Disproof of the Structures and Biosynthesis of Ergoynes, Gs-Polyyne-l-Ergothioneine Cycloadducts from Gynuella sunshinyii YC6258.

Some bacteria produce "bacterial polyynes" bearing a conjugated C≡C bond that starts with a terminal alkyne. Ergoynes A and B have been reported as sulfur-containing metabolites from Gynuella sunshinyii YC6258. These compounds were thought to be formed by cycloaddition between a bacterial polyyne (named Gs-polyyne) and l-ergothioneine. The biosynthetic gene clusters (BGCs), which may contribute to their synthesis, were present in the YC6258 genome. The biosynthetic origin of Gs-polyyne is interesting considering its rare 2-isopentyl fatty acyl skeleton. Here, the structures and biosynthesis of Gs-polyyne and ergoynes were verified by analytical, chemical, and genetic techniques. In the YC6258 extract, which was prepared considering their instability, Gs-polyyne was detected as a major LC peak, and ergoynes were not detected. The NMR data of the isolated Gs-polyyne contradicted the proposed structure and identified it as the previously reported protegenin A. The expression of Gs-polyyne BGC in Escherichia coli BL21(DE3) also yielded protegenin A. The cyclization between protegenin A and l-ergothioneine did not proceed during sample preparation; a base, such as potassium carbonate, was required. Overall, Gs-polyyne was identified as protegenin A, while ergoynes were determined to be artifacts. This cyclization may provide a derivatization to stabilize polyynes or create new chemical space.

Artemdubosides A-G, seven unusual polyacetylenes from Artemisia dubia var. subdigitata and their antihepatoma activity.

Artemdubosides A-E (1-5), the first examples of natural polyacetylenes substituted by 6'-O-crotonyl ß-glucopyranoside, and artemdubosides F-G (6-7) that were two unusual polyacetylenes featuring a 6'-O-acetyl ß-glucopyranoside moiety, were isolated from Artemisia dubia var. subdigitata. Their structures were elucidated based on the spectral data including HRESIMS, UV, IR, 1D and 2D NMR, and ECD calculations. Antihepatoma assay suggested that compound 1 exhibited activity against HepG2, Huh7, and SK-Hep-1 cells with inhibitory ratios of 77.1%, 90.8%, and 73.1% at 200.0 µM, respectively.

Polyacetylenes from Saposhnikovia divaricata and their anticancer activity.

Nine polyacetylenes, including five new compounds named sadivaethynes E-I (1-5), were isolated from the roots of Saposhnikovia divaricata. Structural elucidation of compounds 1-5 was established by extensive spectroscopic analysis, quantum chemical calculations and DP4+ probability analysis. Among them, the absolute configuration of compound 1-2, 4-5 was unambiguous determined by ECD. Also, all compounds were evaluated for cytotoxicity against two human cancer cell lines (A549, HEPG2) in vitro, compound 9 showed moderate inhibitory effect with an IC50 value of 11.66 µM against HEPG2.

Polyacetylene-Based Asymmetric Bicyclic Polymer by Blocking-Cyclization Technique.

A rare asymmetric bicyclic polymer containing different length of conjugated polyacetylene segments is synthesized by metathesis cyclopolymerization-mediated blocking-cyclization technique. The size of each single ring differs from each other, and the unique cyclic polymer topology is controlled by adjusting the feed ratio of monofunctional monomer to catalyst. The topological difference between linear and bicyclic polymers is confirmed by several techniques, and the visualized morphology of asymmetric bicyclic polymer is directly observed without tedious post-modification process. The photoelectric and thermal properties of polymers are investigated. This work expands the pathway for the derivation of cyclic polymers, and such unique topological structure enriches the diversity of cyclic polymer classes.

Neuroinflammation and Acetylcholinesterase Inhibitory Potentials of a Spiroketal-Enol Ether Polyyne Isolated from Artemisia pallens Wall. ex DC.

