Biosynthesis and function of polyacetylenes and allied natural products

Topical Application of Oxylipin (3S)-16,17-Didehydrofalcarinol in Mice Infected with Leishmania mexicana: A Possible Treatment for Localized Cutaneous Leishmaniasis

Pentavalent antimonials are the first-line treatment for localized cutaneous leishmaniasis. However, they have disadvantages such as their elevated toxicity, high costs, and parenteral application. Plant-derived compounds may be an alternative treatment against this disease. Previous in vitro studies have shown that (3S)-16,17-didehydrofalcarinol (1), a polyacetylene oxylipin isolated from Tridax procumbens, is active against Leishmania mexicana. We have analyzed the mechanism of action of compound 1, evaluating reactive oxygen species production, apoptosis of L. mexicana, cytotoxicity in murine macrophages, and its efficacy in controlling the disease progression and parasite load when applied topically in C57BL/6 mice infected with L. mexicana. Results show that parasites incubated with 1.6 μM compound 1 significantly increased reactive oxygen species production (p ≤ 0.05). The percentage of apoptosis also increased significantly (p ≤ 0.05) and did not affect the viability of macrophages. The application of the topical formulations with 0.5% and 0.75% compound 1 for 7 weeks reduced disease progression and parasite load. We demonstrate that compound 1 generates the death of L. mexicana by apoptosis through reactive oxygen species production. We conclude that compound 1 can be used a possible alternative treatment for localized cutaneous leishmaniasis, enabling a less painful and more accessible therapy.

Divergent fatty acid desaturase 2 is essential for falcarindiol biosynthesis in carrot

Carrots produce diverse falcarin-type polyacetylenes (PAs), which function as important antipathogenic phytoalexins and have potential as anticancer agents. Despite their abundance in carrot root tissues, the biosynthesis and evolutionary origins of falcarindiol, a C17-PA, remain unknown. Fatty acid desaturase 2 (FAD2) enzymes diversify PAs by introducing various double and/or triple carbon-carbon bonds into fatty acid chains. Here, we use association analysis to identify candidate FAD2 genes involved in falcarindiol biosynthesis. Using a rapid tobacco transient expression system, we found that DcFAD2 enzymes are highly functionally redundant and promiscuous. Combinatorial assays also revealed unexpected synergistic and redirective effects among FAD2 enzymes, further complicating the biosynthetic pathway. CRISPR-Cas9-mediated mutagenesis and overexpression studies identified previously overlooked DcFAD2 hub genes as essential for falcarindiol production. Evolutionary analysis suggests that the expansion of DcFAD2 genes underpins the abundance of falcarindiol in carrot, independent of the biosynthetic gene cluster previously identified in tomato. This work underscores the complexity of the falcarin biosynthetic network and identifies hub genes essential for falcarindiol biosynthesis in carrot.

The good fight: Minimedusa polyspora and Chaetomium globosum effectively antagonize phytopathogenic fungi in in vitro conditions

In this study, Minimedusa polyspora and Chaetomium globosum and their metabolites were assessed in vitro for their ability to inhibit growth of Alternaria alternata, Berkeleyomyces basicola, and Botrytis cinerea, gaining insights into their biocontrol mechanisms. A dual culture, an assay for volatile antimicrobial compounds effectiveness (performed in two different conditions), and a culture filtrate antifungal assay were designed to discriminate the involved mechanisms. Moreover, the culture filtrates of these strains were assessed for fungistatic and fungicidal activities (determining also the minimum inhibitory concentration and the minimum fungicidal concentration) and for the occurrence of siderophores. The results show that both M. polyspora and C. globosum inhibited, to different extents, growth of all the pathogens in the plate assays. Both culture filtrates showed fungistatic and fungicidal activities, pointing to the release of diffusible compounds as an involved biocontrol mechanism. Based on the results of this study, M. polyspora and C. globosum are promising bioprotection agents of these phytopathogens and species of interest for further studies aimed at validating their potential in in vivo conditions.

Chemical Analysis and Antioxidant Activities of Resin Fractions from Pistacia lentiscus L. var. Chia in Neuroblastoma SH-SY5Y Cells

Chios mastiha is the natural aromatic resin of Pistacia lentiscus L. var. Chia, Anacardiaceae, which is exclusively cultivated in the southern part of the Greek island of Chios. Chios mastiha (P. lenticonus/Chios mastiha) is well-known for its distinctive taste and aroma and has been known since ancient times due to its healing properties in gastrointestinal and inflammatory disorders and because of its anti-bacterial and anti-fungal activities. In this study, the chemical composition, applying LC-QTOF-MS/MS analysis, and the antioxidant activities of three different polarity P. lenticonus/Chios mastiha fractions, apolar, medium polar, and polar, were characterized in human neuroblastoma SH-SY5Y cells. Chemical analysis of the fractions unveiled new components of P. lenticonus/Chios mastiha, mainly fatty acids compounds, known for their antioxidant activity and regulatory effects on lipid metabolism. By applying the MTT assay and confocal microscopy analysis, we showed that P. lenticonus/Chios mastiha fractions, especially the apolar and medium polar fractions, enriched in triterpenes and fatty acids, caused suppression of the H2O2-induced reduction in cell viability, ROS production, and depolarization of the mitochondrial membrane potential, in SH-SY5Y cells. Moreover, Western blot analysis revealed that apolar fraction, enriched in fatty acids, induced expression of the PPARα, which is well-known for its antioxidant activities and its crucial role in lipid metabolism. Induction of PPARα, a GR target gene, was also accompanied by an increase in GR protein levels. Enhanced antioxidant activities of the apolar fraction may be correlated with its chemical composition, enriched in fatty acids and triterpenoids. Thus, our results indicate the neuroprotective actions of P. lenticonus/Chios mastiha fractions, highlighting their potential application as neuroprotective agents in neurodegenerative diseases.

Comparative Phytochemistry of Polyacetylenes of the Genus Artemisia (Asteraceae): Compounds with High Biological Activities and Chemotaxonomic Significance

In spite of the many chemical reports on polyacetylenes of the genus Artemisia, combined conclusions regarding their distribution and biological functions are widely missing. The aim of the present review was to arrange the diversity of polyacetylenes in the genus following biogenetic aspects and group them together into characteristic structural types. The co-occurrence of the dehydrofalcarinol type with the aromatic capillen-isocoumarin type represents a characteristic biogenetic trend, clearly segregating species of the subgenus Dracunculus from those of the subgenera Artemisia and Absinthium, distinguished by the spiroketal enol ether and/or linear triyne type. Various accumulation trends toward specific structures additionally contribute to a more natural species grouping within the subgenera. Biological activities were reported for all four structural types, ranging from antifungal, insecticidal, nematicidal, and cytotoxic properties to allelopathic effects. Of particular interest were their remarkable cytotoxic potencies, from which the very high values of dehydrofalcarin-3,8-diol may be associated with the pronounced affinity of this type to form extremely stable bonds to proteins acting in signaling pathways. The aromatic acetylene capillin inhibited the viability of various tumor cells in a dose- and time-dependent manner. Its potent apoptosis-inducing activity was induced via the mitochondrial pathway. A group of spiroketal enol ethers was identified as inhibitors of PMA-induced superoxide generation. Among them, the epoxide of the isovalerate ester exhibited the highest potency. The ecological impact of acetylene formation was made apparent by the allelopathic effects of DME of the linear triyne type, and the aromatic capillen by inhibiting seed germination and growth of widespread weeds.

