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Sakna, S. T.; Mocan, A.; Sultani, H. N.; El-fiky, N. M.; Wessjohann, L. A.; Farag, M. A. Metabolites profiling of Ziziphus leaf taxa via UHPLC/PDA/ESI-MS in relation to their biological activities Food Chem 293, 233-246, (2019) DOI: 10.1016/j.foodchem.2019.04.097

Ziziphus plants are well recognized for their nutritive and medicinal value worldwide, albeit their chemical profile has yet to be fully reported. The secondary metabolites profile of three traditionally used Ziziphus leaf accessions was investigated via ultra-high performance liquid chromatography coupled to photodiode array and electrospray ionization mass detectors (UHPLC/PDA/ESI-MS). A total of 102 metabolites were characterized revealing the first holistic approach onto Ziziphus leaf metabolome and to include the first report of several novel flavonoids and cyclopeptide alkaloids. Fragmentation pattern for cyclopeptide alkaloids was proposed via ESI-MS. Principal component analysis (PCA) revealed close metabolite resemblance among Z. spina-christi and Z. mauritiana leaf specimens found enriched in saponins and distinct from that of Z. jujuba in which quercetin-3-O-(2-pentosyl)-rhamnoside was most abundant. Further, in-vitro antioxidant, anti-inflammatory and antidiabetic assays revealed for Z. spina-christi and Z. mauritiana strong effects compared to Z. jujuba and in correlation with their metabolites repertoire.

Frolov, A.; Bilova, T.; Paudel, G.; Berger, R.; Balcke, G. U.; Birkemeyer, C.; Wessjohann, L. A. Early responses of mature Arabidopsis thaliana plants to reduced water potential in the agar-based polyethylene glycol infusion drought model J Plant Physiol 208, 70-83, (2017) DOI: 10.1016/j.jplph.2016.09.013

Drought is one of the most important environmental stressors resulting in increasing losses of crop plant productivity all over the world. Therefore, development of new approaches to increase the stress tolerance of crop plants is strongly desired. This requires precise and adequate modeling of drought stress. As this type of stress manifests itself as a steady decrease in the substrate water potential (ψw), agar plates infused with polyethylene glycol (PEG) are the perfect experimental tool: they are easy in preparation and provide a constantly reduced ψw, which is not possible in soil models. However, currently, this model is applicable only to seedlings and cannot be used for evaluation of stress responses in mature plants, which are obviously the most appropriate objects for drought tolerance research. To overcome this limitation, here we introduce a PEG-based agar infusion model suitable for 6–8-week-old A. thaliana plants, and characterize, to the best of our knowledge for the first time, the early drought stress responses of adult plants grown on PEG-infused agar. We describe essential alterations in the primary metabolome (sugars and related compounds, amino acids and polyamines) accompanied by qualitative and quantitative changes in protein patterns: up to 87 unique stress-related proteins were annotated under drought stress conditions, whereas further 84 proteins showed a change in abundance. The obtained proteome patterns differed slightly from those reported for seedlings and soil-based models.

Quang, D. N.; Wagner, C.; Merzweiler, K.; Abate, D.; Porzel, A.; Schmidt, J.; Arnold, N. Pyrofomins A-D, polyoxygenated sesquiterpenoids from Pyrofomes demidoffii. Fitoterapia 112, 229–232, (2016) DOI: 10.1016/j.fitote.2016.06.004

Pyrofomins A-D, four polyoxygenated sesquiterpenoids have been isolated from the methanolic extract of the fruit bodies of Pyrofomes demidoffii. Their structures are elucidated by IR, HR-FTICR-MS, and 2D NMR spectroscopy. Furthermore, the cedrane carbon skeleton of pyrofomin A (1) is confirmed by X-ray crystallographic analysis. The sesquiterpenoids 1–4 show neither cytotoxicity against KB cells nor antimicrobial activity.

Paudel, G.; Bilova, T.; Schmidt, R.; Greifenhagen, U.; Berger, R.; Tarakhovskaya, E.; Stöckhardt, S.; Balcke, G. U.; Humbeck, K.; Brandt, W.; Sinz, A.; Vogt, T.; Birkemeyer, C.; Wessjohann, L.; Frolov, A Osmotic stress is accompanied by protein glycation in Arabidopsis thaliana J. Exp. Bot. 67, 6283-6295, (2016) DOI: 10.1093/jxb/erw395

