An excimer process induced a turn-on fluorescent probe for detection of ultra-low concentration of mercury ions.

The accumulation of mercury pollution in plants can induce severe injury to human beings. It is a great challenge to monitor ultra-low concentrations of mercury in complicated matrixes. In this study, we successfully developed a strategy via Hg2+-triggered naphthalene-based fluorescent probe 1, which formed excimer that subsequently emitted fluorescence for the successful detection of ultra-low concentrations of Hg2+. The coordination of N and S atoms with Hg2+ facilitated the formation of excimer from the naphthalene-conjugated planes that were in sufficiently close proximity. Suppression of CN bond rotation also induced the chelation-enhanced fluorescence (CHEF) effect, and the cumulative result of these effects was obvious fluorescent enhancement. Compared with probe 2, the other key factor for detection of Hg2+ is that the electrons of the hydroxyl group can easily transfer to a naphthalene moiety, resulting in an augmented π-electron density that enhanced the π-π stacking of the naphthalene-conjugated excimer. After detailed spectral studies and mechanism discussions, it was realized that probe 1 was able to detect ultra-low concentrations of Hg2+ in PBS buffer solution. The detection limit was calculated to be 1.98 nM. On account of the excellent performances, the probe was successfully applied in monitoring Hg2+ in water and pea sprouts with the potential for application as an advanced warning of contamination.

Attenuation of phenylnaphthenic acids related to oil sands process water using solar activated calcium peroxide: Influence of experimental factors, mechanistic modeling, and toxicity evaluation.

Refractory naphthenic acids (NAs) are among the primary toxic compounds in oil sands process water (OSPW), a matrix with a complex chemical composition that poses challenges to its remediation. This study evaluated the effectiveness of calcium peroxide (CaO2) combined with solar radiation (solar/CaO2) as an advanced water treatment process for degrading model NAs (1,2,3,4-tetrahydronaphthalene-2-carboxylic acid, pentanoic acid, and diphenylacetic acid) in synthetic water (STW) and provide preliminary insights in treating real OSPW. Solar light and CaO2 acted synergistically to degrade target NAs in STW (>67 of synergistic factor) following a pseudo-first-order kinetic (R2 ≥ 0.95), with an optimal CaO2 dosage of 0.1 g L-1. Inorganic ions and dissolved organic matter were found to hinder the degradation of NAs by solar/CaO2 treatment; however, the complete degradation of NAs was reached in 6.7 h of treatment. The main degradation mechanism involved the generation of hydroxyl radicals (•OH), which contributed ∼90% to the apparent degradation rate constant (K), followed by H2O2 (4-5%) and 1O2 (0-5%). The tentative transformation pathways of three NAs were proposed, confirming an open-ring reaction and resulting in short-chain fatty acid ions as final products. Furthermore, a reduction in acute microbial toxicity and genotoxic effect was observed in the treated samples, suggesting that solar/CaO2 treatment exhibits high environmental compatibility. Furthermore, the solar/CaO2 system was successfully applied as a preliminary step for real-world applications to remove natural NAs, fluorophore organic compounds, and inorganic components from OSPW, demonstrating the potential use of this technology in the advanced treatment of oil-tailing-derived NAs.

A Phenotypic Approach to the Discovery of Potent G-Quadruplex Targeted Drugs.

G-quadruplex (G4) sequences, which can fold into higher-order G4 structures, are abundant in the human genome and are over-represented in the promoter regions of many genes involved in human cancer initiation, progression, and metastasis. They are plausible targets for G4-binding small molecules, which would, in the case of promoter G4s, result in the transcriptional downregulation of these genes. However, structural information is currently available on only a very small number of G4s and their ligand complexes. This limitation, coupled with the currently restricted information on the G4-containing genes involved in most complex human cancers, has led to the development of a phenotypic-led approach to G4 ligand drug discovery. This approach was illustrated by the discovery of several generations of tri- and tetra-substituted naphthalene diimide (ND) ligands that were found to show potent growth inhibition in pancreatic cancer cell lines and are active in in vivo models for this hard-to-treat disease. The cycles of discovery have culminated in a highly potent tetra-substituted ND derivative, QN-302, which is currently being evaluated in a Phase 1 clinical trial. The major genes whose expression has been down-regulated by QN-302 are presented here: all contain G4 propensity and have been found to be up-regulated in human pancreatic cancer. Some of these genes are also upregulated in other human cancers, supporting the hypothesis that QN-302 is a pan-G4 drug of potential utility beyond pancreatic cancer.

