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Biomedical subjects

H Greger

Publications and source records attributed to H Greger.

17 recordsLinked to original sources
PubMed2004

Antifungal 3-butylisocoumarins from Asteraceae-Anthemideae.

Seven new naturally occurring 3-butylisocoumarins were isolated and identified from lipophilic extracts of aerial as well as underground organs: corfin (17) and 3'-hydroxycorfin (18) from the roots of Chamaemelum mixtum and (-)-(R)-2'-methoxydihydroartemidin (5), (+)-(S,R)-epoxyartemidin (6a), dracumerin (12), (+)-(R)-(E)-3'-hydroxyartemidin (13), and capillarin isovalerate (20) from various organs of Artemisia dracunculus (tarragon). Furthermore, six known derivatives, artemidiol (7), (E/Z)-artemidin (11), capillarin (19), artemidinol (21), 8-hydroxyartemidin (22), and 8-hydroxycapillarin (23), were obtained. The antifungal activities of all naturally occurring derivatives were determined in a germ-tube inhibition test against a susceptible strain of rice blast fungus Pyricularia grisea. The 3-butyl side-chain is a prerequisite for high activity. Eleven structurally related synthetic derivatives were additionally tested to explore the influence of structural characteristics on activity. Benlate, blasticidin S, kresoxim-methyl, griseofulvin, and the carrot phytoalexin 6-methoxymellein all served as positive controls.

Antifungal Agents↗
PubMed2003

Naturally occurring lignans efficiently induce apoptosis in colorectal tumor cells.

Plant-derived lignans caused cell loss by apoptosis in colorectal adenoma and carcinoma cells. Nordihydroguaiaretic acid (NDGA), commonly used for the inhibition of lipoxygenase isoenzymes, showed the strongest growth inhibition with an IC50 of 1.9+/-0.5 microg followed by epiashantin (IC50=9.8+/-4.5 microM) and arctigenin (IC50=16.5+/-8.5 microM). The lignans caused a time- and dose-dependent loss of mitochondrial membrane potential (MMP), down regulation of the anti-apoptotic protein bcl(xl) and an increase of the apoptotic index. The time interval until loss of MMP and down modulation of bcl(xl) became evident correlated with the efficiency of growth inhibition by NDGA, epiashantin and yangambin. Bcl2 and caspase 3 were not involved. NDGA also induced a shift of the culture population to the G2/M phase of the cell cycle. With respect to these results, naturally occurring lignans could be useful in the therapy and chemoprevention of colorectal tumors.

Adenoma↗
PubMed2003

[Documentation in the cardiac catheterization laboratory using electronic databases--experiences in 176 German cath labs].

Due to the introduction of a variety of new features to the German health system, such as a new reimbursement system for inpatient work based on diagnosis-related groups, an obligation to detailed documentation for total quality management, as well as due to the continuing increase in the amount of imaging and other data within invasive cardiology, the use of electronic databases for documentation in the cardiac cath lab is of significant importance. The user friendliness and robustness of the software system for daily clinical practice is crucial for the acceptance of electronic documentation systems by physicians, nurses and technicians. This survey was aimed to explore the current practice and experiences of German cardiac catheterization labs with electronic databases particularly designed for documentation in invasive cardiology, including report generation of cath studies, risk and complication management and logistics for medical material ordering for the cath lab. Of the 176 hospitals and practices having agreed in taking part in this surveillance 165, are currently using an electronic database for administration of medical data and study reports. In 64% of the cath labs, a sub-specialized software system for detailed documentation of the course and the results of an invasive procedure, the human and material resources used, generation of the cath report, and documentation of procedural and post-procedural complications for total quality management is used. The acceptance and satisfaction with the software solutions currently available reveals to be rather inhomogeneous. While user-friendliness and flexibility of a number of software products were positively mentioned, main issues, such as missing hardware of software interfaces with the hospital information system for patient administration, missing stability of several systems, image management too complex and report configuration too inconvenient for daily clinical practice, were criticized. In general, in the light of continuing increase of the amount of clinical and imaging data as well as due to the legal obligation of detailed procedural documentation in all areas of invasive cardiology, a documentation system based on electronic databases bears the potential of an enormous economization of the daily workload of a cardiac cath lab. Prerequisites for the acceptance of such a system in clinical practice is not only the stability and reliability of the system but also the ability to link such a sub-system to existing databases via suitable interfaces and the flexibility of the system for modification of its features to meet the individual requirements of each user.