Artemisia pallens Wall. ex DC (Asteraceae) is cultivated for the production of high-value essential oil from its aerial biomass. In this study, the chemical composition of the root (crop-residue) essential oil was investigated for the first time, using column-chromatography, GC-FID, GC-MS, LC-QTOF, and NMR techniques, which led to the identification of twenty constituents, with isolation of (E)-2-(2',4'-hexadiynylidene)-1,6-dioxaspiro [4.5]dec-3-ene (D6). The D6 was evaluated in vitro for neuroinflammation and acetylcholinesterase inhibitory potential. It showed inhibition of neuroinflammation in a concentration-dependent manner with significant inhibition of pro-inflammatory cytokines (TNF-α and IL-6) in LPS-stimulated BV2 microglial cells. D6 did not have any significant effect on the viability of the cells at the therapeutic concentrations. D6 also has shown acetylcholinesterase inhibitory potential (51.90±1.19 %) at the concentration of log 106  nM. The results showed that D6 has a potential role in the resolution of neuroinflammation, and its acetylcholinesterase inhibitory potential directs further investigation of its role in the management of Alzheimer's disease-related pathogenesis.

A naturally occurring polyacetylene isolated from carrots promotes health and delays signatures of aging.

To ameliorate or even prevent signatures of aging in ultimately humans, we here report the identification of a previously undescribed polyacetylene contained in the root of carrots (Daucus carota), hereafter named isofalcarintriol, which we reveal as potent promoter of longevity in the nematode C. elegans. We assign the absolute configuration of the compound as (3 S,8 R,9 R,E)-heptadeca-10-en-4,6-diyne-3,8,9-triol, and develop a modular asymmetric synthesis route for all E-isofalcarintriol stereoisomers. At the molecular level, isofalcarintriol affects cellular respiration in mammalian cells, C. elegans, and mice, and interacts with the α-subunit of the mitochondrial ATP synthase to promote mitochondrial biogenesis. Phenotypically, this also results in decreased mammalian cancer cell growth, as well as improved motility and stress resistance in C. elegans, paralleled by reduced protein accumulation in nematodal models of neurodegeneration. In addition, isofalcarintriol supplementation to both wild-type C57BL/6NRj mice on high-fat diet, and aged mice on chow diet results in improved glucose metabolism, increased exercise endurance, and attenuated parameters of frailty at an advanced age. Given these diverse effects on health parameters in both nematodes and mice, isofalcarintriol might become a promising mitohormesis-inducing compound to delay, ameliorate, or prevent aging-associated diseases in humans.

Polyacetylene Derivatives from the Polypore Fungus (Fistulina hepatica, Agaricomycetes) and Their Antimicrobial Activity.

Chemical investigation of the polypore fungus Fistulina hepatica resulted in the isolation of five compounds, including four new polyacetylenic fatty acid derivatives - isocinnatriacetin B (1), isocinnatriacetin A (2), cinna-triacetin C (3) and ethylcinnatriacetin A (4) together with one known polyacetylene fatty acid derivative - cinnatriacetin A (5). The structures were elucidated using spectroscopic methods (UV, NMR, HR-ESIMS) along with comparison to literature data. Antibacterial activity screening of compounds 1-5 against ESKAPE bacterial strains in vitro with zones of inhibition (ZOI) was performed and MIC values were established for the most active compounds (3 and 4). Together with that morphological and growth parameters under solid-phase cultivation were also researched.

Structures and Biosynthesis of Caryoynencins, Unstable Bacterial Polyynes from Pseudomonas protegens Recombinant Expressing the cayG Gene.

Bacteria in certain genera can produce "bacterial polyynes" that contain a conjugated C≡C bond starting from a terminal alkyne. Protegenin A is a derivative of octadecanoic acid that contains an ene-tetrayne moiety. It was discovered in Pseudomonas protegens Cab57 and exhibits strong antioomycete and moderate antifungal activity. By introducing cayG, a cytochrome P450 gene from Burkholderia caryophylli, into P. protegens Cab57, protegenin A was converted into more complex polyynes, caryoynencins A-E. A purification method that minimized the degradation and isomerization of caryoynencins was established. For the first time, as far as we know, the 1H and 13C{1H} NMR signals of caryoynencins were completely assigned by analyzing the NMR data of the isolated compounds and protegenin A enriched with [1-13C]- or [2-13C]-acetate. Through the structural analysis of caryoynencins D/E and bioconversion experiments, we observed that CayG constructs the allyl alcohol moiety of caryoynencins A-C through sequential hydroxylation, dehydration, and hydroxylation. The recombinant strain exhibited a stronger antioomycete activity compared to the wild-type strain. This paper proposes a stable purification and structural determination method for various bacterial polyynes, and P. protegens Cab57 holds promise as an engineering host for the production of biologically active polyynes.

