Stemona Alkaloids Research Articles

Stemona alkaloid derivative induce ferroptosis of colorectal cancer cell by mediating carnitine palmitoyltransferase 1.

Accumulation of acylcarnitines is a characteristic feature of various metabolic disorders affecting fatty acid metabolism. Despite extensive research, no specific molecules have been identified to induce ferroptosis through the regulation of acylcarnitine metabolism. In this study, acylcarnitine accumulation was identified based on cell metabolomics study after the treatment with Stemona alkaloid derivative (SA-11), which was proved to induce ferroptosis in our previous research. Furthermore, the CPT-1 level was proved to significantly increase, while the CPT-2 level indicated no significant difference, which resulted in the accumulation of acylcarnitine. Besides, the ferroptosis-inducing ability of SA-11 was significantly enhanced by the addition of exogenous acylcarnitine, presumably due to the production of additional ROS. This hypothesis was corroborated by the observation of increased ROS levels in HCT-116 cells treated with SA-11 compared to the control group. These findings suggest that targeting acylcarnitine metabolism, particularly through CPT-1, may offer a novel therapeutic strategy for cancer treatment by enhancing ferroptosis induction.

New alkaloids from Stemona tuberosa and structural revision of tuberostemonols P and R

Three Stemona alkaloids named stemotuberines A–C (1–3) with unique C17N frameworks, presumably formed by elimination of the C-11–C-15 lactone ring of the stichoneurine skeleton, were isolated from the roots of Stemona tuberosa. Their structures were elucidated by spectroscopic analysis, X-ray diffraction, and computational methods. Compounds 2 and 3 showed inhibition (IC50 values of 37.1 and 23.2 μM, respectively) against LPS-induced nitric oxide production in RAW 264.7 cells. In addition, concern was expressed about the reported plant origin (S. sessilifolia) of the recently described alkaloids tuberostemonols O–R (4–7), which should be S. tuberosa. NMR calculations indicated structural misassignment of these compounds except for 6. Isolation of tuberostemonol P (5) from our material of S. tuberosa allowed for a close examination of the spectroscopic data leading to the revised structure 5a. Tuberostemonol R (7) was found to have identical 1H and 13C NMR data to the well-known alkaloid croomine, and therefore its structure including relative stereochemistry must be revised as 7a.

Isolation and Bioactivities of Stemona Alkaloid: A Review

Objective/Background: In Chinese, Vietnamese, and Thai traditional medicine of Southeast Asian countries, Stemonaceae plants have long been employed. Various studies have proved that these herbal plants contain Stemona alkaloids with valuable medicinal value. Although some review articles on Stemona alkaloids have appeared in the literature, they are quite outdated. The current study offers a comprehensive review of the isolation and bioactivities of Stemona alkaloids. The article might be useful for chemists who work in alkaloid chemistry as well as pharmaceutical areas. Methods: “ Stemona alkaloids” was the most useful keyword to search for literature data. References have been collected from various resources such as Google Scholar, SciFinder, and PubMed. More than 120 electronic publications were obtained from these resources. Results: More than 250 Stemona alkaloids from 8 groups have been isolated and structurally elucidated from Stemonaceae plants. Extracts from these plants as well as isolated compounds possess a wide range of bioactivities, such as antituberculosis, antibacterial, antifungal, and antihelmintic properties activities. Conclusion: In this review article, we have summarized 116 studies on the isolation and bioactivities of Stemona alkaloids in the literature. More than 250 Stemona alkaloid compounds have been isolated and identified. In addition, the article also gives an overview of the bioactivities of Stemona alkaloids.

Search for Snail Repellents: Antimollusc Activities from Stemona parviflora and Six Other Chinese Stemona Species.

