Stephania japonica as minor components. A hasubanan alkaloid stephasunoline was converted into metaphanine via prometaphanine.     

New alkaloids from Strychnos icaja

The alkaloids of Strychnos icaja (Loganiaceae) have been studied. An extract from Zaire leaf material yielded nine alkaloids, comprising novacine, the new base 21,22-α-epoxy-4,14-dihydroxy-3-methoxy-N-methyl-sec.-pseudostrychnine, and seven others of known structure previously obtained from the plant. Cameroun leaf material gave five alkaloids, of which one, 21,22-α-epoxy-3,4-dimethoxy-N-methyl-sec.-pseudostrychnine, is new. Fruits from Gabon afforded eight alkaloids; two of them are new and are formulated as 21,22-α-epoxy-4-methoxy-N-methyl-sec.-pseudostrychnine and the corresponding 14-hydroxy derivative.     

Pyrrolizidine alkaloids from seeds of Crotalaria scassellatii

Three pyrrolizidine alkaloids were isolated from the seeds of Crotalaria scassellatii. Axillaridine and axillarine were the two major alkaloids whereas the third minor alkaloid was a new compound. Its structure was determined as desoxyaxillarine.     

Morphinandienone and aporphine alkaloids from Corydalis decumbens

Phytochemical examination of Corydalis decumbens has afforded two new morphinandienone alkaloids, namely, (-)-pallidine N-oxide (1) and (-)-salutaridine N-oxide (2), together with one known analogue, (-)-pallidine (3), and three known aporphine alkaloids (4−6). Their structures were elucidated via comprehensive spectroscopic analysis and chemical correlation. This study represents the first isolation of morphinandienone alkaloids from the title plant. All isolates were tested for their activities towards neuronal excitability in primary cultured neocortical neurons.     

Melohenryines A and B,two new indole alkaloids from Melodinus henryi

Two new monoterpenoid indole alkaloids, melohenryines A and B (1 and 2), along with six known indole alkaloids, were isolated from the twigs and leaves of Melodinus henryi. Structures of the new alkaloids were established by extensive spectroscopic techniques including NMR spectroscopy and mass spectrometry. Melohenryine A (1) represents the first example of monoterpenoid indole alkaloids characterized an ester carbonyl group at C-19 position. All of the new compounds were evaluated for in vitro cytotoxicity against several human cancer cell lines.     

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).     

Two non-hydroxylated alkaloids in Crinum augustum

Several alkaloids were isolated from Crinum augustum grown in Assiut, Egypt. Two were identified as lycorine and buphanisine. In addition two new non-hydroxylated alkaloids of identical molecular formula C₁₇H₁₉NO₄ were investigated by spectroscopic methods. The gross structure of the first, termed augustine, belongs to the 1,2-epoxy-5, 10-b-ethanophenanthridine-type. In contrast the second could not be related to any of the known alkaloid types of the Amaryllidaceae.     

Bioactive benzylisoquinoline alkaloids from Artabotrys hexapetalus

Two new benzylisoquinoline alkaloids, namely, hexapetalines A (1) and B (2), along with 11 known alkaloids were isolated from the stems of Artabotrys hexapetalus. The structures of 1 and 2 with their absolute configurations were elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with data in the literature. All new compounds were evaluated for their cytotoxicities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Alkaloids 1 and 2 exhibited inhibitory effects with IC₅₀ values comparable to those of cisplatin.     

Five new diterpenoid alkaloids from Aconitum sczukinii Turcz.

Ten diterpenoid alkaloids, including five new ones, sczukiniline A–E (1-5), were isolated from the root of Aconitum sczukinii. Their structures were elucidated based on the interpretation of spectroscopic data (HRESI-MS, IR, 1D- and 2D-NMR). Among the five new diterpenoid alkaloids, 1-3 are hetidine-type C₂₀-diterpenoid alkaloids, while compounds 4 and 5 are lycoctonine-type C₁₉-diterpenoid alkaloids. Noteworthily, sczukiniline A (1) features a novel ester group between C-12 and C-14, forming a D ring containing a lactone structure, resulting in a new skeleton of hetidine-type C₂₀-diterpenoid alkaloid.     

