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Biomedical subjects

U Lindequist

Publications and source records attributed to U Lindequist.

At least 19 recordsLinked to original sources
PubMed2006

Bioactive components of the traditionally used mushroom Podaxis pistillaris.

In the course of an ethnobotanical study on fungi used in Yemeni ethnomedicine the fungus Podaxis pistillaris (Podaxales, Podaxaceae, Basidiomycetes) was found to exhibit antibacterial activity against Staphylococcus aureus, Micrococcus flavus, Bacillus subtilis, Proteus mirabilis, Serratia marcescens and Escherichia coli. In the culture medium of P. pistillaris three epidithiodiketopiperazines were identified by activity-guided isolation. Based on spectral data (NMR, ESI-MS and DCI-MS) their identity was established as epicorazine A (1), epicorazine B (2) and epicorazine C (3, antibiotic F 3822), which have not been reported as constituents of P. pistillaris previously. It is assumed that the identified compounds contribute to the antibacterial activity of the extract.

Journal Article↗
PubMed2006

Screening of selected Arabian medicinal plant extracts for inhibitory activity against peptidases.

The methanolic extracts of 20 medicinal plants from the island Soqotra/Yemen were screened with respect to their inhibitory potency against angiotensin converting enzyme (ACE), neutral endopeptidase (NEP) and aminopeptidase N (APN). Eight extracts did not show significant inhibitory activity against the enzymes tested, only Kalanchoe farinacea, Boswellia elongata and Cissus hamaderohensis inhibited all three enzymes. The most active extract was prepared from Kalanchoe farinacea characterized by low IC50 values especially for NEP and APN.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2005

Antimicrobial, cytotoxic and antioxidant activity of selected basidiomycetes from Yemen.

Dichloromethane, methanol and aqueous extracts of 23 selected Basidiomycetes species fruiting bodies collected in Yemen were screened in vitro for their antibacterial activities against three Gram-positive bacteria (Staphyloccocus aureus, Bacillus subtilis, Micrococcus flavus), two Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and against one yeast fungus (Candida maltosa), as well as for their cytotoxic and antioxidant activity. The highest antibacterial activity was shown by extracts from Agaricus sp. (Type 1), Coriolopsis caperata, Ganoderma colossus, Ganoderma resinaceum, Phellorinia herculea and Tulostoma obesum. Strong antioxidative effects employing the DPPH assay were exhibited by methanol extracts from Ganoderma resinaceum, Inonotus ochroporus, Phellinus rimosus and Phellorinia herculea. The results provide evidence that some of the studied fungi might be potential sources for new biologically active agents.

Anti-Bacterial Agents↗
PubMed2004

Red clover extracts stimulate differentiation of human osteoblastic osteosarcoma HOS58 cells.

Different extracts from red clover (Trifolium pratense L.) were tested for their ability to stimulate the activity of osteoblastic osteosarcoma cells (HOS58). As a key marker of osteoblasticity we chose the activity of alkaline phosphatase (ALP). Whereas butanol and methanol extracts had no influence on either ALP or cellular protein production, enzyme activity was increased significantly on incubation with chloroform extracts. All extracts were analysed for isoflavone content. The data clearly suggest a role for red clover isoflavonoids in the stimulation of osteoblastic cell activity.

Alkaline Phosphatase↗
PubMed2004

Apoptosis induction by 4beta-acetoxyscirpendiol from Paecilomyces tenuipes in human leukaemia cell lines.

The carpophores of Paecilomyces tenuipes are known in the Orient for their strong antitumor activity. In continuation of our study on acetoxyscirpendiol (ASD, 4beta-acetoxyscirpene-3alpha,15-diol) as a cytotoxic component from this fungus, we report particularly on the mode of action of ASD in inducing apoptosis in human MOLT-4, THP-1 and Jurkat T cell leukaemia in vitro. The antiproliferative effects of ASD seem attributable to its induction of apoptosis in the cells, as it blocked the cell cycle, induced hypodiploidity and bound annexin V and also cleaved poly-(ADP-ribose) polymerase (PARP) in these cell lines. The 50% inhibitory concentrations (IC50) of ASD on MOLT-4, THP-1 and Jurkat T cells were found to be 60, 85 and 60 ng/ml, respectively. ASD arrested the cell cycle at the G1/S transition and showed hypodiploidity due to the accumulation of sub-G0 population. Annexin V binding was increased in the presence of ASD in the MOLT-4 cell line in a time-dependent manner. ASD and three of its derivatives also induced cleavage of PARP in both MOLT-4 and Jurkat T cell lines. From these data, it is suggested that ASD exerts its cytotoxic activity by inducing apoptosis in leukaemia cell lines in vitro.

