Molecular and microstructural inventory of an isolated fossil bird feather from the Eocene Fur Formation of Denmark

An isolated, yet virtually intact contour feather (FUM‐1980) from the lower Eocene Fur Formation of Denmark was analysed using multiple imaging and molecular techniques, including field emission gun scanning electron microscopy (FEG‐SEM), X‐ray absorption spectroscopy and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). Additionally, synchrotron radiation X‐ray tomographic microscopy (SRXTM) was employed in order to produce a digital reconstruction of the fossil. Under FEG‐SEM, the proximal, plumulaceous part of the feather revealed masses of ovoid microstructures, about 1.7 μm long and 0.5 μm wide. Microbodies in the distal, pennaceous portion were substantially smaller (averaging 0.9 × 0.2 μm), highly elongate, and more densely packed. Generally, the microbodies in both the plumulaceous and pennaceous segments were aligned along the barbs and located within shallow depressions on the exposed surfaces. Biomarkers consistent with animal eumelanins were co‐localized with the microstructures, to suggest that they represent remnant eumelanosomes (i.e. eumelanin‐housing cellular organelles). Additionally, ToF‐SIMS analysis revealed the presence of sulfur‐containing organics – potentially indicative of pheomelanins – associated with eumelanin‐like compounds. However, since there was no correlation between melanosome morphology and sulfur content, we conclude these molecular structures derive from diagenetically incorporated sulfur rather than pheomelanin. Melanosomes corresponding roughly in both size and morphology with those in the proximal part of FUM‐1980 are known from contour feathers of extant parrots (Psittaciformes), an avian clade that has previously been reported from the Fur Formation.     

New preparation techniques for molecular and in‐situ analysis of ancient organic micro‐ and nanostructures

Organic microfossils preserved in three dimensions in transparent mineral matrices such as cherts/quartzites, phosphates, or carbonates are best studied in petrographic thin sections. Moreover, microscale mass spectrometry techniques commonly require flat, polished surfaces to minimize analytical bias. However, contamination by epoxy resin in traditional petrographic sections is problematic for the geochemical study of the kerogen in these microfossils and more generally for the in situ analysis of fossil organic matter. Here, we show that epoxy contamination has a molecular signature that is difficult to distinguish from kerogen with time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). This contamination appears pervasive in organic microstructures embedded in micro‐ to nano‐crystalline carbonate. To solve this problem, a new semi‐thin section preparation protocol without resin medium was developed for micro‐ to nanoscale in situ investigation of insoluble organic matter. We show that these sections are suited for microscopic observation of Proterozoic microfossils in cherts. ToF‐SIMS reveals that these sections are free of pollution after final removal of a <10 nm layer of contamination using low‐dose ion sputtering. ToF‐SIMS maps of fragments from aliphatic and aromatic molecules and organic sulfur are correlated with the spatial distribution of organic microlaminae in a Jurassic stromatolite. Hydrocarbon‐derived ions also appeared correlated with kerogenous microstructures in Archean cherts. These developments in analytical procedures should help future investigations of organic matter and in particular, microfossils, by allowing the spatial correlation of microscopy, spectroscopy, precise isotopic microanalyses, and novel molecular microanalyses such as ToF‐SIMS.     

A high‐resolution chemical and structural study of framboidal pyrite formed within a low‐temperature bacterial biofilm

A novel, anaerobically grown microbial biofilm, scraped from the inner surface of a borehole, 1474 m below land surface within a South African, Witwatersrand gold mine, contains framboidal pyrite. Water flowing from the borehole had a temperature of 30.9 °C, a pH of 7.4, and an Eh of –50 mV. Examination of the biofilm using X‐ray diffraction, field emission gun scanning electron microscope equipped for energy dispersive X‐ray microanalysis demonstrated that the framboids formed within a matrix of bacteria and biopolymers. Focused ion beam sectioning of framboids followed by NEXAFS measurements using both scanning transmission X‐ray microscopy and X‐ray photoelectron emission microscopy revealed that the pyrite crystals grew within an organic carbon matrix consisting of exopolysaccharides and possibly extracellular DNA, which is intuitively important in sulfide mineral diagenesis. Growth of individual pyrite crystals within the framboid occurred inside organic templates confirms the association between framboidal pyrite and organic materials in low‐temperature diagenetic environments and the important role of microenvironments in biofilms in regulating geochemical cycles.     

