Bioactives

Poly(ADP-ribose) polymerases (PARP) are a family of enzymes that were proven to play an essential role in the initiation and activation of DNA repair processes in the case of DNA single-strand breaks. The inhibition of PARP enzymes might be a promising option for the treatment of several challenging types of cancers, including triple-negative breast cancer (TNBC) and non-small cell lung carcinoma (NSCLC). This study utilizes several techniques to screen the compound collection of the Leibniz Institute of Plant Biochemistry (IPB) to identify novel hPARP-1 inhibitors. First, an in silico pharmacophore-based docking study was conducted to virtually screen compounds with potential inhibitory effects. To evaluate these compounds in vitro, a cell-free enzyme assay was developed, optimized, and employed to identify hPARP-1 inhibitors, resulting in the discovery of two novel scaffolds represented by compounds 54 and 57, with the latter being the most active one from the compound library. Furthermore, fluorescence microscopy and synergism assays were performed to investigate the cellular and nuclear pathways of hPARP-1 inhibitor 57 and its potential synergistic effect with the DNA-damaging agent temozolomide. The findings suggest that the compound requires further lead optimization to enhance its ability to target the nuclear PARP enzyme effectively. Nonetheless, this new scaffold demonstrated a five-fold higher PARP inhibitory activity at the enzyme level compared to the core structure of olaparib (OLP), phthalazin-1(2H)-one.

Aetokthonotoxin (AETX) is an emerging environmental toxin produced by the freshwater cyanobacterium Aetokthonos hydrillicola. Accumulating in the food chain, it causes vacuolar myelinopathy, a neurological disease affecting a wide range of wildlife characterized by the development of large intramyelinic vacuoles in the white matter of the brain. So far, the mode of action of AETX is unknown. After discovering that AETX is cytostatic and arrests cancer cell lines in the G1 phase, metabolomic profiling of AETX-treated cells as well as an assessment of the physicochemical properties of the compound suggested that AETX is a weakly acidic uncoupler of mitochondrial respiration. We confirmed this hypothesis by in vitro assays on mammalian cells, finding that AETX has the expected effects on mitochondrial network morphology, mitochondrial membrane potential, and oxygen consumption rate, resulting in affected ATP generation. We confirmed that AETX is capable of transporting protons across lipid bilayers. In summary, we demonstrate that AETX is a protonophore that uncouples oxidative phosphorylation in mitochondria, which is the primary event of AETX intoxication.

The transition to a bioeconomy holds promise for reducing greenhouse gas (GHG) emissions and advancing sustainable development but also presents complex challenges. This perspectives article critically examines the environmental, social, and economic implications of shifting from fossil-based to bio-based resources, addressing key concerns such as land use competition, biodiversity loss, and social equity. Rising biomass demand poses sustainability risks, especially for the Global South, where it may exacerbate food insecurity and ecosystem degradation. Without careful management, this transition could lead to deforestation, biodiversity loss, and increased carbon emissions, undermining its intended benefits. To navigate these challenges, the article outlines pathways for an inclusive and sustainable bioeconomy transition. It emphasizes the need for interdisciplinary approaches that integrate diverse knowledge systems and values to ensure the equitable distribution of benefits and risks. Policymakers should adopt governance frameworks that align sustainable development goals with local realities, fostering a just transition that mitigates socioecological challenges while maximizing long-term sustainability.

The ability to chemoselectively modify either the peptide backbone or specific side chains is critical to advance the fields of bioconjugation and peptide pharmaceuticals. Transition-metal catalysis has been widely used in peptide and protein derivatization but mostly under homogeneous conditions. Herein, we present a first-in-class heterogeneous catalytic approach for the site-selective functionalization of histidinecontaining peptides with aryl and alkenyl moieties bearing fluorescent and affinity tags, lipids, and conjugation handles. This heterogeneous derivatization strategy employs a copper(II) hexacyanometallate to catalyze the Chan−Lam reaction with boronic acids at either the backbone or the histidine imidazole, thus providing novel results that differ from those previously reported for the homogeneous Cu(OAc)2-mediated coupling procedure. A correlation was established between the structural and electronic properties of the copper(II) hexacyanometalate with its ability to catalyze this oxidative cross-coupling. This report expands the toolbox for latestage peptide derivatization and labeling by unlocking the reactivity of the histidine side chain rather than merely acting as a directing group, thus boosting applications of heterogeneous catalysis in drug discovery and development.

NMR-based Metabolomics approach assessed phytochemical profile in seed and husk of three cardamom species: Elettaria cardamomum (green), Amomum subulatum (black), and Aframomum corrorima (white). NMR Spectroscopy identified 20 metabolites belonging to sugars, amino-, organic-, fatty acids, terpenes, and phenolics. Multivariate data analyses revealed distinct metabolic profiles among the 3 species, and further in seed versus husk. A. subulatum seed showed the highest sugar and amino acid levels, while E. cardamomum seed was richer in ω-3 fatty acids. Husk, especially from A. subulatum and E. cardamomum, contained high levels of phenolic acids. Compared to other cardamom taxa, A. corrorima exhibited lower levels of most chemicals. This study highlights the potential value of cardamom husk, particularly from A. subulatum and E. cardamomum species enriched in phenolic acids and terpenes known for their antioxidant and antimicrobial properties, for use as a food preservative. The antimicrobial and antioxidant activities were assessed through in vitro assays, revealing their potential for value-added applications in food preservation and therapeutic uses.

