LC-MS/MS analysis of didehydrostemofoline from Stemona collinsiae roots extracts in rats plasma and pharmacokinetics profile after oral administration.

Stemona collinsiae Craib., Stemonaceae, has been traditionally used as medicinal plants for insecticides, treatment of parasitic worms and various diseases in Southeast Asian countries. Its ethanolic root extract has been postulated for anthelminthic activities which has a potential for development for human gnathostomiasis drug. To investigate the pharmacokinetic profile, liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method for the quantification of didehydrostemofoline in rats' plasma was developed and validated. The chromatographic separation was performed on a C18 column using 1 mM ammonium acetate in water and methanol (50:50, v/v). Tetrahydropalmatine was used as an internal standard. The multiple reaction monitoring mode was used for quantitative analysis. The validated method showed good sensitivity, linearity, precision, and accuracy. The results of stability showed that didehydrostemofoline was stable in the extracted samples in auto-sampler for 24 h and in the plasma samples under room temperature for 24 h, -20 °C for 1 month, and after three freeze-thaw processes. The developed method was applied to the pharmacokinetic study of didehydrostemofoline after oral administration of S. collinsiae root extract. Didehydrostemofoline was rapidly absorbed from the gastrointestinal tract. The time to peak drug concentration was 1.75 ± 0.62 h with maximum drug concentration of 1152.58 ± 271.18 ng/mL. Didehydrostemofoline was rapidly eliminated from the body with terminal half-life of 1.86 ± 0.50 h. Calculated drug clearance of didehydrostemofoline was 96.82 ± 23.51 L/h and volume of distribution was 260.40 ± 96.81 L. The present study provided useful data for understanding drug disposition in the body with dynamic time-course which could be beneficial for further clinical trials.

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.

Study of the Structure and Bioactivity of Polysaccharides from Different Parts of Stemona tuberosa Lour.

The polysaccharides from Stemona tuberosa Lour, a kind of plant used in Chinese herbal medicine, have various pharmacological activities, such as anti-inflammatory and antioxidant properties. However, the effects of the extraction methods and the activity of polysaccharides from different parts are still unknown. Therefore, this study aimed to evaluate the effects of different extraction methods on the yields, chemical compositions, and bioactivity of polysaccharides extracted from different parts of Stemona tuberosa Lour. Six polysaccharides were extracted from the leaves, roots, and stems of Stemona tuberosa Lour through the use of hot water (i.e., SPS-L1, SPS-R1, and SPS-S1) and an ultrasound-assisted method (i.e., SPS-L2, SPS-R2, and SPS-S2). The results showed that the physicochemical properties, structural properties, and biological activity of the polysaccharides varied with the extraction methods and parts. SPS-R1 and SPS-R2 had higher extraction yields and total sugar contents than those of the other SPSs (SPS-L1, SPS-L2, SPS-S1, and SPS-S2). SPS-L1 had favorable antioxidant activity and the ability to downregulate MUC5AC expression. An investigation of the anti-inflammatory properties showed that SPS-R1 and SPS-R2 had greater anti-inflammatory activities, while SPS-R2 demonstrated the strongest anti-inflammatory potential. The results of this study indicated that SPS-L1 and SPS-L2, which were extracted from non-medicinal parts, may serve as potent natural antioxidants, but further study is necessary to explore their potential applications in the treatment of diseases. The positive anti-inflammatory effects of SPS-R1 and SPS-R2 in the roots may be further exploited in drugs for the treatment of inflammation.

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.

Isolation, characterization and anti-inflammatory effect of alkaloids from the roots of Stemona tuberosa Lour.

Six undescribed alkaloids, neotuberostemonol C (1), dehydrostenines C-D (2-3), tuberostemonines Q-R (10-11), and (6R,8R,8aR)-8-hydroxy-6-methyl-hexahydroindolizin-5-one (32), along with twenty-six known analogues were isolated from the dried roots of Stemona tuberosa Lour. The structures and absolute stereochemistry of these compounds were delineated by extensive spectroscopy (1D NMR, 2D NMR, HRESIMS), quantum chemical calculations of the electronic circular dichroism spectra, and pyridine-induced solvent shifts. Tuberostemonines Q-R (10-11) represent tuberostemonine skeleton alkaloids possessing an α-methyl-γ-butyrolactone moiety attached to C-3. In addition, all these isolated compounds were assayed for their inhibitory activity against LPS-induced NO production in RAW264.7 cells using Griess assay.

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.

Larvicidal activity of Stemona collinsiae root extract against Musca domestica and Chrysomya megacephala.