Snails are important agricultural pests difficult to control, but data regarding molluscicidal assays are scant. Stemona alkaloids are typical secondary metabolites for the taxa and have been broadly investigated for their pharmacological and toxicological effects. This makes it possible for us to further develop the toxicities of these compounds to snails. In this work, we tested the antifeedant properties of leaves from seven Chinese Stemona species against the land snail species Bradybaena ravida in choice and non-choice feeding assays. The tested leaves Stemona parviflora exhibited the most deterrent effects, and a further phytochemical investigation of aerial parts led to the identification of 16 alkaloids. Among them, three novel alkaloids could be identified. The alkaloidal fraction and single alkaloids were further assayed against this snail species, and the results suggest a cocktail effect because the impact of the alkaloidal fraction was higher than the effects caused by single alkaloids. The study can promote the search process of natural antimollusc products from plants to control snails.

Characteristic alkaloids from Stemona sessilifolia with lung protective effects

In the research on lung protective effects from the roots of Stemona sessilifolia, twenty-five Stemona alkaloids have been isolated, including four undescribed components (1, 3–5), a new natural product (2) and 20 known alkaloids (6–25). Their structures were analyzed by NMR spectra, high-resolution mass spectrum data, and other chemical methods. UPLC-QTOF/MS method was used to identify the Stemona alkaloids and summarize the fragmentation patterns of mass spectrometry. The lung-protective effects of these compounds were evaluated using MLE-12 cells induced by NNK and nm SiO2. The results showed that compounds 3, 5, 8, 10–11, 17–21 and 23 exhibited protective effects on NNK-induced cell injury. Compounds 2, 8–11, 14, 17–19 and 22 showed improvement in nm SiO2-induced lung epithelial cell injury. Compound 10 (tuberostemonine D), a representative alkaloid with a high content in Stemona sessilifolia, significantly protected C57BL/6 lung injury mice induced by nm SiO2, suggesting it a key component of Stemona alkaloids that play a protective role in lung injury. The results of in vivo activity showed that compound 10 could improve the lung injury of mice, reduce ROS content, and recover the levels of SOD and MDA in serum. Its protective effect on lung injury might be related to Nrf2 activation.

Asymmetric Total Synthesis of Four Stemona Alkaloids.

Asymmetric total syntheses of four Stemona alkaloids were accomplished, and among them, bisdehydrostemoninine A and stemoninine A were synthesized for the first time. Notably, these four alkaloids were divergently synthesized from a common tetracyclic intermediate, which was easily obtained from a known compound. Friedel-Crafts acylation was employed to introduce the key side chain at position C3 of Stemona alkaloids.

Anti-inflammatory maistemonine-class alkaloids of Stemona japonica

Three hitherto undescribed Stemona alkaloids, named stemajapines A–C (1–3), along with six known alkaloids (4–9), were isolated and identified from the roots of Stemona japonica (Blume) Miq. (Stemonaceae). Their structures were established by the analysis of the mass data, NMR spectra, and computational chemistry. Stemjapines A and B were degraded maistemonines without spiro-lactone ring and skeletal methyl from maistemonine. Concurrence of alkaloids 1 and 2 revealed an undescribed way to form diverse Stemona alkaloids. Bioassay results disclosed the anti-inflammatory natural constituents stemjapines A and C with IC50 values of 19.7 and 13.8 µM, respectively, compared to positive control dexamethasone with 11.7 µM. The findings may point out a new direction of Stemona alkaloids inaddition to its traditional antitussive and insecticide activities.

Palladium-Catalyzed Carbonylations: Application in Complex Natural Product Total Synthesis and Recent Developments.

Carbon monoxide is a cheap and abundant C1 building block that can be readily incorporated into organic molecules to rapidly build structural complexity. In this Perspective, we outline several recent (since 2015) examples of palladium-catalyzed carbonylations in streamlining complex natural product total synthesis and highlight the strategic importance of these carbonylation reactions in the corresponding synthesis. The selected examples include spinosyn A, callyspongiolide, perseanol, schizozygane alkaloids, cephanolides, and bisdehydroneostemoninine and related stemona alkaloids. We also provide our perspective about the recent advancements and future developments of palladium-catalyzed carbonylations.

