Weapons or deterrents? Nudibranch molluscs use distinct ecological modes of chemical defence against predators.

Defensive chemicals are used by plants and animals to reduce the risk of predation through different mechanisms, including toxins that cause injury and harm (weapons) and unpalatable or odiferous compounds that prevent attacks (deterrents). However, whether effective defences are both toxins and deterrents, or work in just one modality is often unclear. In this study, our primary aim was to determine whether defensive compounds stored by nudibranch molluscs acted as weapons (in terms of being toxic), deterrents (in terms of being distasteful) or both. Our secondary aim was to investigate the response of different taxa to these defensive compounds. To do this, we identified secondary metabolites in 30 species of nudibranch molluscs and investigated their deterrent properties using antifeedant assays with three taxa: rock pool shrimp, Palaemon serenus, and two fish species: triggerfish Rhinecanthus aculeatus and toadfish Tetractenos hamiltoni. We compared these results to toxicity assays using brine shrimp Artemia sp. and previously published toxicity data with a damselfish Chromis viridis. Overall, we found no clear relationship between palatability and toxicity, but instead classified defensive compounds into the following categories: Class I & II-highly unpalatable and highly toxic; Class I-weakly unpalatable and highly toxic; Class II-highly unpalatable but weakly toxic; WR (weak response)-weakly unpalatable and weakly toxic. We also found eight extracts from six species that did not display activity in any assays indicating they may have very limited chemical defensive mechanisms (NR, no response). We found that the different classes of secondary metabolites were similarly unpalatable to fish and shrimp, except extracts from Phyllidiidae nudibranchs (isonitriles) that were highly unpalatable to shrimp but weakly unpalatable to fish. Our results pave the way towards better understanding how animal chemical defences work against a variety of predators. We highlight the need to disentangle weapons and deterrents in future work on anti-predator defences to better understand the foraging decisions faced by predators, the resultant selection pressures imposed on prey and the evolution of different anti-predator strategies.

Lipid A-Mediated Bacterial-Host Chemical Ecology: Synthetic Research of Bacterial Lipid As and Their Development as Adjuvants.

Gram-negative bacterial cell surface component lipopolysaccharide (LPS) and its active principle, lipid A, exhibit immunostimulatory effects and have the potential to act as adjuvants. However, canonical LPS acts as an endotoxin by hyperstimulating the immune response. Therefore, LPS and lipid A must be structurally modified to minimize their toxic effects while maintaining their adjuvant effect for application as vaccine adjuvants. In the field of chemical ecology research, various biological phenomena occurring among organisms are considered molecular interactions. Recently, the hypothesis has been proposed that LPS and lipid A mediate bacterial-host chemical ecology to regulate various host biological phenomena, mainly immunity. Parasitic and symbiotic bacteria inhabiting the host are predicted to possess low-toxicity immunomodulators due to the chemical structural changes of their LPS caused by co-evolution with the host. Studies on the chemical synthesis and functional evaluation of their lipid As have been developed to test this hypothesis and to apply them to low-toxicity and safe adjuvants.

Host Tree and Geography Induce Metabolic Shifts in the Epiphytic Liverwort Radula complanata.

Bryophytes are prolific producers of unique, specialized metabolites that are not found in other plants. As many of these unique natural products are potentially interesting, for example, pharmacological use, variations in the production regarding ecological or environmental conditions have not often been investigated. Here, we investigate metabolic shifts in the epiphytic Radula complanata L. (Dumort) with regard to different environmental conditions and the type of phorophyte (host tree). Plant material was harvested from three different locations in Sweden, Germany, and Canada and subjected to untargeted liquid chromatography high-resolution mass-spectrometry (UPLC/ESI-QTOF-MS) and data-dependent acquisition (DDA-MS). Using multivariate statistics, variable selection methods, in silico compound identification, and compound classification, a large amount of variation (39%) in the metabolite profiles was attributed to the type of host tree and 25% to differences in environmental conditions. We identified 55 compounds to vary significantly depending on the host tree (36 on the family level) and 23 compounds to characterize R. complanata in different environments. Taken together, we found metabolic shifts mainly in primary metabolites that were associated with the drought response to different humidity levels. The metabolic shifts were highly specific to the host tree, including mostly specialized metabolites suggesting high levels of ecological interaction. As R. complanata is a widely distributed generalist species, we found it to flexibly adapt its metabolome according to different conditions. We found metabolic composition to also mirror the constitution of the habitat, which makes it interesting for conservation measures.