Musca domestica and Chrysomya megacephala, considered synanthropic insects, are medically important flies, as they transmit vector-borne diseases to humans and animals. In Thailand, Stemona (Stemonaceae) plants have been traditionally used as insecticides. This study was designed to determine the larvicidal activity of S. collinsiae root extract against M. domestica and C. megacephala larvae. A 70% ethanol crude extract from S. collinsiae roots was tested against the third-instar larvae of both species using direct and indirect contact methods. The development and mortality rates of the insects were observed, and the LC values were calculated. The extract caused irregular development in both species, shown as segmental puparia that could not emerge as adult flies. The LC50 values of the extract against M. domestica tested by direct and indirect contact methods were 0.0064 ± 0.0005 mg/larva and 0.0165 ± 0.0002 mg/cm2/larva, respectively. In the case of C. megacephala, the LC50 value determined by the indirect contact method was 1.0500 ± 0.0001 mg/cm2/larva. The ethanolic root extract of S. collinsiae was able to kill the larvae of both species after dermal administration. It is of interest to develop S. collinsiae root extract as a natural fly control biopesticide.

Furfural Derivatives and Phenolic Constituents in Stemona tuberosa Lour.

Chemical investigation on the water-soluble constituents of Stemona tuberosa Lour. resulted in the isolation of a previously undescribed furfural derivative namely (S)-5-((R)-hydroxy(5-(hydroxymethyl)furan-2-yl)methyl)-5-methylfuran-2(5H)-one and twenty-five known compounds from the water decoction of the dried root tubers. Their structures were determined by analysis of the extensive spectroscopic data, including 1D/2D NMR, HR-ESI-MS, and ORD, as well as the ECD simulation and comparison. Most of them were phenolic and among them, four compounds were isolated from Stemona plants for the first time. This study uncovers diverse constituents from water decoction of S. tuberosa dedicated for its quality control and allows for the exploitation of chemical markers with potential significance for discrimination of Stemona plants.

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.

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.

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.

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.

The Complete Chloroplast Genome of Endangered Species Stemona parviflora: Insight into the Phylogenetic Relationship and Conservation Implications.

Stemona parviflora is an endangered species, narrowly endemic to Hainan and Southwest Guangdong. The taxonomic classification of S. parviflora remains controversial. Moreover, studying endangered species is helpful for current management and conservation. In this study, the first complete chloroplast genome of S. parviflora was assembled and compared with other Stemona species. The chloroplast genome size of S. parviflora was 154,552 bp, consisting of 87 protein-coding genes, 38 tRNA genes, 8 rRNA genes, and one pseudogene. The ψycf1 gene was lost in the cp genome of S. sessilifolia, but it was detected in four other species of Stemona. The inverted repeats (IR) regions have a relatively lower length variation compared with the large single copy (LSC) and small single copy (SSC) regions. Long repeat sequences and simple sequence repeat (SSR) were detected, and most SSR were distributed in the LSC region. Codon usage bias analyses revealed that the RSCU value of the genus Stemona has almost no difference. As with most angiosperm chloroplast genomes, protein-coding regions were more conservative than the inter-gene spacer. Seven genes (atpI, ccsA, cemA, matK, ndhA, petA, and rpoC1) were detected under positive selection in different Stemona species, which may result from adaptive evolution to different habitats. Phylogenetic analyses show the Stemona cluster in two main groups; S. parviflora were closest to S. tuberosa. A highly suitable region of S. parviflora was simulated by Maxent in this study; it is worth noting that the whole territory of Taiwan has changed to a low fitness area and below in the 2050 s, which may not be suitable for the introduction and cultivation of S. parviflora. In addition, limited by the dispersal capacity of S. parviflora, it is necessary to carry out artificial grafts to expand the survival areas of S. parviflora. Our results provide valuable information on characteristics of the chloroplast genome, phylogenetic relationships, and potential distribution range of the endangered species S. parviflora.

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.

Stilbenoids from the roots of Stemona tuberosa.

Two new stilbenoids, stemobenoids A (1) and B (2), together with three known compounds were obtained from the roots of Stemona tuberosa. The structures of the new compounds were established by extensive spectroscopic analysis, including HRMS, 1D and 2D NMR data. Compounds 1 and 2 displayed potent quinone reductase inducing activity in Hepa 1c1c7 cells.

Revised Structures of Dehydrostenines A and B: Total Syntheses of (±)-Dehydrostenine A and Structure Assigned to Dehydrostenine B.

The first total syntheses of the Stemona alkaloid dehydrostenine A and the structure assigned to dehydrostenine B have been completed from a simple pyrrole substrate in 10 and 11 steps, respectively. Two independent Brønsted-acid-mediated intramolecular Michael additions were exploited to construct the tetracyclic dehydrostenine core. As a result of synthetic studies and associated analysis of the relevant literature, revisions of the structures originally assigned to dehydrostenines A and B are proposed.