Multi-platform comparison and phytochemical insights of Tripleurospermum taxa from Greece

The Tripleurospermum (L.) Sch.Bip, (Asteraceae) genus, comprises 30 to 40 species widely spread in the northern hemisphere, and across the Mediterranean region. Out of the seven taxa encountered in Greece, four can only be found in specific areas, with limited spread throughout the country. The current work describes the phytochemical investigation, using modern analytical techniques, of the differences between the aerial parts of T. tempskyanum and T. rosellum collected from two floristic regions of Greece (Lesvos isl. and Mt. Parnon) and the common chamomile (Matricaria recutita). GC-MS was first applied for the analysis of the essential oils and dichloromethane extracts, significantly differentiating M. recutita from the Tripleurospermum taxa. Afterwards, a fractionation of T. tempskyanum 's non-polar and polar extracts afforded their major compounds, thus assisting to the unambiguous distinction of different isomers of matricaria lactone, as well as the first-time isolation of demethyl brevisnosideyne. Finally, the polar extracts were analyzed by means of UPLC-Orbitrap-HRMS/MS, revealing similarities among the species, with profiles dominated by cinnamic and flavonoid derivatives and fatty acids, with quantitative differences being observed for specific groups of compounds. Overall, the current study provides novel insight on the phytochemical differentiation between the studied genera and species.

Identification of New Polyacetylenes from Dendropanax morbifera with PPAR-α Activity Study

Dendropanax morbifera Leveille is a traditional medicine used to treat migraine headache and dysmenorrhea. In this study, three polyacetylenes, methyl (10E,9R,16R)-16-acetoxy-9-hydroxyoctadeca-10,17-dien-12,14-diynoate (1), methyl (10E,9R,16S)-9,16-dihydroxyoctadeca-10-en-12,14-diynoate (2), and methyl (10Z,9R,16S)-9,16-dihydroxyoctadeca-10,17-dien-12,14-diynoate (3), were isolated from the aerial parts of D. morbifera, together with seven known compounds (4-10). Importantly, the isolates (6 and 8) were found in the family Araliaceae for the first time in this study. Compounds 1-10 were evaluated for their binding affinity to AMPK and CTSS receptors using in silico docking simulations. Only compound 7 increased the protein expression levels of PPAR-α, Sirt1, and AMPK when administered to HepG2 cells as a PPAR-α agonist. On the other hand, 7 did not produce any significant reduction in CTSS activity. This study could pave the way for the discovery of novel treatments from D. morbifera targeting PPAR-α and AMPK.

Natural and Bioinspired Lipidic Alkynylcarbinols as Leishmanicidal, Antiplasmodial, Trypanocidal, Fungicidal, Antibacterial, and Antimycobacterial Agents

The present review article recapitulates for the first time the antipathogenic biological data of a series of lipidic natural products and synthetic analogues thereof characterized by the presence in their structure of an alkynylcarbinol unit. The cytotoxic properties of such natural and bioinspired compounds have been covered by several literature overviews, but to date, no review article detailing their activity against pathogens has been proposed. This article thus aims at providing a comprehensive overview of the field including early studies from the 1970s and 1980s with a specific focus on results published from the late 1990s until nowadays. Publications presenting the data of almost 50 different natural products are reported. Detailed activities encompass the fields of leishmanicidal, antiplasmodial, trypanocidal, fungicidal, and mainly antibacterial and antimycobacterial compounds. The few published studies aimed at exploring the structure-activity relationship in these series are also described. Around 15 different synthetic analogues of natural products, selected among the most active reported, are also presented. The rare data available regarding the antipathogenic mode of action of these products are recalled, and finally, a comparative analysis of the available biological data is proposed with the aim of identifying the key structural determinants for the bioactivity against pathogens of these unusual compounds.

Enediyne natural product biosynthesis unified by a diiodotetrayne intermediate

Enediyne natural products are renowned for their potent cytotoxicities but the biosynthesis of their defining 1,5-diyne-3-ene core moiety remains largely enigmatic. Since the discovery of the enediyne polyketide synthase cassette in 2002, genome sequencing has revealed thousands of distinct enediyne biosynthetic gene clusters, each harboring the conserved enediyne polyketide synthase cassette. Here we report that (1) the products of this cassette are an iodoheptaene, a diiodotetrayne and two pentaynes; (2) the diiodotetrayne represents a common biosynthetic intermediate for all known enediynes; and (3) cryptic iodination can be exploited to increase enediyne titers. These findings establish a unified biosynthetic pathway for the enediynes, set the stage to further advance enediyne core biosynthesis and enable fundamental breakthroughs in chemistry, enzymology and translational applications of enediyne natural products.

One-Pot Synthesis of Terminal Alkynes from Alkenes

The direct synthesis of terminal alkynes from widely available terminal alkenes is an unmet challenge in organic synthesis. Here, we show that alkyl and aromatic terminal alkenes can be converted to the corresponding alkynes in a one-pot process consisting of a Ru-catalyzed dehydrogenative hydrosilylation, followed by an oxidative dehydrogenative reaction of the vinyl silane intermediate, enabled by the combination of PhIO with BF3. This formal alkene dehydrogenation reaction with commercially available reagents and under mild reaction conditions gives access to terminal alkynes in a simple manner, including acetylene.

Chemical structures, biological activities, and biosynthetic analysis of secondary metabolites of the Diatrypaceae family: A comprehensive review

The family Diatrypaceae is a less well-known group within the order Xylariales (Ascomycota). Initially, the focus on its metabolites was related to the pathogenicity of one of its members, Eutypa lata. To date, a total of 254 natural products have been identified from Diatrypaceae strains. These compounds include terpenoids, sterols, polyketones, phenols, and acetylene aromatic compounds, which have shown anticancer, cytotoxic, anti-inflammatory, antimicrobial, and antiviral activities. The complex and diverse structural types, along with the diverse bioactivities, highlight the potential of Diatrypaceae as a valuable source of bioactive natural products. In this review, a deep analysis of the biosynthesis of pimarane diterpenes and scoparasin-type cytochalasins is provided, coupled with a compilation of the biosynthetic pathways of aromatic acetylene compounds in filamentous fungi. This comprehensive review not only enhances our understanding of the natural product chemistry, biological activities, and biosynthesis of secondary metabolites from the Diatrypaceae family but also promotes the exploitation and development of important bioactive compounds and potential strains.