Plant flavonoid inhibition of SARS-CoV-2 main protease and viral replication.

Plant-based flavonoids have been evaluated as inhibitors of ß-coronavirus replication and as therapies for COVID-19 on the basis of their safety profile and widespread availability. The SARS-CoV-2 main protease (Mpro) has been implicated as a target for flavonoids in silico. Yet no comprehensive in vitro testing of flavonoid activity against SARS-CoV-2 Mpro has heretofore been performed. We screened 1,019 diverse flavonoids for their ability to inhibit SARS-CoV-2 Mpro. Multiple structure-activity relationships were identified among active compounds such as enrichment of galloylated flavonoids and biflavones, including multiple biflavone analogs of apigenin. In a cell-based SARS-CoV-2 replication assay, the most potent inhibitors were apigenin and the galloylated pinocembrin analog, pinocembrin 7-O-(3''-galloyl-4'',6''-(S)-hexahydroxydiphenoyl)-beta-D-glucose (PGHG). Molecular dynamic simulations predicted that PGHG occludes the S1 binding site via a galloyl group and induces a conformational change in Mpro. These studies will advance the development of plant-based flavonoids-including widely available natural products-to target ß-coronaviruses.

Hemisynthetic alkaloids derived from trilobine are antimalarials with sustained activity in multidrug-resistant Plasmodium falciparum.

Malaria eradication requires the development of new drugs to combat drug-resistant parasites. We identified bisbenzylisoquinoline alkaloids isolated from Cocculus hirsutus that are active against Plasmodium falciparum blood stages. Synthesis of a library of 94 hemi-synthetic derivatives allowed to identify compound 84 that kills multi-drug resistant clinical isolates in the nanomolar range (median IC50 ranging from 35 to 88 nM). Chemical optimization led to compound 125 with significantly improved preclinical properties. 125 delays the onset of parasitemia in Plasmodium berghei infected mice and inhibits P. falciparum transmission stages in vitro (culture assays), and in vivo using membrane feeding assay in the Anopheles stephensi vector. Compound 125 also impairs P. falciparum development in sporozoite-infected hepatocytes, in the low micromolar range. Finally, by chemical pull-down strategy, we characterized the parasite interactome with trilobine derivatives, identifying protein partners belonging to metabolic pathways that are not targeted by the actual antimalarial drugs or implicated in drug-resistance mechanisms.

Identification of a dihydropyridine scaffold that blocks ryanodine receptors.

Ryanodine receptors (RyRs) are large, intracellular ion channels that control Ca2+ release from the sarco/endoplasmic reticulum. Dysregulation of RyRs in skeletal muscle, heart, and brain has been implicated in various muscle pathologies, arrhythmia, heart failure, and Alzheimer's disease. Therefore, there is considerable interest in therapeutically targeting RyRs to normalize Ca2+ homeostasis in scenarios involving RyR dysfunction. Here, a simple invertebrate screening platform was used to discover new chemotypes targeting RyRs. The approach measured Ca2+ signals evoked by cyclic adenosine 5'-diphosphate ribose, a second messenger that sensitizes RyRs. From a 1,534-compound screen, FLI-06 (currently described as a Notch "inhibitor") was identified as a potent blocker of RyR activity. Two closely related tyrosine kinase inhibitors that stimulate and inhibit Ca2+ release through RyRs were also resolved. Therefore, this simple screen yielded RyR scaffolds tractable for development and revealed an unexpected linkage between RyRs and trafficking events in the early secretory pathway.

NMR Metabolomics and Chemometrics of Lettuce, Lactuca sativa L., under Different Foliar Organic Fertilization Treatments.

