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At least 253 records · Page 14Linked to original sources
PubMed2005

Characterisation of antibacterial Australian medicinal plant extracts by investigation of the mechanism of action and the effect of interfering substances.

Propidium iodide (PI) uptake and salt tolerance assays were used to investigate the mechanism of antibacterial action of an extract of the leaves of Eremophila duttonii, a traditional Australian medicinal plant previously shown to have potent bactericidal activity against Gram positive bacteria. The extract compromised the integrity of the cytoplasmic membrane of Staphylococcus aureus , leading to increased membrane permeability (indicated by uptake of PI) and a decrease in ability to exclude NaCl. The bactericidal action of the E. duttonii extract was concluded to be due to its membrane-active properties. The effect of contaminants on the efficacy of this extract and other medicinal plant extracts was also investigated. Organic contaminants (bakers' yeast and skim milk powder) decreased the efficacy of all extracts investigated, while hard water had no effect. Greater understanding of the biocidal properties of the plant extracts investigated may determine if they have medical, industrial or environmental applications. ((c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

Animals↗
PubMed2000

Rapid identification of saponins in plant extracts by electrospray ionization multi-stage tandem mass spectrometry and liquid chromatography/tandem mass spectrometry.

Electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)) and liquid chromatography coupled with on-line mass spectrometry (LC/MS/MS) were applied to characterize saponins in crude extracts from Panax ginseng. The MS(n) data of the [M - H](-) ions of saponins can provide structural information on the sugar sequences of the saccharide chains and on the sapogins of saponins. By ESI-MS(n), non-isomeric saponins and isomeric saponins with different aglycones can be determined rapidly in plant extracts. LC/MS/MS is a good complementary analytical tool for determination of isomeric saponins. These approaches constitute powerful analytical tools for rapid screening and structural assignment of saponins in plant extracts.

Chromatography, Liquid↗
PubMed2005

Chemical constituents of Lychnophora pohlii and trypanocidal activity of crude plant extracts and of isolated compounds.

Crude extracts of Lychnophora pohlii were tested in vitro against trypomastigote forms of Trypanosoma cruzi, and the dichloromethane and methanol crude extracts from leaves plus inflorescences were found to have trypanocidal activity. The bioassay-guided fractionation of the extracts yielded seven active compounds: the sesquiterpene lactones lychnopholide, centratherin, goyazensolide and 15-desoxygoyazensolide in the dichloromethane extract, and caffeic acid and the flavonoids luteolin and vicenin-2 in the methanol extract. One active caffeoyl quinic acid derivative was isolated from the inactive hydroalcoholic extract of leaves plus inflorescences. Chemically, the plant has sesquiterpene lactone type furanoheliangolides, flavonoids, caffeic acid, a caffeoyl quinic acid derivative, which are characteristic of the Vernonieae.

Animals↗
PubMed2000

Determination of sugar compounds in olive plant extracts by anion-exchange chromatography with pulsed amperometric detection.

We describe a chromatographic method that uses isocratic elution and pulsed amperometric detection to determine soluble carbohydrates in plant tissues. Such a method provides a rapid and convenient means to obtain a complete profile of the sugar components of leaves and roots from olive (Olea europaea L. cv. Coratina) plants. A simple purification of plant extracts using pure water was developed, which is far less time-consuming and retains a high level of accuracy. Excellent separation of myo-inositol, galactinol, mannitol, galactose, glucose, fructose, sucrose, raffinose, and stachyose was achieved with an anion-exchange column and 12 mM NaOH spiked with 1 mM barium acetate as an eluent. At a flow rate of 1.0 mL/min, the time of analysis was less than 25 min, and repeatability of the method on the order of 2.2% as RSD or better for retention times and lower than 5.2% for peak areas. Recoveries approximated 100% (range 97.2-104.5%), and the method provided good precision with a coefficient of variation which ranged between 0.9 and 3.3%. Among identified carbohydrates extracted from leaves and roots of olive plants, glucose and mannitol were major compounds. Their molar ratio was estimated to be 1.2+/-0.1 and 2.2+/-0.3 for olive leaves and roots, respectively. The occurrence of soluble galactinol in plant tissues was also validated.

Anion Exchange Resins↗
PubMed2004

Effect of medicinal plant extracts on forced swimming capacity in mice.

