Evaluating the antibacterial activity of muramyl dipeptide derivatives, retro-tuftsin derivatives, and anthraquinone oligopeptides against a range of pathogenic bacteria

Search for new and efficient antibiotic is crucial because of microbial drug resistance and problems with side effects of the administered medication. In this study, we evaluate the in vitro microbiological activity of muramyl dipeptide derivatives, retro-tuftsin derivatives (i.e., tuftsin with reversed amino acid sequences), and combinations of retro-tuftsin derivatives with substituted anthraquinones. The potency of the investigated derivatives towards methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae ESBL (extended-spectrum β-lactamases) was compared based on the spectroscopically-measured minimal inhibitory concentrations (MIC values). The bacterial growth have also been studied with different concentrations of compounds. Statistical analysis of the results revealed that certain modifications lead to promising activity against S. aureus (anthraquinone analogue – 3c and retro-tuftsin derivative – 2b), while other derivatives exhibit activity against P. aeruginosa (muramyl dipeptide derivative – 1d and retro-tuftsin derivative – 2b). The obtained results of microbiological activity indicate that the structure of the tested compounds may be the basis for further modifications.

The Radiolabeling of a Gly-Sar Dipeptide Derivative with Flourine-18 and Its Use as a Potential Peptide Transporter PET Imaging Agent

We have developed a novel fluorine-18 radiotracer, dipeptide 1, radiolabeled in two steps from mesylate 3. The initial radiolabeling is achieved in a short reaction time (10 min) and purified through solid-phase extraction (SPE) with modest radiochemical yields (rcy = 10 ± 2%, n = 5) in excellent radiochemical purity (rcp > 99%, n = 5). The de-protection of the tert-butyloxycarbonyl (Boc) and trityl group was achieved with mild heating under acidic conditions to provide 18F-tagged dipeptide 1. Preliminary analysis of 18F-dipeptide 1 was performed to confirm uptake by peptide transporters (PepTs) in human pancreatic carcinoma cell lines Panc1, BxPC3, and ASpc1, which are reported to express the peptide transporter 1 (PepT1). Furthermore, we confirmed in vivo uptake of 18F-dipeptide tracer 1 using microPET/CT in mice harboring subcutaneous flank Panc1, BxPC3, and Aspc1 tumors. In conclusion, we have established the radiolabeling of dipeptide 1 with fluoride-18, and demonstrated its potential as an imaging agent which may have clinical applications for the diagnosis of pancreatic carcinomas.

Synthesis and Characterizations of Dipeptide Derivative of Gentamicin

The target derivative are gentamicin linked with L-Val- L-Ala by an ester linkage. These were synthesized by esterification method, which included the reaction of -OH hydroxyl group on (carbon No.5) of gentamicin with the acid chloride of the corresponding dipeptide, The preparation of new derivative of gentamicin involved protected the primary & secondary amine groups of Gentamicin, by Ethylchloroformate (ECF) to give N-carbomethoxy Gentamicin which was used for further chemical synthesis involving the free hydroxyl groups. Then prepared dipeptide (L-Val- L-Ala) by conventional solution method in present DCC & HoBt then reacted with thionyl chloride to prepared acid chloride of dipeptides, then after, linked by ester linkage to N-protection gentamicin in present pyridine as base, finally deportation the amino group of synthesized compound by using TFAA in present anisole. The characterization of the titled compounds were performed utilizing FTIR spectroscopy, CHNS elemental analysis, and by measurements of their physical properties.

Influence of different sequences of l-proline dipeptide derivatives in the pendants on the helix of poly(phenylacetylene)s and their enantioseparation properties

Novel helical poly(phenylacetylene)s bearing different sequences of l-proline dipeptide derivative pendants were prepared and used as CSPs in HPLC for enantioseparation.

Rational design of a supramolecular gel based on a Zn(ii)–salophen bis-dipeptide derivative

We report the rational design and synthesis of a supramolecular gelator based on a Zn(ii)–salophen derivative functionalized with l-valine residues.

Gelation of Fmoc-diphenylalanine is a first order phase transition

We explore the gel transition of the aromatic dipeptide derivative molecule fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF).

The first supramolecular peptidic hydrogelator containing taurine

The conjugation of taurine, a non-proteinogenic amino acid, with a dipeptide derivative affords a cell compatible, small molecular hydrogelator that self-assembles in water to exhibit rich phase behaviors.

Replacement of glutamine with the dipeptide derivative alanyl-glutamine enhances in vitro maturation of porcine oocytes and development of embryos

SummaryThe presence of glutamine (Gln) in in vitro maturation (IVM) and in vitro culture (IVC) medium is a more potent factor for improving porcine oocyte and embryo development than other amino acids. However Gln is inherently unstable and spontaneously breaks down into ammonia, and therefore interferes with proper development. To avoid this adverse effect, Gln was replaced in the present study with its stable dipeptide derivative alanyl-glutamine (Ala-Gln) and the effects of this replacement on porcine IVM and IVC were evaluated. Replacement of Gln with Ala-Gln during IVM did not improve nuclear maturation, however numbers of early cleaved embryos were significantly increased after activation. Blastocyst formation rates were also significantly improved by using Ala-Gln during IVM. Replacement of Gln with Ala-Gln during IVC significantly increased total cell numbers in blastocysts. Blastocyst formation rate was also significantly higher when Ala-Gln was used in both IVM and IVC. In conclusion, the use of Ala-Gln rather than Gln gives better results for development in both porcine IVM and IVC.