Unser 10. Leibniz Plant Biochemistry Symposium am 7. und 8. Mai war ein großer Erfolg. Thematisch ging es in diesem Jahr um neue Methoden und Forschungsansätze der Naturstoffchemie. Die exzellenten Vorträge über Wirkstoffe…
Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Kahsay, B. N.; Ziegler, J.; Imming, P.; Gebre-Mariam, T.; Neubert, R. H. H.; Moeller, L.;Free amino acid contents of selected Ethiopian plant and fungi species: a search for alternative natural free amino acid sources for cosmeceutical applicationsAmino Acids531105-1122(2021)DOI: 10.1007/s00726-021-03008-5
Free amino acids (FAAs), the major constituents of the natural moisturizing factor (NMF), are very important for maintaining the moisture balance of human skin and their deficiency results in dry skin conditions. There is a great interest in the identification and use of nature-based sources of these molecules for such cosmeceutical applications. The objective of the present study was, therefore, to investigate the FAA contents of selected Ethiopian plant and fungi species; and select the best sources so as to use them for the stated purpose. About 59 different plant species and oyster mushroom were included in the study and the concentrations of 27 FAAs were analyzed. Each sample was collected, lyophilized, extracted using aqueous solvent, derivatized with Fluorenylmethoxycarbonyl chloride (Fmoc-Cl) prior to solid-phase extraction and quantified using Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometric (LC-ESI–MS/MS) system. All the 27 FAAs were detected in most of the samples. The dominant FAAs that are part of the NMF were found at sufficiently high concentration in the mushroom and some of the plants. This indicates that FAAs that could be included in the preparations for the management of dry skin condition can be obtained from a single natural resource and the use of these resources for the specified purpose have both economic and therapeutic advantage in addition to fulfilling customer needs.
Publikation
Böhme, B.; Moritz, B.; Wendler, J.; Hertel, T. C.; Ihling, C.; Brandt, W.; Pietzsch, M.;Enzymatic activity and thermoresistance of improved microbial transglutaminase variantsAmino Acids52313-326(2020)DOI: 10.1007/s00726-019-02764-9
Microbial transglutaminase (MTG, EC 2.3.2.13) of Streptomyces mobaraensis is widely used in industry for its ability to synthesize isopeptide bonds between the proteinogenic side chains of glutamine and lysine. The activated wild-type enzyme irreversibly denatures at 60 °C with a pseudo-first-order kinetics and a half-life time (t1/2) of 2 min. To increase the thermoresistance of MTG for higher temperature applications, we generated 31 variants based on previous results obtained by random mutagenesis, DNA shuffling and saturation mutagenesis. The best variant TG16 with a specific combination of five of seven substitutions (S2P, S23Y, S24 N, H289Y, K294L) shows a 19-fold increased half-life at 60 °C (t1/2 = 38 min). As measured by differential scanning fluorimetry, the transition point of thermal unfolding was increased by 7.9 °C. Also for the thermoresistant variants, it was shown that inactivation process follows a pseudo-first-order reaction which is accompanied by irreversible aggregation and intramolecular self-crosslinking of the enzyme. Although the mutations are mostly located on the surface of the enzyme, kinetic constants determined with the standard substrate CBZ-Gln-Gly-OH revealed a decrease in KM from 8.6 mM (± 0.1) to 3.5 mM (± 0.1) for the recombinant wild-type MTG and TG16, respectively. The improved performance of TG16 at higher temperatures is exemplary demonstrated with the crosslinking of the substrate protein β-casein at 60 °C. Using molecular dynamics simulations, it was shown that the increased thermoresistance is caused by a higher backbone rigidity as well as increased hydrophobic interactions and newly formed hydrogen bridges.
Publikation
Méndez, Y.; De Armas, G.; Pérez, I.; Rojas, T.; Valdés-Tresanco, M. E.; Izquierdo, M.; Alonso del Rivero, M.; Álvarez-Ginarte, Y. M.; Valiente, P. A.; Soto, C.; de León, L.; Vasco, A. V.; Scott, W. L.; Westermann, B.; González-Bacerio, J.; Rivera, D. G.;Discovery of potent and selective inhibitors of the Escherichia coli M1-aminopeptidase via multicomponent solid-phase synthesis of tetrazole-peptidomimeticsEur. J. Med. Chem.163481-499(2019)DOI: 10.1016/j.ejmech.2018.11.074
The Escherichia coli neutral M1-aminopeptidase (ePepN) is a novel target identified for the development of antimicrobials. Here we describe a solid-phase multicomponent approach which enabled the discovery of potent ePepN inhibitors. The on-resin protocol, developed in the frame of the Distributed Drug Discovery (D3) program, comprises the implementation of parallel Ugi-azide four-component reactions with resin-bound amino acids, thus leading to the rapid preparation of a focused library of tetrazole-peptidomimetics (TPMs) suitable for biological screening. By dose-response studies, three compounds were identified as potent and selective ePepN inhibitors, as little inhibitory effect was exhibited for the porcine ortholog aminopeptidase. The study allowed for the identification of the key structural features required for a high ePepN inhibitory activity. The most potent and selective inhibitor (TPM 11) showed a non-competitive inhibition profile of ePepN. We predicted that both diastereomers of compound TPM 11 bind to a site distinct from that occupied by the substrate. Theoretical models suggested that TPM 11 has an alternative inhibition mechanism that doesn't involve Zn coordination. On the other hand, the activity landscape analysis provided a rationale for our findings. Of note, compound TMP 2 showed in vitro antibacterial activity against Escherichia coli. Furthermore, none of the three identified inhibitors is a potent haemolytic agent, and only two compounds showed moderate cytotoxic activity toward the murine myeloma P3X63Ag cells. These results point to promising compounds for the future development of rationally designed TPMs as antibacterial agents.
Publikation
Shaaban, S.; Ashmawy, A. M.; Negm, A.; Wessjohann, L. A.;Synthesis and biochemical studies of novel organic selenides with increased selectivity for hepatocellular carcinoma and breast adenocarcinomaEur. J. Med. Chem.179515-526(2019)DOI: 10.1016/j.ejmech.2019.06.075
Nineteen organoselenides were synthesized and tested for their intrinsic cytotoxicity in hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF-7) cell lines and their corresponding selective cytotoxicity (SI) was estimated using normal lung fibroblast (WI-38) cells. Most of the organic selenides exhibited good anticancer activity, and this was more pronounced in HepG2 cells. Interestingly, the naphthoquinone- (5), thiazol- (12), and the azo-based (13) organic selenides demonstrated promising SI (up to 76). Furthermore, the amine 4c, naphthoquinone 5, and azo-based 13 and 15 organic selenides were able to down-regulate the expression of Bcl-2 and up-regulate the expression levels of IL-2, IL-6 and CD40 in HepG2 cells compared to untreated cells. Moreover, most of the synthesized candidates manifested good free radical-scavenging and GPx-like activities comparable to vitamin C and ebselen. The obtained results suggested that some of the presented organoselenium candidates have promising anti-HepG2 and antioxidant activities.