Adult↗
PubMed2002

Antifungal stilbenoids from Stemona collinsae.

Fifteen new stilbenoids including 11 phenylbenzofurans, the stemofurans A-K (1-11), and four dihydrostilbenes, the stilbostemins A (15), C (17), E (19), and F (20), were isolated and identified from a methanolic extract of Stemona collinsae roots together with five known derivatives, the stilbenes pinosylvin (13) and 4'-methylpinosylvin (14), the dihydrostilbenes, stilbostemins B (16) and D (18), and the dihydrophenanthrene racemosol (12) as well as (+)-sesamin, coniferyl alcohol, and stigmasterol. Bioautographic tests with Cladosporium herbarum displayed antifungal activity for stilbenoids of all four structural types. Ten derivatives were tested against five microfungi using the microdilution technique linked with digital image analysis of germ tubes.

Alternaria↗
PubMed2001

Stress induced carbazole phytoalexins in Glycosmis species.

Induced formation of a series of carbazole alkaloids was observed in leaves of Glycosmis parviflora and G. pentaphylla after wounding, UV-irradiation, and particularly after inoculation with the fungus Botrytis cinerea. Chemical variation between different provenances and even individuals of G. parviflora led to an accumulation of different derivatives from which three proved to be undescribed natural products. Their structures were identified by spectroscopic methods and named carbalexins A, B, and C. Bioautographic tests on TLC plates with Cladosporium herbarum exhibited strong antifungal activity for the new carbalexins as well as for the already known 2-hydroxy-3-methylcarbazole, but only weak effects for the pyranocarbazole glycoborinine. Detailed experiments with marked infection areas confirmed the restricted accumulation of carbazole derivatives which could not be detected in non-infected areas of the same leaf. Apart from carbazoles, in some individuals of G. parviflora an additional accumulation of the pyranoquinolones flindersine and methylflindersine was induced, which supports the already previously discussed biogenetic connections between carbazoles and prenylated quinolones.

Alkaloids↗
PubMed2000

Prenylated sulfonyl amides from Glycosmis species.

Nine new sulfur containing amides were isolated from the lipophilic leaf extracts of different varieties of Glycosmis chlorosperma and G. ex aff. pseudoracemosa mainly collected in Thailand. Their structures were elucidated by spectroscopic methods. All amides were shown to be characterized by a methylsulfonylpropenoic acid moiety linked to a p-geranyloxy- or p-prenyloxy-phenethylamide rest. The compounds differ by different states of oxidation (i) at the 2-position of the ethylamine unit, (ii) at the aromatic m-position of phenethylamine, or (iii) at the terminal methyl group of the geranyloxy side chain.

Amides↗
PubMed2000

Cyclopenta[b]benzofurans from Aglaia species with pronounced antifungal activity against rice blast fungus (Pyricularia grisea).

Eight flavaglines, six cyclopenta[b]benzofurans, a cyclopenta[bc]benzopyran, and a benzo[b]oxepine, together with an aromatic butyrolactone were isolated from Aglaia odorata, A. elaeagnoidea, and A. edulis (Meliaceae) and tested against the three plant pathogens Pyricularia grisea, Fusarium avenaceum, and Alternaria citri for antifungal properties. Using the microdilution technique linked with digital image analysis of germ tubes, the benzofurans displayed strong activity, whereas the benzopyran, benzoxepine, and butyrolactone were inactive at the highest concentration tested. P. grisea, responsible for rice blast disease, was the most susceptible fungus against all benzofurans, with rocaglaol as the most active derivative. Based on EC(50), EC(90), and MIC values, the antifungal activity of rocaglaol was clearly higher than of the reference compounds, blasticidin S and Benlate.

Alternaria↗
PubMed2000

Infraspecific variation of sulfur-containing bisamides from Aglaia leptantha.

Six new amides, leptaglin (1), hemileptaglin (2), aglanthin (3), agleptin (4), isoagleptin (5), and leptanthin (6), together with known lignans yangambin, eudesmin, grandisin (7), epigrandisin (8), and dehydrodiconiferyl alcohol, were isolated and identified from the lipophilic leaf and stem bark extracts of Aglaia leptantha. The dominating sulfur-containing bisamides contained either putrescine or the corresponding pyrrolidine ring as the diamine part, linked to phenylacetic and/or methylthiopropenoic acid moieties showing a remarkable infraspecific variation in eight individuals from two different habitats. Structures were determined by MS and NMR, including lanthanide-induced shifts.