Analysis of archaeal core ether lipids using Time of Flight–Secondary Ion Mass Spectrometry (ToF-SIMS): Exploring a new prospect for the study of biomarkers in geobiology

The capability of Time of Flight–Secondary Ion Mass Spectrometry (ToF‐SIMS) of analysing molecular archaeal biomarkers in geobiological samples was tested and demonstrated. Using a bismuth cluster primary ion source, isopranyl glycerol di‐ and tetraether core lipids were detected in small amounts of total organic extracts from methanotrophic microbial mats, simultaneously and without further chemical treatment and chromatographic separation. ToF‐SIMS was also employed to track the distribution of fossilized ether lipids in a massive carbonate (aragonite) microbialite that precipitated as a result of the microbial anaerobic oxidation of methane. An unambiguous signal was obtained when analysing a freshly broken rock surface (base of a microdrill core). Though some limitation occurred due to µm‐topographical effects (sample roughness), it was possible to display the abundance of high molecular weight (C₈₆) of tetraethers exposed in particular regions of the rock surface. ‘Molecular mapping’ revealed that a part of these molecules was encased within the rock fabric in a cluster‐like distribution that might trace the arrangement of the calcifying microbial colonies in the once active mat system. The results reveal promising perspectives of ToF‐SIMS for (i) the quasi‐nondestructive analysis of lipids in extremely small geobiological samples at low concentrations; (ii) resolving the spatial distribution of these compounds on a µm²‐ to cm²‐scale; and (iii) the more exact assignment of lipid biomarkers to their biological source.     

DNA metabarcoding reveals that 200‐μm‐size‐fractionated filtering is unable to discriminate between planktonic microbial and large eukaryotes

Microeukaryotic plankton (0.2–200 μm) are critical components of aquatic ecosystems and key players in global ecological processes. High‐throughput sequencing is currently revolutionizing their study on an unprecedented scale. However, it is currently unclear whether we can accurately, effectively and quantitatively depict the microeukaryotic plankton communities using traditional size‐fractionated filtering combined with molecular methods. To address this, we analysed the eukaryotic plankton communities both with, and without, prefiltering with a 200 μm pore‐size sieve –by using SSU rDNA‐based high‐throughput sequencing on 16 samples with three replicates in each sample from two subtropical reservoirs sampled from January to October in 2013. We found that ~25% reads were classified as metazoan in both size groups. The species richness, alpha and beta diversity of plankton community and relative abundance of reads in 99.2% eukaryotic OTUs showed no significant changes after prefiltering with a 200 μm pore‐size sieve. We further found that both >0.2 μm and 0.2–200 μm eukaryotic plankton communities, especially the abundant plankton subcommunities, exhibited very similar, and synchronous, spatiotemporal patterns and processes associated with almost identical environmental drivers. The lack of an effect on community structure from prefiltering suggests that environmental DNA from larger metazoa is introduced into the smaller size class. Therefore, size‐fractionated filtering with 200 μm is insufficient to discriminate between the eukaryotic plankton size groups in metabarcoding approaches. Our results also highlight the importance of sequencing depth, and strict quality filtering of reads, when designing studies to characterize microeukaryotic plankton communities.     

