Analysis of Swainsonine and Swainsonine <i>N</i>-Oxide as Trimethylsilyl Derivatives by Liquid Chromatography–Mass Spectrometry and Their Relative Occurrence in Plants Toxic to Livestock

Swainsonine—a cytotoxic fungal alkaloid and a potential cancer therapy drug—is produced by the insect pathogen and plant symbiont Metarhizium robertsii, the clover pathogen Slafractonia leguminicola, locoweed symbionts belonging to Alternaria sect. Undifilum, and a recently discovered morning glory symbiont belonging to order Chaetothyriales. Genome sequence analyses revealed that these fungi share orthologous gene clusters, designated “SWN,” which included a multifunctional swnK gene comprising predicted adenylylation and acyltransferase domains with their associated thiolation domains, a β-ketoacyl synthase domain, and two reductase domains. The role of swnK was demonstrated by inactivating it in M. robertsii through homologous gene replacement to give a ∆swnK mutant that produced no detectable swainsonine, then complementing the mutant with the wild-type gene to restore swainsonine biosynthesis. Other SWN cluster genes were predicted to encode two putative hydroxylases and two reductases, as expected to complete biosynthesis of swainsonine from the predicted SwnK product. SWN gene clusters were identified in six out of seven sequenced genomes of Metarhzium species, and in all 15 sequenced genomes of Arthrodermataceae, a family of fungi that cause athlete’s foot and ringworm diseases in humans and other mammals. Representative isolates of all of these species were cultured, and all Metarhizium spp. with SWN clusters, as well as all but one of the Arthrodermataceae, produced swainsonine. These results suggest a new biosynthetic hypothesis for this alkaloid, extending the known taxonomic breadth of swainsonine producers to at least four orders of Ascomycota, and suggest that swainsonine has roles in mutualistic symbioses and diseases of plants and animals.

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“…Cultures were air-dried and extracted with 2% acetic acid. Swainsonine was analyzed by LC-MS using methods described by Gardner and Cook (2016).…”

Section: Methodsmentioning

confidence: 99%

Swainsonine Biosynthesis Genes in Diverse Symbiotic and Pathogenic Fungi

Cook

Donzelli

Creamer

et al. 2017

G3 Genes|Genomes|Genetics

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“…Additionally, it has been shown that swainsonine N-oxide is as effective as swainsonine in inhibiting alpha-mannosidase [1]. To better define the swainsonine N-oxide, Gardner et al [52] established an effective method for the detection of swainsonine N-oxide and detected swainsonine N-oxide fro m Alternaria oxytropis. Beyond swainsonine, and swainsonine N-oxide, the other three alkaloids were isolated and identified from the metabolites of Alternaria oxytropis .…”

Section: Discussionmentioning

confidence: 99%

The study of metabolites from fermentation culture of Alternaria oxytropis

et al. 2019

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BackgroundThe indolizidine alkaloid-swainsonine is produced by an endophytic fungus Alternaria oxytropis, which was isolated from locoweeds. Swainsonine has many biological activities such as anti-tumorigenic, anti-viral and bacteriostatic. However, the full complement of metabolites produced by Alternaria oxytropis is not known. This study is a chemical analysis of Alternaria oxytropis metabolites, which not only unravels the potential compounds from the fermentation broth but also in which solvent are they extracted, facilitating industrial application.ResultsAlternaria oxytropis isolated from Oxytropis gansuensis was cultured in Czapek’s medium for 30d to collect the fermentation broth. The fermentation broth is treated with methanol and then evaporated to dryness to obtain a concentrate of the fermentation broth. The concentrate is added with water for the subsequent fractional extraction with petroleum ether, chloroform, ethyl acetate and n-butanol. Different fractions of the extract were eluted by wet packing and dry loading. The obtained eluate was combined by TLC to detect the same fraction, and then characterized by GC-MS and LC-MS. The results of GC-MS showed that 105 different compounds existed in the petroleum ether, chloroform, and ethyl acetate phases of Alternaria oxytropis fermentation broth. Moreover, the results of LC-MS indicated that the fermentation broth of Alternaria oxytropis contained five alkaloids, 2-hydroxy-indolizidine, retronecine, lentiginosine, swainsonine and swainsonine N-oxide.ConclusionsIn addition to swainsonine and swainsonine N-oxide, 2-hydroxy-indolizidine, retronecine and lentiginosine were identified as the secondary metabolites of Alternaria oxytropis. Other compounds were also detected including 5,6-dihydroergosterol, eburicol, lanosterol, and L-phenylalanyl-L-proline lactam, which have potential applications as drugs.Electronic supplementary materialThe online version of this article (10.1186/s12866-019-1408-8) contains supplementary material, which is available to authorized users.

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“…"Locoweed," mainly including Astragalus, Oxytropis, and Swainsona species distributed throughout the world, are responsible for the neurologic disease of poisoned livestock and wild life. [1][2][3][4][5] Based on the bioactive principle of the neurologic symptom, the notorious alkaloid swainsonine (SW) (1S, 2R, 8R, 8aR-1, 2, 8-trihydroxyoctahydroindolizine, 1) was isolated by Colegate et al in 1979 from the Swainsona canescens, [6] though Guengerich et al in 1973 first purified this compound from fungus Rhizoctonia leguminicola. [7] In addition, SW was also isolated from the Metarhizium anisopliae as an immunoreactive substance.…”

Section: Introductionmentioning

confidence: 99%

Systematical NMR analysis of swainsonine, a mycotoxin from endophytic fungus Alternaria oxytropis

Tan

Wang

Liu

et al. 2020

Magnetic Reson in Chemistry

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Swainsonine (SW, 1), a unique indolizine with poly-hydroxyl groups, was re-isolated from the plant endophytic fungus Alternaria oxytropis. The structure (including planar structure and relative configuration) was systematically elucidated by NMR spectra (including 1 H, 13 C, 1 H-1 H COSY, HMQC, HMBC, and NOESY spectra in DMSO-d 6 and in CD 3 OD); 1 H NMR spectra of the modified Mosher's products were first used to determine the absolute configuration of SW. More importantly, the complex coupled features of H-7α, H-7β, and H-6α in the 1 H NMR spectrum of (1) were analyzed in details, which will provide aids for the planar and relative configuration determination of analogs.

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Analysis of Swainsonine and Swainsonine N-Oxide as Trimethylsilyl Derivatives by Liquid Chromatography–Mass Spectrometry and Their Relative Occurrence in Plants Toxic to Livestock

Cited by 5 publications

References 23 publications

Swainsonine Biosynthesis Genes in Diverse Symbiotic and Pathogenic Fungi

Swainsonine Biosynthesis Genes in Diverse Symbiotic and Pathogenic Fungi

The study of metabolites from fermentation culture of Alternaria oxytropis

Systematical NMR analysis of swainsonine, a mycotoxin from endophytic fungus Alternaria oxytropis

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