- Graz, Steiermark, Austria
Olaf Kunert
University of Graz, Pharmaceutical Sciences, Faculty Member
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Research Interests: Natural Products, Biology, Medicine, Biological Sciences, Zingiberaceae, and 13 moreCHEMICAL SCIENCES, Anti-Bacterial Agents, Efflux, Seeds, Catechols, Microbial Sensitivity Tests, Fatty Alcohols, Guaiacol, Molecular Structure, Ethidium bromide, ketones, Mycobacterium smegmatis, and Medical and Health Sciences
ABSTRACT
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A simplified method of synthesis of triterpene l,2-trans-glycosides was developed using the glycosylation of glycyrrhetic acid (GLA) and 18,19-dehydro-GLA by beta-pyranose peracetates in the presence of SnCl(4) and molecular sieves 4 A.... more
A simplified method of synthesis of triterpene l,2-trans-glycosides was developed using the glycosylation of glycyrrhetic acid (GLA) and 18,19-dehydro-GLA by beta-pyranose peracetates in the presence of SnCl(4) and molecular sieves 4 A. The synthesized glycosides exhibited hepatoprotective activity toward the human hepatoma HepG2 cell line on the model of alcohol hepatitis and decreased the level of TNF-alpha protein.
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ABSTRACT
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The oil gland secretion of the oribatid mite Nothrus palustris is known to show the phenomenon of juvenile–adult polymorphism, i.e., juvenile instars produce secretions predominated by geranial, whereas adults secrete dehydrocineole along... more
The oil gland secretion of the oribatid mite Nothrus palustris is known to show the phenomenon of juvenile–adult polymorphism, i.e., juvenile instars produce secretions predominated by geranial, whereas adults secrete dehydrocineole along with a number of chemically unidentified compounds. We here re-analyzed the secretions of adult N. palustris by GC–MS and NMR spectroscopy, eventually identifying the unknown compounds as p-menthane monoterpenoids. The major components were two isomeric 6-isopropenyl-3-methyl-cyclohex-3-en-1-yl formates (= p-1,8-menthadien-5-yl formates), which accounted for about 75% of the secretion. These were accompanied by five additional, only partly identified p-menthanes (or p-methane-derivatives), all of which represented minor or trace components. In addition, adult secretions contained two C21-hydrocarbons, 1,12-heneicosadiene (major) and a heneicosatriene (minor). Menthane monoterpenoids represent a novel sub-class of terpene compounds in the oil gland ...
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The scent glands of harvestmen (Opiliones) produce secretions of taxon-specific composition. One class of compounds, assumed to be a key group in opilionid chemosystematics and prevalent among sclerosomatid Eupnoi, was termed... more
The scent glands of harvestmen (Opiliones) produce secretions of taxon-specific composition. One class of compounds, assumed to be a key group in opilionid chemosystematics and prevalent among sclerosomatid Eupnoi, was termed “sclerosomatid compounds” (SCs). Known compounds of this group comprise acyclic 4-methyl-branched ethyl-ketones and -alcohols as well as 2,4-dimethyl-branched primary alcohols and aldehydes, originally described from several species of North American Leiobuninae. We analyzed the scent gland secretions of Nelima ssp. (Sclerosomatidae, Leiobuninae) from two continents by gas chromatography-mass spectrometry, NMR, stereoselective synthesis, and chiral chromatography. We found a surprising chemical dichotomy: while North American N. paesserli produced typical acyclic SCs such as (E)-4-methyl-4-hexen-3-one, the secretions of European Nelima species exhibited a mixture of aromatic and aliphatic compounds, namely (R)-2-methyl-1-phenyl-pentan-3-one (MPP), 4-phenyl-2-bu...
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The ongoing development of more and more new psychoactive substances continues to be a huge problem in 2022 affecting the European and international drug market. Through slight alterations in the structure of illicit drugs, a way to... more
The ongoing development of more and more new psychoactive substances continues to be a huge problem in 2022 affecting the European and international drug market. Through slight alterations in the structure of illicit drugs, a way to circumvent the law is created, as the created derivatives serve as legal alternatives with similar effects. A common way of structure modification is the induction of a halogen residue. Recently, halogenated derivatives of the well-known designer drug 4-methylaminorex appeared on the market and are available in various online shops. In this study, three novel halogenated 4-methylaminorex derivatives, namely 4′-fluoro-4-methylaminorex, 4′-chloro-4-methylaminorex, and 4′-bromo-4-methylaminorex, were purchased online and characterized using nuclear magnetic resonance (NMR) spectroscopy, liquid chromatography-high-resolution mass spectrometry (LC-HRMS), and chiral high-performance liquid chromatography with ultraviolet detection (HPLC-UV). These derivatives ...