Lettuce plants were grown in a greenhouse affected by the fungal pathogen Fusarium oxysporum to test the effects on plant metabolomics by different organic treatments. Three foliar application treatments were applied: a commercial compost tea made of aerobically fermented plant organic matter, a pure lyophilized microalga Artrospira platensis, commonly named spirulina, and the same microalga previously exposed during its culture to a natural uptake from medium enriched with F. oxysporum fragmented DNA (NAT). The experiment is the first attempt to observe in field conditions, the use and effects of a natural microbial library as a carrier of pathogenic fungal DNA for disease control. Untargeted NMR metabolomics and chemometrics showed that foliar organic application significantly reduced fumaric and formic acids, aromatic amino acids, and nucleosides, while increasing ethanolamine. A strong decrease in phenolic acids and an increase in citric acid and glutamine were specifically observed in the NAT treatment. It is noteworthy that the exposure of a known biostimulant microalga to fungal DNA in its culture medium was sufficient to induce detectable changes in the metabolomic profiles of the fertilized plants. These findings deserve further investigation to assess the potential relevance of the presented approach in the field of crop biostimulation and biocontrol of plant pathogens.

A pain-causing and paralytic ant venom glycopeptide.

Ants (Hymenoptera: Formicidae) are familiar inhabitants of most terrestrial environments. Although we are aware of the ability of many species to sting, knowledge of ant venom chemistry remains limited. Herein, we describe the discovery and characterization of an O-linked glycopeptide (Mg7a) as a major component of the venom of the ant Myrmecia gulosa. Electron transfer dissociation and higher-energy collisional dissociation tandem mass spectrometry were used to localize three α-N-acetylgalactosaminyl residues (α-GalNAc) present on the 63-residue peptide. To allow for functional studies, we synthesized the full-length glycosylated peptide via solid-phase peptide synthesis, combined with diselenide-selenoester ligation-deselenization chemistry. We show that Mg7a is paralytic and lethal to insects, and triggers pain behavior and inflammation in mammals, which it achieves through a membrane-targeting mode of action. Deglycosylation of Mg7a renders it insoluble in aqueous solution, suggesting a key solubilizing role of the O-glycans.

The comparison of the properties of nanocellulose isolated from colonial and solitary marine tunicates.

This is the first comparative of tunicate cellulose nanocrystalline (t-CNC) from colonial and solitary tunicates. The t-CNC from the colonial tunicate Eudistoma sp. (CL1) was compared with solitary tunicates Polycarpa reniformis (CL2) and Phallusia nigra (CL3). Tunicate samples were extracted by methanol. Residues from the methanol extraction were then subjected to further cellulose purification using pre-hydrolysis, kraft-cooking, bleaching, and sulfuric acid hydrolysis to yield t-CNC. The solitary tunicates yielded higher microfibril contents after the bleaching step but obtained similar t-CNC content to the colonial one after acid hydrolysis. The isolated t-CNC were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermalgravimetric analysis, and transmission electron microscopy. Both colonial and solitary tunicates yielded cellulose type I. The pure cellulose type I was successfully isolated from solitary tunicates whereas high inorganic impurities were observed in colonial tunicates. The isolate t-CNC showed high aspect ratios. The solitary and colonial tunicates provided t-CNC with crystallinity indexes over 97% and 35%, respectively. The crystalline size of t-CNCs ranged from 55-124 Å. The thermal stability of all isolated t-CNC was slightly decreased due to the sulfate functional groups gained after acid hydrolysis. We concluded that solitary tunicates were better than colonial tunicates as a source of t-CNC preparation.

Design, synthesis, and physicochemical study of a biomass-derived CO2 sorbent 2,5-furan-bis(iminoguanidine).