The tonic effect of Cordyceps militaris (CM), Paecilomyces japonia (PJ), Phellinus linteus (PL), Ganoderma lucidum (GL), Grifola frondosa (GF), and Panax ginseng (PG) was examined based on the forced swimming capacity and the change of biochemical parameters in ICR mice. The treatment groups were orally administered medicinal plant extracts (500 mg/kg per day), while the control group received distilled water for 4 weeks. The swimming times to exhaustion were longer in the CM, PJ, and GF groups than in the control group (P < 0.05). Plasma TG levels were lower in the treatment groups than in the control group. Plasma glucose levels were not significantly different between the control group and each treatment group except the PG group. Plasma lactate and ammonia levels of the PJ and GF groups were lower than those of the control group (P < 0.05). There were no significant differences in the content of liver and gastrocnemius muscle glycogen between the control group and each treatment group. In conclusion, PJ and GF extracts enhanced the forced swimming capacity of mice by increasing fat utilization and by delaying the accumulation of plasma lactate and ammonia.

Animals↗
PubMedDate not supplied

Screening of plant extracts for antioxidant activity: a comparative study on three testing methods.

Three methods widely employed in the evaluation of antioxidant activity, namely 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method, static headspace gas chromatography (HS-GC) and beta-carotene bleaching test (BCBT), have been compared with regard to their application in the screening of plant extracts. The strengths and limitations of each method have been illustrated by testing a number of extracts, of differing polarity, from plants of the genus Sideritis, and two known antioxidants (butylated hydroxytoluene and rosmarinic acid). The sample polarity was important for the exhibited activity in the BCBT and HS-GC methods but not for the DPPH method. The complex composition of the extracts and partition phenomena affected their activity in each assay. The value of the BCBT method appears to be limited to less polar samples. Although slow, the HS-GC method is preferable for assessing the antioxidant inhibitory properties on the formation of unwanted secondary volatile products. Being rapid, simple and independent of sample polarity, the DPPH method is very convenient for the quick screening of many samples for radical scavenging activity.

Antioxidants↗
PubMed2001

[A modification of the in ovo-method for the determination of the antihemorrhagic activity of plant extracts].

Up to now there has been only a method available for testing the antihaemorrhagic activity of plant extracts, in which chicken embryos had to be transferred to a special container on the fifth day of incubation. Furthermore, the test could not be conducted on the extraembryonal circulatory system until two days later. In the test method described here the embryos remain inside the egg. After removal of the eggshell through the air cell and removal of the inner shell membrane, direct access to the extraembryonal circulatory system is possible, minimising external influences on the test system. This represents a dramatic simplification in technique and permits testing already on the fourth day of incubation. The application of this method to determine the antihaemorrhagic properties of samples has the advantage of permitting the simple and quick production of haemorrhages by snake venom on the yolk sac circulatory system.

Animals↗
PubMedDate not supplied

Screening of Asteraceae (Compositae) plant extracts for larvicidal activity against Aedes fluviatilis (Diptera:Culicidae).

Ethanol extracts of 83 plants species belonging to the Asteraceae (Compositae) family, collected in the State of Minas Gerais, Brazil, were tested for larvicidal activity against the mosquito Aedes fluviatilis--Diptera: Culicidae). The extract from Tagetes minuta was the most active with a LC90 of 1.5 mg/l and LC50 of 1.0 mg/l. This plant has been the object of several studies by other groups and its active components have already been identified as thiophene derivatives, a class of compounds present in many Asteraceae species. The extract of Eclipta paniculata was also significantly active, with a LC90 of 17.2 mg/l and LC50 of 3.3 mg/l and no previous studies on its larvicidal activity or chemical composition could be found in the literature. Extracts of Achryrocline satureoides, Gnaphalium spicatum, Senecio brasiliensis, Trixis vauthieri, Tagetes patula and Vernonia ammophila were less active, killing more than 50% of the larvae only at the higher dose tested (100 mg/l).

Aedes↗
PubMedDate not supplied

Comparative choleretic and hepatoprotective properties of young sprouts and total plant extracts of Rosmarinus officinalis in rats.

Lyophilised ethanol and aqueous extracts of Rosmarinus officinalis young sprouts and total plant have been evaluated for choleretic and hepatoprotective activities in the rat. R. officinalis ethanol extracts prepared from young sprouts show a significant dose-related choleretic activity and are more active than the total plant extract. Aqueous extracts of young sprouts show a significant hepatoprotective effect on plasma GPT levels when given as pretreatment before carbon tetrachloride intoxication while the whole plant extract was inactive. Both sprouts and whole plant aqueous extracts were ineffective when given after carbon tetrachloride administration.