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The in vitro inhibitory potential of 50 extracts from various species of the flowering plant genus Hypericum was investigated using the KirbyBauer disk diffusion susceptibility test against Paenibacillus larvae, a spore‐forming,... more
The in vitro inhibitory potential of 50 extracts from various species of the flowering plant genus Hypericum was investigated using the KirbyBauer disk diffusion susceptibility test against Paenibacillus larvae, a spore‐forming, Gram‐positive bacterial pathogen that causes American foulbrood (AFB), a lethal disease affecting honeybee brood worldwide. Of the tested extracts, 14 were identified as highly active against P. larvae as compared to the activity of the positive control, indicating the presence of highly potent antibacterial compounds in the extracts. Examination of these extracts using TLC and HPLC/MS analyses revealed the presence of acylphloroglucinol and filicinic‐acid derivatives. Six pure compounds isolated from these extracts, viz., hyperforin (1), uliginosin B (2), uliginosin A (3), 7‐epiclusianone (4), albaspidin AA (5), and drummondin E (6), displayed strong antibacterial activity against the vegetative form of P. larvae (MIC ranging from 0.168–220 μM). Incubation of P. larvae spores with the lipophilic extract of Hypericum perforatum and its main acylphloroglucinol constituent 1 led to the observation of significantly fewer colony forming units as compared to the negative control, indicating that the acylphloroglucinol scaffold represents an interesting lead structure for the development of new AFB control agents.
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The unambiguous identification of plant material is a prerequisite of rational phytotherapy. Misidentification can even cause serious health problems, as in the case of the Chinese medicinal herb Zicao. Commercial material labelled... more
The unambiguous identification of plant material is a prerequisite of rational phytotherapy. Misidentification can even cause serious health problems, as in the case of the Chinese medicinal herb Zicao. Commercial material labelled “Zicao” may be derived from the roots of Arnebia euchroma (ruan zicao), Lithospermum erythrorhizon (ying zicao), or Onosma paniculata (dian zicao). All of these roots contain shikonin derivatives as main bioactive constituents, but ying zicao and dian zicao contain also hepatotoxic pyrrolizidine alkaloids in high amounts. Therefore, the use of A. euchroma with a very low pyrrolizidine alkaloid content is desirable. Confusions of the species occur quite often, indicating an urgent need for an unambiguous identification method. Discrimination of 23 zicao samples has been achieved by analyses of the nuclear internal transcribed spacer ITS2 and trnL-F intergenic spacer of the chloroplast DNA. Data were analyzed using Bioedit, ClustalX, Mega 11 and BLAST. Results indicate that ITS2 barcoding can accurately distinguish Arnebia euchroma from their adulterants. Subsequently, an HPTLC method has been developed allowing a chemical discrimination of the most widely used species. (22E)-Ergosta-4,6,8(14),22-tetraen-3-one has been identified as characteristic marker compound, allowing an unambiguous discrimination of A. euchroma and L. erythrorhizon.
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A bioassay-guided phytochemical analysis of the ethanolic extract of Grindelia argentina Deble & Oliveira-Deble (Asteraceae) allowed... more
A bioassay-guided phytochemical analysis of the ethanolic extract of Grindelia argentina Deble & Oliveira-Deble (Asteraceae) allowed the isolation of a known flavone, hispidulin, and three new oleanane-type saponins, 3-O-β-D-xylopyranosyl-(1→3)-β-D-glucopyranosyl-2β,3β,16α,23-tetrahydroxyolean-12-en-28-oic acid 28-O-β-D-xylopyranosyl-(1→2)-β-D-apiofuranosyl-(1→3)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl ester (2), 3-O-β-D-glucopyranosyl-2β,3β,23-trihydroxyolean-12-en-28-oic acid 28-O-β-D-xylopyranosyl-(1→2)-β-D-apiofuranosyl-(1→3)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl ester, (3) and 3-O-β-D-xylopyranosyl-(1→3)-β-D-glucopyranosyl-2β,3β,23-trihydroxyolean-12-en-28-oic acid 28-O-β-D-xylopyranosyl-(1→2)-β-D-apiofuranosyl-(1→3)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl ester (4), named grindeliosides A-C, respectively. Their structures were determined by extensive 1D- and 2D-NMR experiments along with mass spectrometry and chemical evidence. The isolated compounds were evaluated for their inhibitory activities against LPS/IFN-γ-induced NO production in RAW 264.7 macrophages and for their cytotoxic activities against the human leukemic cell line CCRF-CEM and MRC-5 lung fibroblasts. Hispidulin markedly reduced LPS/IFN-γ-induced NO production (IC50 51.4 μM), while grindeliosides A-C were found to be cytotoxic, with grindelioside C being the most active against both CCRF-CEM (IC50 4.2±0.1 μM) and MRC-5 (IC50 4.5±0.1 μM) cell lines.