In this study, the concept of biomass-based direct air capture is proposed, and the aminoguanidine CO2 chemical sorbent 2,5-furan-bis(iminoguanidine) (FuBIG) was designed, synthesized, and elucidated for the physicochemical properties in the process of CO2 capture and release. Results showed that the aqueous solution of FuBIG could readily capture CO2 from ambient air and provided an insoluble tetrahydrated carbonate salt FuBIGH2(CO3) (H2O)4 with a second order kinetics. Hydrogen binding modes of iminoguanidine cations with carbonate ions and water were identified by single-crystal X-ray diffraction analysis. Equilibrium constant (K) and the enthalpies (ΔH) for CO2 absorption/release were obtained by thermodynamic and kinetic analysis (K7 = 5.97 × 104, ΔH7 = -116.1 kJ/mol, ΔH8 = 209.31 kJ/mol), and the CO2-release process was conformed to the geometrical phase-boundary model (1-(1-α)1/3 = kt). It was found that the FuBIGH2(CO3) (H2O)4 can release CO2 spontaneously in DMSO without heating. Zebrafish models revealed a favorable biocompatibility of FuBIG.

Phylobioactive hotspots in plant resources used to treat Chagas disease.

Globally, more than six million people are infected with Trypanosoma cruzi, the causative protozoan parasite of the vector-borne Chagas disease (CD). We conducted a cross-sectional ethnopharmacological field study in Bolivia among different ethnic groups where CD is hyperendemic. A total of 775 extracts of botanical drugs used in Bolivia in the context of CD and botanical drugs from unrelated indications from the Mediterranean De Materia Medica compiled by Dioscorides two thousand years ago were profiled in a multidimensional assay uncovering different antichagasic natural product classes. Intriguingly, the phylobioactive anthraquinone hotspot matched the antichagasic activity of Senna chloroclada, the taxon with the strongest ethnomedical consensus for treating CD among the Izoceño-Guaraní. Testing common 9,10-anthracenedione derivatives in T. cruzi cellular infection assays demarcates hydroxyanthraquinone as a potential antichagasic lead scaffold. Our study systematically uncovers in vitro antichagasic phylogenetic hotspots in the plant kingdom as a potential resource for drug discovery based on ethnopharmacological hypotheses.

Selection of Small Molecules that Bind to and Activate the Insulin Receptor from a DNA-Encoded Library of Natural Products.

Although insulin is a life-saving medicine, administration by daily injection remains problematic. Our goal was to exploit the power of DNA-encoded libraries to identify molecules with insulin-like activity but with the potential to be developed as oral drugs. Our strategy involved using a 104-member DNA-encoded library containing 160 Traditional Chinese Medicines (nDEL) to identify molecules that bind to and activate the insulin receptor. Importantly, we used the natural ligand, insulin, to liberate bound molecules. Using this selection method on our relatively small, but highly diverse, nDEL yielded a molecule capable of both binding to and activating the insulin receptor. Chemical analysis showed this molecule to be a polycyclic analog of the guanidine metformin, a known drug used to treat diabetes. By using our protocol with other, even larger, DELs we can expect to identify additional organic molecules capable of binding to and activating the insulin receptor.

High-Throughput Preparation of Antibacterial Polymers from Natural Product Derivatives via the Hantzsch Reaction.

The Hantzsch and free-radical polymerization reactions were combined in a one-pot high-throughput (HTP) system to simultaneously prepare 30 unique polymers in parallel. Six aldehydes derived from natural products were used as the starting materials to rapidly prepare the library of 30 poly(1,4-dihydropyridines). From this library, HTP evaluation methods led to the identification of an antibacterial polymer. Mechanistic studies revealed that the dihydropyridine group in the polymer side-chain structure plays an important role in resisting bacterial attachment to the polymer surface, thus leading to the antibacterial function of this polymer. This research demonstrates the value of multicomponent reactions (MCRs) in interdisciplinary fields by discovering functional polymers for possible practical applications. It also provides insights to further developing new functional polymers using MCRs and HTP methods with important implications in organic chemistry, polymer chemistry, and materials science.

Synthesis and evaluation of novel chromanone and quinolinone analogues of uniflorol as anti-leishmanial agents.