Design, synthesis and biological evaluation of naphthyl amide derivatives as reversible monoacylglycerol lipase (MAGL) inhibitors.

Monoacylglycerol lipase (MAGL) is a key enzyme responsible for the metabolism of the endocannabinoid 2-arachidonoylglycerol (2-AG), and has attracted great interest due to its involvement in various physiological and pathological processes, such as cancer progression. In the past, a number of covalent irreversible inhibitors have been reported for MAGL, however, experimental evidence highlighted some drawbacks associated with the use of these irreversible agents. Therefore, efforts were mainly focused on the development of reversible MAGL inhibitor in recent years. Here, we designed and synthesized a series of naphthyl amide derivatives (12-39) as another type of reversible MAGL inhibitors, exemplified by ± 34, which displayed good MAGL inhibition with a pIC50 of 7.1, and the potency and selectivity against endogenous MAGL were further demonstrated by competitive ABPP. Moreover, the compound showed appreciable antiproliferative activities against several cancer cells, including H460, HT29, CT-26, Huh7 and HCCLM-3. The investigations culminated in the discovery of the naphthyl amide derivative ± 34, and it may represent as a new scaffold for MAGL inhibitor development, particularly for the reversible ones.

A novel 3D nitrogen-doped porous carbon supported Fe-Cu bimetallic nanoparticles composite derived from lignin: an efficient peroxymonosulfate activator for naphthalene degradation.

A novel 3D nitrogen-doped porous carbon supported Fe-Cu bimetallic nanoparticles composite (Fe-Cu-N-PC) was prepared via direct pyrolysis by employing black liquor lignin as a main precursor, and it was utilized as a novel catalyst for PMS activation in degrading naphthalene. Under the optimum experimental conditions, the naphthalene degradation rate was up to 93.2% within 60 min in the Fe-Cu-N-PC/PMS system. The porous carbon framework of Fe-Cu-N-PC could facilitate the quick molecule diffusion of reactants towards the inner bimetallic nanoparticles and enriched naphthalene molecules from the solution by a specific adsorption, which increased the odds of contact between naphthalene and reactive oxygen species and improved the reaction efficiency. The quenching reaction proved that the non-free radical pathway dominated by 1O2 was the main way in naphthalene degradation, while the free radical pathway involving SO4·- and ·OH only played a secondary role. Moreover, owing to its high magnetization performance, Fe-Cu-N-PC could be magnetically recovered and maintained excellent naphthalene degradation rate after four degradation cycles. This research will offer a theoretical basis for the construction of facile, efficient, and green technologies to remediate persistent organic pollutants in the environment.

Evaluating Natural Source Zone Depletion and Enhanced Source Zone Depletion in laboratory columns via soil redox continuous sensing and microbiome characterization.

To optimally employ Natural Source Zone Depletion (NSZD) and Enhanced Source Zone Depletion (ESZD) at sites impacted by light non-aqueous phase liquids (LNAPL), monitoring strategies are required. Emerging use of subsurface oxidation-reduction potential (ORP) sensors shows promise for tracking redox evolution, which reflects ongoing biogeochemical processes. However, further understanding of how soil redox dynamics relate to subsurface microbial activity and LNAPL degradation pathways is needed. In this work, soil ORP sensors and DNA and RNA sequencing-based microbiome analysis were combined to elucidate NSZD and ESZD (biostimulation via periodic sulfate addition and biosparging) processes in columns containing LNAPL-impacted soils from a former petroleum refinery. Results show expected relationships between continuous soil redox and active microbial communities. Continuous data revealed spatial and temporal detail that informed interpretation of the hydrocarbon biodegradation data. Redox increases were transient for sulfate addition, and sequencing revealed how hydrocarbon concentration and composition impacted microbiome structure and naphthalene degradation. Periodic biosparging did not result in fully aerobic conditions suggesting observed biodegradation improvements could be explained by alternative anaerobic metabolisms (e.g., iron reduction due to air oxidizing reduced iron). Collectively, data suggest combining continuous redox sensing with microbiome analysis provides insights beyond those possible with either monitoring tool alone.

Push-Pull Fluorescent Dyes with Trifluoroacetyl Acceptor for High-Fidelity Sensing of Polarity and Heterogeneity of Lipid Droplets.

