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1,185 results

3. Chlorophyll Catabolites in Senescent Leaves of the Plum Tree (Prunus domestica)

Author

Erhart, Theresia, Mittelberger, Cecilia, Vergeiner, Clemens, Scherzer, Gerhard, Holzner, Barbara, Robatscher, Peter, Oberhuber, Michael, and Kräutler, Bernhard

Subjects
Chlorophyll, Plant Leaves, Porphyrins, Full Paper, Fruit, Molecular Conformation, Prunus domestica, Full Papers, Phyllobilins, Plant senescence
Abstract

In cold extracts of senescent leaves of the plum tree (Prunus domestica ssp. domestica), six colorless non‐fluorescent chlorophyll catabolites (NCCs) were characterized, named Pd‐NCCs. In addition, several minor NCC fractions were tentatively classified. The structure of the most polar one of the NCCs, named Pd‐NCC‐32, featured an unprecedented twofold glycosidation pattern. Three of the NCCs are also functionalized at their 32‐position by a glucopyranosyl group. In addition, two of these glycosidated NCCs carry a dihydroxyethyl group at their 18‐position. In the polar Pd‐NCC‐32, the latter group is further glycosidated at the terminal 182‐position. Four other major Pd‐NCCs and one minor Pd‐NCC were identified with five NCCs from higher plants known to belong to the ‘epi’‐series. In addition, tentative structures were derived for two minor fractions, classified as yellow chlorophyll catabolites, which represented (formal) oxidation products of two of the observed Pd‐NCCs. The chlorophyll catabolites in leaves of plum feature the same basic structural pattern as those found in leaves of apple and pear trees.

Published
2016

4. Synthesis, Characterization and in vitro Studies of a Cathepsin B‐Cleavable Prodrug of the VEGFR Inhibitor Sunitinib

Author

Bernhard K. Keppler, Petra Heffeter, Walter Berger, Claudia Karnthaler-Benbakka, Marlene Mathuber, Bettina Koblmüller, Katharina Holste, and Christian R. Kowol

Subjects
medicine.drug_class, cathepsin B, sunitinib, Bioengineering, Angiogenesis Inhibitors, Antineoplastic Agents, In Vitro Techniques, 01 natural sciences, Biochemistry, Cathepsin B, Tyrosine-kinase inhibitor, tyrosine kinase inhibitor, prodrugs, Cell Line, Tumor, inhibitors, medicine, Humans, Viability assay, Molecular Biology, Cathepsin, Full Paper, vascular endothelial growth factor receptor (VEGFR), 010405 organic chemistry, Chemistry, Sunitinib, General Chemistry, General Medicine, Prodrug, Full Papers, In vitro, 3. Good health, 0104 chemical sciences, Enzyme Activation, 010404 medicinal & biomolecular chemistry, Receptors, Vascular Endothelial Growth Factor, Drug Design, Proteolysis, Cancer research, Molecular Medicine, Drug Screening Assays, Antitumor, Tyrosine kinase, medicine.drug
Abstract

Since several decades, the prodrug concept has raised considerable interest in cancer research due to its potential to overcome common problems associated with chemotherapy. However, for small‐molecule tyrosine kinase inhibitors, which also cause severe side effects, hardly any strategies to generate prodrugs for therapeutic improvement have been reported so far. Here, we present the synthesis and biological investigation of a cathepsin B‐cleavable prodrug of the VEGFR inhibitor sunitinib. Cell viability assays and Western blot analyses revealed, that, in contrast to the non‐cathepsin B‐cleavable reference compound, the prodrug shows activity comparable to the original drug sunitinib in the highly cathepsin B‐expressing cell lines Caki‐1 and RU‐MH. Moreover, a cathepsin B cleavage assay confirmed the desired enzymatic activation of the prodrug. Together, the obtained data show that the concept of cathepsin B‐cleavable prodrugs can be transferred to the class of targeted therapeutics, allowing the development of optimized tyrosine kinase inhibitors for the treatment of cancer.

