Alkaloids of Senecio Taiwanensis Hayata and Senecio Morrisonensis Hayata

Two alkaloids, rosmarinine (I) from Senecio taiwanensis Hayata and integerrimine(II) from Senecio morrisonensis Hayata, were isolated and identified respectively.     

Preparative Isolation of Pyrrolizidine Alkaloids Derived from Senecio Vulgaris

Abstract

A large scale method for the isolation of pyrrolizidine alkaloids has been adapted from a previously published analytical method. This method is a reverse phase high pressure liquid chromatography technique, utilizing a .005 M KH₂ PO₄ (pH 6.3) — methanol solvent system. The pyrrolizidine alkaloids derived from Senecio vulgaris (common groundsel) have been utilized in this system.     

Comment on Pyrrolizidine Alkaloids and Terpenes from Senecio (Asteraceae): Chemistry and Research Gaps in Africa

The genus Senecio is one of the largest in Asteraceae. There are thousands of species across the globe, either confirmed or awaiting taxonomic delimitation. While the species are best known for the toxic pyrrolizidine alkaloids that contaminate honeys (as bees select pollen from the species) and teas via lateral transfer and accumulation from adjacent roots of Senecio in the rhizosphere, they are also associated with more serious cases leading to fatality of grazing ruminants or people by contamination or accidental harvesting for medicine. Surprisingly, there are significantly more sesquiterpenoid than pyrrolizidine alkaloid-containing species. The main chemical classes, aside from alkaloids, are flavonoids, cacalols, eremophilanes, and bisabolols, often in the form of furan derivatives or free acids. The chemistry of the species across the globe generally overlaps with the 469 confirmed species of Africa. A small number of species express multiple classes of compounds, meaning the presence of sesquiterpenes does not exclude alkaloids. It is possible that there are many species that express the pyrrolizidine alkaloids, in addition to the cacalols, eremophilanes, and bisabolols. The aim of the current communication is, thus, to identify the research gaps related to the chemistry of African species of Senecio and reveal the possible chemical groups in unexplored taxa by way of example, thereby creating a summary of references that could be used to guide chemical assignment in future studies.     

Comparison of High Performance Liquid Chromatography with 1H Nuclear Magnetic Resonance Spectrometry for the Quantitative Analysis of Pyrrolizidine Alkaloids from Senecio Vulgaris

Abstract

A high-performance liquid chromatographic method for the analysis of pyrrolizidine alkaloids from Senecio vulgaris has been developed using narceine-HCl as an internal standard. A reversed phase procedure with a methanol/.01 M KH₂PO₄30/70 solvent system is described, and compared with a quantitative¹H Nuclear Magnetic Resonance spectrometric method. Some advantages and limitations are discussed.     

Sesquiterpenoids from Senecio argunensis

Investigation of unpolar extracts from the aerial parts of Senecio argunensis afforded two new sesquiterpenoids, 1β‐hydroxyeudesma‐4,11‐dien‐15‐al ( 1 ) and 4(15)‐cadinene‐5α,10α‐diol, ( 2 ) as well as six known compounds, 3 – 8 . The structures of all isolates were elucidated on the basis of extensive analyses of spectroscopic data and comparison with literature data.     

Bioactive eremophilanolides from Senecio poepigii

A new bioactive eremophilanolide, 1alpha-tigloyloxy-8betaH,10betaH-eremophil-7(11)-en-8alpha,12-olide, was isolated from Senecio poepigii and its structure was elucidated by spectral analysis. 1alpha-Angeloyloxy-8beta-methoxy-10betaH-eremophil-7(11)-en-8alpha,12-olide was also isolated. Antifungal and insect antifeedant properties were evaluated.     

New Eremophilenolides from Senecio dianthus

From the aerial parts of Senecio dianthus, four new eremophilenolides ( 1 – 4 , resp.) and one new eremophilenolide alkaloid ( 5 ), of the relatively uncommon eremophilenoid‐type sesquiterpenoid lactones, were isolated together with three known sesquiterpenoid lactones, 10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 6 ), 8β,10β‐dihydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 7 ), and 10α‐hydroxy‐1‐oxoeremophila‐7(11),8(9)‐dien‐12,8‐olide ( 8 ). On the basis of IR, MS, and NMR data, particularly 2D‐NMR analyses, the structures of the new compounds were established as: 2β‐(angeloyloxy)‐10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 1 ), 6β‐(angeloyloxy)‐10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 2 ), 2β‐(angeloyloxy)‐8β,10β‐dihydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 3 ), 2β‐(angeloyloxy)‐8α‐hydroxyeremophila‐7(11),9(10)‐dien‐12,8β‐olide ( 4 ), and 8β‐amino‐10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 5 ). In addition, the relative configuration of 1 was corroborated by X‐ray diffraction analysis.     

New Eremophilenolactones from Senecio nemorensis

Three new eremophilane sesquiterpenes were isolated from the MeOH extract of the roots of Senecio nemorensis. Their structures were identified as 8α‐hydroxy‐6β‐(isobutanoyloxy)‐1‐oxoeremophila‐7(11),9‐dieno‐12,8β‐lactone ( 1 ), 6β,8β‐dimethoxy‐1‐oxoeremophila‐7(11),9‐dieno‐12,8α‐lactone ( 2 ), and 10α‐hydroxy‐6β‐(isobutanoyloxy)‐1‐oxoeremophila‐7(11),8‐dieno‐12,8‐lactone ( 3 ), respectively, based on spectroscopic data, including IR, EI‐MS, HR‐ESI‐MS, and 1D‐ and 2D‐NMR data.