Evaluating Volatile Plant Compounds of Psidium galapageium (Myrtales: Myrtaceae) as Repellents Against Invasive Parasitic Diptera in the Galapagos Islands

Plant-based repellents represent a safe, economic, and viable alternative to managing invasive insects that threaten native fauna. Observations of self-medication in animals can provide important cues to the medicinal properties of plants. A recent study in the Galapagos Islands found that Darwin's finches apply the leaves of Psidium galapageium (Hooker 1847) to their feathers, extracts of which were repellent to mosquitoes and the parasitic fly Philornis downsi (Dodge & Aitkens 1968; Diptera: Muscidae). Introduced mosquitoes are suspected vectors of avian pathogens in the Galapagos Islands, whereas the larvae of P. downsi are blood-feeders, causing significant declines of the endemic avifauna. In this study, we investigated the volatile compounds found in P. galapageium, testing each against a model organism, the mosquito Anopheles arabiensis (Patton 1905; Diptera: Culicidae), with the aim of singling out the most effective compound for repelling dipterans. Examinations of an ethanolic extract of P. galapageium, its essential oil and each of their respective fractions, revealed a mixture of monoterpenes and sesquiterpenes, the latter consisting mainly of guaiol, trans-nerolidol, and β-eudesmol. Of these, trans-nerolidol was identified as the most effective repellent to mosquitoes. This was subsequently tested at four different concentrations against P. downsi, but we did not find a repellence response. A tendency to avoid the compound was observed, albeit significance was not achieved in any case. The lack of repellence suggests that flies may respond to a combination of the volatile compounds found in P. galapageium, rather than to a single compound.

Catechol alkenyls from Semecarpus anacardium: acetylcholinesterase inhibition and binding mode predictions

ETHNOPHARMACOLOGICAL RELEVANCE

The fruits of Semecarpus anacardium L. f. (Anacardiaceae) are used in Ayurvedic medicine and also in Iranian Traditional Medicine for various indications, among those for retarding and treatment of dementia.

AIM OF THE STUDY

The severity of Alzheimer's disease obviously correlates with a cholinergic deficit. In a screening for acetylcholinesterase (AChE) inhibitory activity, an extract from the fruit resin of Semecarpus anacardium was among the most active ones. Thus, the aim of this study was to isolate the active compounds and to investigate them in detail. Their binding mode to the active site of AChE was investigated by in silico docking experiments.

MATERIALS AND METHODS

From a dichloromethane extract in an activity-guided fractionation the active compounds were isolated under use of different chromatographic techniques. Their structures were unambiguously identified by one and two-dimensional (1)H and (13)C NMR spectroscopy and mass spectrometry and their cholinesterase inhibitory activities were determined by a microplate assay. In order to compare the 3D active sites of AChE from Torpedo californica (TcAChE) and from Electrophorus electricus (EeAChE), three files from the Protein Data Bank (PDB) were used and for docking experiments, GOLD 3.1 software was employed. The concentrations of active compounds in the extract and the fruits were determined by HPLC analysis.

RESULTS

The active compounds were determined as 1',2'-dihydroxy-3'-pentadec-8-enylbenzene (A) and 1',2'-dihydroxy-3'-pentadeca-8,11-dienylbenzene (B). Their IC(50) values in an in vitro assay on AChE inhibition were determined as 12 and 34 μg/mL, respectively, while they were not active in the inhibition of butyrylcholinesterase (BChE). In silico docking experiments showed a similar bioactivity for compounds A and B. The concentration of compounds A and B in the fruits was 1.85% and 1.88%, respectively.

CONCLUSION

In the search for the active principle of the fruit resin of Semecarpus anacardium, compounds A and B were identified as two selective inhibitors for AChE versus BChE.

Inhibition of angiogenesis and inflammation by an extract of red clover (Trifolium pratense L.)