Within this work, we describe the design and synthesis of a range of novel chromanones and quinolinones, based on natural products reported to possess anti-leishmanial action. The core heterocycles were obtained either via classical or ionic liquid mediated Kabbe condensation in the case of chromanones, or aqueous Sonogashira based alkynylation followed by acid-catalysed cyclisation in the case of quinolinones. Upon testing in promastigotes, axenic amastigotes and Leishmania-infected macrophages, compound 13c was identified as displaying interesting activity, inhibiting axenic amastigotes and intracellular amastigotes with IC50s of 25.3 and 24.6µM respectively.

Effects of commonly used food additives on haematological parameters of Wistar rats.

This study was done to investigate the effects of common food additives such as sodium benzoate (SB) and ascorbic acid (AA) on haematological parameters of male Wistar rats. Forty-eight (48) male albino rats with an average weight of 105 g were grouped into twelve (n = 4) of Basal Control and other 11 groups orally administered 1 mg of SB, 10 mg of SB, 10 mg of AA, 0.2 mg of AA + 0.5 mg of SB, 0.2 mg of AA + 1 mg of SB, 0.2 mg of AA + 10 mg of SB, 0.2 mg of SB + 0.1 mg of AA, 0.2 mg of SB + 0.5 mg of AA, carbonated soft drinks (CSD)+ 0.1 mg of AA, CSD + 1 mg of AA and CSD + 10 mg of AA, respectively for 21 non-consecutive days. At the end of the experiment, blood samples were collected in EDTA anticoagulant tubes, haematological parameters were evaluated, and data were analyzed. There was a dose-dependent increase (p < 0.05) in White Blood Cell counts of SB treated rats compared with the control group. The lymphocyte exhibited significant reduction (p < 0.05) in the groups treated with 1mg SB and 10mg SB/kg bodyweight of 67 ± 2.96 and 58 ± 4.18%, respectively. The mean corpuscular haemoglobin showed no significant difference at 95% confidence interval. However, mean corpuscular haemoglobin concentration, haematocrit and platelet were affected by an increase in the concentrations of SB. High SB concentrations increased the destruction of erythrocytes, which directly increased the catabolism of haemoglobin. However, AA administration mitigated the adverse effects of SB on the haematological parameters of the animal.

Bioassay-guided isolation and identification of antidiabetic compounds from Garcinia cowa leaf extract.

Garcinia cowa Roxb. ex Choisy (Clusiaceae) is a Thai local edible plant, which has been used for the treatment of diabetes. The aim of this study is to discover and identify bioactive compounds related to antidiabetic properties from the leaf extract of G. cowa. α-Glucosidase inhibitory bioassay-guided isolation of the ethyl acetate extract of the leaves of G.cowa resulted in the isolation and identification of 11 compounds. Of these, a decahydro-1H-xanthene derivative, garciniacowone K (1), was identified as a novel compound. Their structures were characterized by spectroscopic data and by comparison of their NMR spectroscopic data with those previously reported. All compounds were evaluated for their α-glucosidase inhibitory and glucose consumption activities. Compound 2 showed the highest efficacy in inhibiting α-glucosidase enzyme and promoting glucose consumption activity by 3T3-L1 cells, with IC50 values of 0.5 µM and 13.1 µM, respectively, without causing toxicity to cells.

Polycyclic aromatic hydrocarbons in soybean grains.

During the burning of the organic material (firewood) in the drying, combustion may occur incompletely, thus generating smoke contaminants such as polycyclic aromatic hydrocarbons (PAHs) in the furnaces. This study aimed to identify possible contamination by PAHs in soybean grains from storage units in municipalities in the Midwest region that have undergone drying in a direct-fired furnace with firewood as fuel. The soybean grains were collected in different municipalities of the Midwest region of Brazil, totaling 22 samples. A survey of possible contamination of soybean grains by PAHs was carried out using High-Performance Liquid Chromatography. The experiment was carried out in a completely randomized design with three replicates, and the data were subjected to analysis of variance, with means compared by Tukey test. The sum of the groups was: PAH4 - 1.45 µg kg-1 for Edéia (2), PAH8 - 2.97 µg kg-1 for Catalão (19) and PAHT - 5.06 µg kg-1 for Edéia (2); for benzo(a)pyrene, the sum was below 2.0 µg kg-1, not exceeded by the value of 0.64 µg kg-1 for Edéia (1). The values found of PAHs did not exceed the maximum limits established by the European Union, except for infant food.

