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Publikationen - Natur- und Wirkstoffchemie

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Guerra, T.; Schilling, S.; Hake, K.; Gorzolka, K.; Sylvester, F.; Conrads, B.; Westermann, B.; Romeis, T. Calcium‐dependent protein kinase 5 links calcium‐signaling with N‐Hydroxy‐L‐pipecolic acid‐ and SARD1‐dependent immune memory in systemic acquired resistance New Phytol (2019) DOI: 10.1111/nph.16147

Systemic acquired resistance (SAR) prepares infected plants for faster and stronger defense activation upon subsequent attacks. SAR requires an information relay from primary infection to distal tissue and the initiation and maintenance of a self‐maintaining phytohormone salicylic acid (SA)‐defense loop.In spatial and temporal resolution, we show that calcium‐dependent protein kinase CPK5 contributes to immunity and SAR. In local basal resistance CPK5 functions upstream of SA‐synthesis, ‐perception, and ‐signaling. In systemic tissue, CPK5 signaling leads to accumulation of SAR inducing metabolite N‐Hydroxy‐L‐pipecolic acid (NHP) and SAR marker genes including Systemic Acquired Resistance Deficient 1 (SARD1)Plants of increased CPK5‐, but not CPK6‐ signaling, display an ‘enhanced SAR' phenotype toward a secondary bacterial infection. In sard1‐1 background, CPK5‐mediated basal resistance is still mounted, but NHP level is reduced and ‘enhanced SAR' is lost.The biochemical analysis determines CPK5 half maximal kinase activity for calcium K50 [Ca2+] to ~100 nM close to the cytoplasmic resting level. This low threshold uniquely qualifies CPK5 to decode subtle changes in calcium prerequisite to signal relay and onset and maintenance of priming at later time points in distal tissue. Our data explain why CPK5 functions as a hub in basal and systemic plant immunity.
Publikation

Drača, D.; Mijatović, S.; Krajnović, T.; Kaluđerović, G. N.; Wessjohann, L. A.; Maksimović-Ivanić, D. Synthetic Tubulysin Derivative, Tubugi-1, Against Invasive Melanoma Cells: The Cell Death Triangle Anticancer Res 39, 5403-5415, (2019) DOI: 10.21873/anticanres.13734

Background/Aim: Tubugi-1 is a more stable and accessible synthetic counterpart of natural tubulysins. This study aimed to evaluate its cytotoxic potential against anaplastic human melanoma cells. Materials and Methods: The viability of A-375 cells was determined by 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and crystal violet assay. The type of cell death and proliferative rate were investigated using flow cytometry and fluorescent microscopy, while the molecular background was evaluated by western blot. Results: Tubugi-1 reduced the viability of A-375 cells, inducing massive micronucleation, followed by augmented expression of inhibitor of nuclear factor-κB and caspase-2, typical of a mitotic catastrophe. Disturbed proliferation and G2M block with prominent caspase activity, weakened the expression of B-cell lymphoma 2 and B-cell lymphoma 2-associated X transient up-regulation, coexisted with intensive autophagy. Specific inhibition of autophagy by chloroquine resulted in conversion from mitotic catastrophe to rapid apoptosis. Conclusion: Multilevel anticancer action of tubugi-1 is extended by co-application of an autophagy inhibitor, giving a new dimension in further preclinical advancement of this potential agent.
Publikation

Hoffmann, A.; Nong, J. P.; Porzel, A.; Bremer, M.; Fischer, S. Modification of Lignoboost Kraft Lignin from softwoods with dihydroxybenzenes React Funct Polym 142, 112-118, (2019) DOI: 10.1016/j.reactfunctpolym.2019.06.011

Lignin, a component of the cell walls of plants and the second most abundant biopolymer has long been regarded as disturbing substance in pulp production by paper industry. This view has changed in recent decades. Thus, lignin is increasingly regarded as an alternative to crude oil. Tuned and modified lignins have suitable properties to use them as building blocks for various applications as well as for the production of basic chemicals. By modifying lignin, its reactivity and uniformity can be increased. In addition, properties of the lignin can be changed and influenced by selective modification. By a solvent-free modification with dihydroxybenzene, aliphatic OH groups of the lignin side chain can be removed and covalent CC bonds to the aromatics can be formed. At the same time, aryl-alkyl ether cleavage occurs, which reduces the molecular weight of lignin by about one third. In addition, ongoing reactions result in the reduction in the molecular weight distribution. All this leads to a more uniform and reactive lignin which is interesting as a precursor for various applications. This work provides a deeper understanding of ongoing reactions with dihydroxybenzenes and the structure of modified lignins.
Publikation

