Quantitative Standards of 4-O-Acetyl- and 9-O-Acetyl-N-Acetylneuraminic Acid for the Analysis of Plasma and Serum

N-Acetylneuraminic acid (sialic acid, Neu5Ac) is one of a large, diverse family of nine-carbon monosaccharides that play roles in many biological functions such as immune response. Neu5Ac has previously been identified as a potential biomarker for the presence and pathogenesis of cardiovascular disease (CVD), diabetes and cancer. More recent research has highlighted acetylated sialic acid derivatives, specifically Neu5,9Ac₂, as biomarkers for oral and breast cancers, but advances in analysis have been hampered due to a lack of commercially available quantitative standards. We report here the synthesis of 9-O- and 4-O-acetylated sialic acids (Neu5,9Ac₂ and Neu4,5Ac₂) with optimisation of previously reported synthetic routes. Neu5,9Ac₂ was synthesised in 1 step in 68 % yield. Neu4,5Ac₂ was synthesised in 4 steps in 39 % overall yield. Synthesis was followed by analysis of these standards via quantitative NMR (qNMR) spectroscopy. Their utilisation for the identification and quantification of specific acetylated sialic acid derivatives in biological samples is also demonstrated.     

Recruiting the Host's Immune System to Target Helicobacter pylori's Surface Glycans

Due to the increased prevalence of bacterial strains that are resistant to existing antibiotics, there is an urgent need for new antibacterial strategies. Bacterial glycans are an attractive target for new treatments, as they are frequently linked to pathogenesis and contain distinctive structures that are absent in humans. We set out to develop a novel targeting strategy based on surface glycans present on the gastric pathogen Helicobacter pylori (Hp). In this study, metabolic labeling of bacterial glycans with an azide‐containing sugar allowed selective delivery of immune stimulants to azide‐covered Hp. We established that Hp's surface glycans are labeled by treatment with the metabolic substrate peracetylated N‐azidoacetylglucosamine (Ac₄GlcNAz). By contrast, mammalian cells treated with Ac₄GlcNAz exhibited no incorporation of the chemical label within extracellular glycans. We further demonstrated that the Staudinger ligation between azides and phosphines proceeds under acidic conditions with only a small loss of efficiency. We then targeted azide‐covered Hp with phosphines conjugated to the immune stimulant 2,4‐dinitrophenyl (DNP), a compound capable of directing a host immune response against these cells. Finally, we report that immune effector cells catalyze selective damage in vitro to DNP‐covered Hp in the presence of anti‐DNP antibodies. The technology reported herein represents a novel strategy to target Hp based on its glycans.     

Selective Inhibition of Heparan Sulphate and Not Chondroitin Sulphate Biosynthesis by a Small,Soluble Competitive Inhibitor

The glycosaminoglycan, heparan sulphate (HS), orchestrates many developmental processes. Yet its biological role has not yet fully been elucidated. Small molecule chemical inhibitors can be used to perturb HS function and these compounds provide cheap alternatives to genetic manipulation methods. However, existing chemical inhibition methods for HS also interfere with chondroitin sulphate (CS), complicating data interpretation of HS function. Herein, a simple method for the selective inhibition of HS biosynthesis is described. Using endogenous metabolic sugar pathways, Ac₄GalNAz produces UDP-GlcNAz, which can target HS synthesis. Cell treatment with Ac₄GalNAz resulted in defective chain elongation of the polymer and decreased HS expression. Conversely, no adverse effect on CS production was observed. The inhibition was transient and dose-dependent, affording rescue of HS expression after removal of the unnatural azido sugar. The utility of inhibition is demonstrated in cell culture and in whole organisms, demonstrating that this small molecule can be used as a tool for HS inhibition in biological systems.     