Nematocidal alkaloids from the roots of Stemona mairei (H.Lév.)K.Krause and identification of their pharmacophoric moiety

Fifteen undescribed Stemona alkaloids, named as stemarines A–O (1–15), along with 25 known alkaloids (16–40), were isolated and identified from the roots of Stemona mairei (H.Lév.)K.Krause (Stemonaceae). Their structures were elucidated through the analysis of the NMR spectra, mass data, and computational chemistry. All the hitherto undescribed compounds possess a pyrrolo[1,2-α]azepine core structure but differ in important structural features, which reflects their nematocidal activities. Alkaloids 3–6 featured a carboxylic side chain and exhibited significant nematocidal activity against the nematode Caenorhabditis elegans. Transections of fresh roots combined with application of the Dragendorff’ reagent on the tissue indicated accumulation of alkaloids mainly in the epidermis and the pith. These results suggest the key pharmacophore of these alkaloids lies in the aliphatic side chain of these compounds and its spatial distribution in the roots indicate protective effects against underground herbivores.

Total Synthesis and Anti-inflammatory Activity of Stemoamide-Type Alkaloids Including Totally Substituted Butenolides and Pyrroles

AbstractTotally substituted butenolide including two tetrasubstituted olefins is a distinct structural motif seen in Stemona alkaloids, but efficient methods for its synthesis are not well developed. As an ongoing program aimed at the collective total synthesis of the stemoamide group, we report a stereodivergent method to give either (E)- or (Z)-totally substituted butenolide from the same intermediate. While AgOTf­-mediated elimination via an E1-type mechanism results in the formation of the kinetic (Z)-tetrasubstituted olefin, subsequent TfOH-mediated isomerization gives the thermodynamic (E)-tetrasubstituted olefin. The pyrrole ring is another important structure found in Stemona alkaloids. The direct oxidation of pyrrolidine rings with MnO2 and careful purification gives the pyrrole groups without isomerization of the stereocenter in the lactone group. These two methods enabled us to synthesize a series of stemoamide-type alkaloids including tricyclic, tetracyclic, and pentacyclic frameworks. The anti-inflammatory activities by inhibition of iNOS expression in macrophage cell line RAW264.7 indicate that the most potent anti-inflammatory compounds without cytotoxicity are protostemonines, which consist of pentacyclic frameworks including the totally substituted butenolide.

Structural Revision of the Stemona Alkaloids Tuberostemonine O, Dehydrocroomines A and B, and Dehydrocroomine.

The structural revision of four Stemona alkaloids from Stemona tuberosa is reported. The misassignment of the tuberostemonine O structure (1) was recognized when a new alkaloid, tuberostemonine P, was isolated and unambiguously assigned structure 1 in this work. Reinvestigation of the spectroscopic data and NMR calculations led to the revised structure 1a for tuberostemonine O. The structural misassignment of dehydrocroomine A as 2 was corrected by reinterpreting the X-ray crystal structure, which was consistent with 2a. The structural reassignments of dehydrocroomine B (3 to 3a) and dehydrocroomine (4 to 4a) were confirmed by X-ray crystallography and NMR calculations, respectively.

Structural Revision of Parvistemoamide: Informing Biosynthetic Proposals of Stemona Alkaloids.

The natural product parvistemoamide was isolated in 1991 and has ostensibly eluded synthesis. Its distinctive assigned structure represents the first and only Stemona alkaloid within its class. For over 30 years, this structure has influenced biosynthetic proposals concerning this family of natural products. Following synthetic studies and comprehensive analysis of relevant literature, a revised structure of parvistemoamide is proposed that is consistent with the fundamental Stemona alkaloid stemoamide.

Formal Syntheses of (±)‐Tuberostemospiroline and (±)‐Stemona‐lactam R and Total Synthesis of (±)‐Stemoamide

AbstractThe structure proposed for the putative Stemona alkaloid named as parvistemoamide (4 a or 4 b) has been questioned after revising the literature data and an attempted preparation of structure 4 a, which led to a 5 : 1 mixture of (±)‐stemoamide (1). Studies on the intramolecular Friedel‐Crafts alkylation of a furan 12 containing a Z double bond tethered to a precursor of a N‐acyliminium ion are reported. As shown for bromo substituted furan 31, the cyclization occurred when a 4‐carbon saturated tether was present, allowing for the formal syntheses of racemic tuberostemospiroline (2) and stemona‐lactam R (3).