Genetic control of abiotic stress-related specialized metabolites in sunflower

BACKGROUND

Abiotic stresses in plants include all the environmental conditions that significantly reduce yields, like drought and heat. One of the most significant effects they exert at the cellular level is the accumulation of reactive oxygen species, which cause extensive damage. Plants possess two mechanisms to counter these molecules, i.e. detoxifying enzymes and non-enzymatic antioxidants, which include many classes of specialized metabolites. Sunflower, the fourth global oilseed, is considered moderately drought resistant. Abiotic stress tolerance in this crop has been studied using many approaches, but the control of specialized metabolites in this context remains poorly understood. Here, we performed the first genome-wide association study using abiotic stress-related specialized metabolites as molecular phenotypes in sunflower. After analyzing leaf specialized metabolites of 450 hybrids using liquid chromatography-mass spectrometry, we selected a subset of these compounds based on their association with previously known abiotic stress-related quantitative trait loci. Eventually, we characterized these molecules and their associated genes.

RESULTS

We putatively annotated 30 compounds which co-localized with abiotic stress-related quantitative trait loci and which were associated to seven most likely candidate genes. A large proportion of these compounds were potential antioxidants, which was in agreement with the role of specialized metabolites in abiotic stresses. The seven associated most likely candidate genes, instead, mainly belonged to cytochromes P450 and glycosyltransferases, two large superfamilies which catalyze greatly diverse reactions and create a wide variety of chemical modifications. This was consistent with the high plasticity of specialized metabolism in plants.

CONCLUSIONS

This is the first characterization of the genetic control of abiotic stress-related specialized metabolites in sunflower. By providing hints concerning the importance of antioxidant molecules in this biological context, and by highlighting some of the potential molecular mechanisms underlying their biosynthesis, it could pave the way for novel applications in breeding. Although further analyses will be required to better understand this topic, studying how antioxidants contribute to the tolerance to abiotic stresses in sunflower appears as a promising area of research.

Integrative analysis of transcriptome and metabolome reveals the sesquiterpenoids and polyacetylenes biosynthesis regulation in Atractylodes lancea (Thunb.) DC

Atractylodes lancea (Thunb.) is a perennial medicinal herb, with its dry rhizomes are rich in various sesquiterpenoids and polyacetylenes components (including atractylodin, atractylon and β-eudesmol). However, the contents of these compounds are various and germplasms specific, and the mechanisms of biosynthesis in A. lancea are still unknown. In this study, we identified the differentially expressed candidate genes and metabolites involved in the biosynthesis of sesquiterpenoids and polyacetylenes, and speculated the anabolic pathways of these pharmaceutical components by transcriptome and metabolomic analysis. In the sesquiterpenoids biosynthesis, a total of 28 differentially expressed genes (DEGs) and 6 differentially expressed metabolites (DEMs) were identified. The beta-Selinene is likely to play a role in the synthesis of atractylon and β-eudesmol. Additionally, the polyacetylenes biosynthesis showed the presence of 3 DEGs and 4 DEMs. Notably, some fatty acid desaturase (FAB2 and FAD2) significantly down-regulated in polyacetylenes biosynthesis. The gamma-Linolenic acid is likely involved in the biosynthesis of polyacetylenes and thus further synthesis of atractylodin. Overall, these studies have investigated the biosynthetic pathways of atractylodin, atractylon and β-eudesmol in A. lancea for the first time, and present potential new anchor points for further exploration of sesquiterpenoids and polyacetylenes compound biosynthesis pathways in A. lancea.

A review on the impact of TRAIL on cancer signaling and targeting via phytochemicals for possible cancer therapy

Anticancer therapies have been the continual pursuit of this age. Cancer has been ravaging all across the globe breathing not just threats but demonstrating them. Remedies for cancer have been frantically sought after. Few have worked out, yet till date, the available cancer therapies have not delivered a holistic solution. In a world where the search for therapies is levitating towards natural remedies, solutions based on phytochemicals are highly prospective attractions. A lot has been achieved with inputs from plant resources, providing numerous natural remedies. In the current review, we intensely survey the progress achieved in the treatment of cancer through phytochemicals-based programmed cell death of cancer cells. More specifically, we have further reviewed and discussed the role of phytochemicals in activating apoptosis via Tumor Necrosis Factor-Alpha-Related Apoptosis-Inducing Ligand (TRAIL), which is a cell protein that can attach to certain molecules in cancer cells, killing cancer cells. The objective of this review is to enlist the various phytochemicals that are available for specifically contributing towards triggering the TRAIL cell protein-mediated cancer therapy and to point out the research gaps that require future research motivation. This is the first review of this kind in this research direction.

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-β-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.

The Type of Grain Counts: Effectiveness of Three Essential Oil-Based Nanoemulsions against Sitophilus oryzae

Essential oil (EO)-based nanoemulsions (NEs) are promising grain protectants in the management of stored-product pests. However, the potential impact of the stored-grain species on the green insecticide effectiveness has been poorly studied. In this study, two concentrations of EO-based NEs from Carlina acaulis L., Mentha longifolia (L.) Huds., and Hazomalania voyronii (Jum.) Capuron were evaluated as insecticides against the major stored-product pest Sitophilus oryzae (L.) on barley, oats, and maize kernels. The C. acaulis EO-based NE applied at 1000 ppm on barley achieved the highest mortality, killing 94.4% of S. oryzae adults after a 7-day exposure, followed by 1000 ppm of H. voyronii EO-based NE (83.3%). The lowest mortality (1.1%) was recorded with 500 ppm of M. longifolia EO-based NE on maize after the same interval. All tested NEs exhibited elevated efficacy when applied on barley, while mortalities were lower on oats and maize. Furthermore, C. acaulis EO-based NE was the most effective when applied on all commodities, followed by H. voyronii and M. longifolia EO-based NEs. Overall, our results highlighted the significant impact of the stored cereal on the insecticidal effectiveness of EO-based NE used for stored-product pest control. Sitophilus oryzae adults on barley can be adequately controlled through the application of C. acaulis and H. voyronii EO-based NEs.

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.

An Overview of Potential Natural Photosensitizers in Cancer Photodynamic Therapy

Cancer is one of the main causes of death worldwide. There are several different types of cancer recognized thus far, which can be treated by different approaches including surgery, radiotherapy, chemotherapy or a combination thereof. However, these approaches have certain drawbacks and limitations. Photodynamic therapy (PDT) is regarded as an alternative noninvasive approach for cancer treatment based on the generation of toxic oxygen (known as reactive oxygen species (ROS)) at the treatment site. PDT requires photoactivation by a photosensitizer (PS) at a specific wavelength (λ) of light in the vicinity of molecular oxygen (singlet oxygen). The cell death mechanisms adopted in PDT upon PS photoactivation are necrosis, apoptosis and stimulation of the immune system. Over the past few decades, the use of natural compounds as a photoactive agent for the selective eradication of neoplastic lesions has attracted researchers' attention. Many reviews have focused on the PS cell death mode of action and photonanomedicine approaches for PDT, while limited attention has been paid to the photoactivation of phytocompounds. Photoactivation is ever-present in nature and also found in natural plant compounds. The availability of various laser light setups can play a vital role in the discovery of photoactive phytocompounds that can be used as a natural PS. Exploring phytocompounds for their photoactive properties could reveal novel natural compounds that can be used as a PS in future pharmaceutical research. In this review, we highlight the current research regarding several photoactive phytocompound classes (furanocoumarins, alkaloids, poly-acetylenes and thiophenes, curcumins, flavonoids, anthraquinones, and natural extracts) and their photoactive potential to encourage researchers to focus on studies of natural agents and their use as a potent PS to enhance the efficiency of PDT.