Synthesis and Anticancer Activity of 3‐(Substituted Aroyl)‐4‐(3,4,5‐trimethoxyphenyl)‐1H‐pyrrole Derivatives

A series of 3‐(substituted aroyl)‐4‐(3,4,5‐trimethoxyphenyl)‐1H‐pyrrole derivatives were synthesized and determined for their anticancer activity against eleven cancer cell lines and two normal tissue cell lines using MTT assay. Among the synthesized compounds, compound 3f was the most potent compound against A375, CT‐26, HeLa, MGC80‐3, NCI‐H460 and SGC‐7901 cells (IC₅₀ = 8.2 – 31.7 μm ); 3g , 3n and 3a were the most potent compounds against CHO (IC₅₀ = 8.2 μm ), HCT‐15 (IC₅₀ = 21 μm ) and MCF‐7 cells (IC₅₀ = 18.7 μm ), respectively. Importantly, all the target compounds showed no cytotoxicity towards the normal tissue cell (IC₅₀ > 100 μm ). Thus, these compounds with the potent anticancer activity and low toxicity have potential for the development of new anticancer chemotherapy agents.     

Biomarkers at the microscopic range: ToF-SIMS molecular imaging of Archaea-derived lipids in a microbial mat

Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS) with a bismuth cluster primary ion source was used for analysing microbial lipid biomarkers in 10‐µm‐thick microscopic cryosections of methanotrophic microbial mats from the Black Sea. Without further sample preparation, archaeal isopranyl glycerol di‐ and tetraether core lipids, together with their intact diglycoside (gentiobiosyl‐) derivatives, were simultaneously identified by exact mass determination. Utilizing the imaging capability of ToF‐SIMS, the spatial distributions of these biomarkers were mapped at a lateral resolution of < 5 µm in 500 × 500 µm² areas on the mat sections. Using cluster projectiles in the burst alignment mode, it was possible to reach a lateral resolution of 1 µm on an area of 233 × 233 µm, thus approaching the typical size of microbial cells. The mappings showed different ‘provenances’ within the sections that are distinguished by individual lipid fingerprints, namely (A) the diethers archaeol and hydroxyarchaeol co‐occurring with glycerol dialkyl glycerol tetraethers (GDGT), (B) hydroxyarchaeol and dihydroxyarchaeol, and (C) GDGT and gentiobiosyl‐GDGT. Because ToF‐SIMS is a virtually nondestructive technique affecting only the outermost layers of the sample surface (typically 10–100 nm), it was possible to further examine the studied areas using conventional microscopy, and associate the individual lipid patterns with specific morphological traits. This showed that provenance (B) was frequently associated with irregular, methane‐derived CaCO₃ crystallites, whereas provenance (C) revealed a population of fluorescent, filamentous microorganisms showing the morphology of known methanotrophic ANME‐1 archaea. The direct coupling of imaging mass spectrometry with microscopic techniques reveals interesting perspectives for the in‐situ study of lipids in geobiology, microbial ecology, and organic geochemistry. After further developing protocols for handling different kinds of environmental samples, ToF‐SIMS could be used as a tool to attack many challenging problems in these fields, such as the attribution of biological source(s) to particular biomarkers in question, or the high‐resolution tracking of biogeochemical processes in modern and ancient natural environments.     

Analysis of flumequine enantiomers in rat plasma by UFLC‐ESI‐MS/MS

In this study the analysis and confirmation of flumequine enantiomers in rat plasma by ultra‐fast liquid chromatography coupled with electron spray ionization mass spectrometry (using propranolol as an internal standard [IS]) was developed and validated. Plasma samples were prepared by liquid–liquid extraction using methyl tert‐butyl ether as the extraction solvent. Direct resolution of the R‐ and S‐isomers was performed on a CHIRALCEL OJ‐RH column (4.6 × 150 mm, 5 μm) using acetonitrile / 0.1% formic acid / 1 mM ammonium acetate as the mobile phase. Detection was operated by electron spray ionization in the selected ion monitoring and positive ion mode. The target ions at m/z 262.1 and m/z 260.1 were selected for the quantification of the enantiomers and IS, respectively. The linear range was 0.5–500 ng/mL. The precisions (coefficient of variation, CV%) and recoveries were 1.43–8.68 and 94.24–106.76%, respectively. The lowest quantitation limit for both enantiomers is 0.5 ng/mL, which is sensitive enough to be applied to sample analysis in other related studies.     