Imaging and sensing of lipid droplets (LDs) attracted significant attention due to growing evidence for their important role in cell life. Solvatochromic dyes are promising tools to probe LDs' local polarity, but this analysis is biased by their non-negligible emission from intracellular membranes and capacity to emit from both the apolar core and polar interface of LDs. Here, we developed two push-pull solvatochromic dyes based on naphthalene and fluorene cores bearing an exceptionally strong electron acceptor, the trifluoroacetyl group. The latter was found to boost the optical properties of the dyes by shifting their absorption and emission to red and increasing their extinction coefficient, photostability, and sensitivity to solvent polarity (solvatochromism). In contrast to classical solvatochromic dyes, such as parent aldehydes and reference Nile Red, the new dyes exhibited strong fluorescence quenching by millimolar water concentrations in organic solvents. In live cells, the trifluoroacetyl dyes exhibited high specificity to LDs, whereas the parent aldehydes and Nile Red showed a detectable backgrounds from intracellular membranes. Experiments in model lipid membranes and nanoemulsion droplets confirmed the high selectivity of new probes to LDs in contrast to classical solvatochromic dyes. Moreover, the new probes were found to be selective to the LDs oil core, where they can sense lipid unsaturation and chain length. Their ratiometric imaging in cells revealed strong heterogeneity in polarity within LDs, which covered the range of polarities of unsaturated triglyceride oils, whereas Nile Red failed to properly estimate the local polarity of LDs. Finally, the probes revealed that LDs core polarity can be altered by fatty acid diets, which correlates with their chain length and unsaturation.

Design and synthesis of dual functional NBD-fluorophore-incorporated naphthalene diimide derivatives as G-quadruplex ligands.

Nitrobenzoxadiazole (NBD)-incorporated naphthalene diimide derivatives were designed and synthesized as candidates of antitumor agents with cytotoxicity against human pancreatic cancer cell MIA PaCa-2. Among these, compounds 1NND and 3NND exhibited fluorescent "turn-off" property toward human telomeric G-quadruplex (G4), which allows the direct measurement of dissociation constant (Kd) of ligands against G4 by fluorescence titration method. Notably, the compound 1NND not only exhibited great cytotoxic activity against MIA PaCa-2 with a half maximal inhibitory concentration (IC50) of 77.9 nM, but also exhibited high affinity against G4 with Kd of 1.72 µM. Furthermore, the target binding properties were investigated by circular dichroism (CD) spectra and further studied by molecular docking methods.

A naphthyl appended ninhydrin based colorimetric chemosensor for Cu2+ ion: Detection of cysteine and ATP.

A ninhydrin-based colorimetric chemosensor (LH) was synthesized using 3-hydroxy-2-naphthoic hydrazide and 11H-indeno[1,2-b]quinoxalin-11-one. It was characterized by spectroscopic and single crystal X-ray diffraction techniques. In a semi-aqueous (MeOH/HEPES) system, LH displayed a characteristic chromogenic change from colorless to yellow upon adding Cu2+ ion, with the appearance of a new peak at λmax = 460 nm. A 1:1 binding stoichiometry between LH and Cu2+ ion has been found, with LOD = 2.3 µM (145 ppb) and LOQ = 8 µM (504 ppb). Based on experimental results the formula of [Cu(L)Cl(H2O)2] (1) was assigned and this in-situ generated 1 was found to exhibit a discoloration of upon gradual addition of cysteine (LOD = 60 nM) as well as ATP (LOD = 130 nM) having 1:2 and 1:1 stoichiometry respectively. The LH was useful for recognition of Cu2+ ion in real water samples and on filter paper strips. A two-input-two-output logic gate circuitry was also constructed by employing 1 and cysteine. The DFT/TDDFT calculations performed on LH and 1 were consistent with experimental findings. The binding affinity of LH towards HSA and BSA were determined with HSA having greater affinity than BSA, which was also supported by theoretical calculations.

Rationalizing Diverse Binding Mechanisms to the Same Protein Fold: Insights for Ligand Recognition and Biosensor Design.