Thermochromic Behavior of Polydiacetylene Nanomaterials Driven by Charged Peptide Amphiphiles.

The tunability of chromatic phases adapted by chromogenic polymers such as polydiacetylene (PDA) is key to their utility for robust sensing applications. Here, we investigated the influence of charged peptide interactions on the structure-dependent thermochromicity of amphiphilic PDAs. Solid-state NMR and circular dichroism analyses show that our oppositely charged peptide-PDA samples have distinct degrees of structural order, with the coassembled sample being in between the ß-sheet-like positive peptide-PDA and the relatively disordered negative peptide-PDA. All solutions exhibit thermochromicity between 20 and 80 °C, whereby the hysteresis of the blue, planar phase is much larger than that of the red, twisted phase. Resonance Raman spectroscopy of films demonstrates that only coassemblies with electrostatic complementarity stabilize coexisting blue and red PDA phases. This work reveals the nature of the structural changes responsible for the thermally responsive chromatic transitions of biomolecule-functionalized polymeric materials and how this process can be directed by sequence-dictated electrostatic interactions.

Polyacetylenes with xanthine oxidase inhibitory activity from the medicinal and edible fruits of Cyclocodon lancifolius (Roxburgh) Kurz.

Five new polyacetylene derivatives (1-5), cyclocodonlandiynosides A-E, and eight known analogues (6-13) were isolated and identified from the fruits of Cyclocodon lancifolius. Their structures were established via spectroscopic and chemical methods, including NMR, HRESIMS, enzymatic hydrolysis, Mo2(OAc)4-induced circular dichroism and sugar derivatization. Compound 1 contains a nitrogenous fragment, which was rarely found in C14 polyacetylenes. Compounds 3 and 4 are polyacetylene glucosides possessing novel aglycones. All the isolated polyacetylenes (except 12) were screened for their xanthine oxidase (XO) inhibitory activity. All the tested compounds, at the concentration of 62.5 µg/mL, showed XO inhibiting effects. Among them, 13 and 3 showed the most potent XO inhibitory activity with IC50 values of 87.65 and 96.32 µM, compared to the positive control allopurinol with an IC50 value of 19.25 µM.

Design, Synthesis, and Antifungal Activity of Polyacetylenic Alcohol Derivatives and Stereoisomers against Phytopathogenic Fungi.

Falcarindiol is active against phytopathogenic fungi. In the present study, racemic falcarindiol analogs (8a-8q) were designed, synthesized, and tested for their activities against eight economically significant phytopathogenic fungal species. The compound 8o displayed the best antifungal activities and up to 54.6-fold in vitro potency improvement against Phytophthora capsici than the natural product stipudiol. Its half-maximum effective concentrations ranged from 4 to 23 µg/mL against all tested fungal species. Racemic 8o was 195-fold more potent than the fungicide carbendazim against P. capsici in vitro. The isomer (1S, 6S)-8o exhibited an EC50 of 1.10 and 2.70 µg/mL against Monilia fructigena and P. capsici, respectively, which was 47 and 11 times lower than (1R, 6S)-8o and (1S, 6R)-8o. In addition, in vivo bioassay results showed that (1S, 6S)-8o had high antifungal activity against infection of M. fructigena and P. capsici to apricot and pepper fruits and pepper plants, which the efficacy was similar or better than carbendazim. The high potency and selectivity of 8o stereoisomers against the phytopathogens warrant an interest in elucidating the molecular target for fungicide development.

Substituent Effects from the Point of View of Energetics and Molecular Geometry in Acene, Polyene, and Polyyne Derivatives.