Two liquid chromatographic approaches for the simultaneous determination of xipamide and its degradation product (2,6‐xylidine) using time‐programmed fluorescence detection

A study of the performance of reversed‐phase chromatography with a programmable multiwavelength fluorimetric technique using either conventional hydro‐organic or micellar eluent is established for the determination of xipamide (XIP) in the presence of its degradation product, 2,6‐xylidine (XY). In conventional liquid chromatography (CLC), the analyses were carried out on a Promosil ODS 100 Å column (250 mm × 4.6 mm i.d., 5 μm) using a mobile phase consisting of methanol/0.1 M phosphate buffer (65: 35, v/v) at pH 4.0. For micellar liquid chromatography (MLC), a short Spherisorb column (150 mm × 4.6 mm i.d., 5 μm) was employed in conjunction with a greener mobile phase (pH 5.0) containing 0.1 M sodium dodecyl sulfate and 15% n‐propanol. CLC proved to be superior to MLC in terms of sensitivity for the determination of the degradation product because it could detect trace amounts down to 10.0 ng/ml of XY as a degradation product in XIP. However, MLC represents an eco‐friendly approach for the simultaneous determination of XIP and XY. In addition, the opportunity for the direct introduction of biological matrices into the chromatographic system is one of the distinctive benefits of MLC. The proposed methods were applied for the determination of XIP in its tablets, human urine and content uniformity testing. The results of the proposed methods were statistically compared with those obtained using the comparison fluorimetric method, revealing no significant differences in the performance of the methods regarding accuracy and precision.     

Amino‐substituted para‐Benzoquinones as Potential Herbicides

Although quinones present a large array of biological activities, a few studies on the herbicidal potential of 2,5‐bis(alkyl/arylamino)‐1,4‐benzoquinones have been reported to date. In this work, starting from benzoquinone, 13 2,5‐bis(alkyl/arylamino)‐1,4‐benzoquinones were prepared in 46 – 93% yield. The products were fully characterized by spectroscopic analyses and their phytotoxicity against Cucumis sativus and Sorghum bicolor seedlings was investigated. At 100 ppm, compounds caused 10 – 88% growth inhibition of the dicotyledonous species, whereas the monocotyledon was less affected. Most compounds exerted little inhibitory effect on a cyanobacterial model strain. However, at 100 μm , compounds 8  –  10 caused about 50% inhibition of algal growth, and compounds 1 and 2 reduced cell viability in the 1 – 10 μm range. The ability of benzoquinone derivatives to interfere with the light‐driven ferricyanide reduction by isolated spinach chloroplasts was evaluated. Some substances showed a moderate effect as uncouplers, but no relationship was found between this property and their biological activity, indicating that the herbicidal effect is not associated with the inhibition of the photosynthetic electron transport chain. Phytotoxic compounds were not toxic to insects, strengthening the possibility that they may serve as lead for the development of eco‐friendly herbicides.     

Optimization of ASE and SPE conditions for the HPLC‐FLD detection of piperazine in chicken tissues and pork

Accelerated solvent extraction (ASE) and solid‐phase extraction (SPE) conditions were optimized by a high‐performance liquid chromatography‐fluorescence detector (HPLC‐FLD) method for the detection of piperazine in chicken tissues and pork. Piperazine residues were determined by precolumn derivatization with trimethylamine and dansyl chloride. Samples were extracted with 2% formic acid in acetonitrile using an ASE apparatus and purified using a Strata‐X‐C SPE column. The monosubstituted product of the reaction of piperazine with dansyl chloride was 1‐dansyl piperazine (1‐DNS‐piperazine). Chromatographic separations were performed on an Athena C₁₈ column (250 × 4.6 mm, id: 5 μm) with gradient elution using ultrapure water and acetonitrile (5:95, V/V) as the mobile phase. The calibration curves showed good linearity over a concentration range of LOQ‐200.0 μg/kg with a coefficient of determination (R²) ≥ .9992. The recoveries and relative standard deviations (RSD values) ranged from 78.49% to 97.56% and 1.19% to 5.32%, respectively, across the limit of quantification (LOQ) and 0.5, 1, and 2.0 times the maximum residue limit (MRL; μg/kg). The limits of detection (LODs) and LOQs were 0.96 to 1.85 μg/kg and 3.20 to 5.50 μg/kg, respectively. The method was successfully applied for the validation of animal products in the laboratory.     