Novel Highly Acidic Nanoporous Cage Type Materials and Their Catalysis

Acylation of aromatic compounds such as veratrole (1,2-dimethoxybenzene), anisole, isobutyl benzene, and 2-methoxynaphthalene with acetic anhydride (Ac₂O) has been investigated over different solid acid catalysts such as MWW, BEA, FAU, MOR, and MFI. MWW catalysts have been characterized by X-ray diffraction, N₂ adsorption–desorption isotherm, and HR-FESEM characterization techniques. The reaction is studied in the temperature range 313–353 K under N₂ atmosphere. Among the catalysts tested, MWW was found to be more active than other zeolites. This is mainly due to its three dimensional porous structure with excellent textural characteristics. The effect of veratrole/Ac₂O molar ratio, catalyst concentration, and reaction temperature has been optimized to get higher conversion of Ac₂O. Under the optimized reaction conditions, MWW gave the Ac₂O conversion of 64.3% with a selectivity to acetoveratrone (3′,4′-dimethoxyacetophenone) (100%). It was also found that the structural features and acidity play an important role in the conversion and product distribution in the acylation of different aromatic substrates like anisole, isobutyl benzene, and 2-methoxy naphthalene. MWW catalyst has been reused in few cycles after regeneration by washing with ethyl acetate followed by calcination at 500 °C for 4 h without loss in its activity. The reaction kinetics of the catalyst was also studied and the results are discussed in detail.     

M2(Si,Al)4(N,C)7 (M=La,Y,Ca) carbonitrides: I. Synthesis and structural characterisation by XRD and NMR

A series of new nitrides and carbonitrides has been identified with crystal structures similar to those of the hexagonal quaternary nitrides of the type (Ba,Sr,Eu)YbSi₄N₇. The large divalent cations in these structures can be replaced by trivalent cations such as Ln and/or Y, if valency balance is preserved by the simultaneous substitution of carbon for nitrogen in the unique [4]-coordinated anion site. This has been demonstrated by carbon-13 magic-angle spinning NMR spectra which for the yttrium member of this series shows a peak at 36.7 ppm corresponding to carbon atoms occupying the central non-metal atom site in the characteristic [C(NSi₃)₄] structural unit. The resulting compounds have compositions of the types La₂Si₄N₆C, Y₂Si₄N₆C or (La,Y)₂Si₄N₆C; the crystal structure of a related mixed (Ca,Y) derivative of composition (Ca,Y)₂Si₄(N,C)₇ is reported in Part II of this series. When the two large cations are different, the hexagonal symmetry characteristic of the (Ba,Sr,Eu)YbSi₄N₇ compounds is maintained; when both cations are the same, lower symmetries are observed. The powder diffraction pattern of La₂Si₄N₆C indexes on an orthorhombic unit cell with a=6.0360(7), b=10.1246(9), c=10.5664(11) Å and the crystal structure has been determined. An alternative way of achieving valency balance without incorporation of carbon is to replace some of the silicon by aluminium; related derivatives of the type M₂Si₃AlN₇, where M=La, Y or mixed La,Y have been prepared and their unit cell dimensions are reported.     

Synthesis and characterization of novel copolymers of poly(ether ketone ketone) and poly(ether ketone sulfone imide)

A new monomer containing sulfone and imide linkages, bis{4-[4-(p-phenoxyphenylsulfonylphenoxy)benzoyl]-1,2-benzenedioyl}-N,N,N′,N′-4,4′-diaminodiphenyl ether (BPSPBDADPE), was prepared by the Friedel–Crafts reaction of bis(4-chloroformyl-1,2-benzenedioyl)-N,N,N′,N′-4,4′-diaminodiphenyl ether with 4,4′-diphenoxydiphenyl sulfone. Novel copolymers of poly(ether ketone ketone) and poly(ether ketone sulfone imide) were synthesized by electrophilic Friedel–Crafts solution copolycondensation of terephthaloyl chloride with a mixture of DPE and BPSPBDADPE. The polymers were characterized by different physico-chemical techniques. The polymers with 10–25?mol% BPSPBDADPE are semicrystalline and had increased T _gs over commercially available PEEK and PEKK (70/30) due to the incorporation of sulfone and imide linkages in the main chains. The polymer IV with 25?mol% BPSPBDADPE had not only high T _g of 194?°C but also moderate T _m of 338?°C, having good potential for melt processing and exhibited high thermal stability and good resistance to common organic solvents.     

Influence of guests and protonation on the conformation of N,N′-dipyridyl-bis-aza-18-crown-6

Crystallisation of the sodium perchlorate adduct of N,N^′-dipyridyl-bis-aza-18-crown-6 from acidic aqueous conditions yielded [(H₃O)(N,N^′-dipyridyl-bis-aza-18-crown-6)][ClO₄] and [Na·N,N^′-dipyridyl-bis-aza-18-crown-6]₂ [(H⁺)₂N,N^′-dipyridyl-bis-aza-18-crown-6][ClO₄]₄·2H₂O. The conformations of crown ethers were significantly influenced by incorporation of an H₃O⁺ or sodium ion, or protonation of the amino nitrogen atoms resulting in three different structures for the macrocycle.     