Synthetic Studies towards Pyrido[1,2-a]azepine Stemona Alkaloids

AbstractThe carbon skeleton of the Stemona alkaloids stemokerrin and cochinchistemonine was assembled from three building blocks (a piperidine, a furan, and a tetronate). Key steps linking the fragments included a Stille cross-coupling (piperidine/furan) and an aldol-type addition of a tetronate. The furan served as a latent 1,4-difunctional compound which was converted into a γ-ketolactone by a type II photooxygenation. Attempts to construct the C12–C13 double bond of stemokerrin by a late-stage oxidation or by an elimination remained unsuccessful. The non-natural products dihydrostemokerrin and furostemokerrin were obtained instead.

Recent advances in the transformations of different types of Stemona alkaloids

Transformations among Stemona alkaloids with different ring systems have improved the synthetic efficiency toward diverse alkaloids. Recent advances in the transformations of different types of Stemona alkaloids were reviewed for the first time.

Total syntheses of seven stemoamide-type Stemona alkaloids

Six Stemona alkaloids were synthesized racemically using stemoamide, obtained via a cascade cyclization or our reported transannular cyclization of parvistemoamide, as the common intermediate.

Strategies for the synthesis of Stemona alkaloids: an update.

Covering: 2009 to 2022The Stemona alkaloids, which are found in plant species from the family Stemonaceae, represent a tremendously large and structurally-diverse family of natural products. This review presents and discusses a selection of case studies, grouped by alkaloid class, that showcase the key strategies and overall progress that has been made in the synthesis of Stemona alkaloids and related compounds since 2009. Structural reassignments that have been reported over this period are also identified where necessary.

Unique assembly of carbonylpyridinium and chromene reveals mitochondrial thiol starvation under ferroptosis and novel ferroptosis inducer.

To reveal the delicate function of mitochondria, spatiotemporally precise detection tools remain highly desirable. However, current probes with positively charged warheads for targeting mitochondria diffuse out of the mitochondria as the potential of the mitochondrial membrane changes, which directly influences the accuracy of the detection. Herein, we assembled carbonylpyridinium and chromene to afford the probe CM-Mit. Following the ultrafast response to thiol and the dissociation of carbonylpyridinium, the formation of o-quinone methide from CM-Mit was proposed to label proteins, thus avoiding diffusion out of the mitochondria. Therefore, the accurate spatiotemporal detection of thiol in mitochondria was realized. With this excellent probe, ferroptosis inducers were proved to stimulate thiol starvation in mitochondria for the first time in cancer cells. Moreover, CM-Mit was used to screen a compound library developed in-house and the stemona alkaloid analog SA-11 was shown to induce ferroptosis in various cancer cell lines, including a drug-resistant one.

Asymmetric total syntheses of five pyrrole-type Stemona alkaloids

The asymmetric total syntheses of five pyrrole-type Stemona alkaloids were accomplished, among which 3-n-butylneostemonine and bisdehydroneostemonine were synthesized for the first time, and the NMR data of bisdehydroneostemonine were revised.

Ir-Catalyzed Asymmetric Total Syntheses of Bisdehydrotuberostemonine D, Putative Bisdehydrotuberostemonine E and Structural Revision of the Latter.

The first total syntheses of bisdehydrotuberostemonine D (8) and putative bisdehydrotuberostemonine E (9), two novel pyrrole Stemona alkaloids, along with the synthesis of bisdehydrotuberostemonine (3) have been completed in 12-13 steps. Our strategy harnesses the power of transition-metal-catalyzed reactions employing Ir, Ru, and Pd, in particular Ir-catalyzed asymmetric allylation of aldehydes, two distinct protocols recently developed by Carreira and Krische, respectively. The threefold use of Ir catalysis, first in the stereodivergent construction of two contiguous stereocenters at C (9,10) and then in rapid formation of the two γ-butyrolactone motifs, enabled the route's efficiency. Through this work, the originally assigned structure of bisdehydrotuberostemonine E (9) should be revised as 18α-bisdehydrotuberostemonine D (8*).