Chiral HPLC Separation and Modeling of Four Stereomers of DL‐Leucine‐DL‐Tryptophan Dipeptide on Amylose Chiral Column

Chiral high‐performance liquid chromatography (HPLC) separation and modeling of four stereomers of DL‐leucine‐tryptophan DL‐dipeptide on AmyCoat‐RP column are described. The mobile phase applied was ammonium acetate (10 mM)‐methanol‐acetonitrile (50:5:45, v/v). The flow rate of the mobile phases was 0.8 mL/min with UV detection at 230 nm. The values of retention factors for LL‐, DD‐, DL‐, and LD‐ stereomers were 2.25, 3.60, 5.00, and 6.50, respectively. The values of separation and resolution factors were 1.60, 1.39, and 1.30 and 7.76, 8.05, and 7.19. The limits of detection and quantitation were ranging from 1.0–2.3 and 5.6–14.0 μg/mL. The simulation studies established the elution orders and the mechanism of chiral recognition. It was seen that π–π connections and hydrogen bondings were the main forces for enantiomeric resolution. The reported chiral HPLC method may be applied for the enantiomeric separation of DL‐leucine‐DL‐tryptophan in unknown matrices. Chirality 28:642–648, 2016. © 2016 Wiley Periodicals, Inc.     

Superbanone,A New 2‐Aryl‐3‐benzofuranone and Other Bioactive Constituents from the Tube Roots of Butea superba

Phytochemical investigation from the tube roots of Butea superba, led to the isolation and identification of a new 2‐aryl‐3‐benzofuranone named superbanone ( 1 ), one benzoin, 2‐hydroxy‐1‐(2‐hydroxy‐4‐methoxyphenyl)‐2‐(4‐methoxyphenyl)ethanone ( 2 ), eight pterocarpans ( 3  –  10 ), and eleven isoflavonoids ( 11  –  21 ). Compound 2 was identified for the first time as a natural product. The structure of the isolated compounds was elucidated using spectroscopic methods, mainly 1D‐ and 2D‐NMR. The isolated compounds and their derivatives were evaluated for α‐glucosidase inhibitory and antimalarial activities. Compounds 3 , 7 , 8 , and 11 showed promising α‐glucosidase inhibitory activity (IC₅₀ = 13.71 ± 0.54, 23.54 ± 0.75, 28.83 ± 1.02, and 12.35 ± 0.36 μm , respectively). Compounds 3 and 11 were twofold less active than the standard drug acarbose (IC₅₀ = 6.54 ± 0.04 μm ). None of the tested compounds was found to be active against Plasmodium falciparum strain 94. On the basis of biological activity results, structure–activity relationships are discussed.     

Enantioselective analysis of ibuprofen enantiomers in mice plasma and tissues by high‐performance liquid chromatography with fluorescence detection: Application to a pharmacokinetic study