Rehman, N. U.; Hussain, H.; Ali, L.; Khan, A.; Mabood, F.; Shinwari, Z. K.; Hussain, J.; Al-Harrasi, A. Chemical Constituents of Acridocarpus orientalis and Their Chemotaxonomic Significance Chem Nat Compd 55, 586-588, (2019) DOI: 10.1007/s10600-019-02752-1

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Hussain, H.; Green, I. R.; Saleem, M.; Raza, M. L.; Nazir, M. Therapeutic Potential of Iridoid Derivatives: Patent Review Inventions 4, 29, (2019) DOI: 10.3390/inventions4020029

Iridoids belong to a family of monoterpenoids comprising the cyclopentan[c]-pyran system; this class of compounds offers a wide range of biological effects, namely antileishmanial, anticancer, antiplasmodial, and anti-inflammatory potency. To date, a large number of biologically active iridoid derivatives have been reported from various plant families, including Rubiaceae, Plantaginaceae, Scrophulariaceae, and Verbenaceae. Furthermore, iridoids have the potential to form conjugates with other anticancer, antidiabetic, antileishmanial, and antimalarial drugs which synergistically have the potential to increase their effects. Additionally, future research should focus on the synthesis of halo analogs as well as preparing homo dimers or heterodimers of iridoids, since these might quite conceivably possess an increased bioactivity.
Publikation

Farag, M. A.; El Senousy, A. S.; El-Ahmady, S. H.; Porzel, A.; Wessjohann, L. A. Comparative metabolome-based classification of Senna drugs: a prospect for phyto-equivalency of its different commercial products Metabolomics 15, 80, (2019) DOI: 10.1007/s11306-019-1538-x

IntroductionThe demand to develop efficient and reliable analytical methods for the quality control of nutraceuticals is on the rise, together with an increase in the legal requirements for safe and consistent levels of its active principles.ObjectiveTo establish a reliable model for the quality control of widely used Senna preparations used as laxatives and assess its phyto-equivalency.MethodsA comparative metabolomics approach via NMR and MS analyses was employed for the comprehensive measurement of metabolites and analyzed using chemometrics.ResultsUnder optimized conditions, 30 metabolites were simultaneously identified and quantified including anthraquinones, bianthrones, acetophenones, flavonoid conjugates, naphthalenes, phenolics, and fatty acids. Principal component analysis (PCA) was used to define relative metabolite differences among Senna preparations. Furthermore, quantitative 1H NMR (qHNMR) was employed to assess absolute metabolites levels in preparations. Results revealed that 6-hydroxy musizin or tinnevellin were correlated with active metabolites levels, suggesting the use of either of these naphthalene glycosides as markers for official Senna drugs authentication.ConclusionThis study provides the first comparative metabolomics approach utilizing NMR and UPLC–MS to reveal for secondary metabolite compositional differences in Senna preparations that could readily be applied as a reliable quality control model for its analysis.
Publikation

Shumilina, J.; Kusnetsova, A.; Tsarev, A.; Janse van Rensburg, H. C.; Medvedev, S.; Demidchik, V.; Van den Ende, W.; Frolov, A. Glycation of Plant Proteins: Regulatory Roles and Interplay with Sugar Signalling? Int J Mol Sci 20, 2366, (2019) DOI: 10.3390/ijms20092366

Glycation can be defined as an array of non-enzymatic post-translational modifications of proteins formed by their interaction with reducing carbohydrates and carbonyl products of their degradation. Initial steps of this process rely on reducing sugars and result in the formation of early glycation products—Amadori and Heyns compounds via Schiff base intermediates, whereas their oxidative degradation or reactions of proteins with α-dicarbonyl compounds yield a heterogeneous group of advanced glycation end products (AGEs). These compounds accompany thermal processing of protein-containing foods and are known to impact on ageing, pathogenesis of diabetes mellitus and Alzheimer’s disease in mammals. Surprisingly, despite high tissue carbohydrate contents, glycation of plant proteins was addressed only recently and its physiological role in plants is still not understood. Therefore, here we summarize and critically discuss the first steps done in the field of plant protein glycation during the last decade. We consider the main features of plant glycated proteome and discuss them in the context of characteristic metabolic background. Further, we address the possible role of protein glycation in plants and consider its probable contribution to protein degradation, methylglyoxal and sugar signalling, as well as interplay with antioxidant defense.
Publikationen in Druck