The substituent effect (SE) is one of the most important topics in organic chemistry and related fields, and Hammett constants (σ) are commonly used to describe it. The results of the computational studies carried out for Y-R-X systems (reaction sites Y = NO2, O-; substituents X = NO2, CN, Cl, H, OH, NH2; spacers R = polyene, polyyne, acene with n = 1-5 repeatable units) show that the substituent properties depend significantly on n, the type of R, and Y. Results of the analysis of the substituent effect stabilization energy and geometrical parameters of the Y-R-X systems reveal that (i) the SE strength and its inductive and resonance components decay with the increase in spacer length, its weakening depends on the Y and R type; quantitative relations describing decay are presented; (ii) the ratio between inductive and resonance effect strength changes with n and depends on Y; (iii) differences in the substituents' properties are examples of reverse SE; (iv) in general, structural parameters are mutually well correlated as well as with the SE descriptors; (v) due to the strong O- resonance effect, the changes in π-electron delocalization within R are well correlated with the SE strength only for Y = O- systems.

In Vitro and In Silico Investigation of Polyacetylenes from Launaea capitata (Spreng.) Dandy as Potential COX-2, 5-LOX, and BchE Inhibitors.

Diverse secondary metabolites are biosynthesized by plants via various enzymatic cascades. These have the capacity to interact with various human receptors, particularly enzymes implicated in the etiology of several diseases. The n-hexane fraction of the whole plant extract of the wild edible plant, Launaea capitata (Spreng.) Dandy was purified by column chromatography. Five polyacetylene derivatives were identified, including (3S,8E)-deca-8-en-4,6-diyne-1,3-diol (1A), (3S)-deca-4,6,8-triyne-1,3-diol (1B), (3S)-(6E,12E)-tetradecadiene-8,10-diyne-1,3-diol (2), bidensyneoside (3), and (3S)-(6E,12E)-tetradecadiene-8,10-diyne-1-ol-3-O-ß-D-glucopyranoside (4). These compounds were investigated for their in vitro inhibitory activity against enzymes involved in neuroinflammatory disorders, including cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX), and butyrylcholinesterase (BchE) enzymes. All isolates recorded weak-moderate activities against COX-2. However, the polyacetylene glycoside (4) showed dual inhibition against BchE (IC50 14.77 ± 1.55 µM) and 5-LOX (IC50 34.59 ± 4.26 µM). Molecular docking experiments were conducted to explain these results, which showed that compound 4 exhibited greater binding affinity to 5-LOX (-8.132 kcal/mol) compared to the cocrystallized ligand (-6.218 kcal/mol). Similarly, 4 showed a good binding affinity to BchE (-7.305 kcal/mol), which was comparable to the cocrystallized ligand (-8.049 kcal/mol). Simultaneous docking was used to study the combinatorial affinity of the unresolved mixture 1A/1B to the active sites of the tested enzymes. Generally, the individual molecules showed lower docking scores against all the investigated targets compared to their combination, which was consistent with the in vitro results. This study demonstrated that the presence of a sugar moiety (in 3 and 4) resulted in dual inhibition of 5-LOX and BchE enzymes compared to their free polyacetylenes analogs. Thus, polyacetylene glycosides could be suggested as potential leads for developing new inhibitors against the enzymes involved in neuroinflammation.

Elemane-Type Sesquiterpene, Acetonide Derived Polyacetylene and Other Constituents from the Whole Plant of Gymnanthemum theophrastifolium (Schweinf. ex Oliv. & Hiern) H.Rob. and Their Chemophenetic Significance.

The chemical investigation of the methanol extract of the whole plant of Gymnanthemum theophrastifolium (Schweinf. ex Oliv. & Hiern) H.Rob. (Asteraceae) led to the isolation of a new elemane-type sesquiterpene (1), a new acetonide derived polyacetylene (2) and a naturally occurring compound (3) from the plant kingdom along with sixteen known compounds (4-19). Their structures were elucidated by extensive NMR and MS analysis. This is the first report on the chemical constituents of G. theophrastifolium. Furthermore, compounds 12, 13, and 14 are reported for the first time from the family Asteraceae, while compound 9 is reported for the first time from the genus Gymnanthemum. Thus, the present results provide valuable insights to the chemophenetic knowledge of G. theophrastifolium, which is also discussed in this work.

Polyacetylene Isomers Isolated from Bidens pilosa L. Suppress the Metastasis of Gastric Cancer Cells by Inhibiting Wnt/ß-Catenin and Hippo/YAP Signaling Pathways.