Among the environmental alterations accompanying oncoming climate changes, drought is the most important factor influencing crop plant productivity. In plants, water deficit ultimately results in the development of oxidative stress and accumulation of osmolytes (e.g. amino acids and carbohydrates) in all tissues. Up-regulation of sugar biosynthesis in parallel to the increasing overproduction of reactive oxygen species (ROS) might enhance protein glycation, i.e. interaction of carbonyl compounds, reducing sugars and α-dicarbonyls with lysyl and arginyl side-chains yielding early (Amadori and Heyns compounds) and advanced glycation end-products (AGEs). Although the constitutive plant protein glycation patterns were characterized recently, the effects of environmental stress on AGE formation are unknown so far. To fill this gap, we present here a comprehensive in-depth study of the changes in Arabidopsis thaliana advanced glycated proteome related to osmotic stress. A 3 d application of osmotic stress revealed 31 stress-specifically and 12 differentially AGE-modified proteins, representing altogether 56 advanced glycation sites. Based on proteomic and metabolomic results, in combination with biochemical, enzymatic and gene expression analysis, we propose monosaccharide autoxidation as the main stress-related glycation mechanism, and glyoxal as the major glycation agent in plants subjected to drought. 

Bobach, C.; Tennstedt, S.; Palberg, K.; Denkert, A.; Brandt, W.; de Meijere, A.; Seliger, B.; Wessjohann, L. A. Screening of synthetic and natural product databases: Identification of novel androgens and antiandrogens Eur J Med Chem 90, 267-279, (2015) DOI: 10.1016/j.ejmech.2014.11.026

The androgen receptor is an important pharmaceutical target for a variety of diseases. This paper presents an in silico/in vitro screening procedure to identify new androgen receptor ligands. The two-step virtual screening procedure uses a three-dimensional pharmacophore model and a docking/scoring routine. About 39,000 filtered compounds were docked with PLANTS and scored by Chemplp. Subsequent to virtual screening, 94 compounds, including 28 steroidal and 66 nonsteroidal compounds, were tested by an androgen receptor fluorescence polarization ligand displacement assay. As a result, 30 compounds were identified that show a relative binding affinity of more than 50% in comparison to 100 nM dihydrotestosterone and were classified as androgen receptor binders. For 11 androgen receptor binders of interest IC50 and Ki values were determined. The compound with the highest affinity exhibits a Ki value of 10.8 nM. Subsequent testing of the 11 compounds in a PC-3 and LNCaP multi readout proliferation assay provides insights into the potential mode of action. Further steroid receptor ligand displacement assays and docking studies on estrogen receptors α and β, glucocorticoid receptor, and progesterone receptor gave information about the specificity of the 11 most active compounds.

Barroso, S.; Coelho, A. M.; Gómez-Ruiz, S.; Calhorda, M. J.; Žižak, Ž.; Kaluđerović, G. N.; Martins, A. M. Correction: Synthesis, cytotoxic and hydrolytic studies of titanium complexes anchored by a tripodal diamine bis(phenolate) ligand Dalton Trans 44, 2497-2497, (2015) DOI: 10.1039/C4DT90194K

Correction for ‘Synthesis, cytotoxic and hydrolytic studies of titanium complexes anchored by a tripodal diamine bis(phenolate) ligand’ by Sónia Barroso et al., Dalton Trans., 2014, 43, 17422–17433.

Ali, N. A. A.; Wurster, M.; Denkert, A.; Al-Sokari, S. S.; Lindequist, U.; Wessjohann. L. Cytotoxic and antiphytofungal activity of the essential oils from two artemisia species. World J Pharmaceutical Res 3, 1350-1354, (2014)

Hydrodistilled essential oils from aerial parts of Artemisia abyssinica Sch.Bip. ex A. Rich, and Artemisia arborescens L. growing in Yemen were screened for their cytotoxic and  antiphytofungal properties as well as their chemical compositions. Twenty-seven components were identified in the essential oils and the main components of these species were found to be davanone (42.34%), camphor (22.88%), nerolidol (8.96%), and chamazulene (4.46%), from A. abyssinica oil and artemisia ketone (51.05%), camphor (14.09%), α-bisabolol (12.56%) and α-phellandrene (8.69%) from A. arborescens. At concentration of 50 and 25 μg/mL, A. arborescens oil showed a strong cytotoxic activity with growth inhibition of 95%(±1.6) and 74%(±3.8) (IC50 of 16.91 μg/mL) against HT29 tumor cells (Human colonic adenocarcinoma cells), while A. abyssinica oil exhibited at concentration of 100 and 50 μg/mL growth inhibition of 71.0% (±12.5) and 27.3%(±14.4) (IC50 of 75.42 μg/mL) respectively. Bioautographic assay was used to evaluate the antiphytofungal activity of the oils against Cladosporium cucumerinum.