Annexin A5↗
PubMed2004

Proteomic signatures for daunomycin and adriamycin in Bacillus subtilis.

The influence of the two anthracyclin antibiotics daunomycin and adriamycin on the proteome of Bacillus subtilis was investigated. They intercalate in the double helix causing strand breaks. Both compounds induce proteins related to DNA damage and oxidative stress as indicated by the induction of some members of the PerR and the DinR-regulon. The mild induction of some members of the HrcA- and the CtsR-regulon may indicate protein oxidation as well. Furthermore, an influence on the sigmaB-dependent general stress response was shown. These data show that the proteomic signature is a valuable experimental tool for a comprehensive evaluation of the action of different drugs.

Anti-Bacterial Agents↗
PubMed2003

Antiviral activity of Inonotus hispidus.

The antiviral activity of two phenolic compounds, hispolon and hispidin, isolated from the fruit bodies of the basidiomycete Inonotus hispidus as well as of some extracts prepared from fruit bodies and mycelial cultures of this fungus was investigated in allantois on the shell-test system. Ethanolic extracts, hispidin and hispolon showed considerable antiviral activity against influenza viruses type A and B.

Antiviral Agents↗
PubMed2003

Inhibitory effect of Bergenia ligulata on influenza virus A.

Methanol water extract from rhizomes of Bergenia ligulata, a plant used in Nepalese ethnomedicine, inhibited in vitro the replication of influenza virus in a dose dependent manner and did not show virucidal activity at effective concentration. Pretreatment of cells with B. ligulata extract was shown to be most effective to prevent cell destruction. The extract inhibited viral RNA synthesis and reduced viral peptide synthesis at 10 microg/ml. The virus inhibitory effect is related to the presence of condensed tannins in the extract.

Animals↗
PubMed2002

Effect of an orally applied herbal immunomodulator on cytokine induction and antibody response in normal and immunosuppressed mice.

The influence of the oral administration of a herbal immunomodulator, consisting of an aqueous-ethanolic extract of the mixed herbal drugs Thujae summitates, Baptisiae tinctoriae radix, Echinaceae purpureae radix and Echinaceae pallidae radix, on cytokine induction and antibody response against sheep red blood cells was investigated in mice. The treatment of the animals with the extract caused no enhancement of the cytokine titers in the serum. Spleen cells isolated from the treated mice, however, produced higher amounts of IL-2, IFNgamma and GM-CSF ex vivo in comparison to spleen cells isolated from control animals, especially after additional stimulation by lipopolysaccharides or concanavalin A. The application of the extract also triggered the production of IL-1 and TNFalpha by peritoneal macrophages ex vivo. The influence of the herbal extract on the antibody response was examined by the plaque forming cell assay. The administration of the extract caused a significant enhancement of the antibody response against sheep red blood cells, inducing an increase in the numbers of splenic plaque forming cells and the titers of specific antibodies in the sera of the treated animals. In mice, immunosuppressed by old age or additional treatment with hydrocortisone, the therapy with the extract resulted in a normalization of the antibody response against sheep red blood cells.

Adjuvants, Immunologic↗
PubMed2002

The usefulness of a biosensor controlled perfusion cell culture for the investigation of new drugs demonstrated with the marine fungus Kirschsteiniothelia maritima.

The investigation of new biological active substances from limited sources for example from marine organisms needs sensitive and evident test systems. Such a system is the glucose biosensor controlled perfusion cell culture. The glucose consumption of cells is a very sensitive parameter which allows the continuous measurement of external effects of test substances on the cells under in vivo-like conditions. Cytotoxic concentrations of active substances as well as a virus infection lowers the glucose consumption of continuously perfused cells. This effect can be monitored using a glucose biosensor. The influence of drugs and the virus infection can be observed simultaneously in the same system continuously over several days. With two substances isolated from the marine fungus Kirschsteiniothelia maritima investigations for cytotoxic and for antiviral effects are demonstrated.