Five new alkaloids from Aconitum apetalum (Ranunculaceae)

Twenty-one alkaloids, including five new ones, acoapetaldines A–E (1–5), were isolated from the whole plants of Aconitum apetalum. Among them, 1 is an aconitine-type diterpenoid alkaloid, 2 and 3 are aporphine alkaloids and 4 and 5 are napelline-type diterpenoid alkaloids. The structures of the new alkaloids were elucidated by spectroscopic data analysis and that of acoapetaldine D (4) was confirmed by single crystal X-ray crystallography. Acoapetaldine A (1) and aconorine (12) exhibited moderate anti-tobacco mosaic virus (anti-TMV) activity, while corydine (15) displayed moderate antimicrobial activity against Pseudomonas aeruginosa.     

Four new diterpenoid alkaloids from Delphinium elatum

Diterpenoid alkaloids exhibit remarkable chemical properties and biological activities. Such compounds are frequently found in plants of the genera Aconitum, Delphinium, and Garrya. Several diterpenoid alkaloid components from Delphinium elatum cv. Pacific Giant and their derivatives exhibited cytotoxic activity against lung, prostate, nasopharyngeal, and vincristine-resistant nasopharyngeal cancer cell lines. Phytochemical investigations on the seeds of D. elatum cv. Pacific Giant led to the isolation of four new C₁₉-diterpenoid alkaloids, melpheline (1), 19-oxoisodelpheline (2), N-deethyl-19-oxoisodelpheline (3), and N-deethyl-19-oxodelpheline (4). The isolated alkaloids were elucidated by extensive spectroscopic methods including NMR (1D and 2D), IR, and MS (HRMS).     

Biodiversity of Convolvulaceous species that contain ergot alkaloids,indole diterpene alkaloids,and swainsonine

Convolvulaceous species have been reported to contain several bioactive principles thought to be toxic to livestock including the calystegines, swainsonine, ergot alkaloids, and indole diterpene alkaloids. Swainsonine, ergot alkaloids, and indole diterpene alkaloids are produced by seed transmitted fungal symbionts associated with their respective plant host, while the calystegines are produced by the plant. To date, Ipomoea asarifolia and Ipomoea muelleri represent the only Ipomoea species and members of the Convolvulaceae known to contain indole diterpene alkaloids, however several other Convolvulaceous species are reported to contain ergot alkaloids. To further explore the biodiversity of species that may contain indole diterpenes, we analyzed several Convolvulaceous species (n = 30) for indole diterpene alkaloids, representing four genera, Argyreia, Ipomoea, Stictocardia, and Turbina, that had been previously reported to contain ergot alkaloids. These species were also verified to contain ergot alkaloids and subsequently analyzed for swainsonine. Ergot alkaloids were detected in 18 species representing all four genera screened, indole diterpenes were detected in two Argyreia species and eight Ipomoea species of the 18 that contained ergot alkaloids, and swainsonine was detected in two Ipomoea species. The data suggest a strong association exists between the relationship of the Periglandula species associated with each host and the occurrence of the ergot alkaloids and/or the indole diterpenes reported here. Likewise there appears to be an association between the occurrence of the respective bioactive principle and the genetic relatedness of the respective host plant species.     

Peptide and tetrahydroisoquinoline alkaloids from Euonymus europaeus

Three p-aryloxy macrocyclic peptide alkaloids frangulanine, franganine and frangufoline together with the 1-benzyltetrahydroisoquinoline alkaloid armepavine have been isolated from Euonymus europaeus native to Poland. These types of alkaloids are new to the Celastraceae and are of chemotaxonomic interest.     

Tropane alkaloids from Darlingia darlingiana

A new γ-pyranotropane, darlingine N-oxide, was isolated from the bark and leaves of Darlingia darlingiana, along with the known compound, darlingine. 1D-NOESY NMR experiments indicated that the N-methyl groups of both alkaloids were orientated towards the pyran ring.     

Polycyclic monoterpenoid indole alkaloids from Alstonia rostrata and their reticulate derivation

Five new alkaloids together with 20 known ones were isolated from Alstonia rostrata, and identified on the base of NMR, MS, UV and IR spectroscopic data. Additionally, alstrostine G (1) possessed an unprecedented 6/5/6/6/5/6-ring system. The analysis of those alkaloids’ biosynthetic pathway partly indicated their reticulate metabolic relationship. The research result disclosed diverse biogenesis of monoterpenoid indole alkaloids from Alstonia rostrata speciesin combination with previous reported alstrostine A.     

Two new pyrrolizidine alkaloids from Crotalaria albida

Two new pyrrolizidine alkaloids, namely, neocroalbidine and neocroalbidinone, were isolated from the herbs of Crotalaria albida. Their structures were established using a combination of NMR spectroscopy and mass spectrometry techniques. The absolute stereochemistry of the two alkaloids presented herein was determined by single-crystal X-ray diffraction analysis.