Molbank, Volume 2019, Issue 3 (September 2019) – 14 articles

Digyaindoleacid A (1) is one of the novel alkaloids produced by the Ghanaian Paenibacillus sp. DE2SH (GenBank Accession Number: MH091697) isolated from the mangrove rhizosphere soils of the Pterocarpus santalinoides tree growing in the wetlands of the Digya National Park, Brong Ahafo Region, Ghana. This compound was isolated on HPLC at t_R ≈ 60 min and its structure determined by MS, 1D, and 2D-NMR data. When tested against Trypanosoma brucei subsp. brucei strain GUTat 3.1, 1 produced a half-maximal inhibitory concentration (IC₅₀) 5.21 μM compared to the standard diminazene aceturate (IC₅₀ = 1.86 μM). In the presence of normal mouse macrophages RAW 264.7, 1 displayed a higher selectivity towards T. brucei subsp. brucei (selectivity indices (SI) = 30.2) with low toxicity. This result is interesting given that the drug diminazene aceturate is considerably toxic and 1 is a natural product isolate. The structure of 1 incorporates the backbone of the amino acid tryptophan which is crucial in the metabolism of Trypanosoma brucei subsp. brucei strain GUTat 3.1. It is possible that 1, could interfere with the normal uptake and metabolism of tryptophan in the parasite. However, 1 (IC₅₀ = 135.41 μM) produced weak antileishmanial activity when tested against Leishmania donovani (Laveran and Mesnil) Ross (D10). Full article

Synthesis of A-ring-modified lupane, oleanane and ursane type triterpenoid conjugates with spermidine through an aldimine linkage or diethylentriamine via an amide bond is described. These derivatives were evaluated for their in vitro antimicrobial properties against human pathogens. Except for derivatives 1 and 7, all compounds have moderate to weak minimum inhibitory concentrations (MICs) against Gram-positive Staphylococcus aureus bacteria, with MICs varying from 3.125 to 200 µM. Compound 11 is efficient against Escherichia coli and Pseudomonas aeruginosa, with MICs of 25 and 50 µM, respectively, while all other derivatives do not possess important antimicrobial activities against these Gram-negative bacteria. Full article

The compound 2-(3,5-dimethyl-1H-pyrazol-1-yl)thiazolo[4,5-b]pyridine (1) was synthesized with a yield of 71% by the reaction of 1-(thiazolo[4,5-b]pyridine-2-yl)hydrazine and acetylacetone. The structure was characterized by a single-crystal X-ray structure determination as well as ¹H and ¹³C{¹H} NMR spectroscopy. X-ray crystallography on 1 confirms the molecule consists of a pyridine–thiazole moiety and the pyrazole ring, and all non-hydrogen atoms are planar. Full article

The Biginelli reaction is an acid-catalyzed, three-component reaction between an aldehyde, a hydrogen methylene active compound, and urea (or its analogue) and constitutes a rapid and easy synthesis of highly functionalized heterocycles. Synthesis of ethyl 6-methyl-2-oxo-4-{4-[(1-phenyl-1H-1,2,3-triazol-4-yl)methoxy]phenyl}-1,2,3,4-tetrahydropyrimidine-5-carboxylate, identified by our laboratory code LaSOM^® 293, was achieved using the Biginelli reaction as the key step, followed by the Huisgen 1,3-dipolar cycloaddition in a convergent four-step route. The product LaSOM^® 293 was obtained with a yield of 84%. Full article

The title compound, N-benzo[c][1,2,5]thiazol-4-yl-3-trifluoromethylbenzamide (1) was synthesized by reacting 3-trifluoromethylbenzoyl chloride (4) and 4-aminobenzo[c][1,2,5]thiadiazole (5). The compound was characterized by various spectroscopic methods (¹H NMR, ¹³C NMR, IR, GC-MS) and its composition confirmed by elemental analysis. The importance of this compound lies in its possession of an N,N-bidentate directing group. Such a structural motif is potentially suitable for metal-catalyzed C-H bond functionalization reactions. Full article

The compound, 4-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-4-methyl-2-phenyl-4,5-dihydrooxazole 2 was prepared in high yield, through nucleophilic substitution reaction of the O-tosyl oxazoline derivative 1, by heating in dimethyl sulfoxide (DMSO) and in presence of KOH as base. The structure of the synthesized compound was established on the basis of NMR spectroscopy (¹H, ¹³C), MS data and elemental analysis. Full article

The plant Zanthoxylum zanthoxyloides (Lam.) Zepern. & Timler is one of the most important medicinal species of the genus Zanthoxylum on the African continent. It is used in the treatment and management of parasitic diseases in sub-Saharan Africa. These properties have inspired scientists to investigate species within the genus for bioactive compounds. However, a study, which details a spectroscopic, spectrometric and bioactivity guided extraction and isolation of antiparasitic compounds from the genus Zanthoxylum is currently non-existent. Tortozanthoxylamide (1), which is a derivative of the known compound armatamide was isolated from Z. zanthoxyloides and the full structure determined using UV, IR, 1D/2D-NMR and high-resolution liquid chromatography tandem mass spectrometry (HRESI-LC-MS) data. When tested against Trypanosoma brucei subsp. brucei, the parasite responsible for animal African trypanosomiasis in sub-Saharan Africa, 1 (IC₅₀ 7.78 µM) was just four times less active than the commercially available drug diminazene aceturate (IC₅₀ 1.88 µM). Diminazene aceturate is a potent drug for the treatment of animal African trypanosomiasis. Tortozanthoxylamide (1) exhibits a significant antitrypanosomal activity through remarkable alteration of the cell cycle in T. brucei subsp. brucei, but it is selectively non-toxic to mouse macrophages RAW 264.7 cell lines. This suggests that 1 may be considered as a scaffold for the further development of natural antitrypanosomal compounds. Full article

The title compound, [dicyclohexyl(sulfanylidene)-λ⁵-phosphanyl]methanol, Cy₂P(=S)CH₂OH (1), was obtained from the reaction between [Cy₂P(CH₂OH)₂]Cl with one molar equivalent of NaOH and an excess of elemental sulfur (powdered). Characterization was by a single-crystal X-ray structure determination as well as IR, and 1D-NMR (¹H, ¹³C{¹H}, ³¹P{¹H}), and 2D-NMR (DEPT-135 and HSQC) spectroscopy, ESI mass spectrometry, and elemental analysis. X-ray crystallography on Compound 1 shows the phosphorus atom to be tetrahedrally coordinated within a non-symmetric C₃S donor set but with relatively minor distortions from the ideal geometry. In the molecular packing, hydroxyl-O–H⋯S(thione) hydrogen bonds led to supramolecular helical chains along the b-axis direction. Full article

6R/S-deutero-α-d-mannopyranoside 1-phosphate was synthesised from a C6 aldehydic mannose thioglycoside donor in four steps. Using NaBD₄ as the reductant, isotopic enrichment at C6 was achieved and the resultant C6-deuterated material was converted through to the glycosyl 1-phosphate using a protection/glycosylation/deprotection sequence. The product was fully characterised by ¹H, ¹³C, ³¹P and 2D NMR, alongside MS analysis. Full article