Anti-Bacterial Agents↗
PubMed2001

Screening of Yemeni medicinal plants for antibacterial and cytotoxic activities.

Ethanolic extracts of 20 selected plant species used by Yemeni traditional healers to treat infectious diseases were screened for their antibacterial activity against both Gram-positive and Gram-negative bacteria, as well as for cytotoxic activity. Fourteen of the ethanolic extracts showed variable degrees of antibacterial activity. The active ethanolic extracts were partitioned between ethyl acetate and water for a first separation. The ethyl acetate extract of Lawsonia inermis was found to be the most active one against all bacteria in the test system. Other promising results could be obtained from extracts of Aloe perryi, Indigofera oblongifolia, Meriandra benghalensis and Ziziphus spina christi. Additionally, the ethanolic extracts of the 20 plants under investigation were tested for their cytotoxic effects on FL-cells using the neutral red assay. Extracts of Calotropis procera, Chenopodium murale, Pulicaria orientalis, Tribulus terrestris and Withania somniferum displayed a remarkable activity.

Anti-Bacterial Agents↗
PubMed2001

Actaeaepoxide 3-O-beta-D-xylopyranoside, a new cycloartane glycoside from the rhizomes of Actaea racemosa (Cimicifuga racemosa).

A new cycloartane glycoside (1) was obtained from a minor triterpene fraction of the rhizome extract of Actaea racemosa (synonym: Cimicifuga racemosa) along with a known compound, cimigenol 3-O-beta-D-xylopyranoside. The structure of 1 was elucidated as 20(S),22(R),23(R),24(S)-12beta-acetoxy-16beta:23,23alpha:24-diepoxy-3beta,22beta,25-trihydroxy-9,19-cyclolanost-7-ene 3-O-beta-D-xylopyranoside (actaeaepoxide 3-O-beta-D-xylopyranoside) on the basis of spectral and chemical evidence.

Chromatography, Gas↗
PubMed1999

Cyanobacteria--a potential source of new biologically active substances.

Hydrophilic and lipophilic extracts of twelve cyanobacterial strains, isolated from fresh and brackish water, and two waterblooms, collected during the summer from the Baltic Sea, were investigated for their antibiotic activities against seven microorganisms. No inhibitory effects were found against the three Gram-negative bacteria Escherichia coli, Proteus mirabilis and Serratia marcescens and the yeast Candida maltosa. Of all cyanobacterial samples, extracts from seven species inhibited the growth of at least one of the Gram-positive bacteria Micrococcus flavus, Staphylococcus aureus and Bacillus subtilis. M. flavus proved to be the most sensitive bacterium in the agar diffusion test system. In particular, the hexane and dichlormethane extracts showed antimicrobial effects. But only one water extract, prepared from material of a natural waterbloom, was found to be active.

Anti-Bacterial Agents↗
PubMed1999

Aspects of the antimicrobial efficacy of grapefruit seed extract and its relation to preservative substances contained.

The antimicrobial efficacy as well as the content of preservative agents of six commercially available grapefruit seed extracts were examined. Five of the six extracts showed a high growth inhibiting activity against the test germs Bacillus subtilis SBUG 14, Micrococcus flavus SBUG 16, Staphylococcus aureus SBUG 11, Serratia marcescens SBUG 9, Escherichia coli SBUG 17, Proteus mirabilis SBUG 47, and Candida maltosa SBUG 700. In all of the antimicrobial active grapefruit seed extracts, the preservative benzethonium chloride was detected by thin layer chromatography. Additionally, three extracts contained the preserving substances triclosan and methyl parabene. In only one of the grapefruit seed extracts tested no preservative agent was found. However, with this extract as well as with several self-made extracts from seed and juiceless pulp of grapefruits (Citrus paradisi) no antimicrobial activity could be detected (standard serial broth dilution assay, agar diffusion test). Thus, it is concluded that the potent as well as nearly universal antimicrobial activity being attributed to grapefruit seed extract is merely due to the synthetic preservative agents contained within. Natural products with antimicrobial activity do not appear to be present.

Anti-Bacterial Agents↗