Pantelić, N.; Zmejkovski, B. B.; Stanojković, T. P.; Jevtić, V. V.; Radić, G. P.; Trifunović, S. R.; Kaluđerović, G. N.; Sabo, T. J. Synthesis and high in vitro cytotoxicity of some (S,S)-ethylenediamine-N,N’-di-2-propanoatedihydrochloride esters J. Serb. Chem. Soc. 79, 649–658, (2014) DOI: 10.2298/JSC130512022P

A novel (S,S)-R2eddip ester, O,O′-diisopentyl-(S,S)-ethylenediamine--N,N′-di-2-propanoate dihydrochloride (1) was synthesized and characterized by IR, 1H- and 13C-NMR spectroscopy, mass spectroscopy and elemental analysis. In vitro antitumor action of 1, and two more R2eddip esters, dialkyl(S,S)-ethylenediamine-N,N′-di-2-propanoate dihydrochlorides, obtained before (alkyl = n-Bu or n-Pe, 2 and 3, respectively), was determined against cervix adenocarcinoma (HeLa), human melanoma (Fem-x), human chronic myelogenous leukemia (K562) cells, and a non-cancerous cell line human embryonic lung fibroblast (MRC-5), using the microculture tetrazolium test MTT assay. Esters 1–3 showed higher cytotoxicity and better selectivity in comparison to cisplatin, used as reference compound. The highest activity was expressed by 1, with IC50(Fem-x) value of 1.51±0.09 μM.

Gómez-Ruiz, S.; Žižak, Z.; Kaluđerović, G. N. Structural studies and cytotoxic activity against human cancer cell lines of mono and dinuclear tin(IV) complexes with the α,α′-dimercapto-o-xylene ligand Inorganica Chimica Acta 423 B, 117–122, (2014) DOI: 10.1016/j.ica.2014.04.023

The reaction of α,α′-dimercapto-o-xylene (H2dmox) with SnPh2Cl2 (1:1) and SnPh3Cl (1:2) in the presence of two equivalents of NEt3 led to the formation of the complexes [SnPh2(dmox)] (1) and [SnPh3(μ-dmox)]2 (2), respectively. Both complexes have been characterized by multinuclear NMR and IR spectroscopy, mass spectrometry and elemental analysis. In addition, the molecular structure of complex 2 has been determined by single crystal X-ray diffraction studies. The cytotoxic activity of 1 and 2 was tested against the tumor cell lines human cervix adenocarcinoma HeLa, breast carcinoma MDA-MB-453, colon carcinoma LS174 and human myelogenous leukemia K562. In addition, the toxicity of both complexes to non-stimulated and stimulated peripheral blood mononuclear cells (PBMC) has been tested. The in vitro cytotoxicity tests show very high antiproliferative activity of both complexes, being much higher that of 2. In addition, this compound shows a higher cytotoxic activity towards cancer cell lines than to non-stimulated and stimulated PBMC, indicating a slight selectivity to cancer cell lines.

Zmejkovski, B. B.; Savić, A.; Poljarević, J.; Pantelić, N.; Aranđelović, S.; Radulović, S.; Grgurić-Šipka, S.; Kaluđerović, G. N.; Sabo, T. J. Synthesis, characterization and in vitro antitumor activity of new palladium(II) complexes with (S,S)-R2edda-type esters Polyhedron 80, 106–111, (2014) DOI: 10.1016/j.poly.2014.02.026

Six palladium(II) complexes with (S,S)-R2edda-type esters ((S,S)-R2edda-type: (S,S)-eddch = (S,S)-ethylenediamine-N,N′-di-2-(3-cyclohexyl)propanoate, R = Me, Et, n-Pr, 1–3; (S,S)-pddch = (S,S)-propylenediamine-N,N′-di-2-(3-cyclohexyl)propanoate, R = Et, n-Pr, 4, 5; and (S,S)-eddip = (S,S)-ethylenediamne-N,N′-di-2-propanoate, R = i-Am, 6) were synthesized, characterized by IR, NMR spectroscopy, ESI-MS and elemental analysis. DFT calculations indicate that in case of 1–4, the most stable isomers are with (S,S)- and (R,S)-configuration of nitrogen atoms, but for complex 6 (R,R)- and (R,S)-N,N′-configured isomers. Furthermore, complex 5 was obtained as (S,S)-N,N′ configured isomer. Cytotoxicity study was performed against human cervical adenocarcinoma (HeLa), human alveolar basal adenocarcinoma (A549) and non-cancerous human fetal lung fibroblast (MRC-5) cell lines using colorimetric MTT assay. From the investigated palladium(II) complexes 2, 3 and 5 exhibited highest cytotoxic potential against HeLa (IC50: 28.5 ± 3.9, 29.5 ± 1.3 and 34.3 ± 3.2, respectively).

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