Synthesis of the Proposed Structures of Parvistemoamide and Their Transformations to Stemoamide Derivatives.

The proposed structures of parvistemoamide have been achieved by macrolactamization, but none of the characterization data of synthetic samples matched with those of the natural sample. The transformation of the highly strained 10-membered lactam ring in parvistemoamide into the pyrrolo[1,2-a]-azepine nucleus in stemoamide is accomplished for the first time by either transannular cyclization or Pilli's transformation. This research may promote the total synthesis of other more complex stemoamide-type or medium-sized-ring-containing Stemona alkaloids.

Comparative genome analysis revealed gene inversions, boundary expansions and contractions, and gene loss in the Stemona sessilifolia (Miq.) Miq. chloroplast genome.

Stemona sessilifolia (Miq.) Miq., commonly known as Baibu, is one of the most popular herbal medicines in Asia. In the Chinese Pharmacopoeia, Baibu has multiple authentic sources and there are many similar herbs sold as Baibu in herbal medicine markets. The existence of counterfeits of Baibu brings challenges to its identification. To assist in its accurate identification, we sequenced and analyzed the complete chloroplast genome of S. sessilifolia using next-generation sequencing technology. The genome was found to be 154,037 bp in length, possessing a typical quadripartite structure consisting of a pair of inverted repeats (IRs: 27,090 bp) separated by a large single copy (LSC: 81,949 bp) and a small single copy (SSC: 17,908 bp). A total of 112 unique genes were identified, including 80 protein-coding, 28 transfer RNA and four ribosomal RNA genes. In addition, 45 tandem, 27 forward, 23 palindromic and 104 simple sequence repeats were detected in the genome by repeated analysis. Compared with its counterfeits (Asparagus officinalis and Carludovica palmata) we found that IR expansion and SSC contraction events of S. sessilifolia resulted in two copies of the rpl22 gene in the IR regions and a partial duplication of the ndhF gene in the SSC region. An approximately 3-kb-long inversion was also identified in the LSC region, leading to the petA and cemA genes being presented in the complementary strand of the chloroplast DNA molecule. Comparative analysis revealed some highly variable regions, including trnF-GAA_ndhJ, atpB_rbcL, rps15_ycf1, trnG-UCC_trnR-UCU, ndhF_rpl32, accD_psaI, rps2_rpoC2, trnS-GCU_trnG-UCC, trnT-UGU_trnL-UAA and rps16_trnQ-UUG. Finally, gene loss events were investigated in the context of phylogenetic relationships. In summary, the complete plastome of S. sessilifolia will provide valuable information for the distinction between Baibu and its counterfeits and assist in elucidating the evolution of S. sessilifolia.

Tailored Synthesis of Skeletally Diverse Stemona Alkaloids through Chemoselective Dyotropic Rearrangements of ß-Lactones.

The collective synthesis of skeletally diverse Stemona alkaloids featuring tailored dyotropic rearrangements of ß-lactones as key elements is described. Specifically, three typical 5/7/5 tricyclic skeletons associated with stemoamide, tuberostemospiroline and parvistemonine were first accessed through chemoselective dyotropic rearrangements of ß-lactones involving alkyl, hydrogen, and aryl migration, respectively. By the rational manipulation of substrate structures and reaction conditions, these dyotropic rearrangements proceeded with excellent efficiency, good chemoselectivity and high stereospecificity. Furthermore, several polycyclic Stemona alkaloids, including saxorumamide, isosaxorumamide, stemonine and bisdehydroneostemoninine, were obtained from the aforementioned tricyclic skeletons through late-stage derivatizations. A novel visible-light photoredox-catalyzed formal [3+2] cycloaddition was also developed, which offers a valuable tool for accessing oxaspirobutenolide and related scaffolds.

Discovery of a potent ß-catenin destabilizer for overcoming the resistance of 5-fluorouracil in colorectal cancer.

Wnt/ß-catenin signalling is frequently activated in colorectal cancer, in which nuclear ß-catenin accumulation contributes to tumour initiation and progression. However, therapeutic agents in clinical use targeting this pathway are lacking. In this report, we describe the synthesis of novel stemona alkaloid analogues and their biological evaluation, among which compound 3 was identified to efficiently inhibit various CRC cells, including 5-fluorouracil-resistant CRC cells. Mechanistically, this study revealed that compound 3 reduced the protein level of ß-catenin without affecting its mRNA level, which suggests an alternative mechanism for ß-catenin degradation. The expression of downstream proteins, including c-myc, survivin, and cyclin D1, was also significantly inhibited, even in Wnt-activated CRC cells. Briefly, our data highlight the potential of compound 3 as a destabilizer of ß-catenin for the treatment of CRC patients.