Genome Mining Discovery of Protegenins A-D, Bacterial Polyynes Involved in the Antioomycete and Biocontrol Activities of Pseudomonas protegens

Some bacteria uniquely produce "bacterial polyynes", which possess a conjugated C≡C bond starting with a terminal alkyne, and use them as chemical weapons against hosts and competitors. Pseudomonas protegens Cab57, a biocontrol agent against plant pathogens, has an orphan biosynthetic gene cluster for bacterial polyynes (named protegenins). In this study, the isolation, structure elucidation, and biological characterization of protegenins A-D are reported. The structures of protegenins A-D determined by spectroscopic and chemical techniques were octadecanoic acid derivatives possessing an ene-tetrayne, ene-triyne-ene, or ene-triyne moiety. The protegenins exhibited weak to strong antioomycete activity against Pythium ultimum OPU774. The deletion of proA, a protegenin biosynthetic gene, resulted in the reduction of the antioomycete activity of P. protegens. The Gac/Rsm system, a quorum sensing-like system of Pseudomonas bacteria, regulated the production of protegenins. The production profile of protegenins was dependent on the culturing conditions, suggesting a control mechanism for protegenin production selectivity. P. protegens suppressed the damping-off of cucumber seedlings caused by P. ultimum, and this protective effect was reduced in the proA-deletion mutant. Altogether, protegenins are a new class of bacterial polyynes which contribute to the antioomycete and plant-protective effects of P. protegens.

Allelopathy and Allelochemicals of Solidago canadensis L. and S. altissima L. for Their Naturalization

Solidago canadensis L. and Solidago altissima L. are native to North America and have naturalized many other continents including Europa and Asia. Their species is an aggressive colonizer and forms thick monospecific stands. The evidence of the allelopathy for S. canadensis and S. altissima has accumulated in the literature since the late 20th century. The root exudates, extracts, essential oil and rhizosphere soil of S. canadensis suppressed the germination, growth and the arbuscular mycorrhizal colonization of several plants, including native plant species. Allelochemicals such as fatty acids, terpenes, flavonoids, polyphenols and their related compounds were identified in the extracts and essential oil of S. canadensis. The concentrations of total phenolics, total flavonoids and total saponins in the rhizosphere soil of S. canadensis obtained from the invasive ranges were greater than those from the native ranges. Allelochemicals such as terpenes, flavonoids, polyacetylene and phenols were also identified in the extracts, essential oil and the rhizosphere soil in S. altissima. Among the identified allelochemicals of S. altissima, the cis-dehydromatricaria ester may be involved in the allelopathy considering its growth inhibitory activity and its concentration in the rhizosphere soil. Therefore, the allelopathy of S. canadensis and S. altissima may support their invasiveness, naturalization and formation of thick monospecific stands. This is the first review article focusing on the allelopathy of both of S. canadensis and S. altissima.

Thiotemplated Biosynthesis of Bacterial Polyyne Fatty Acids by a Designated Desaturase Triad

Various bacterial species are capable of producing highly modified fatty acid derivatives with conjugated triple bonds, which play important ecological roles as antifungals and toxins in mutualistic and pathogenic interactions. Furthermore, the terminal polyyne moiety is of interest as pharmacophore and as tag in bioorthogonal chemistry and live imaging. To gain insight into the assembly of these highly reactive natural products, we investigated tetrayne (caryoynencin and protegencin) biosynthesis genes (cay and pgn) from Trinickia caryophylli and Pseudomonas protegens. Pathway dissection and reconstitution in the heterologous host Burkholderia graminis revealed the genes minimally required for polyyne formation. Mutational analyses and biochemical assays demonstrated that polyyne biosynthesis is thiotemplated, involving a fatty acyl-AMP ligase, a designated acyl carrier protein, and a thioesterase. Heterologous expression of point-mutated desaturase genes showed that three desaturases work synergistically to introduce four triple bonds. These findings point to an intricate desaturase complex and provide important information for future bioengineering experiments.

Polyacetylenes in herbal medicine: A comprehensive review of its occurrence, pharmacology, toxicology, and pharmacokinetics (2014-2021)

Polyacetylenes are a kind of small active compounds with carbon-carbon triple bond with vast occurrence in plants. Polyacetylenes have attracted considerable attention owing to their diverse biofunctions like tumor suppression, immunity regulation, depression resistance and neural protection. The present review intends to reconstruct data concerning the occurrence, pharmacology, toxicology and pharmacokinetics of polyacetylenes from herbal medicine in a systematic and integrated way, with a view to backing up their curative potential and healthcare properties (2014-2021). The natural polyacetylene-related data were all acquired from the scientific search engines and databases that are globally recognized, such as PubMed, Web of Science, Elsevier, Google Scholar, ResearchGate, SciFinderⁿ and CNKI. A total of 183 polyacetylenes were summarized in this paper. Modern pharmacological studies indicated that polyacetylenes possess multiple biological activities including antitumor, immunomodulatory, neuroprotective, anti-depression, anti-obesity, hypoglycemic, antiviral, antibacterial, antifungal, hepatoprotective and renoprotective activities. As important bioactive components of herbal medicine, the pharmacological curative potential of polyacetylenes has been described against carcinomas, inflammatory responses, central nervous system, endocrine disorders and microbial infection in this review. While, further in-depth studies on the aspects of polyacetylenes for toxicity, pharmacokinetics, and molecular mechanisms are still limited, thereby intensive research and assessments should be performed.

Variation on a theme: the structures and biosynthesis of specialized fatty acid natural products in plants

Plants are able to construct lineage-specific natural products from a wide array of their core metabolic pathways. Considerable progress has been made toward documenting and understanding, for example, phenylpropanoid natural products derived from phosphoenolpyruvate via the shikimate pathway, terpenoid compounds built using isopentyl pyrophosphate, and alkaloids generated by the extensive modification of amino acids. By comparison, natural products derived from fatty acids have received little attention, except for unusual fatty acids in seed oils and jasmonate-like oxylipins. However, scattered but numerous reports show that plants are able to generate many structurally diverse compounds from fatty acids, including some with highly elaborate and unique structural features that have novel bioproduct functionalities. Furthermore, although recent work has shed light on multiple new fatty acid natural product biosynthesis pathways and products in diverse plant species, these discoveries have not been reviewed. The aims of this work, therefore, are to (i) review and systematize our current knowledge of the structures and biosynthesis of fatty acid-derived natural products that are not seed oils or jasmonate-type oxylipins, specifically, polyacetylenic, very-long-chain, and aromatic fatty acid-derived natural products, and (ii) suggest priorities for future investigative steps that will bring our knowledge of fatty acid-derived natural products closer to the levels of knowledge that we have attained for other phytochemical classes.