Ion-exchange voltammetry of tris(2,2′-bipyridine) nickel(II), cobalt(II), and Co(salen) at polyestersulfonated ionomer coated electrodes in acetonitrile: Reactivity of the electrogenerated low-valent complexes

The electrochemical behaviour of [Ni(bpy)₃(BF₄)₂], [Co(bpy)₃(BF₄)₂], and Co(salen) (where bpy = 2,2′-bipyridine, and salen = N,N′-bis(salicylidene)ethylenediamine) is studied at a glassy carbon electrode modified with the poly(estersulfonate) ionomer Eastman AQ 55 in acetonitrile (MeCN). It is shown that the nickel complex is strongly incorporated into the polymer. The reduction of the divalent nickel compound features a two-electron process leading to a nickel(0) species which is released from the coating because of the lack of electrostatic attraction with the ionomer. Yet, the neutral zerovalent nickel-bipyridine complex is reactive towards ethyl 4-iodobenzoate and di-bromocyclohexane despite the presence of the polymer. The activation of the aryl halide occurs through an oxidative addition, whereas, an electron transfer is involved in the presence of the alkyl halide making the catalyst regeneration much faster in the latter case. The electrochemical study of [Co(bpy)₃(BF₄)₂] shows that incorporation of the cobalt complex into the polymer is efficient, provided excess bpy is used. This excess bpy does not interfere with the electrocatalytic activity of the cobalt complex incorporated in the AQ coating and efficient electrocatalysis is observed towards di-bromocyclohexane and benzyl-bromide as substrates. Finally, replacement of the bpy ligand with the macrocycle N,N′-bis(salicylidene)ethylenediamine, salen, leads to the incorporation of the non-charged Co^II(salen) complex into the AQ 55 polymer showing the relevancy of hydrophobic interactions. The reaction between the electrogenerated [Co^I(salen)]⁻ with 1,2-dibromocyclohexane exhibits a fast inner sphere electron transfer.     

Chemo-Enzymatic Synthesis and Antimicrobial Evaluation of Alkyloxy Propanol Amine-Based Cationic Ether Lipids

The present study involved the synthesis and antimicrobial evaluation of alkyloxy propanol amine-based cationic lipids N,N-dimethyl-1-octadecylamino-3-alkyloxy-2-propanol (series A, 7a–e) and N-methyl-N,N-di-(2-hydroxy-3-alkyloxy-2 propyl) octadecylamine (series B, 9a–e) and their acetylated derivatives (8a–e and 10a–e). A simple three-step chemo-enzymatic approach was employed for the synthesis of 7a–e and 9a–e in 71–80 and 67–88 % yields, respectively. The first step involved the synthesis of a series of glycidyl ethers from a series of alcohols (C₄, C₈, C₁₀, C₁₂, C₁₄) which were opened in the second step with octadecylamine to obtain 1-octadecylamino-3-alkyloxy-2 propanol (5a–e) and N,N-di-(2-hydroxy-3-alkyloxypropyl) octadecylamine (6a–e). In the third step, alkyloxy propanolamines (5a–e, 6a–e) were quaternized using methyl iodide to yield quaternized ammonium salts. The quaternized ammonium salts were enzymatically acetylated using Candida antarctica lipase-B based immobilized enzyme Novozym 435 to obtain their acetylated derivatives. The quaternized salts as well as their acetylated derivatives were evaluated for antibacterial and antifungal properties. The title compounds were found to possess moderate to good antibacterial activities against all the studied bacterial strains namely, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Klebsiella aerogenes compared to streptomycin and cetyl trimethyl ammonium bromide (CTAB). The title compounds exhibited relatively good antifungal activities against Candida albicans and no significant activities against other fungal strains namely, Saccharomyces cerevisiae, Rhizopus oryzae and Aspergillus niger when compared to amphotericin B and CTAB.     