Antiangiogenic compounds are gaining more and more interest as a new approach in the prevention and treatment of cancer and inflammatory diseases. The objective of this study was the evaluation of the antiangiogenic effect of a red clover extract (RCE) used in food supplements for menopausal complaints as well as of its main isoflavones in an in vivo system, the chorioallantoic membrane assay of fertilized hen's eggs. At a dosage of 250 microg/pellet the red clover extract showed excellent inhibition of angiogenesis. The antiangiogenic activity of the non-methylated isoflavones daidzein and genistein was higher than that of the methylated compounds formononentin and biochanin A. The results demonstrate that RCE is not only suitable for menopausal complaints, but might also be a powerful chemopreventive agent against chronic diseases e.g. which have a high incidence especially in elderly female.

Anthocyanin- and proanthocyanidin-rich extracts of berries in food supplements--analysis with problems

The fundamental nutritional benefit of fruit and vegetables in the prevention of degenerative diseases--especially in the light of the current "anti-aging wave"--has directed the attention of scientists and consumers to a variety of berry fruits and their constituents. Many of these fruits, e.g. blueberries, elderberries or cranberries, have a long tradition in European and North American folk medicine. Based on these experiences and due to the growing interest the number of food supplements on the market containing fruit powders, juice concentrates or extracts of these fruits has increased considerably. Advertising for these products mainly focusses on the phenolic compounds, especially the anthocyanins and proanthocyanidins and their preventive effects. Most of the preparations are combinations, e.g. of extracts of different fruits with vitamins and trace elements, etc. which are labelled in a way which does not allow a comparison of the products. Typically, information on the extraction solvent, the drug: extract ratio and the content of anthocyanins and proanthocyanidins is missing. Besides that, the analysis of these polyphenols causes additional problems. Whereas the quality control of herbal medicinal products is regulated in detail, no uniform requirements for food supplements are existing. A broad spectrum of methods is used for the assay of the constituents, leading to differing, incomparable results. In addition to that, the methods are quite interference-prone and consequently lead to over- or underestimation of the contents. This publication provides an overview of some selected berries (lingonberry, cranberry, black elderberry, black chokeberry, black currant, blueberry), their constituents and use. The analytical methods currently used for the identification and quantification of the polyphenols in these berries are described, including an evaluation of their advantages and disadvantages.

An efficient HPLC method for the quantification of isoflavones in soy extracts and soy dietary supplements in routine quality control

Food supplements containing soy extracts are increasingly used to treat menopausal complaints. For the quality control of such products a RP-HPLC method for the quantification of daidzein, genistein, glycitein and their respective glucosides and acetylglucosides in soy extracts and nutraceuticals was developed and validated. The extraction of the samples is very simple and avoids time-consuming handling and expensive cartridges or reagents. The compounds are quantified by internal standardization with 4'-hydroxyflavanon which is easily available at a reasonable price. On a base-deactivated C18 column good separation and excellent peak shape of the analytes are achieved in short time by gradient elution with water and acetonitrile. Accompanying substances do not interfere. The method was applied to the analysis of different commercial soy preparations.

Dose reduction in multidetector CT of the urinary tract. Studies in a phantom model

A novel ureter phantom was developed for investigations of image quality and dose in CT urography. The ureter phantom consisted of a water box (14 cm x 32 cm x 42 cm) with five parallel plastic tubes (diameter 2.7 mm) filled with different concentrations of contrast media (1.88-30 mg iodine/ml). CT density of the tubes and noise of the surrounding water were determined using two multidetector scanners (Philips MX8000 with four rows, Siemens Sensation 16 with 16 rows) with varying tube current-time product (15-100 mAs per slice), voltage (90 kV, 100 kV, 120 kV), pitch (0.875-1.75), and slice thickness (1 mm, 2 mm, 3.2 mm). Contrast-to-noise ratio as a parameter of image quality was correlated with dose (CTDI) and was compared with image evaluation by two radiologists. The CT densities of different concentrations of contrast media and contrast-to-noise ratio were significantly higher when low voltages (90 kV versus 120 kV, 100 kV versus 120 kV) were applied. Smaller slice thickness (1 mm versus 2 mm) did not change CT density but decreased contrast-to-noise ratio due to increased noise. Contrast phantom studies showed favourable effects of low tube voltage on image quality in the low dose range. This may facilitate substantial dose reduction in CT urography.

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.