Published
2018

5. Inhibition of Pro-Inflammatory Functions of Human Neutrophils by Constituents of Melodorum fruticosum Leaves

Author

Hung Tran, Birgit Waltenberger, Anna K. Kiss, Hermann Stuppner, Nora S. Engels, Barbara Michalak, and Loi Huynh

Subjects
0301 basic medicine, Neutrophils, natural products, Annonaceae, Bioengineering, 01 natural sciences, Biochemistry, 03 medical and health sciences, Structure-Activity Relationship, Humans, Melodorum fruticosum, L-Selectin, Cytotoxicity, Molecular Biology, IC50, chemistry.chemical_classification, Inflammation, Reactive oxygen species, CD11b Antigen, biology, Dose-Response Relationship, Drug, Full Paper, 010405 organic chemistry, Cell adhesion molecule, Tumor Necrosis Factor-alpha, Anti-Inflammatory Agents, Non-Steroidal, Interleukin-8, General Chemistry, General Medicine, Full Papers, biology.organism_classification, cytokines, 3. Good health, 0104 chemical sciences, Plant Leaves, 030104 developmental biology, Integrin alpha M, chemistry, Phytochemical, biology.protein, Molecular Medicine, cytotoxicity, Tumor necrosis factor alpha, Reactive Oxygen Species
Abstract

In an initial screening, the dichloromethane extract from the leaves of Melodorum fruticosum showed distinct inhibitory effects on the release of interleukin‐8 (IL‐8) in human neutrophils. Therefore, the aim of the present study was the phytochemical and pharmacological investigation of this extract, to better understand which compounds might be responsible for the anti‐inflammatory effect. Phytochemical analysis led to the isolation of 12 known compounds and two new natural products, 5‐hydroxy‐6‐(2‐hydroxybenzyl)‐4′,7‐dimethoxyflavanone (13) and 2′,4′‐dihydroxy‐3′‐(2‐hydroxybenzyl)‐4,6′‐dimethoxychalcone (14). The influence of the isolated compounds on the production and release of the pro‐inflammatory factors IL‐8, tumor necrosis factor alpha (TNF‐α), reactive oxygen species (ROS), and adhesion molecules (CD62L and CD11b) in human neutrophils was evaluated. Three constituents, melodamide A, 2′,4′‐dihydroxy‐4,6′‐dimethoxychalcone, and 2′,6′‐dihydroxy‐4′‐methoxychalcone, showed significant inhibition of IL‐8 release (IC50=6.6, 8.6, and 11.6 μm, respectively) and TNF‐α production (IC50=4.5, 13.3, and 6.2 μm, respectively).

Published
2018
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6. A Comparative Analysis of the ‘Green’ Techniques Applied for Polyphenols Extraction from Bioresources

Author

Irina Volf, Valentin I. Popa, and Adina Iulia Talmaciu

Subjects
Food industry, media_common.quotation_subject, Biomass, Bioengineering, Chemical Fractionation, Biochemistry, Cosmetics, Microwaves, Molecular Biology, media_common, Plant Extracts, business.industry, Chemistry, Extraction (chemistry), Supercritical fluid extraction, Polyphenols, Green Chemistry Technology, General Chemistry, General Medicine, Pulp and paper industry, Highly sensitive, Biotechnology, Ultrasonic Waves, Polyphenol, Agriculture, Molecular Medicine, business
Abstract

From all the valuable biomass extractives, polyphenols are a widespread group of secondary metabolites found in all plants, representing the most desirable phytochemicals due to their potential to be used as additives in food industry, cosmetics, medicine, and others fields. At present, there is an increased interest to recover them from plant of spontaneous flora, cultivated plant, and wastes resulted in agricultural and food industry. That is why many efforts have been made to provide a highly sensitive, efficiently, and eco-friendly methods, for the extraction of polyphenols, according to the green chemistry and sustainable development concepts. Many extraction procedures are known with advantages and disadvantages. From these reasons, the aim of this article is to provide a comparative analysis regarding technical and economical aspects related to the most innovative extraction techniques studied in the last time: microwave-assisted extraction (MAE), supercritical fluid extraction (SFE), and ultrasound-assisted extraction (UAE).

Published
2015
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