Comparative study on the chemical composition of laurel (Laurus nobilis L.) leaves from Greece and Georgia and the antibacterial activity of their essential oil.

Laurel (Laurus nobilis L.) is a plant species from Lauraceae family, and is native to the Mediterranean region. The goal of this study was to compare chemical composition of laurel leaves and antibacterial activity of its essential oil (EO) from wild-grown trees in Greece and Georgia. The laurel leaves from the two native habitats had dissimilar concentrations of phenolic acids. Of the conjugated flavonols and flavons, kaempferol (1981.3 µg/g) and apigenin (1433.6 µg/g) were the major representatives in the leaves from Greece, while luteolin (839.1 µg/g) and kaempferol (688.1 µg/g) were the major ones in the leaves from Georgia, respectively. The EO content was 1.42% and 4.54% in the leaves from Greece and Georgia, respectively. The main EO constituents of the Greek laurel plants were 1,8-cineole (30.8%), α-terpinyl acetate (14.9%), α-terpineol (8.0%), sabinene (7.9%), and terpinen-4-ol (6.0%). The main EO constituents of the Georgian laurel plants were 1,8-cineole (29.2%), α-terpinyl acetate (22.6%), sabinene (12.2%), and methyleugenol (8.1%). The EO antimicrobial activities against 20 microorganisms were determined. Among the Gram-positive bacteria, the Enterococcus faecalis strain was the most sensitive, followed by Staphylococcus aureus ATCC 6538. Among the Candida species, C. albicans ATCC 10231 was the most sensitive to the laurel leaf EOs.

Synthesis, pharmacological evaluation and structure-activity relationship of recently discovered enzyme antagonist azoles.

Global people are suffering from the legion of diseases. Cytotoxic property of the chemical compound would not solely influence effective drug properties and reduce unnecessary side effects. Proteins/enzymes responsible for microbe proliferation or survival are specifically targeted and inhibited successfully making the cells to undergo apoptosis. Furthermore, isoforms of essential enzymes have distinct physiological functions; thereby inhibition of essential enzyme isoforms is an apt way to the clinical approach of disease neutralization. Drugs are designed so as to play significant roles such as signaling pathways in the oncogenic process including cell proliferation, invasion, and angiogenesis. The present review comprises collective information of the recent synthesis of various organic drug compounds in brief, which could inhibit particular enzyme. The review also covers the correlation of the structure of a drug molecule designed and its inhibitory activity. Also, the most significant enzyme inhibitors are highlighted and structural moieties/core units responsible for remarkable inhibitory values are emphasized.

Characterization and the evaluation of antimicrobial activities of silver nanoparticles biosynthesized from Carya illinoinensis leaf extract.

A green, direct and cost-effective fabrication method is proposed for Eco-environmentally silver nanoparticles (AgNPs) through leaf extraction of Carya illinoinensis from Iran. Formation of Ag NPs was confirmed through different characterization techniques such as UV-Vis Spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). UV-Visible spectrophotometer showed absorbance peak at 440 nm due to the Surface Plasmon Resonance (SPR). Based on XRD results and SEM and TEM analysis, AgNPs were crystalline with face-centered cubic geometry and in different sizes ranged 12-30 nm. Furthermore, FTIR Spectroscopy was utilized to recognize the specific functional groups responsible for reducing ion silver to silver nanoparticles and the capping agents available in the leaf extract. In addition, the antibacterial effect of Eco-friendly synthesized nanoparticles and also leaf extract, were evaluated on four pathogens by implementing minimum inhibitory concentration test (MIC) and agar diffusion assay. The MIC results exhibits more inhibiting activity against gram-negative microorganisms (Escherichia coli and Pseudomonas aeruginosa) rather than gram-positive microorganisms (Staphylococcus aureus and Listeria monocytogenes). Compared to leaf extract, nanoparticles have better antimicrobial activity against both Gram-positive and Gram-negative bacteria.