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Introduction: Climate change poses various threats to marine life, particularly in shallow tropical waters. Objective: The impact of increased temperature and ultraviolet (UV) exposure on two photosymbiotic cnidarians, a common bubble-tip anemone and an upside-down jellyfish, was investigated. Methods: To illustrate the response of aquatic organisms, the metabolomes of unstressed Entacmaea quadricolor and Cassiopea andromeda were compared for detailed metabolite profiling. UHPLC-MS cou-pled with chemometrics and GNPS molecular networking was employed for sample classification and identification of markers unique to stress responses in each organism. Results: Several compounds with bioactive functions, including peptides and terpenoids, were reported for the first time in both organisms, viz. cyclic tetraglutamate, campestriene, and ceramide aminoethyl phosphonate (CEAP d18:2/16:0). Both anemone and jellyfish were subjected to either elevated UV-B light intensity up to 6.6 KJ m-2 or increased temperatures (28°C, 30°C, 32°C, and 34°C) over 4 days. Phospholipids, steroids, and ceramides emerged as chief markers of both types of stress, as revealed by the multivariate data analysis. Lysophosphatidylcholine (LPC 16:0), LPC (18:0/0:0), and echinoclasterol sulfate appeared as markers in both UV and thermal stress models of the anemone, whereas methyl/pro-pyl cholestane-hexa-ol were discriminatory in the UV stress model only. In the case of jellyfish, nonpolar glycosyl ceramide GlcCer (d14:1/28:6) served as a marker for UV stress, whereas polar peptides were ele-vated in the thermal stress model. Interestingly, both models of jellyfish share a phospholipid, lysophos-phatidylethanolamine (LPE 20:4), as a distinctive marker for stress, reported to be associated indirectly with the activity of innate immune response within other photosymbiotic Cnidaria such as corals and appears to be a fundamental stress response in marine organisms. Conclusion: This study presents several bioinformatic tools for the first time in two cnidarian organisms to provide not only a broader coverage of their metabolome but also broader insights into cnidarian bleaching in response to different stressors, i.e., heat and UV light, by comparing their effects in anemone versus jellyfish.

Two connected histopathological hallmarks of Alzheimer’s disease (AD) are chronic neuroinflammation and synaptic dysfunction. The accumulation of the most prevalent posttranslationally modified form of Aβ1–42, pyroglutamylated amyloid-β (Aβ3(pE)-42) in astrocytes is directly linked to glial activation and the release of proinflammatory cytokines that in turn contribute to early synaptic dysfunction in AD. At present, the mechanisms of Aβ3(pE)-42 uptake to astrocytes are unknown and pharmacological interventions that interfere with this process are not available. Here we developed a simple screening assay to identify substances from a plant extract library that prevent astroglial Aβ3(pE)-42 uptake. We first show that this approach yields valid and reproducible results. Second, we show endocytosis of Aβ3(pE)-42 oligomers by astrocytes and that quercetin, a plant flavonol, is effective to specifically block astrocytic buildup of oligomeric Aβ3(pE)-42. Importantly, quercetin does not induce a general impairment of endocytosis. However, it efficiently protects against early synaptic dysfunction following exogenous Aβ3(pE)-42 application.

Hornstedtia scyphifera (J.Koenig) Steud. represents a lesser-known member of the ginger family (Zingiberaceae) that is used in Malaysia as spice and traditional medicine. The phytochemical investigation of leaves from this species utilizing diverse analytical methods has provided comprehensive insights into its chemical profile for the first time. Headspace gas chromatography-mass spectrometry (HS-GCMS) and GCMS analyses of essential oil and nonpolar extracts verified α-pinene, camphene, p-cymene, and camphor as main volatile compounds. Metabolite profiling of the crude extract by ultra-high-performance-liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) unveiled terpenoids, flavonoids and other phenolics as major compound classes. Isolation and follow-up structure elucidation, involving 1D and 2D NMR, HRMS, UV and CD analysis, yielded two new sesquiterpenoids, (1R,5S,6S,7R,10R)-mustak-14-oic acid (1) and (1R,6S,7S,10R)-6-hydroxy-anhuienosol (2), along with 24 known compounds (seven terpenoids, seven flavonoids, ten phenolics), 21 of these never reported for H. scyphifera. Additionally, the crude extract and fractions from the purification process were screened for antibacterial and antifungal activity. This is supplemented by an extensive literature research for described bioactivities of all isolated compounds. Our results support and explain previously detected antimicrobial, antifungal and neuroprotective effects of H. scyphifera extracts and provide evidence for its potential pharmacological importance.

We report the multistep synthesis of a new array of 4,5-annelated bicyclic sydnone imine – (6-cyano-1-substituted-[1,2,3]oxadiazolo[5,4-b]pyridin-1-ium-5-yl)amide hydrochlorides. These bicyclic compounds are featured with the mesomeric charge spread out over the two fused aromatic fragments. Thus, these molecules can be considered as a new type of sydnone imine. The molecular structures of the bicyclic compounds were investigated in detail by X-ray and 1H, 13C, and 15N NMR studies. In addition, the characterization of these compounds and their synthetic intermediaries was undertaken to ascertain their effectiveness as potential plant stress protectants or herbicides.