Incorporation of disperse dye in N,N-dimethylacrylamide modified poly(ethylene terephthalate) fibers with supercritical CO2

The effects of modifying agents and dyeing conditions of dispersed dyes for PET films and fibers has been thoroughly studied. This research reports on the dye incorporation process of non-modified and N,N-dimethylacrylamide modified PET fibers with supercritical CO₂. Spectral analysis in the infrared region to the modified PET fibers showed peaks of the modifier, but the thermal stability of the modified fiber did not show variation when compared with the non-modified. The amount of disperse dye incorporated in the PET fibers was determined by UV–Vis spectroscopy at 579 nm through the dye extraction using N,N-dimethylformamide. A 2⁴ factorial design was realized with the purpose to study the influence of variables in the dye incorporation process as well as their interaction effects. The pre-treatment of the PET fibers with N,N-dimethylacrylamide increases the amount of incorporated dye 3.8 times, in average. The main effect on the dye incorporation was the dyeing time for the modified fibers, but for the non-modified fibers, the pressure and the temperature presented analogous main effect     

Glass electrode response to lithium ion activity. Effects of sodium,potassium, ammonium,tetramethyl-, tetraethyl-, and tetra-n-butyl ammonium ions in water and 50% water-ethanol mixture

Competing effects of Na⁺, K⁺, NH⁺₄ and three quaternary ammonium ions, Me₄N⁺, Et₄N⁺, and n-Bu₄N⁺, on the response of a lithium ion-selective glass electrode have been investigated in water and 50% water-ethanol mixture. The results have been analysed according to an ion-exchange model developed earlier for solutions in propylene carbonate. It appears that the effects of the two groups of cations can be rationalized in terms of the relative ease (or difficulty) or desolvation experienced by a lithium ion, in their presence, prior to its incorporation into the glass phase.     

Bonding characterization and nano-indentation study of the amorphous SiCxNy films with and without hydrogen incorporation

The hardness and effective modulus of hydrogen-containing and hydrogen-free amorphous SiC_xN_y films were studied by nano-indentation. Amorphous SiC_xN_y films with and without hydrogen were deposited by electron cyclotron resonance plasma chemical vapor deposition (ECR-CVD) using a SiH₄–CH₃NH₂–N₂–H₂ gas mixture and hydrogen-free ion-beam sputtering deposition (IBSD), respectively. Fourier-transform infrared spectroscopy (FTIR) studies were used to investigate the bonding states of the SiC_xN_y materials. SiH, CH and NH bonds were detected by FTIR in ECR-CVD, but not in IBSD, films. The incorporation of hydrogen led to a reduction in both the hardness and modulus of the amorphous SiC_xN_y films. From nano-indentation measurements, the hardness and effective modulus of the IBSD coated, hydrogen-free amorphous SiC_xN_y films were 27–30 and 211–258 GPa, respectively. The corresponding values for the ECR-CVD coated, hydrogen-containing amorphous SiC_xN_y were 22–26 and 115–144 GPa, respectively.     

Methane and nitrous oxide emissions from irrigated lowland rice paddies after wheat straw application and midseason aeration

Straw application and midseason drainage play role in controlling methane (CH₄) and nitrous oxide (N₂O) emissions from rice paddy fields, but little information is available on their integrative effect on CH₄ and N₂O emissions. A two-year field experiment was conducted to study the combined effect of timing and duration of midseason aeration and wheat straw incorporation on mitigation of global warming potential (GWP) of CH₄ and N₂O emissions from irrigated lowland rice paddy fields. Results showed that incorporation of wheat straw increased CH₄ by a factor of 5–9 under various water regimes, but simultaneously decreased N₂O emission by 19–42 % during the rice growing season. Without straw incorporation, prolonged aeration significantly reduced the net 100-year GWP of CH₄ and N₂O emissions by 6 %, but also decreased rice production when compared with normal aeration. With straw incorporation, the lowest GWP was found by early aeration, which reduced GWP by 7 and 20 % in 2007 and 2008, respectively. Estimation of net GWPs of CH₄ and N₂O emissions indicated that early midseason drainage with straw incorporation offered the potential to mitigate CH₄ and N₂O emissions from irrigated lowland rice paddies in China.     