Functions and biosynthesis of plant signaling metabolites mediating plant-microbe interactions

Covering: 2015-2022Plants and microbes have coevolved since their appearance, and their interactions, to some extent, define plant health. A reasonable fraction of small molecules plants produced are involved in mediating plant-microbe interactions, yet their functions and biosynthesis remain fragmented. The identification of these compounds and their biosynthetic genes will open up avenues for plant fitness improvement by manipulating metabolite-mediated plant-microbe interactions. Herein, we integrate the current knowledge on their chemical structures, bioactivities, and biosynthesis with the view of providing a high-level overview on their biosynthetic origins and evolutionary trajectory, and pinpointing the yet unknown and key enzymatic steps in diverse biosynthetic pathways. We further discuss the theoretical basis and prospects for directing plant signaling metabolite biosynthesis for microbe-aided plant health improvement in the future.

Biosynthesis of Isonitrile- and Alkyne-Containing Natural Products

Natural products are a diverse class of biologically produced compounds that participate in fundamental biological processes such as cell signaling, nutrient acquisition, and interference competition. Unique triple-bond functionalities like isonitriles and alkynes often drive bioactivity and may serve as indicators of novel chemical logic and enzymatic machinery. Yet, the biosynthetic underpinnings of these groups remain only partially understood, constraining the opportunity to rationally engineer biomolecules with these functionalities for applications in pharmaceuticals, bioorthogonal chemistry, and other value-added chemical processes. Here, we focus our review on characterized biosynthetic pathways for isonitrile and alkyne functionalities, their bioorthogonal transformations, and prospects for engineering their biosynthetic machinery for biotechnological applications.

Diverse polyacetylenes from Atractylodes chinensis and their anti-osteoclastogenesis activity

The phytochemical investigation on Atractylodes chinensis afforded 15 polyacetylenes 1-15 and one meroterpenoid 16. Of the 16 isolates, compounds 4 and 9 are new ones, and compounds 8 and 16 are first reported from nature. In addition, the relative configuration of 1 and the available NMR data of compounds 1, 8, and 16 were first provided. Their structures were elucidated by extensive analysis of MS, UV, IR, and NMR spectroscopic data. Besides, all isolated compounds were evaluated for their effects on RANKL-induced osteoclastogenesis in BMMs. Among them, polyacetylenes 12-14 showed potent inhibitory activity with IC₅₀ values of 0.67 ± 0.05 μM, 0.72 ± 0.31 μM, and 2.40 ± 0.41 μM, respectively. The current work demonstrates the polyacetylenes are the main active constituents of A. chinensis against osteoclastogenesis.

New Bioactive Polyacetylenes from the Marine Sponge Petrosia sp

Three new polyacetylenes, pellynols P (1), Q (2), and R (3) were isolated from the marine sponge Petrosia sp., along with the known compound pellynol H (4). Their structures were determined by analyses of extensive NMR, HR-MS, and ESI-MS/MS data. All compounds displayed potent cytotoxicities against human hepatocellular carcinoma HepG2, human melanoma A375, and human colorectal carcinoma HT29 cell lines with IC₅₀ values at the range of 1.4-4.4 μM.

Structural diversity, biosynthesis, and function of plant falcarin-type polyacetylenic lipids

The polyacetylenic lipids falcarinol, falcarindiol, and associated derivatives, termed falcarins, have a widespread taxonomical distribution in the plant kingdom and have received increasing interest for their demonstrated health-promoting properties as anti-cancer and anti-inflammatory agents. These fatty acid-derived compounds are also linked to plant pathogen resistance through their potent antimicrobial properties. Falcarin-type polyacetylenes, which contain two conjugated triple bonds, are derived from structural modifications of the common fatty acid oleic acid. In the past half century, much progress has been made in understanding the structural diversity of falcarins in the plant kingdom, whereas limited progress has been made on elucidating falcarin function in plant-pathogen interactions. More recently, an understanding of the biosynthetic machinery underlying falcarin biosynthesis has emerged. This review provides a concise summary of the current state of knowledge on falcarin structural diversity, biosynthesis, and plant defense properties. We also present major unanswered questions about falcarin biosynthesis and function.

Cytotoxic Alkylynols of the Sponge Cribrochalina vasculum: Structure, Synthetic Analogs and SAR Studies

A series of twenty-three linear and branched chain mono acetylene lipids were isolated from the Caribbean Sea sponge Cribrochalina vasculum. Seventeen of the compounds, 1–17, are new, while six, 18–23, were previously characterized from the same sponge. Some of the new acetylene-3-hydroxy alkanes 1, 6, 7, 8, 10 were tested for selective cytotoxicity in non-small cell lung carcinoma (NSCLC) cells over WI-38 normal diploid lung fibroblasts. Compound 7, presented clear tumor selective activity while, 1 and 8, showed selectivity at lower doses and 6 and 10, were not active towards NSCLC cells at all. The earlier reported selective cytotoxicity of some acetylene-3-hydroxy alkanes (scal-18 and 23), in NSCLC cells and/or other tumor cell types were also confirmed for 19, 20 and 22. To further study the structure activity relationships (SAR) of this group of compounds, we synthesized several derivatives of acetylene-3-hydroxy alkanes, rac-18, scal-S-18, R-18, rac-27, rac-32, R-32, S-32, rac-33, rac-41, rac-42, rac-43, rac-45, rac-48 and rac-49, along with other 3-substituted derivatives, rac-35, rac-36, rac-37, rac-38, rac-39 and rac-40, and assessed their cytotoxic activity against NSCLC cells and diploid fibroblasts. SAR studies revealed that the alcohol moiety at position 3 and its absolute R configuration both were essential for the tumor cell line selective activity while for its cytotoxic magnitude the alkyl chain length and branching were of less significance.

Non-peptide secondary metabolites from poisonous mushrooms: overview of chemistry, bioactivity, and biosynthesis

Covering: up to June 2021A wide variety of mushrooms have traditionally been recognized as edible fungi with high nutritional value and low calories, and abundantly produce structurally diverse and bioactive secondary metabolites. However, accidental ingestion of poisonous mushrooms can result in serious illnesses and even death. Chemically, mushroom poisoning is associated with secondary metabolites produced in poisonous mushrooms, causing specific toxicity. However, many poisonous mushrooms have not been fully investigated for their secondary metabolites, and the secondary metabolites of poisonous mushrooms have not been systematically summarized for details such as chemical composition and biosynthetic mechanisms. The isolation and identification of secondary metabolites from poisonous mushrooms have great research value since these compounds could be lethal toxins that contribute to the toxicity of mushrooms or could provide lead compounds with remarkable biological activities that can promote advances in other related disciplines, such as biochemistry and pharmacology. In this review, we summarize the structures and biological activities of secondary metabolites identified from poisonous mushrooms and provide an overview of the current information on these metabolites, focusing on their chemistry, bioactivity, and biosynthesis.