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Research Interests: Chemistry, Complementary and Alternative Medicine, Traditional Medicine, Plant Biology, Medicine, and 15 morePhytomedicine, Phytochemical, Ursolic Acid, Enzyme, High Pressure Liquid Chromatography, Ascorbic Acid, Plant extracts, Rosa, DPPH, Total Phenolic Content, Arachidonic Acid, Linoleic Acid, Linolenic Acid, Pharmacology and pharmaceutical sciences, and Radical scavenging activity
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Three flavonolignans derived from the flavone tricin were isolated from Avena sativa herb. This is the first report of the presence of flavonolignans in A. sativa. In the known compounds 1a and 1b, a coniferyl alcohol moiety is linked to... more
Three flavonolignans derived from the flavone tricin were isolated from Avena sativa herb. This is the first report of the presence of flavonolignans in A. sativa. In the known compounds 1a and 1b, a coniferyl alcohol moiety is linked to the flavone by an ether bond; in the new natural product 2, it is linked by C-C bonds. Structure elucidation of compound 2 was performed by 1D and 2D NMR experiments, and the absolute configuration was determined from circular dichroic data.
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During an investigation of the Indian heterosporous fern Selaginella chrysocaulos, two novel C28 spirostene monosides, chrysocauloside A and B were identified. Chrysocauloside A (1β,3β-dihydroxy-20 S,22 R-spirost-5-ene-1-yl... more
During an investigation of the Indian heterosporous fern Selaginella chrysocaulos, two novel C28 spirostene monosides, chrysocauloside A and B were identified. Chrysocauloside A (1β,3β-dihydroxy-20 S,22 R-spirost-5-ene-1-yl β-D-glucopyranoside) and chrysocauloside B (1β,3β-dihydroxy-20 S,22 R-spirost-5-ene-1-yl β-D-galactopyranoside) are O-glycosylated at C-1 and each bear a methyl group at C-24 and C-25. Spectroscopic (NMR) and MS data for the new compounds are given and the taxonomic significance of the occurrence of spirostenes in the group of Lycophyta is discussed.
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Research Interests: Engineering, Chemistry, Analytical Chemistry, Chromatography, Bioanalysis, and 15 moreComparative Study, Medicine, Quality Control, Biological Sciences, High Pressure Liquid Chromatography, CHEMICAL SCIENCES, Maillard reaction, Derivatization, Cancer Patient, Clinical Study, Reproducibility of Results, Analytical and Bioanalytical Chemistry, Sensitivity and Specificity, Hydroxymethylfurfural, and Reference standards
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Research Interests: Genetics, Analytical Chemistry, Hematology, Developmental Biology, Complementary and Alternative Medicine, and 15 moreCancer, Biology, Cell Cycle, Drug Discovery, Cell Biology, Cytotoxicity, Apoptosis, Cell Culture, Biological Sciences, Humans, Boraginaceae, Caspase, CHEMICAL SCIENCES, Cancer Cell Lines, and Cell Lines
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Research Interests: Biochemistry, Chemistry, Hematology, Developmental Biology, Natural Products, and 15 moreBiotechnology, Cancer, Biology, Cytotoxicity, Medicine, Cell Culture, Biological Sciences, In Vitro, Ic, CHEMICAL SCIENCES, Cancer Cell Lines, HCT, Antiproliferative Activity, Compound, and Medical and Health Sciences
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Complete assignments of 1H and 13C NMR chemical shifts for oleanolic acid, 18α‐oleanolic acid, ursolic acid and their 11‐oxo derivatives based on 1H, 13C, 2D DQF‐COSY, NOESY, HSQC, HMBC and HSQC‐TOCSY experiments were achieved. Copyright... more
Complete assignments of 1H and 13C NMR chemical shifts for oleanolic acid, 18α‐oleanolic acid, ursolic acid and their 11‐oxo derivatives based on 1H, 13C, 2D DQF‐COSY, NOESY, HSQC, HMBC and HSQC‐TOCSY experiments were achieved. Copyright © 2003 John Wiley & Sons, Ltd.