The engineering of novel protein-ligand binding interactions, particularly for complex drug-like molecules, is an unsolved problem, which could enable many practical applications of protein biosensors. In this work, we analyzed two engineered biosensors, derived from the plant hormone sensor PYR1, to recognize either the agrochemical mandipropamid or the synthetic cannabinoid WIN55,212-2. Using a combination of quantitative deep mutational scanning experiments and molecular dynamics simulations, we demonstrated that mutations at common positions can promote protein-ligand shape complementarity and revealed prominent differences in the electrostatic networks needed to complement diverse ligands. MD simulations indicate that both PYR1 protein-ligand complexes bind a single conformer of their target ligand that is close to the lowest free-energy conformer. Computational design using a fixed conformer and rigid body orientation led to new WIN55,212-2 sensors with nanomolar limits of detection. This work reveals mechanisms by which the versatile PYR1 biosensor scaffold can bind diverse ligands. This work also provides computational methods to sample realistic ligand conformers and rigid body alignments that simplify the computational design of biosensors for novel ligands of interest.

Spectroscopic Study of a Novel Binaphthyl Amine Fluorescent Probe for Chiral Recognition of D/L-Lysine.

Lysine plays a crucial role in promoting development, enhancing immune function, and improving the function of central nervous system tissues. The two configurational isomers of amino acids have significantly different effects. Currently, methods for chiral recognition of lysine have been reported; however, previous detection methods have drawbacks such as expensive equipment and complicated detection processes. Fluorescence analysis, on the other hand, boasts high sensitivity, strong selectivity, and simple operation. In this study, we synthesized four novel Binaphthyl-Amine (BINAM)-based fluorescent probes capable of specifically identifying the L-configuration of lysine among the twenty amino acids that constitute human proteins. The enantiomeric fluorescence enhancement ratio (ef or ΔIL/ΔID) reached up to 15.29, demonstrating high enantioselectivity. In addition, we assessed the probe's recognition capabilities under varying pH levels, reaction times, and metal ion conditions, along with its limit of detection (LOD) and quantum yield. Our results suggest that this probe serves as a highly stable tool for the detection of chiral lysine.

Highly Functionalized Spirobisnaphthalenes from Roussoella sp. KT4147.

Highly functionalized spirobisnaphthalenes, preussomerins N (1) and O (2), and simpler compounds, such as 2,3-α-epoxypalmarumycin CP18 (3), 3α-hydroxy-CJ-12,372 (4), and 16 known structurally related congeners, were isolated from a culture broth of Roussoella sp. KT4147. Structural analysis revealed that 1 was a dimer of preussomerin G (6), connected by a nitrogen atom, and 2 was a derivative of 6 with a macommelin substructure. Preussomerin N (1) was considered to be biosynthetically derived via the Michael-type 1,4-addition of ammonia to 6, followed by another Michael addition to another molecule of 6. Contrarily, 2 was suggested to be derived through an endo-Diels-Alder cycloaddition between a diene derived from the (E)-enol form of macommelinal via an ene-reaction and dienophile 6. Compounds 1 and 2 exhibited potent cytotoxicity against COLO-201 human colorectal cancer cells.

Effects of salinity on naphthalene adsorption and toxicity of polyethylene microparticles on Artemia salina.

Plastic pollution in aquatic ecosystems is increasing and plastic particles may adsorb and transport a diverse array of contaminants, thereby increasing their bioavailability to biota. This investigation aimed to evaluate the effects of varying polyethylene microplastics (PE MPs) and naphthalene (NAPH) concentrations on the survival and feeding rates of the model organism, Artemia salina, as well as NAPH adsorption to microplastics at different salinity levels (17, 75, 35.5 and 52.75 g L-1) under selected climate change scenarios. Survival (48 h) and feeding rates (6 h) of A. salina were also monitored, revealing that the presence of higher PE and NAPH concentrations lead to decreased survival rates while also increasing the number and size of microplastic particles in the saline solutions. Higher PE concentrations negatively affected A. salina feeding rates and NAPH concentrations were positively correlated with particle number and size, as well as with NAPH and PE adsorption rates in solution. Our findings demonstrate that the co-occurrence of microplastics and NAPH in aquatic environments can result in detrimental zooplankton survival and feeding rate effects. Furthermore, this interaction may contribute to the accumulation of these contaminants in the environment, highlighting the need to simultaneously monitor and mitigate the presence of microplastics and organic pollutants, like NAPH, in aquatic environments.

Biosynthesis, biological activities, and structure-activity relationships of decalin-containing tetramic acid derivatives isolated from fungi.