The genetic control of polyacetylenes involved in bitterness of carrots (Daucus carota L.): Identification of QTLs and candidate genes from the plant fatty acid metabolism

BACKGROUND

Falcarinol-type polyacetylenes (PAs) such as falcarinol (FaOH) and falcarindiol (FaDOH) are produced by several Apiaceae vegetables such as carrot, parsnip, celeriac and parsley. They are known for numerous biological functions and contribute to the undesirable bitter off-taste of carrots and their products. Despite their interesting biological functions, the genetic basis of their structural diversity and function is widely unknown. A better understanding of the genetics of the PA levels present in carrot roots might support breeding of carrot cultivars with tailored PA levels for food production or nutraceuticals.

RESULTS

A large carrot F₂ progeny derived from a cross of a cultivated inbred line with an inbred line derived from a Daucus carota ssp. commutatus accession rich in PAs was used for linkage mapping and quantitative trait locus (QTL) analysis. Ten QTLs for FaOH and FaDOH levels in roots were identified in the carrot genome. Major QTLs for FaOH and FaDOH with high LOD values of up to 40 were identified on chromosomes 4 and 9. To discover putative candidate genes from the plant fatty acid metabolism, we examined an extended version of the inventory of the carrot FATTY ACID DESATURASE2 (FAD2) gene family. Additionally, we used the carrot genome sequence for a first inventory of ECERIFERUM1 (CER1) genes possibly involved in PA biosynthesis. We identified genomic regions on different carrot chromosomes around the found QTLs that contain several FAD2 and CER1 genes within their 2-LOD confidence intervals. With regard to the major QTLs on chromosome 9 three putative CER1 decarbonylase gene models are proposed as candidate genes.

CONCLUSION

The present study increases the current knowledge on the genetics of PA accumulation in carrot roots. Our finding that carrot candidate genes from the fatty acid metabolism are significantly associated with major QTLs for both major PAs, will facilitate future functional gene studies and a further dissection of the genetic factors controlling PA accumulation. Characterization of such candidate genes will have a positive impact on carrot breeding programs aimed at both lowering or increasing PA concentrations in carrot roots.

Untargeted Identification of Alkyne-Containing Natural Products Using Ruthenium-Catalyzed Azide Alkyne Cycloaddition Reactions Coupled to LC-MS/MS

Alkyne-containing natural products have been identified from plants, insects, algae, fungi, and bacteria. This class of natural products has been characterized as having a variety of biological activities. Polyynes are a subclass of acetylenic natural products that contain conjugated alkynes and are underrepresented in natural product databases due to the fact that they decompose during purification. Here we report a workflow that utilizes alkyne azide cycloaddition (AAC) reactions followed by LC-MS/MS analysis to identify acetylenic natural products. In this report, we demonstrate that alkyne azide cycloaddition reactions with p-bromobenzyl azide result in p-bromobenzyl-substituted triazole products that fragment to a common brominated tropylium ion. We were able to identify a synthetic alkyne spiked into the extract of Anabaena sp. PCC 7120 at a concentration of 10 μg/mL after optimization of MS/MS conditions. We then successfully identified the known natural product fischerellin A in the extract of Fischerella muscicola PCC 9339. Lastly, we identified the recently identified natural products protegenins A and C from Pseudomonas protegens Pf-5 through a combination of genome mining and RuAAC reactions. This is the first report of RuAAC reactions to detect acetylenic natural products. We also compare CuAAC and RuAAC reactions and find that CuAAC reactions produce fewer byproducts compared to RuAAC but is limited to terminal-alkyne-containing compounds. In contrast, RuAAC is capable of identification of both terminal and internal acetylenic natural products, but byproducts need to be eliminated from analysis by creation of an exclusion list. We believe that both CuAAC and RuAAC reactions coupled to LC-MS/MS represent a method for the untargeted identification of acetylenic natural products, but each method has strengths and weaknesses.

Synthesis of Alkyne-Substituted Dihydropyrrolones as Bacterial Quorum-Sensing Inhibitors of Pseudomonas aeruginosa

The Quorum-sensing system in Pseudomonas aeruginosa is responsible for the pathogenicity and the production of virulence factors and biofilm formation. Dihydropyrrolones were previously found to act as inhibitors of QS-dependent bacterial phenotypes. In this study, a range of dihydropyrrolone (DHP) analogues was synthesized via the lactone-lactam conversion of lactone intermediates followed by the formation of novel acetylene analogues of dihydropyrrolones from brominated dihydropyrrolones via Sonogashira coupling reactions in moderate to high yields. Upon biological testing, the most potent compounds, 39–40 and 44, showed higher bacterial quorum-sensing inhibitory (QSI) activity against P. aeruginosa reporter strain at 62.5 µM. Structure–activity relationship studies revealed that di-alkynyl substituent at the exocyclic position of DHPs possessed higher QSI activities than those of mono-alkynyl DHPs. Moreover, a hexyl-substituent at C3 of DHPs was beneficial to QSI activity while a phenyl substituent at C4 of DHPs was detrimental to QSI activity of analogues.

Atrachinenynes A–D, four diacetylenic derivatives with unprecedented skeletons from the rhizomes of Atractylodes chinensis

Atrachinenynes A–D (1–4), four undescribed acetylenic derivatives with diverse skeletons, were isolated from Atractylodes chinensis.

Lethal and behavioural effects of a green insecticide against an invasive polyphagous fruit fly pest and its safety to mammals

Plant essential oil-based insecticides, with special reference to those that may be obtained from largely available biomasses, represent a valuable tool for Integrated Pest Management. However, the sublethal effects and the potential effects on aggressive insect traits of these green insecticides are understudied. Herein, the lethal and sub-lethal effects of the carlina oxide, constituting more than 97% of the whole Carlina acaulis (Asteraceae) root essential oil (EO), were determined against an invasive polyphagous tephritid pest, Ceratitis capitata (medfly). The carlina oxide was formulated in a mucilaginous solution containing carboxymethylcellulose sodium salt, sucrose, and hydrolysed proteins, showing high ingestion toxicity on medfly adults. The behavioural effects of carlina oxide at LC₁₀ and LC₃₀ were evaluated on the medfly aggressive traits, which are crucial for securing reproductive success in both sexes. Insecticide exposure affected the directionality of aggressive actions, but not the aggression escalation intensity and duration. The EO safety to mammals was investigated by studying its acute toxicity on the stomach, liver, and kidney of rats after oral administration. Only the highest dose (1000 mg/kg) of the EO caused modest neurological signs and moderate effects on the stomach, liver, and kidney. The other doses, which are closer to the practical use of the EO when formulated in protein baits, did not cause side effects. Overall, C. acaulis-based products are effective and safe to non-target mammals, deserving further consideration for eco-friendly pesticide formulations.