A direct fluorometric high‐performance liquid chromatography (HPLC) method was developed and validated for the analysis of ibuprofen enantiomers in mouse plasma (100 μl) and tissues (brain, liver, kidneys) using liquid–liquid extraction and 4‐tertbutylphenoxyacetic acid as an internal standard. Separation of enantiomers was accomplished in a Chiracel OJ‐H chiral column based on cellulose tris(4‐methylbenzoate) coated on 5 μm silica‐gel, 250 x 4.6 mm at 22 °C with a mobile phase composed of n‐hexane, 2‐propanol, and trifluoroacetic acid that were delivered in gradient elution at a flow rate of 1 ml min⁻¹. A fluorometric detector was set at: λ_excit. = 220 nm and λ_emis. = 290 nm. Method validation included the evaluation of the selectivity, linearity, lower limit of quantification (LLOQ), within‐run and between‐run precision and accuracy. The LLOQ for the two enantiomers was 0.125 μg ml⁻¹ in plasma, 0.09 μg g⁻¹ in brain, and 0.25 μg g⁻¹ in for liver and kidney homogenates. The calibration curves showed good linearity in the ranges of each enantiomers: from 0.125 to 35 μg ml⁻¹ for plasma, 0.09–1.44 μg g⁻¹ for brain, and 0.25–20 μg g⁻¹ for liver and kidney homogenates. The method was successfully applied to a pharmacokinetic study of ibuprofen enantiomers in mice treated i.v. with 10 mg kg⁻¹ of racemate.     

Nisin adsorption on hydrophilic and hydrophobic surfaces: evidence of its interactions and antibacterial activity

Study of peptides adsorption on surfaces remains a current challenge in literature. A complementary approach, combining X‐ray photoelectron spectroscopy (XPS) and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) was used to investigate the antimicrobial peptide nisin adsorption on hydrophilic and hydrophobic surfaces. The native low density polyethylene was used as hydrophobic support and it was grafted with acrylic acid to render it hydrophilic. XPS permitted to confirm nisin adsorption and to determine its amount on the surfaces. ToF‐SIMS permitted to identify the adsorbed bacteriocin type and to observe its distribution and orientation behavior on both types of surfaces. Nisin was more oriented by its hydrophobic side to the hydrophobic substrate and by its hydrophilic side to the outer layers of the adsorbed peptide, in contrast to what was observed on the hydrophilic substrate. A correlation was found between XPS and ToF‐SIMS results, the types of interactions on both surfaces and the observed antibacterial activity. Such interfacial studies are crucial for better understanding the peptides interactions and adsorption on surfaces and must be considered when setting up antimicrobial surfaces. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Responses of the weed Bidens pilosa L. to exogenous application of the steroidal saponin protodioscin and plant growth regulators 24‐epibrassinolide,indol‐3‐acetic acid and abscisic acid

• The exogenous application of plant hormones and their analogues has been exploited to improve crop performance in the field. Protodioscin is a saponin whose steroidal moiety has some similarities to plant steroidal hormones, brassinosteroids. To test the possibility that protodioscin acts as an agonist or antagonist of brassinosteroids or other plant growth regulators, we compared responses of the weed species Bidens pilosa L. to treatment with protodioscin, brassinosteroids, auxins (IAA) and abscisic acid (ABA).
• Seeds were germinated and grown in agar containing protodioscin, dioscin, brassinolides, IAA and ABA. Root apex respiratory activity was measured with an oxygen electrode. Malondialdehyde (MDA) and antioxidant enzymes activities were assessed.
• Protodioscin at 48–240 μm inhibited growth of B. pilosa seedlings. The steroidal hormone 24‐epibrassinolide (0.1–5 μm ) also inhibited growth of primary roots, but brassicasterol was inactive. IAA at higher concentrations (0.5–10.0 μm ) strongly inhibited primary root length and fresh weight of stems. ABA inhibited all parameters of seedling growth and also seed germination. Respiratory activity of primary roots (KCN‐sensitive and KCN‐insensitive) was activated by protodioscin. IAA and ABA reduced KCN‐insensitive respiration. The content of MDA in primary roots increased only after protodioscin treatment. All assayed compounds increased APx and POD activity, with 24‐epibrassinolide being most active. The activity of CAT was stimulated by protodioscin and 24‐epibrassinolide.
• The results revealed that protodioscin was toxic to B. pilosa through a mechanism not related to plant growth regulator signalling. Protodioscin caused a disturbance in mitochondrial respiratory activity, which could be related to overproduction of ROS and consequent cell membrane damage.