Bini Araba, A.; Ur Rehman, N.; Al-Araimi, A.; Al-Hashmi, S.; Al-Shidhani, S.; Csuk, R.; Hussain, H.; Al-Harrasi, A.; Zadjali, F. New derivatives of 11-keto-β-boswellic acid (KBA) induce apoptosis in breast and prostate cancers cells Nat Prod Res (2019) DOI: 10.1080/14786419.2019.1593165

A series of new 11-keto-β-boswellic acid were partially-synthesized by modifying the hydroxyl and carboxylic acid functional groups of ring A. The structures of the new analogs were confirmed by detailed spectral data analysis. Compounds 4, 5 and 9 exhibited potent anti-cancer results against two human tumor cancer cell lines having IC50 value of MCF-7 (breast) and LNCaP (prostate): 123.6, 9.6 and 88.94 μM and 9.6, 44.12 and 12.03 μM, respectively. Additionally, a maximum nuclear fragmentation was observed for 4 (78.44%) in AKBA treated cells after 24 hr followed by 5 and 9 with (74.25 and 66.9% respectively). This study suggests that the presence of hydrazone functionality (4 and 9) has effectively improved the potency of AKBA. Interestingly, compound 5 with a lost carboxylic acid group of ring A showed comparable potent activity. Highly selective AKBA requires further modification to improve its bioavailability and solubility inside the cancer cells.
Publikation

Soboleva, A.; Mavropulo-Stolyarenko, G.; Karonova, T.; Thieme, D.; Hoehenwarter, W.; Ihling, C.; Stefanov, V.; Grishina, T.; Frolov, A. Multiple Glycation Sites in Blood Plasma Proteins as an Integrated Biomarker of Type 2 Diabetes Mellitus Int J Mol Sci 20, 2329, (2019) DOI: 10.3390/ijms20092329

Type 2 diabetes mellitus (T2DM) is one of the most widely spread metabolic diseases. Because of its asymptomatic onset and slow development, early diagnosis and adequate glycaemic control are the prerequisites for successful T2DM therapy. In this context, individual amino acid residues might be sensitive indicators of alterations in blood glycation levels. Moreover, due to a large variation in the half-life times of plasma proteins, a generalized biomarker, based on multiple glycation sites, might provide comprehensive control of the glycemic status across any desired time span. Therefore, here, we address the patterns of glycation sites in highly-abundant blood plasma proteins of T2DM patients and corresponding age- and gender-matched controls by comprehensive liquid chromatography-mass spectrometry (LC-MS). The analysis revealed 42 lysyl residues, significantly upregulated under hyperglycemic conditions. Thereby, for 32 glycation sites, biomarker behavior was demonstrated here for the first time. The differentially glycated lysines represented nine plasma proteins with half-lives from 2 to 21 days, giving access to an integrated biomarker based on multiple protein-specific Amadori peptides. The validation of this biomarker relied on linear discriminant analysis (LDA) with random sub-sampling of the training set and leave-one-out cross-validation (LOOCV), which resulted in an accuracy, specificity, and sensitivity of 92%, 100%, and 85%, respectively.
Publikation

Drača, D.; Mijatović, S.; Krajnović, T.; Pristov, J. B.; Đukić, T.; Kaluđerović, G. N.; Wessjohann, L. A.; Maksimović-Ivanić, D. The synthetic tubulysin derivative, tubugi-1, improves the innate immune response by macrophage polarization in addition to its direct cytotoxic effects in a murine melanoma model Exp Cell Res 380, 159-170, (2019) DOI: 10.1016/j.yexcr.2019.04.028

Synthetic tubugis are equally potent but more stable than their natural forms. Their anticancer potential was estimated on a solid melanoma in vitro and in vivo. Tubugi-1 induced the apoptosis in B16 cells accompanied with strong intracellular production of reactive species, subsequently imposing glutathione and thiol group depletion. Paradoxically, membrane lipids were excluded from the cascade of intracellular oxidation, according to malondialdehyde decrease. Although morphologically apoptosis was typical, externalization of phosphatidylserine (PS) as an early apoptotic event was not detected. Even their exposition is pivotal for apoptotic cell eradication, primary macrophages successfully eliminated PS-deficient tubugi-1 induced apoptotic cells. The tumor volume in animals exposed to the drug in therapeutic mode was reduced in comparison to control as well as to paclitaxel-treated animals. Importantly, macrophages isolated from tubugi-1 treated animals possessed conserved phagocytic activity and were functionally and phenotypically recognized as M1. The cytotoxic effect of tubugi-1 is accomplished through its ability to polarize the macrophages toward M1, probably by PS independent apoptotic cell engulfment. The unique potential of tubugi-1 to prime the innate immune response through the induction of a specific pattern of tumor cell apoptosis can be of extraordinary importance from fundamental and applicable aspects.
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