Amides↗
PubMed1998

Bisamides, lignans, triterpenes, and insecticidal Cyclopenta[b]benzofurans from Aglaia species.

Twelve new derivatives of bisamides [piriferinol (5), edulimide (7)], lignans [lariciresinol acetat (10)], triterpenes [4-bis-norcycloartane-type triterpenes (11a, 12a+b, 13a+b)], cyclopenta[b]benzofurans [pannellin (15), pannellin 1-O-acetate (16), 3'-methoxypannellin (17)], and an aromatic butyrolactone [aglalactone (18)] were isolated and identified from lipophilic leaf, stem, and root extracts of Aglaia spp. elaeagnoidea, edulis, grandis, silvestris, and tomentosa. Two cyclopenta[b]benzofurans (flavaglines), pannellin (15) and pannellin 1-O-acetate (16), displayed very strong insecticidal activity against Spodoptera littoralis and Lymantria dispar, comparable with the activity of azadirachtin.

Animals↗
PubMed1997

Prenylated phenylpropenes from Coleonema pulchellum with antimicrobial activity.

The lipophilic root extract of Coleonema pulchellum was analysed and tested for antifungal and antibacterial activity. Eight previously undescribed prenyloxy and geranyloxy phenylpropenes, were isolated as major compounds together with the known evofolin-C as well as the lignans (+/-)-sesamin and (+/-)-prenylpiperitol, the diterpene (-)-pimara-9(11),15-dien-19-oic acid and the 2,4-decadienoic acid isobutylamide. All structures were established by spectroscopic evidence. From the new phenylpropenes, named evofolin-C-acetate, colenemol, colenemal, prenycol acetate, dehydroprenycol acetate, precolpuchol, colpuchol and colpuchol acetate, the dihydroxylated precolpuchol displayed the strongest antifungal and antibacterial activity against Cladosporium herbarum and Staphylococcus aureus, respectively.

Anti-Bacterial Agents↗
PubMed1996

Bioactive amides from Glycosmis species.

Besides the known imide ritigalin (9), six new phenethyl/styrylamine-derived amides isolated from lipophilic leaf extracts of Glycosmis cf. mauritiana, Glycosmis cf. cyanocarpa, and Glycosmis crassifolia displayed pronounced antifungal and/or insecticidal activity against Cladosporium herbarum and Spodoptera littoralis, respectively, the methylthiocarbonic acid derivatives niranin (1), dehydroniranin A (2), and dehydroniranin B (3) as well as the isovaleric and senecioic acid derivatives thalebanin B (4), dehydrothalebanin B (5), and dehydrothalebanin A (6).

Amides↗
PubMed1994

In vitro inhibition of cyclooxygenase and 5-lipoxygenase by alkamides from Echinacea and Achillea species.

Polyunsaturated alkamides isolated from Achillea species, Echinacea angustifolia DC., Anacyclus pyrethrum (L.) Link, and Aaronsohnia pubescens (Desf.) Bremer & Humphries, (Compositae) were shown to possess inhibitory activity in in vitro cyclooxygenase (sheep seminal microsomes) and 5-lipoxygenase (porcine leukocytes) assays. Activity appeared to depend on the particular structure of the alkamides.

Amides↗
PubMed1990

Comparative HPLC Analyses of Alkamides within the Achillea millefolium Group.

Petrol/Et (2)O extractable alkamides from the subterranean parts of different members of the ACHILLEA MILLEFOLIUM group were separated and compared by reversed phase HPLC. Apart from different retention times, each peak could be characterized by its typical UV spectrum obtained by on-line photodiode array detection. Based on previously isolated and identified alkamides, a library search program of UV spectra and corresponding retention times was prepared which greatly facilitated a general comparison of the different HPLC profiles. Apart from the dominating deca-2 E,4 E,6Z-trienoic piperideide in the European representatives ( A. MILLEFOLIUM, A. PANNONICA, A. COLLINA, A. ASPLENIIFOLIA, A. SETACEA), the different cytotypes may be characterized by various accumulation tendencies, mainly towards two isomeric decatetraenoic piperideides and (+)-sesamin. The amide patterns of the Asian and North American members ( A. ASIATICA, A. LANULOSA) clearly deviate; the characteristic decatrienoic and decatetraenoic piperideides are replaced here by a preponderance of decadienoic acid-derived isobutylamide and piperideide. Since there are no diploid members known from North America, the striking chemical similarities with the diploid Asian members strongly suggest an Asian origin.

Journal Article↗