Covering: up to December 2023Decalin-containing tetramic acid derivatives, especially 3-decalinoyltetramic acids (3-DTAs), are commonly found as fungal secondary metabolites. Numerous biological activities of this class of compounds, such as antibiotic, antiviral, antifungal, antiplasmodial, and antiprotozoal properties, have been the subject of ongoing research. For this reason, these molecules have attracted a lot of interest from the scientific community and various efforts including semi-synthesis, co-culturing with bacteria and biosynthetic gene sequencing have been made to obtain more derivatives. In this review, 3-DTAs are classified into four major groups based on the absolute configuration of the bicyclic decalin ring. Their biosynthetic pathways, various biological activities, and structure-activity relationship are then introduced.

The modification of surface basicity and its role in naphthalene oxidation: The effect of the basic sites introduced by Ce.

A series of V-xCe/Ti catalysts was prepared by a step impregnation method with gradual increased Ce amount. Compared to the commercial V-W/Ti catalysts, the V-xCe/Ti catalysts exhibited considerably higher COx selectivity during the oxidation of naphthalene (Nap), and less intermediates or by-products were detected both in gas phase and on the surface of the catalysts. Through a series of characterizations, it was found that abundance of weak basic sites in the form of OH was introduced by Ce, as well as the oxygen vacancies caused by the redox cycle of V4++Ce4+↔V5++Ce3+. The weak basic sites introduced by Ce could greatly enhance the Nap adsorption, and the Nap adsorbed was quickly converted to naphthol on Ce-OH. Furthermore, V existed at a high valence with the interaction of V and Ce, and the oxygen vacancies also increased the Oads and OOH. It improved the redox ability and the regeneration of Ce-OH on V-xCe/Ti catalysts. The intermediates could be further oxidized, and the Ce-OH consumed in the reaction could recover quickly. Therefore, almost 100% Nap conversion and a high COx selectivity was observed in the V-xCe/Ti catalysts system.

Structure-Activity Study on Substituted, Core-Extended, and Dyad Naphthalene Diimide G-Quadruplex Ligands Leading to Potent Antitrypanosomal Agents.

Several G-quadruplex nucleic acid (G4s) ligands have been developed seeking target selectivity in the past decade. Naphthalene diimide (NDI)-based compounds are particularly promising due to their biological activity and red-fluorescence emission. Previously, we demonstrated the existence of G4s in the promoter region of parasite genomes, assessing the effectiveness of NDI-derivatives against them. Here, we explored the biological activity of a small library of G4-DNA ligands, exploiting the NDI pharmacophore, against both Trypanosoma brucei and Leishmania major parasites. Biophysical and biological assays were conducted. Among the various families analyzed, core-extended NDIs exhibited the most promising results concerning the selectivity and antiparasitic effects. NDI 16 emerged as the most potent, with an IC50 of 0.011 nM against T. brucei and remarkable selectivity vs MRC-5 cells (3454-fold). Fascinating, 16 is 480-fold more potent than the standard drug pentamidine (IC50 = 5.3 nM). Cellular uptake and parasite localization were verified by exploiting core-extended NDI red-fluorescent emission.

Evaluation of potency and metabolic stability of diphyllin-derived Vacuolar-ATPase inhibitors.

Diphyllin is a naturally occurring lignan comprised of an aryl naphthalene lactone scaffold that demonstrates beneficial biological activities in disease models of cancer, obesity, and viral infection. A target of diphyllin and naturally occurring derivatives is the vacuolar ATPase (V-ATPase) complex. Although diphyllin-related natural products are active with in vitro models for viral entry, the potencies and unknown pharmacokinetic properties limit well-designed in vivo evaluations. Previous studies demonstrated that diphyllin derivatives have the utility of blocking the Ebola virus cell entry pathway. However, diphyllin shows limited potency and poor oral bioavailability in mice. An avenue to improve the potency was used in a new library of synthetic derivatives of diphyllin. Diphyllin derivatives exploiting ether linkages at the 4-position with one-to-three carbon spacers to an oxygen or nitrogen atom provided compounds with EC50 values ranging from 7 to 600 nM potency and selectivity up to >500 against Ebola virus in infection assays. These relative potencies are reflected in the Ebola virus infection of primary macrophages, a cell type involved in early pathogenesis. A target engagement study reveals that reducing the ATPV0a2 protein expression enhanced the potency of diphyllin derivatives to block EBOV entry, consistent with effects on the endosomal V-ATPase function. Despite the substantial enhancement of antiviral potencies, limitations were identified, including rapid clearance predicted by in vitro microsome stability assays. However, compounds with similar or improved half-lives relative to diphyllin demonstrated improved pharmacokinetic profiles in vivo. Importantly, these derivatives displayed suitable plasma levels using oral administration, establishing the feasibility of in vivo antiviral testing.