Comprehensive characterization of polyacetylenes and diterpenes from the underground parts of Solidago altissima L. and their contribution to the overall allelopathic activity

Solidago altissima L. (Asteraceae), a perennial plant native to North America, is considered one of the most invasive weeds in Asia and Europe. The successful invasion of S. altissima is possibly due to its allelopathic effect along with high seed productivity and strong vegetative propagation through rhizomes. Herein, to understand the invasion of S. altissima via the allelopathic effect, we isolated and characterized known and undescribed compounds from the underground parts of S. altissima and evaluated their contribution to the overall allelopathic activity of the plant. NMR spectroscopy and LC-MS analyses clarified the chemical structure of ten specialized metabolites including three undescribed compounds, i.e., (4Z, 8Z)-10-tigloyloxy matricaria lactone, (4Z, 8Z)-10-angeloyloxy matricaria lactone, and (2Z, 8Z)-10-methacryloyloxy matricaria ester. The evaluation of the content and allelopathic ability of each compound showed that cis-dehydromatricaria ester contributes to the allelopathic activities of the S. altissima extract.

Polyacetylene Glycosides: Isolation, Biological Activities and Synthesis

Polyacetylene glycosides (PAGs) constitute a relatively small class of secondary metabolites characterized by the presence of a sugar unit anomerically connected to a polyacetylene. These compounds are found in fungi, seaweed, and more often in plants. PAGs exhibit a wide range of biological and pharmacological activities and, as a result, the literature of these compounds has grown exponentially in recent years.

Bioactivity of Carlina acaulis Essential Oil and Its Main Component towards the Olive Fruit Fly, Bactrocera oleae: Ingestion Toxicity, Electrophysiological and Behavioral Insights

Among botanical insecticides based on essential oils (EOs) or their main components, Carlina acaulis EO and the aromatic polyacetylene carlina oxide, constituting more than 90% of its EO, were recently proven to be effective against the larvae and adults of some insect vectors and pests. In this study, the toxicity of C. acaulis EO and carlina oxide were tested on Bactrocera oleae adults using a protein bait formulation. The LC50 values of the C. acaulis EO and carlina oxide were 706 ppm and 1052 ppm, respectively. Electroantennographic (EAG) tests on B. oleae adults showed that both carlina EO and oxide elicited EAG dose-dependent responses in male and female antennae. The responses to the EO were significantly higher than those to carlina oxide, indicating that other compounds, despite their lower concentrations, can play a relevant role. Moreover, Y-tube assays carried out to assess the potential attractiveness or repellency of carlina oxide LC90 to B. oleae adults showed that it was unattractive to both males and females of B. oleae, and the time spent by both sexes in either the control or the treatment arm did not differ significantly. Overall, this study points out the potential use of C. acaulis EO and carlina oxide for the development of green and effective "lure-and-kill" tools.

Autotandem Catalysis: Inexpensive and Green Access to Functionalized Ketones by Intermolecular Iron-Catalyzed Amidoalkynylation/Hydration Cascade Reaction via N-Acyliminium Ion Chemistry

Iron-based catalysts were applied in cascade-type reactions for the synthesis of different carbonyl compounds. The reactions proceeded by a new iron-catalyzed cascade of alkynylation/hydration by using both the σ- and π-Lewis acid properties of iron salts. The alkynylation reactions of several endo and exocyclic acetoxylactams were achieved with three different catalysts including FeCl 3 .6H 2 O, FeCl 3 , and Fe(OTf) 3 showing the efficiency of σ-Lewis acidity of iron (III) salts in catalyzing the alkynylation reaction. We also demonstrated that the reaction sequence could be shortened by the direct use of hydroxylactams, leading to an environmentally friendly protocol, avoiding the need to perform unnecessary lengthy steps. A combination of the hard/soft iron Lewis acid properties was then used to implement an unprecedented tandem intermolecular alkynylation/intramolecular hydration sequence allowing expedient access to a new carbonyl structures from trivial materials.

Phytochemical studies on traditional herbal medicines based on the ethnopharmacological information obtained by field studies

Traditional herbal medicines, which have been used in the matured traditional medical systems as well as those have been used in ethnic medical systems, are invaluable resources of drug seeds. Ethnobotanical and ethnopharmacological survey may provide useful information of these herbal medicines, which are valuable for searching new bioactive molecules. From this viewpoint, we have been performing the ethnobotanical and ethnopharmacological field studies in Yunnan Province and Guangxi Zhuang Autonomous Region, China, and Mongolia. Phytochemical studies on traditional herbal medicines were performed based on the information obtained by our ethnobotanical survey. Herbal medicines used in Uzbekistan and Bangladesh were also investigated on the basis of the ethnopharmacological information obtained from collaborative researchers in the respective regions. Some studies were carried out for searching active substance(s) based on bioassay-guided fractionation and isolation. Over 150 new molecules were isolated in these studies, and their various biological activities were also demonstrated. This review summarizes the results of phytochemical studies of those traditional herbal medicines as well as biological activities of the isolated molecules.

Search for Non-Protein Protease Inhibitors Constituted with an Indole and Acetylene Core

A possible inhibitor of proteases, which contains an indole core and an aromatic polar acetylene, was designed and synthesized. This indole derivative has a molecular architecture kindred to biologically relevant species and was obtained through five synthetic steps with an overall yield of 37% from the 2,2'-(phenylazanediyl)di(ethan-1-ol). The indole derivative was evaluated through docking assays using the main protease (SARS-CoV-2-M^pro) as a molecular target, which plays a key role in the replication process of this virus. Additionally, the indole derivative was evaluated as an inhibitor of the enzyme kallikrein 5 (KLK5), which is a serine protease that can be considered as an anticancer drug target.

Bioherbicides: An Eco-Friendly Tool for Sustainable Weed Management

Weed management is an arduous undertaking in crop production. Integrated weed management, inclusive of the application of bioherbicides, is an emerging weed control strategy toward sustainable agriculture. In general, bioherbicides are derived either from plants containing phytotoxic allelochemicals or certain disease-carrying microbes that can suppress weed populations. While bioherbicides have exhibited great promise in deterring weed seed germination and growth, only a few in vitro studies have been conducted on the physiological responses they evoke in weeds. This review discusses bioherbicide products that are currently available on the market, bioherbicide impact on weed physiology, and potential factors influencing bioherbicide efficacy. A new promising bioherbicide product is introduced at the end of this paper. When absorbed, phytotoxic plant extracts or metabolites disrupt cell membrane integrity and important biochemical processes in weeds. The phytotoxic impact on weed growth is reflected in low levels of root cell division, nutrient absorption, and growth hormone and pigment synthesis, as well as in the development of reactive oxygen species (ROS), stress-related hormones, and abnormal antioxidant activity. The inconsistency of bioherbicide efficacy is a primary factor restricting their widespread use, which is influenced by factors such as bioactive compound content, weed control spectrum, formulation, and application method.