Rapid synthesis and characterization of advanced ceramic-polymeric nanocomposites for efficient photocatalytic decontamination of hazardous organic pollutant under visible light and inhibition of microbial biofilm

Ceramic-polymeric 3C–silicon carbide-graphitic carbon nitride (3C–SiC@g-C₃N₄) nanocomposites were synthesized by decorating cubic phased, ceramic 3C-Silicon carbide (3C–SiC) on the framework of the nanosheets of metal free polymeric graphitic carbon nitride (g-C₃N₄) by single step pulsed laser ablation in liquid (PLAL) method. Morphological, structural, elemental and optical characterizations of the synthesized 3C–SiC@g-C₃N₄ nanocomposites were carried out. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) studies confirm the perfect anchoring of 3C–SiC on g-C₃N₄ nanosheets in 3C–SiC@g-C₃N₄ nanocomposites synthesized by PLAL method. Ultra-violet diffuse reflectance spectra (UV-DRS) of 3C–SiC@g-C₃N₄ indicated the enhancement of visible light absorption and also the narrowing down of band gap energy in 3C–SiC@g-C₃N₄ nanocomposites, as a result of the anchoring of 3C–SiC on g-C₃N₄. Also we noticed the decrease of photoluminescence (PL) emission intensities in the PL spectra of 3C–SiC@g-C₃N₄ with respect to pure g-C₃N₄, which indicates the reduced photo-induced charge recombination by the presence of 3C–SiC content on g-C₃N₄ nanosheets. In the application side, PLAL synthesized 3C–SiC@g-C₃N₄ nanocomposites exhibited enhanced visible light driven photocatalytic degradation of methylene blue dye in water, improved antibacterial activity against Pseudomonas aeruginosa (gram-negative) and Staphylococcus aureus (gram-positive) bacteria, and also served as better inhibiting agent for biofilm formation, compared to pure g-C₃N₄ nanosheets. It is quite obvious from our studies that this ceramic-polymeric nanocomposite, 3C–SiC@g-C₃N₄ has the potential application for antibacterial and anti-biofilm activities in addition to its remarkable photocatalytic performance.     

Nano-carbon nitride synthesis from a bio-molecular target for ion beam sputtering at low temperature

Nano-crystalline carbon nitride has been successfully synthesized at a temperature below 100 °C from an adenine(C₅N₅H₅) target sputtered by an Ar ion beam. Because adenine possesses a ring structure similar to the hypothetical β-C₃N₄ phase, the use of this bio-molecular compound as the target is believed to reduce the energy barrier of carbon-nitride growth. The effect of Ar ion-sputtering voltage on the film growth and the effect of extra-N-atom incorporation on the carbon-nitride film growth are examined in this study. Only a carbon film is formed with an ion energy of 500 V. For the ion-beam energy above 750 V, carbon nitride films are deposited, and there is some hydrogen incorporation in the films. The N/C composition ratio in the films could reach 1:1 and is independent on the ion beam voltage. The nitrogen is bonded with carbon within the films, as determined by the IR and XPS measurements. However, the films deposited at a higher ion voltage could possess some original functional groups of adenine. A strong and broad peak at a d-spacing of 0.32 nm, comparable to the calculated d-spacing of the β-C₃N₄(110), is observed in the XRD spectra of the carbon nitride films. The TEM results indicated that the film contained nano-crystalline grains. Several d values are also in good agreement with those of adenine and the calculated values of β-C₃N₄. The C/N ratios of the films are still kept at almost 1:1 with N atoms added during deposition. The XRD spectra and IR spectra of these films are all similar to the film deposited without nitrogen source.     

Kinetic model for the NOx reduction process by potassium containing coal char pellets at moderate temperature (350–450 °C) in the presence of O2 and H2O

A four-step mechanism is proposed to describe the reduction of NO_x by potassium containing coal char pellets under O₂-rich atmospheres. The four-step mechanism includes the chemisorption of both O₂ (step 1) and NO_x (step 3) on the so-called free sites (C_f) of carbon, which generates surface oxygen complexes (denoted by (CO)^#). The step 2 considers the direct decomposition of (CO)^# to yield CO₂ and the step 4 the reaction between NO_x and (CO)^# to yield CO₂ and C_f. NO_x reduction isothermal reactions between 350 and 450 °C have been carried out with potassium containing coal char pellets (16.8% w/w of catalyst) under 0.2%NO_x/5%O₂/N₂ and 0.2%NO_x/2%H₂O/5%O₂/N₂. The NO_x reduction and sample conversion experimental profiles have been successfully simulated by the system of algebraic and differential equations deduced from the four-step mechanism, which indicates that the mechanism seems to be feasible. Experimental results pointed out that the selectivity of pellets towards NO_x reduction against O₂ combustion decreases with temperature. This is in agreement with the elemental step rate constants (k_{step number = 1, 2, 3, or 4}) predicted by the model, that is, k₁ and k₂ increased with temperature in a major extent than k₃ and k₄, which are the steps in which NO_x are involved. The selectivity also decreases when H₂O is present in the reactive mixture. This is due to the destabilisation of (CO)^# in the presence of H₂O, thus creating C_f through step 2 that react with O₂ (step 1) in a major extent than with NO_x (step 3), as it is also deduced from the elemental step rate constants predicted by the model.     

