Field-Grown and In Vitro Propagated Round-Leaved Sundew (Drosera rotundifolia L.) Show Differences in Metabolic Profiles and Biological Activities

Drosera rotundifolia L. is a carnivorous plant used in traditional medicine for its therapeutic properties. Because of its small size, its collection in nature is laborious and different cultivation methods have been studied to ensure availability. However, only a few studies exist where the lab-grown sundew tissue and field-grown sundew would have been compared in their functionality or metabolic profiles. In this study, the antioxidant and antiviral activities of lab-grown and field-grown sundew extracts and their metabolic profiles are examined. The effect of drying methods on the chromatographic profile of the extracts is also shown. Antioxidant activity was significantly higher (5–6 times) in field-grown sundew but antiviral activity against enterovirus strains coxsackievirus A9 and B3 was similar in higher extract concentrations (cell viability ca. 90%). Metabolic profiles showed that the majority of the identified compounds were the same but field-grown sundew contained higher numbers and amounts of secondary metabolites. Freeze-drying, herbal dryer, and oven or room temperature drying of the extract significantly decreased the metabolite content from −72% up to −100%. Freezing was the best option to preserve the metabolic composition of the sundew extract. In conclusion, when accurately handled, the lab-grown sundew possesses promising antiviral properties, but the secondary metabolite content needs to be higher for it to be considered as a good alternative for the field-grown sundew.     

N-rich salts of 2-methyl-5-nitraminotetrazole: secondary explosives with low sensitivities

2-Methyl-5-nitraminotetrazole (1) was formed by nitration of 2-methyl-5-aminotetrazole. 2-Methyl-5-aminotetrazole was obtained by an improved synthesis starting from sodium 5-aminotetrazolate, which is methylated with dimethyl sulfate in dimethyl formamide giving 2-methyl-5-aminotetrazole in 29% yield. Nitrogen-rich salts such as guanidinium (2), 1-aminoguanidinium (3), 1,3-diamino-guanidinium (4), 1,3,5-triamino-guanidinium (5), azidoformamidinium (6), hydrazinium (7), diaminouronium 2-methyl-5-nitraminotetrazolate (8), as well as an urea adduct (9), were prepared by facile deprotonation or metathesis reactions. Diaminourea was synthesized by hydrazinolysis of dimethyl carbonate with hydrazine hydrate. All compounds were fully characterized by vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC) measurements. The crystal structures of 2-6, 8, and 9 could be determined using single crystal X-ray diffraction. The heats of formation of 2-9 were calculated using the atomization method based on CBS-4M enthalpies. With these values and the experimental (X-ray) densities several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code. In addition, the sensitivities toward impact, friction, and electrical discharge were tested using the BAM drop hammer, BAM friction tester, as well as a small scale electrical discharge device.     

1-Nitratoethyl-5-nitriminotetrazole derivatives - Shaping future high explosives

1-(2-Nitratoethyl)-5-nitriminotetrazole (2) was formed by the reaction of 1-(2-hydroxyethyl-5-aminotetrazole (1) and 100% HNO₃. Compound 1 was obtained by alkylation of 5-amino-1H-tetrazole. Next to the known byproduct 1-(2-hydroxyethyl)-5-nitriminotetrazole (3), a second one, 1-(2-nitratoethyl)-5-aminotetrazolium nitrate (4) was obtained and fully characterized. Nitrogen-rich salts such as the ammonium (5), hydroxylammonium (6), guanidinium (7), aminoguanidinium (8), diaminoguanidinium (9) and triaminoguanidinium (10) 1-(2-nitratoethyl)-5-nitriminotetrazolate were prepared by deprotonation or metathesis reactions. The reaction of 2 and diaminourea yielded 1-(2-nitratoethyl)-5-aminotetrazole (11). Compounds 4-11 were fully characterized by single crystal X-ray diffraction, vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis and DSC measurements. The heats of formation of 5-10 were calculated by the atomization method based on CBS-4M enthalpies. Regarding the possible application of these compounds as energetic materials or high explosives, several detonation parameters such as the detonation pressure, velocity, energy and temperature were computed using the EXPLO5 code and the X-ray densities as well as the computed heats of formation. In addition the sensitivities towards impact, friction and electrical discharge were tested using the BAM drophammer, a friction tester as well as a small scale electrical discharge device.     

Tuning the hydrogen storage capacity of MOF-650 by Mg2+/Ca2+ substitution and B,N co-doped atoms: Grand canonical Monte Carlo simulation and periodic density functional theory

This study used periodic density functional theory and grand canonical Monte Carlo simulations to investigate the effects of the co-doping of B and N atoms and substituting Zn²⁺ with Mg²⁺ or Ca²⁺ in the organic linker groups of MOF-650. The functionalization increased the polarity of the organic groups, stabilizing the interaction between the MOF and hydrogen molecules. The highest average binding energy of the adsorbed hydrogen in MOF-650 NB-C7-azulene-Mg was calculated to be −4.75 to 5.40 kcal/mol for the α adsorption sites. Using the substitution of NB azulene and metal cations being Mg²⁺ or Ca²⁺, The hydrogen storage capacity of functionalized MOF-650 was increased to 22 mg/g at 90 bar/298 K, implying the modification strategy of MOF-650 would strengthen the interaction between MOF frameworks and hydrogen molecules.     

5-Methylcytosine is Oxidized to the Natural Metabolites of TET Enzymes by a Biomimetic Iron(IV)-Oxo Complex

Ten-eleven-translocation (TET) methyl cytosine dioxygenases play a key role in epigenetics by oxidizing the epigenetic marker 5-methyl cytosine (5mC) to 5-hydroxymethyl cytosine (5hmC), 5-formyl cytosine (5fC), and 5-carboxy cytosine (5cC). Although much of the metabolism of 5mC has been studied closely, certain aspects—such as discrepancies among the observed catalytic activity of TET enzymes and calculated bond dissociation energies of the different cytosine substrates—remain elusive. Here, it is reported that the DNA base 5mC is oxidized to 5hmC, 5fC, and 5cC by a biomimetic iron(IV)-oxo complex, reminiscent of the activity of TET enzymes. Studies show that 5hmC is preferentially turned over compared with 5mC and 5fC and that this is in line with the calculated bond dissociation energies. The optimized syntheses of d₃-5mC and d₂-5hmC are also reported and in the reaction with the biomimetic iron(IV)-oxo complex these deuterated substrates showed large kinetic isotope effects, confirming the hydrogen abstraction as the rate-limiting step. Taken together, these results shed light on the intrinsic reactivity of the C−H bonds of epigenetic markers and the contribution of the second coordination sphere in TET enzymes.     

On Beckenbach–Radó type integral inequalities

Beckenbach and Radó characterized logarithmically subharmonic functions in the plane in terms of integral inequalities involving spherical averages. In this work we generalize this result to higher dimensions and thus answer to a question raised by Beckenbach and Radó. We also consider generalizations of integral inequalities suggested by Beckenbach and Radó and discuss connections to reverse Hölder inequalities and Muckenhoupt weights.