Assessment of anti-inflammatory-like, antioxidant activities and molecular docking of three alkynyl-substituted 3-ylidene-dihydrobenzo[d]isothiazole 1,1-dioxide derivatives

The presence of enyne and benzoisothiazole functions in the molecular architecture of compounds 1, 2 and 3 were expected to provide biochemical activities. In the present work, we first examined the molecular surface contact of three alkynyl-substituted 3-ylidenedihydrobenzo[d] isothiazole 1,1-dioxides. The analysis of the Hirshfeld surfaces reveals that only compound 3 exhibited a well-defined red spots, indicating intermolecular interactions identified as S-O⋯H, C-H⋯O and C-O⋯H contacts. Comparative fingerprint histograms of the three compounds show that close pair interactions are dominated by C-H⋯H-C contact. By UV-visible analysis, compound 1 showed the most intense absorbances at 407 and 441 nm, respectively. The radical scavenging activity explored in the DPPH test, shows that only 1 exhibited low anti-radical activity. Furthermore, cellular antioxidant capacity of benzoisothiazoles 1-3 was investigated with PMA-activated HL-60 cells using chemiluminescence and fluorescence techniques in the presence of L-012 and Amplex Red probe, respectively. Results highlight that compound 1 exhibited moderate anti-ROS capacity while compounds 2 and 3 enhanced ROS production. The cytotoxicity test performed on HL-60 cells, using the MTS assay, confirmed the lack of toxicity of the tested benzoisothiazole 1 compared to 2 and 3 which show low cytotoxicity (≤30%). Anti-catalytic activity was evaluated by following the inhibitory potential of the benzoisothiazoles on MPO activity and depicted benzoisothiazoles-MPO interactions by docking. Both SIEFED and docking studies demonstrated an anti-catalytic activity of the tested benzoisothiazoles towards MPO with the best activity for compound 2.

Phytochemicals as a Complement to Cancer Chemotherapy: Pharmacological Modulation of the Autophagy-Apoptosis Pathway

Bioactive plant derived compounds are important for a wide range of therapeutic applications, and some display promising anticancer properties. Further evidence suggests that phytochemicals modulate autophagy and apoptosis, the two crucial cellular pathways involved in the underlying pathobiology of cancer development and regulation. Pharmacological targeting of autophagy and apoptosis signaling using phytochemicals therefore offers a promising strategy that is complementary to conventional cancer chemotherapy. In this review, we sought to highlight the molecular basis of the autophagic-apoptotic pathway to understand its implication in the pathobiology of cancer, and explore this fundamental cellular process as a druggable anticancer target. We also aimed to present recent advances and address the limitations faced in the therapeutic development of phytochemical-based anticancer drugs.

Palladium-Catalyzed Decarbonylative Sonogashira Coupling of Terminal Alkynes with Carboxylic Acids

A direct decarbonylative Sonogashira coupling of terminal alkynes with carboxylic acids was achieved through palladium catalysis. This reaction did not use overstoichiometric oxidants, thus overcoming the homocoupling issue of terminal alkynes. Under the reaction conditions, a wide range of carboxylic acids including those bioactive ones could couple readily with various terminal alkynes, thus providing a relative general method for preparing internal alkynes.

Traditional uses, phytochemistry, pharmacology, and toxicology of Coreopsis tinctoria Nutt.: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Coreopsis tinctoria Nutt. (family Asteraceae) is an important traditional medicine in North America, Europe, and Asia for quite a long historical period, which has received great attention due to its health-benefiting activities, including disinfection, treatment sexual infection, diarrhoea, acute and chronic dysentery, red-eye swelling as well as pain, heat, thirst, hypertension, palpitation, gastrointestinal discomfort, and loss of appetite.

AIM OF THE REVIEW

The purpose of this review is to give an overview of the current phytochemistry and pharmacological activities of C. tinctoria, and reveals the correlation among its traditional uses, phytochemistry, pharmacological profile, and potential toxicity.

MATERIALS AND METHODS

This review is based on published studies and books from electronic sources and library, including the online ethnobotanical database, ethnobotanical monographs, Scopus, SciFinder, Baidu Scholar, CNKI, and PubMed. These reports are related to the traditional uses, phytochemistry, pharmacology, and toxicology of C. tinctoria.

RESULTS

Coreopsis tinctoria is traditionally used in diarrhoea, infection, and chronic metabolic diseases. From 1954 to now, more than 120 chemical constituents have been identified from C. tinctoria, such as flavonoids, polyacetylenes, polysaccharides, phenylpropanoids, and volatile oils. Flavonoids are the major bioactive components in C. tinctoria. Current research has shown that its extracts and compounds possess diverse biological and pharmacological activities such as antidiabetes, anti-cardiovascular diseases, antioxidant, anti-inflammatory, protective effects on organs, neuroprotective effects, antimicrobial, and antineoplastic. Studies in animal models, including acute toxicity, long-term toxicity, and genotoxicity have demonstrated that Snow Chrysanthemum is a non-toxic herb, especially for its water-soluble parts.

CONCLUSIONS

Recent findings regarding the main phytochemical and pharmacological properties of C. tinctorial have confirmed its traditional uses in anti-infection and treatment of chronic metabolic disease and, more importantly, have revealed the plant as a valuable medicinal plant resource for the treatment of a wide range of diseases. The available reports indicated that most of the bioactivities in C. tinctorial could be attributed to flavonoids. However, higher quality studies on animals and humans studies are required to explore the efficacy and mechanism of action of C. tinctoria in future.

Anticancer Properties of Lobetyolin, an Essential Component of Radix Codonopsis (Dangshen)

Lobetyolin (LBT) is a polyacetylene glycoside found in diverse medicinal plants but mainly isolated from the roots of Codonopsis pilosula, known as Radix Codonopsis or Dangshen. Twelve traditional Chinese medicinal preparations containing Radix Codonopsis were identified; they are generally used to tonify spleen and lung Qi and occasionally to treat cancer. Here we have reviewed the anticancer properties of Codonopsis extracts, LBT and structural analogs. Lobetyolin and lobetyolinin are the mono- and bis-glucosylated forms of the polyacetylenic compound lobetyol. Lobetyol and LBT have shown activities against several types of cancer (notably gastric cancer) and we examined the molecular basis of their activity. A down-regulation of glutamine metabolism by LBT has been evidenced, contributing to drug-induced apoptosis and tumor growth inhibition. LBT markedly reduces both mRNA and protein expression of the amino acid transporter Alanine-Serine-Cysteine Transporter 2 (ASCT2). Other potential targets are proposed here, based on the structural analogy with other anticancer compounds. LBT and related polyacetylene glycosides should be further considered as potential anticancer agents, but more work is needed to evaluate their efficacy, toxicity, and risk-benefit ratio.