Thermal curing mechanisms and cross-linking network structure of a novel silicon-containing arylacetylene resin with 2,7-diethynylnaphthalene unit.

Silicon-containing arylacetylene resin and its composites have attracted great interest as emerging heat-resistant materials, but their curing mechanisms and products are still elusive. In this work, the influences of the terminal and inner acetylenes on the curing mechanisms of silicon-containing arylacetylene resin with 2,7-diethynylnaphthalene were first identified by density functional theory. Two reaction pathways were proposed and their products include polyenes, anthracene dimers, and benzene trimers. To gain a distinct observation of the cross-linking process, molecular dynamics simulations were used to construct a cross-linking polymerization model. The effects of the temperature on the cured structure were investigated by analyzing the characteristics of the cross-linked network. As expected, higher curing temperature will make the larger proportion of polyene chain and aromatic ring in the terminal alkyne-terminal alkyne route, meanwhile, for the inner alkyne-inner alkyne route, the short chains and a small amount of aromatic rings are major productions. Overall, our cross-linking method may provide an unique guidance for studying the cured structure of other thermosetting resins.

Hydrogen-Bonding-Regulated Morphology Control and the Impact on the Antibacterial Activity of Cationic π-Amphiphiles.

This manuscript describes the synthesis, self-assembly, and antibacterial properties of naphthalene-diimide (NDI)-derived cationic π-amphiphiles. Three such asymmetric NDI derivatives with a nonionic hydrophilic wedge and a guanidine group in the two opposite sides of the NDI chromophore were considered. They differ by a single functional group (hydrazide, amide, and ester for NDI-1, NDI-2, and NDI-3, respectively), located in the linker between the NDI and the hydrophilic wedge. For NDI-1, the H-bonding among the hydrazides regulated unilateral stacking and a preferential direction of curvature of the resulting supramolecular polymer, producing an unsymmetric polymersome with the guanidinium groups displayed at the outer surface. NDI-3, lacking any H-bonding group, exhibits π-stacking without any preferential orientation and generates spherical particles with a relatively poor display of the guanidium groups. In sharp contrast to NDI-1, NDI-2 exhibits an entangled one-dimensional (1D) fibrillar morphology, indicating the prominent role of the H-bonding motif of the amide group and flexibility of the linker. The antibacterial activity of these assemblies was probed against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative). NDI-1 showed the most promising antibacterial activity with a minimum inhibitory concentration (MIC) of ∼7.8 µg/mL against S. aureus and moderate activity (MIC ∼ 125 µg/mL) against E. coli. In sharp contrast, NDI-3 did not show any significant activity against the bacteria, suggesting a strong impact of the H-bonding-regulated directional assembly. NDI-2, forming a fibrillar network, showed moderate activity against S. aureus and negligible activity against E. coli, highlighting a significant impact of the morphology. All of these three molecules were found to be compatible with mammalian cells from the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) and hemolysis assay. The mechanistic investigation by membrane polarization assay, live/dead fluorescence assay, and microscopy studies confirmed the membrane disruption mechanism of cell killing for the lead candidate NDI-1.

New Naphthalene Derivatives from the Mangrove Endophytic Fungus Daldinia eschscholzii MCZ-18.

Five new naphthalene derivatives dalesconosides A-D, F (1-4, 6), a known synthetic analogue named dalesconoside E (5), and eighteen known compounds (7-24) were isolated from Daldinia eschscholzii MCZ-18, which is an endophytic fungus obtained from the Chinese mangrove plant Ceriops tagal. Differing from previously reported naphthalenes, compounds 1 and 2 were bearing a rare ribofuranoside substituted at C-1 and the 5-methyltetrahydrofuran-2,3-diol moiety, respectively. Their structures were determined by detailed nuclear magnetic resonance (NMR) and mass spectroscopic (MS) analyses, while the absolute configurations were established by theoretical electronic circular dichroism (ECD) calculation. Compounds 1, 3, 13-17 and 19 showed broad ranges of antimicrobial spectrum against five indicator test microorganisms (Enterococcus faecalis, Methicillin-resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans); especially, 1, 16 and 17 were most potent. The variations in structure and attendant biological activities provided fresh insights concerning structure-activity relationships for the naphthalene derivatives.