Phytochemical Analysis of Anvillea garcinii Leaves: Identification of Garcinamines F–H and Their Antiproliferative Activities

Anvillea garcinii is a medicinal plant used in the Arab region for intestinal diseases, lung and liver diseases, digestive problems, and as an antidiabetic agent. Repeated chromatographic purifications of A. garcinii leaves led to the isolation of three undescribed guaiane sesquiterpene derivatives, named garcinamines F–H, characterized by the presence of an amino acid unit, along with five known sesquiterpene lactones (garcinamines B–E and 9β-hydroxyparthenolide). The structures of the new compounds were established using spectroscopic (1D and 2D NMR) and spectrometric methods (ESIMS). Garcinamine H possesses a double bond at the Δ1,10 position, a structural feature rarely reported in guaianolide-type sesquiterpenes. The antiproliferative activity of the isolated sesquiterpenes was screened against three different cancer cell lines, and 9β-hydroxyparthenolide and garcinamines C and D displayed significant effects against lung carcinoma (A549), colon carcinoma (LoVo), and breast carcinoma (MCF7) cell lines.

Amycolatomycins A and B, Cyclic Hexapeptides Isolated from an Amycolatopsis sp. 195334CR

The rare actinobacterium Amycolatopsis sp. strain 195334CR was found to produce previously undescribed cyclic hexapeptides, which we named amycolatomycin A and B (1 and 2). Their planar structures were determined by high-resolution mass spectrometry as well as extensive 1D and 2D NMR spectroscopy, while the absolute stereochemistry of its amino acids were determined by Marfey’s method. Moreover, 1 and 2 differ by the incorporation of l-Ile and l-allo-Ile, respectively, whose FDVA (Nα-(2,4-Dinitro-5-fluorphenyl)-L-valinamide) derivatives were separated on a C4 column. Their hallmark in common is a unique 2,6-dichloro-tryptophan amino acid unit. Amycolatomycin A (1) exhibited weak activity against Bacillus subtilis DSM 10 (minimum inhibitory concentration (MIC) = 33.4 µg/mL).

Synthesis, Characterization, Investigation of Capacitance and Redox Properties of Self-assembled Phe-Phe with Ferrocene Conjugates

The synthesis, nanostructure self-assembly and electrochemical properties of a series of ferrocene conjugated peptides derived from the dipeptide Phe-Phe, nucleoside and the peptide nucleic acid unit which are covalently attached...

Biosynthetic strategies for tetramic acid formation

Over 30 biosynthetic gene clusters for natural tetramate have been identified. This highlight reviews the biosynthetic strategies for formation of tetramic acid unit for the first time, discussing the individual molecular mechanism in detail.

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

Two novel unnatural amino acids, prepared by linking a dicationic purple-coloured and fluorescent naphthalene diimide (NDI) at core position to amino acid side chains of variable length, strongly interacted with ds-DNA/RNA by threading intercalation. Different from a reference NDI dye with identical visible range absorbance (520–540 nm) and Stokes shifts in emission (+60 nm, quantum yield > 0.2), only these amino acid–NDI conjugates showed selective fluorimetric response for GC-DNA in respect to AT(U)-polynucleotides. The DNA/RNA binding-induced circular dichroism (ICD) response of NDI at 450–550 nm strongly depended on the length and rigidity of the linker to the amino acid unit, which controls the orientation of the NDI unit inside within the intercalative binding site. The ICD selectivity also depends on the type of polynucleotide, thus the studied NDI dyes act as dual fluorimetric/ICD probes for sensing the difference between here used GC-DNA, AT-DNA and AU-RNA.

Impact of amino acids on the aqueous self-assembly of benzenetrispeptides into supramolecular polymer bottlebrushes

The choice of the amino acid unit in benzenetrispeptide-PEO conjugates allows to fine-tune the self-assembly strength and to control the resulting solution morphologies in water.

Performance and Cost Analysis of Lithium-Ion Battery for Powering Off-Grid Telecoms Base Stations in Africa

Most African remote telecoms base stations are powered from diesel generators, however, these generators are losing attractiveness due to their less reliability in addition to high operational and maintenance costs. Over 65% of the loss of telecom services observed in remote areas are caused by outages resulting from diverse types of failures that these generators can suffer, on top of their impacts on the environment. As alternative, off-grid renewable energy systems are often employed in place of diesel generators due to their capability to provide reliable electricity at an acceptable cost. This study proposes an off-grid system based on PV generators and backup energy storage consisting of lithium-ion batteries as an extended solution for powering remote telecom base stations in Africa. Modelling and simulation is performed using Matlab/Simulink environment. The findings showed better characteristics of lithium-ion battery bank as compared to lead-acid unit; lithium-ion battery bank displayed higher initial current and voltage over lead-acid battery bank. Moreover, when, both battery banks reached 50 % of their state of charge, lithium-ion bank current was still higher than that of lead-acid bank. In the same vein, lithium-ion battery bank presented a slower discharge time than lead-acid battery bank on top higher values at 50 % and 70% state of charges. Lastly, the state of charge of the lead-acid battery at the end of the simulation was 50 %, while that of the lithium-ion battery bank was around 60 %.

Coralmycin Derivatives with Potent Anti-Gram Negative Activity Produced by the Myxobacteria Corallococcus coralloides M23

Seven new coralmycin derivatives, coralmycins C (1), D (2), E (3), F (4), G (5), H (6), and I (7), along with three known compounds, cystobactamids 891-2 (8), 905-2 (9), and 507 (10), were isolated from a large-scale culture of the myxobacteria Corallococcus coralloides M23. The structures of these compounds, including their relative stereochemistries, were elucidated by interpretation of their spectroscopic and CD data. The structure-activity relationships of their antibacterial and DNA gyrase inhibitory activities indicated that the para-nitrobenzoic acid unit is critical for the inhibition of DNA gyrase and bacterial growth, while the nitro moiety of the para-nitrobenzoic acid unit and the isopropyl chain at C-4 could be important for permeability into certain Gram-negative bacteria, including Pseudomonas aeruginosa and Klebsiella pneumoniae, and the β-methoxyasparagine moiety could affect cellular uptake into all tested bacteria. These results could facilitate the chemical optimization of coralmycins for the treatment of multidrug-resistant Gram-negative bacteria.