Alanine Transaminase↗
PubMed2000

Search for antiviral activity in higher plant extracts.

In the course of our search for plant natural products as antiviral agents, extracts of ten plants from the Iberian Peninsula were tested for antiviral activity against herpes simplex type I (HSV-1), vesicular stomatitis virus (VSV) and poliovirus type 1. Aqueous extracts of five of these medicinal plants, namely Nepeta nepetella (150-500 microg/mL), Nepeta coerulea (150-500 microg/mL), Nepeta tuberosa (150-500 microg/mL), Dittrichia viscosa (50-125 microg/mL) and Sanguisorba minor magnolii (50-125 microg/mL), showed a clear antiviral activity against two different DNA and RNA viruses, i.e. HSV-1 and VSV. Only the medicinal plant Dittrichia viscosa was active against an additional virus, poliovirus type 1.

Antiviral Agents↗
PubMed1983

Antihormonal effects of plant extracts. Pharmacodynamic effects of lithospermum officinale on the thyroid gland of rats; comparison with the effects of iodide.

The antithyrotropic activity of freeze-dried-extracts from Lithospermum officinale (Lith. off. FDE) was investigated in the rat. When administered together with TSH, Lith. off. FDE blocked the TSH-induced increase in endocytotic activity of the thyroid glands followed by a strong decline of thyroid hormone levels. Furthermore, when Lith. off. FDE was injected alone it caused a decline in endogenous TSH-levels as well as in thyroidal secretion and thyroid hormone levels. The efficacy of the extract in blocking thyroid secretion was compared to that of potassium iodide and it was found that the effect of Lith. off. FDE was of more rapid onset and of longer duration, suggesting that the FDE may have a different mode of action from that of KJ. A specific interaction between TSH and the active constituents of the plant extract is discussed. Experiments on thyroidectomized and T4 substituted rats have demonstrated as an additional pharmacodynamic effect of Lith. off. FDE an inhibition of peripheral T4-deiodination.

Animals↗
PubMed1987

A cell-free plant extract for accurate pre-tRNA processing, splicing and modification.

An intron-containing tobacco tRNA(Tyr) precursor synthesized in a HeLa cell nuclear extract has been used to develop a cell-free processing and splicing system from wheat germ. Removal of 5' and 3' flanking sequences, accurate excision of the intervening sequence, ligation of the resulting tRNA halves, addition of the 3'-terminal CCA sequence and modification of seven nucleosides were achieved in appropriate wheat germ S23 and S100 extracts. The maturation of pre-tRNA(Tyr) in these extracts resembles the pathway observed in vivo for tRNA biosynthesis in Xenopus oocytes and yeast in that processing of the flanks precedes intron excision. Most of the modified nucleosides (m2(2) G, psi 35, psi 55, m7G and m1A) are introduced into the intron-containing pre-tRNA with mature ends, whereas two others (m1G and psi 39) are only found in the mature tRNA(Tyr). Processing and splicing proceed very efficiently in the wheat germ extracts, leading to complete maturation of 5' and 3' ends followed by about 65% conversion to mature tRNA(Tyr) under our standard conditions. The activity of the wheat germ endonuclease is stimulated 3-fold by the non-ionic detergent Triton X-100. All previous attempts to demonstrate the presence of a splicing endonuclease in wheat germ had failed (Gegenheimer et al., 1983). Hence, this is the first cell-free plant extract which supports pre-tRNA processing and splicing in vitro.

Cell Nucleus↗
PubMedDate not supplied

Determining acetylcholinesterase inhibitory activity in plant extracts using a fluorimetric flow assay.

A fluorometric assay for acetylcholinesterase inhibitory activity was developed in a flow system using the fluorogenic substrate 7-acetoxy-1-methyl quinolinium iodide which is hydrolysed to the highly fluorescent 7-hydroxy-1-methyl quinolinium iodide. The detection limit of galanthamine is 0.5 microM, which is about 20 times more sensitive than in the colorimetric flow assay. In the presence of 30% methanol or of 5% acetonitrile, about 70% of the enzyme activity could still be detected. Various plant extracts have been screened using the described system including bulbs of Galanthus nivalis, Eucharis amazonica (E. x grandiflora), Crinum powelli and Nerine bowdenii (all members of the Amaryllidaceae), which showed strong AchE inhibitory activity.

Acetylcholinesterase↗