Preparation and properties of LDHs/polyimide nanocomposites

Layered double hydroxides/polyimide (LDHs/PI) nanocomposites were prepared from solution of polyamic acid (polyimide precursor) and LDH-amino benzoate using N,N-dimethylacetamide as a solvent. LDH-amino benzoate (LDH-AB) was obtained by coprecipitation method. The amino benzoate, grafted on the surface of the Mg/Al nanolayers, as a connector improved the compatibility between the inorganic Mg/Al nanolayers and the organic polyimide molecules. The dispersion behavior of Mg/Al nanolayers was investigated by transmission electron microscopy and X-ray diffraction, indicating that the Mg/Al nanolayers were exfoliated in PI matrix to form LDH-AB/PI nanocomposites. The maximum tensile strength and elongation of the LDH-AB/PI nanocomposites were found with the LDH-AB content of 5 and 4 wt%, respectively. The initial tensile modulus of these nanocomposites was increased with the LDH-AB content. These nanocomposites exhibited higher storage and loss moduli compared to those of pure PI. T_g of these nanocomposites increased with the LDH-AB content. Coefficients of thermal expansion (CTE, below and above T_g) of these nanocomposites deceased with the LDH-AB content. The thermal properties of these nanocomposites were enhanced by the incorporation of Mg/Al nanolayers in PI matrix.     

Poly[N-(2-hydroxypropyl)methacrylamide]-Modified Magnetic γ-F2O3 Nanoparticles Conjugated with Doxorubicin for Glioblastoma Treatment

With the aim to develop a new anticancer agent, we prepared poly[N-(2-hydroxypropyl)methacrylamide-co-methyl 2-methacrylamidoacetate] [P(HP-MMAA)], which was reacted with hydrazine to poly[N-(2-hydroxypropyl)methacrylamide-co-N-(2-hydrazinyl-2-oxoethyl)methacrylamide] [P(HP-MAH)] to conjugate doxorubicin (Dox) via hydrazone bond. The resulting P(HP-MAH)-Dox conjugate was used as a coating of magnetic γ-Fe₂O₃ nanoparticles obtained by the coprecipitation method. In vitro toxicity of various concentrations of Dox, P(HP-MAH)-Dox, and γ-Fe₂O₃@P(HP-MAH)-Dox nanoparticles was determined on somatic healthy cells (human bone marrow stromal cells hMSC), human glioblastoma line (GaMG), and primary human glioblastoma (GBM) cells isolated from GBM patients both at a short and prolonged exposition time (up to 7 days). Due to hydrolysis of the hydrazone bond in acid milieu of tumor cells and Dox release, the γ-Fe₂O₃@P(HP-MAH)-Dox nanoparticles significantly decreased the GaMG and GBM cell growth compared to free Dox and P(HP-MAH)-Dox in low concentration (10 nM), whereas in hMSCs it remained without effect. γ-F₂O₃@PHP nanoparticles alone did not affect the viability of any of the tested cells.     

Dielectric properties and magnetoelectric coupling in polar magnet (Fe,Zn)2Mo3O8

A complete understanding of magnetoelectric (ME) coupling in polar magnet Fe₂Mo₃O₈ (FMO) remains elusive. Here, we report the magnetodielectric (MD) and ME effects of (Fe_1-xZn_x)₂Mo₃O₈ (x = 0, 0.05) single crystals. The observation of MD effect in FMO shows a sharp peak once T is below T_N due to the metamagnetic transition, which is converted into an obvious step upon cooling. Meanwhile, the change of magnetization M modulated by electric field E is striking at the dielectric constant peak/step. In (Fe_0.95Zn_0.05)₂Mo₃O₈, however, the sharp peak at just below T_N is intact, while the step at much lower T_N is highly damaged. The ME response to 5% Zn²⁺ dopants at the two T-ranges shows different behavior. Combining with spin wave theory, it is possible to speculate that the inverse Dzyaloshinskii-Moriya interaction might play a dominant role in the ME nature at just below T_N, which is different from that at much lower T_N.