Motivated by the culinary and ethnopharmacological use of Acmella oleracea (L.) R.K. Jansen, this study aimed to unveil new chemical compounds from its essential oil (EO). Acmella oleracea, known for its anesthetic and spicy properties, has been used in traditional medicine and cuisine, particularly in Northern Brazil. Through a detailed GC-MS analysis, 180 constituents were identified, including 12 tentatively identified long-chain α-keto esters of various acids. Additionally, 18 new esters were synthesized for structural verification. This research expands the known chemical diversity of A. oleracea EO, providing a basis for potential pharmacological applications. The identification of new natural products, including homologs and analogs of acmellonate, underscores the EO\'s rich chemical profile and its potential for novel bioproduct development.

The investigation of cycloaddition reactions involving acridine-based dipolarophiles revealed distinct regioselectivity patterns influenced mainly by the electronic factor. Specifically, the reactions of methyl-(2E)-3-(acridin-4-yl)-prop-2-enoate and 4-[(1E)-2-phenylethenyl]acridine with unstable benzonitrile N-oxides were studied. For methyl-(2E)-3-(acridin-4-yl)-prop-2-enoate, the formation of two regioisomers favoured the 5-(acridin-4-yl)-4,5-dihydro-1,2-oxazole-4-carboxylates, with remarkable exclusivity in the case of 4-methoxybenzonitrile oxide. Conversely, 4-[(1E)-2-phenylethenyl]acridine displayed reversed regioselectivity, favouring products 4-[3-(substituted phenyl)-5-phenyl-4,5-dihydro-1,2-oxazol-4-yl]acridine. Subsequent hydrolysis of isolated methyl 5-(acridin-4-yl)-3-phenyl-4,5-dihydro-1,2-oxazole-4-carboxylates resulted in the production of carboxylic acids, with nearly complete conversion. During NMR measurements of carboxylic acids in CDCl3, decarboxylation was observed, indicating the formation of a new prochiral carbon centre C-4, further confirmed by a noticeable colour change. Overall, this investigation provides valuable insights into regioselectivity in cycloaddition reactions and subsequent transformations, suggesting potential applications across diverse scientific domains.

Four new diterpenoids, isodosins A-D (1-4), together with nine known compounds (5-13) were isolated and identified from the aerial parts of Isodon serra (Maxim.) Hara. The structures of the new diterpenoids were elucidated based on the analysis of HR-ESI-MS data, 1D/2D-NMR-spectroscopic data, and electronic circular dichroism (ECD) calculations. Cytotoxicities of compounds 2, 3, 5, 6, and 9 against the HepG2 and H1975 cell lines were evaluated with the MTT assay. As a result, compounds 2, 3, and 6 revealed higher levels of cytotoxicity against HepG2 cells than against H1975 cells. Moreover, compund 6 demonstrated the most efficacy in inhibiting the proliferation of HepG2 cells, with an IC50 value of 41.13 ± 3.49 μM. This effect was achieved by inducing apoptosis in a dose-dependent manner. Furthermore, the relationships between the structures and activities of these compounds are briefly discussed.

Although carbanions, which are usually regarded as reactive species and powerful metalation reagents, can be stabilized through choice of the substitution pattern, they have rarely been considered for the design of weakly coordinating anions (WCA).  Here, we report on an evaluation of the potential of a series of differently substituted carbanions to serve as WCA by computational methods. This led us to the synthesize the water- and air-stable allyl anion 1 with triflyl and 3,5-bis(trifluoromethyl)phenyl (ArF) moieties, which can be isolated in high yields even on a gram-scale. Single crystal X-ray crystallography and NMR studies confirmed the weak coordination ability of the anion by showing negligible or only weak interactions with different cations. This property enabled the application of 1 in the stabilization of reactive group 14 and 15 cations. In addition to the crystallization of a phosphenium cation, the first all-carbon salt with a non-aromatic carbanion is reported, which revealed to be a convenient reagent for hydride abstraction such as from silanes. Overall, this work demonstrates the so far untapped potential of carbanions as WCA, that are accessible with a variety of different cations for various applications.

The endophytic fungus Chaetomium nigricolor culture filtrate\'s hexane extract was used to identify a cytotoxic very long-chain fatty acid. Based on multiple spectroscopic investigations, the structure of the compound was predicted to be an unsaturated fatty acid, Nonacosenoic acid (NA). Using the MTT assay, the compound\'s cytotoxic potential was evaluated against MCF-7, A-431, U-251, and HEK-293 T cells. The compound was moderately cytotoxic to breast carcinoma cell line, MCF-7 cells and negligibly cytotoxic to non-cancerous cell line HEK-293 T cells. The compound exhibited mild cytotoxic activity against A-431 and U-251 cells. The compound also induced ROS generation and mitochondrial depolarization in MCF-7 cells when assessed via the NBT and JC-1 assays, respectively. This is the first report on the production of nonacosenoic acid from the endophytic fungus Chaetomium nigricolor and the assessment of its bioactivity.