(E)-7-Phenyl-2-hepten-4,6-diyn-1-ol (1) and (Z)-7-Phenyl-2-hepten-4,6-diyn-1-ol (2) are isomeric natural polyacetylenes isolated from the Chinese medicinal plant Bidens pilosa L. This study first revealed the excellent anti-metastasis potential of these two polyacetylenes on human gastric cancer HGC-27 cells and the distinctive molecular mechanisms underlying their activities. Polyacetylenes 1 and 2 significantly inhibited the migration, invasion, and adhesion of HGC-27 cells at their non-toxic concentrations in a dose-dependent manner. The results of a further mechanism investigation showed that polyacetylene 1 inhibited the expressions of Vimentin, Snail, ß-catenin, GSK3ß, MST1, YAP, YAP/TAZ, and their phosphorylation, and upregulated the expression of E-cadherin and p-LATS1. In addition, the expressions of various downstream metastasis-related proteins, such as MMP2/7/9/14, c-Myc, ICAM-1, VCAM-1, MAPK, p-MAPK, Sox2, Cox2, and Cyr61, were also suppressed in a dose-dependent manner. These findings suggested that polyacetylene 1 exhibited its anti-metastasis activities on HGC-27 cells through the reversal of the EMT process and the suppression of the Wnt/ß-catenin and Hippo/YAP signaling pathways.

Carrot Intake and Risk of Developing Cancer: A Prospective Cohort Study.

A prospectively followed Danish cohort of 55,756 citizens with an observation time upwards of 25 years was investigated for association between eating raw carrots on a regular basis and developing various adenocarcinoma-dominant cancers and leukemia. Mean age at inclusion was 56.2 years (SD 4.4 years), and 52% were females. A dose-dependent reduction in incidence was seen for cancer of the lung (HR 0.76, CI95% 0.66; 0.87) and pancreas (HR 0.79, CI95% 0.61; 1.03), as well as leukemia (HR 0.91, CI95% 0.68; 1.21). Only for lung cancer was the association significant. In the case of pancreatic cancer, a possible type 1 error was present due to a low number of cancers. In cases of breast and prostate cancer, no association and no dose response were demonstrated. The association seen for lung and pancreatic cancer parallels that earlier demonstrated for large bowel cancer and indicates a cancer-protective effect from daily intake of raw carrots not limited to gastrointestinal adenocarcinomas. Processed carrots exhibited no effect. The preventive effect could be due to the polyacetylenic compounds falcarinol and falcarindiol in carrots, whereas carotene may not have an effect. The polyacetylenes are inactivated by heating, supporting our findings that only raw carrot intake has an effect. Indirect evidence for the cancer preventive effect of carrots in humans has reached a level where a prospective human trial is now timely.

Polyacetylenic caffeoyl amides from Ammodaucus leucotrichus.

Six undescribed polyacetylenic caffeoyl amides, five known flavones and three known lignans were obtained from the fruits of the North African traditional medicinal plant Ammodaucus leucotrichus Coss. & Durieu (Apiaceae). Isolation was achieved by a combination of chromatographic methods, and structures were established by extensive 1D and 2D NMR spectroscopy, mass spectrometry, electronic circular dichroism, and by GC-MS analysis of sugar derivatives. Polyacetylenic caffeoyl amides are reported for the first time as specialized metabolites.

Advances in Polyynes to Model Carbyne.