     

Fabrication of nitrogen‐ and phosphorous‐doped carbon dots by the pyrolysis method for iodide and iron(III) sensing

A facile and novel strategy to synthesize nitrogen‐ and phosphorous‐doped carbon dots (NPCDs) by single step pyrolysis method is described here. Citric acid is used as carbon source and di‐ammonium hydrogen phosphate is used as both nitrogen and phosphorous sources, respectively. Through the extensive study on optical properties, morphology and chemical structures of the synthesized NPCDs, it is found that as‐synthesized NPCDs exhibited good excitation‐dependent luminescence property, spherical morphology and high stability. The obtained NPCDs are stable in aqueous medium and possess a quantum yield of 10.58%. In this work, a new assay method is developed to detect iodide ions using the synthesized NPCDs. Here, the inner filter effect is applied to detect the iodide ion and exhibited a wide linear response concentration range (10–60 μM) with a limit of detection (LOD) of 0.32 μM. Furthermore, the synthesized NPCDs are used for the selective detection of iron(III) (Fe³⁺) ions and cell imaging. Fe³⁺ ions sensing assay shows a detection range from 0.2 to 30 μM with a LOD of 72 nM. As an efficient photoluminescence sensor, the developed NPCDs have an excellent biocompatibility and low cytotoxicity, allowing Fe³⁺ ion detection in HeLa cells.     

New Furanone Derivatives and Alkaloids from the Co‐Culture of Marine‐Derived Fungi Aspergillus sclerotiorum and Penicillium citrinum

Six new compounds including two furanone derivatives sclerotiorumins A and B ( 1 and 2 ), one novel oxadiazin derivative sclerotiorumin C ( 3 ), one pyrrole derivative 1‐(4‐benzyl‐1H‐pyrrol‐3‐yl)ethanone ( 4 ), and two complexes of neoaspergillic acid aluminiumneohydroxyaspergillin ( 5 ) and ferrineohydroxyaspergillin ( 6 ) were isolated from the co‐culture of marine‐derived fungi Aspergillus sclerotiorum and Penicillium citrinum. Compound 3 was the first natural 1,2,4‐oxadiazin‐6‐one. Compound 5 showed significant and selective cytotoxicity against human histiocytic lymphoma U937 cell line (IC₅₀ = 4.2 μm ) and strong toxicity towards brine shrimp (LC₅₀ = 6.1 μm ), and oppositely increased the growth and biofilm formation of Staphylococcus aureus.     

Size‐structured vulnerability of the colonial cyanobacterium,Microcystis aeruginosa,to grazing by zebra mussels (Dreissena polymorpha)

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Two New Anti‐Proliferative C18‐Norditerpenes from the Roots of Podocarpus macrophyllus

Activity‐guided fractionation strategy was used to investigate chemical constituents from the roots of Podocarpus macrophyllus. Successfully, two new norditerpenes, 2β‐hydroxymakilactone A ( 1 ) and 3β‐hydroxymakilactone A ( 2 ), along with ten known analogues ( 3  –  12 ) were isolated. The structures of 1 and 2 were elucidated by spectroscopic analysis including 1D‐, 2D‐NMR, and HR‐ESI‐MS data. The previously reported structure of 2,3‐dihydro‐2α‐hydroxypodolide was revised as 2,3‐dihydro‐2β‐hydroxypodolide ( 3 ) by spectroscopic analysis, and was further confirmed by X‐ray crystallographic analysis. Cytotoxic activities of all isolated compounds against five human solid tumour cell lines (AGS, HeLa, MDA‐MB‐231, HepG‐2, and PANC‐1) were evaluated. All of them exhibited anti‐proliferative activities (IC₅₀ = 0.3 – 27 μm ), except for 10 . Compounds 1 , 4 , 5 , 6 , and 8 exhibited potent inhibitory activities with IC₅₀ < 1 μm against HeLa and AGS cells.