Millipedes have long been known to produce a diverse array of chemical defense agents that deter predation. These compounds, or their precursors, are stored in high concentration within glands (ozadenes) and are released upon disturbance. The subterclass Colobognatha contains four orders of millipedes, all of which are known to produce terpenoid alkaloids-spare the Siphonophorida that produce terpenes. Although these compounds represent some of the most structurally-intriguing millipede-derived natural products, they are the least studied class of millipede defensive secretions. Here, we describe the chemistry of millipede defensive secretions from three species of Brachycybe: Brachycybe producta, Brachycybe petasata, and Brachycybe rosea. Chemical investigations using mass spectrometry-based metabolomics, chemical synthesis, and 2D NMR led to the identification of five alkaloids, three of which are new to the literature. All identified compounds are monoterpene alkaloids with the new compounds representing indolizidine (i.e. hydrogosodesmine) and quinolizidine alkaloids (i.e. homogosodesmine and homo-hydrogosodesmine). The chemical diversity of these compounds tracks the known species phylogeny of this genus, rather than the geographical proximity of the species. The indolizidines and quinolizidines are produced by non-sympatric sister species, B. producta and B. petasata, while deoxybuzonamine is produced by another set of non-sympatric sister species, B. rosea and Brachycybe lecontii. The fidelity between the chemical diversity and phylogeny strongly suggests that millipedes generate these complex defensive agents de novo and begins to provide insights into the evolution of their biochemical pathways.

Phytochemical studies on cigar tobacco leaves led to the isolation of 18 ionone-type compounds, including previously undescribed cigatobanes E (1) and F (2). Additionally, compounds vomifoliol acetate (3), dehydrovomifoliol (4), 8,9-dihydromegastigmane-4,6-diene-3-one (5), 7α,8α-epoxyblumenol B (6), 3-oxoactinidol (12), and loliolide acetate (15), 4β-hydroxy-dihydroactinidiolide (17), were found in tobacco leaves for the first time. The structural elucidation of all compounds was accomplished through rigorous spectral analysis.

Ten C-geranylated flavonoids, along with three known analogues, were isolated from the leaves of Artocarpus communis. The chemical structures of these compounds were unambiguously determined via comprehensive spectroscopic analysis, single-crystal X-ray diffraction experiments, and quantum chemical electronic circular dichroism calculations. Structurally, artocarones A-I (1-9) represent a group of unusual, highly modified C-geranylated flavonoids, in which the geranyl chain is cyclised with the ortho-hydroxy group of flavonoids to form various heterocyclic scaffolds. Notably, artocarones E and G-I (5 and 7-9) feature a 6H-benzo[c]chromene core that is hitherto undescribed in C-geranylated flavonoids. Artocarone J (10) is the first example of C-9-C-16 connected C-geranylated aurone. Meanwhile, the plausible biosynthetic pathways for these rare C-geranylated flavonoids were also proposed. Notably, compounds 1, 2, 4, 8, 11, and 12 exhibited promising in vitro inhibitory activities against respiratory syncytial virus and herpes simplex virus type 1.

Ash dieback, caused by the fungal pathogen Hymenoscyphus fraxineus (Helotiales, Ascomycota), is threatening the existence of the European ash, Fraxineus excelsior. During our search for biological control agents for this devastating disease, endophytic fungi were isolated from healthy plant tissues and co-cultivated with H. fraxineus to assess their antagonistic potential. Among the strains screened, Penicillium cf. manginii DSM 104493 most strongly inhibited the pathogen. Initially, DSM 104493 showed promise in planta as a biocontrol agent. Inoculation of DSM 104493 into axenically cultured ash seedlings greatly decreased the development of disease symptoms in seedlings infected with H. fraxineus. The fungus was thus cultivated on a larger scale in order to obtain sufficient material to identify active metabolites that accounted for the antibiosis observed in dual culture. We isolated PF1140 (1) and identified it as the main active compound in the course of a bioassay-guided isolation strategy. Furthermore, its derivative 2, the mycotoxin citreoviridin (3), three tetramic acids of the vancouverone type (4-6), and penidiamide (7) were isolated by preparative chromatography. The structures were elucidated mainly by NMR spectroscopy and high-resolution mass spectrometry (HRMS), of which compounds 2 and 6 represent novel natural products. Of the compounds tested, not only PF1140 (1) strongly inhibited H. fraxineus in an agar diffusion assay but also showed phytotoxic effects in a leaf puncture assay. Unfortunately, both the latent virulent attributes of DSM 104493 observed subsequent to these experiments in planta and the production of mycotoxins exclude strain Penicillium cf. manginii DSM 104493 from further development as a safe biocontrol agent.IMPORTANCEEnvironmentally friendly measures are urgently needed to control the causative agent of ash dieback, Hymenoscyphus fraxineus. Herein, we show that the endophyte DSM 104493 exhibits protective effects in vitro and in planta. We traced the activity of DSM 104493 to the antifungal natural product PF1140, which unfortunately also showed phytotoxic effects. Our results have important implications for understanding plant-fungal interactions mediated by secondary metabolites, not only in the context of ash dieback but also generally in plant-microbial interactions.

A chemical investigation of the arils of Torreya grandis led to the isolation of seven abietane-type diterpenoids (compounds 1-7) including three previously undescribed compounds, one unreported natural product, and three known analogs. The structures of these compounds were determined by means of spectroscopy, single-crystal X-ray diffraction, and ECD spectra. An antibacterial activity assay showed that compounds 5 and 6 had significant inhibitory effects on methicillin-resistant Staphylococcus aureus, with MIC values of 100 μM. Moreover, compounds 1, 3, 4, and 7 exhibited anti-neuroinflammatory activity in LPS-stimulated BV-2 microglia cells, with the IC50 values ranging from 38.4 to 67.9 μM.