The formation and study of molecules that model the sp-hybridized carbon allotrope, carbyne, is a challenging field of synthetic physical organic chemistry. The target molecules, oligo- and polyynes, are often the preferred candidates as models for carbyne because they can be formed with monodisperse lengths as well as defined structures. Despite a simple linear structure, the synthesis of polyynes is often far from straightforward, due in large part to a highly conjugated framework that can render both precursors and products highly reactive, i.e., kinetically unstable. The vast majority of polyynes are formed as symmetrical products from terminal alkynes as precursors via an oxidative, acetylenic homocoupling reaction based on the Glaser, Eglinton-Galbraith, and Hay reactions. These reactions are very efficient for the synthesis of shorter polyynes (e.g., hexaynes and octaynes), but yields often drop dramatically as a function of length for longer derivatives, usually starting with the formation of decaynes. The most effective approach to circumvent unstable precursors and products has been through the incorporation of sterically demanding end groups that serve to "protect" the polyyne skeleton. This approach was arguably identified in the early 1950s by Bohlmann and co-workers with the synthesis of tBu-end-capped polyynes. During the next 50 years, a polyyne with 14 contiguous alkyne units remained the longest isolated derivative until 2010, when the record was extended to 22 alkyne units. The record length was broken again in 2020, when a polyyne consisting of 24 alkynes was isolated and characterized. Beyond polyynes, there have been several reports describing the potential synthesis of carbyne, but conclusive characterization and proof of structure have been tenuous. The sole example of synthetic carbyne arises from synthesis within carbon nanotubes, when chains of thousands of sp carbon atoms have been linked to form polydisperse samples of carbyne. Thus, model compounds for carbyne, the polyynes, remain the best means to examine and predict the experimental structure and properties of this carbon allotrope.This Account will discuss the general synthesis of polyynes using homologous series of polyynes with up to 10 alkyne units as examples (decaynes). The limited number of specific syntheses of series with longer polyynes will then be presented and discussed in more detail based on end groups. The monodisperse polyynes produced from these synthetic efforts are then examined toward providing our best extrapolations for the expected characteristics for carbyne based on 13C NMR spectroscopy, UV-vis spectroscopy, X-ray crystallography, and Raman spectroscopy.

Effects of Structural Variations on Antibacterial Properties for Conjugated Diynes Generated through Glaser Hay Couplings.

Antibiotic resistance is a growing problem facing global societies today. Many new antibiotics are derivatized versions of already existing antibiotics, which allows for antibiotic resistance to arise. To combat this issue, new antibiotics with different core structures need to be elucidated. Asymmetrical polyacetylenes have been isolated from natural products and they have previously been demonstrated to exhibit antimicrobial and antibacterial activity; however, their synthetic preparation has not made them easily amenable to rapid derivatization for SAR studies. Using a combination of solution and solid-supported chemistries, an array of diynes inspired by a known natural product were prepared and assessed for antibacterial activity. Ultimately, several compounds were identified with improved activity in bacterial viability assays. Moreover, some compounds were discovered that displayed a degree of specificity for E. coli over P. fluorescens and vice versa. These new compounds show promise, and further investigation is needed to pinpoint the specific structural components that elicit biological activity.

A molecular phenotypic screen reveals that lobetyolin alleviates cardiac dysfunction in 5/6 nephrectomized mice by inhibiting osteopontin.

BACKGROUND: Cardiovascular diseases are the major cause of mortality in patients with advanced chronic kidney diseases. The predominant abnormality observed among this population is cardiac dysfunction secondary to myocardial remodelings, such as hypertrophy and fibrosis, emphasizing the need to develop potent therapies that maintain cardiac function in patients with end-stage renal disease. AIMS: To identify potential compounds and their targets as treatments for cardiorenal syndrome type 4 (CRS) using molecular phenotyping and in vivo/in vitro experiments. METHODS: Gene expression was assessed using bioinformatics and verified in animal experiments using 5/6 nephrectomized mice (NPM). Based on this information, a molecular phenotyping strategy was pursued to screen potential compounds. Picrosirius red staining, wheat germ agglutinin staining, Echocardiography, immunofluorescence staining, and real-time quantitative PCR (qPCR) were utilized to evaluate the effects of compounds on CRS in vivo. Furthermore, qPCR, immunofluorescence staining and flow cytometry were applied to assess the effects of these compounds on macrophages/cardiac fibroblasts/cardiomyocytes. RNA-Seq analysis was performed to locate the targets of the selected compounds. Western blotting was performed to validate the targets and mechanisms. The reversibility of these effects was tested by overexpressing Osteopontin (OPN). RESULTS: OPN expression increased more remarkably in individuals with uremia-induced cardiac dysfunction than in other cardiomyopathies. Lobetyolin (LBT) was identified in the compound screen, and it improved cardiac dysfunction and suppressed remodeling in NPM mice. Additionally, OPN modulated the effect of LBT on cardiac dysfunction in vivo and in vitro. Further experiments revealed that LBT suppressed OPN expression via the phosphorylation of c-Jun N-terminal protein kinase (JNK) signaling pathway. CONCLUSIONS: LBT improved CRS by inhibiting OPN expression through the JNK pathway. This study is the first to describe a cardioprotective effect of LBT and provides new insights into CRS drug discovery.