Comparison of hormonal activity (estrogen, androgen and progestin) of standardized plant extracts for large scale use in hormone replacement therapy

Extracts from red clover (Trifolium pratense), soybean (Glycine max.) and black cohosh (Cimicifuga racemosa) are frequently used as alternative compounds for hormone replacement therapy (HRT) to treat menopausal disorders. Fifteen commercially available products made either from red clover, soybean or black cohosh were tested in in vitro assays in this study. The main polycyclic phenolic compounds of soy and red clover products were biochanin A, genistein, daidzein, formononetin, and glycitein. In red clover products glycitein was not abundant. All the compounds showed clear estrogenic activity through estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta) and affinity to progesterone receptor (PR) and androgen receptor (AR), whereas the compounds from black cohosh did not. This was corroborated by synthetic isoflavones such as biochanin A, daidzein, genistein and formononetin. They exerted affinity to PR and AR in the range of 0.39-110 mM. Statistical analysis applying principal component analysis (PCA) revealed that all red clover and soy products are grouped in different clusters. Red clover products showed a higher affinity to AR and PR than soy products, which is explained by the higher amount of isoflavones present. In vitro assays and chemical analysis showed that theoretical estrogenic activity expressed as equivalent E2 concentration is in the same range as recommended for synthetic estrogens. Broader spectrum of action and hypothesized lower side effects by action through ERbeta make them suitable for alternative hormone replacement therapy.

Estrogenic activity of two standardized red clover extracts (Menoflavon) intended for large scale use in hormone replacement therapy

Isoflavones are the most potent estrogenic compounds in red clover extracts. Standardized extracts have been discussed as an alternative for hormone replacement therapy. Variation due to extraction procedure and natural seasonal variation and variations originating from agricultural conditions have prevented the large scale use of such phytochemicals. An improved extraction procedure and careful analysis of the raw material yielded in a highly standardized preparation (Menoflavon) with an average isoflavone content of approximately 9% (dry weight) determined by HPLC. The estrogenic activity has been further evaluated by a yeast two plasmid system using estrogen receptor alpha (ER alpha) and estrogen receptor beta (ER beta). An estrogenic activity corresponding to a transactivational capacity of ca. 18 microg 17 beta-estradiol per g red clover extract for ER alpha and ca. 78 microg 17 beta-estradiol per g red clover for ER beta was obtained. The difference is explained by the higher affinity of ER beta to isoflavones than that observed for ER alpha. Calculation of potency from isoflavone content measured by HPLC yielded a comparable potency to that experimentally determined by the bioassay. The high content of isoflavones as well as the higher transactivational potency for ER beta than ER alpha make these extracts interesting candidates for HRT.

Flavon- and flavonolglycosides from Achillea pannonica Scheele

The detailed investigation of a methanolic extract of aerial parts of Achillea pannonica SCHEELE. within a chemotaxonomic study led to the isolation of 6 flavonoid glycosides. Besides rutin, apigenin-7-O-glucopyranoside, luteolin-7-O-glucopyranoside, apigenin-7-O-rutinoside and acacetin-7-O-rutinoside, an unusual flavondiglucoside was isolated. Its structure was established by UV, 1H NMR and 13C NMR spectroscopic methods including 2D-NMR techniques and ESI-MS as luteolin-7,4'-O-beta-diglucoside. This substance is reported for the first time in the genus Achillea. Chemotaxonomic aspects are discussed briefly.

Anti-inflammatory and spasmolytic activity of extracts from Droserae herba

An ethanolic extract of Drosera madagascariensis inhibited human neutrophil elastase with an IC50 of 9.4 microg/ml. The naphthoquinones present in the extract were not responsible for this effect, but flavonoids like quercetin (IC50 0.8 microg/ml), hyperoside (IC50 0.15 microg/ml) and isoquercitrin (IC50 0.7 microg/ml) contributed to inhibition of the enzyme. In guinea-pig ileum the extract (0.5-1 mg/ml) induced a spasmolytic effect via affecting cholinergic M3 receptors and histamine H1 receptors, respectively. At contractile prostanoid receptors of guinea-pig trachea the Drosera extract was not effective.

Bufadienolides from Drimia robusta BAK

From bulbs of Drimia robusta 7 bufadienolides were isolated, 3 of them new natural compounds. Structure elucidation was performed by comparison with authentic substances or by means of 1H-, 13C-NMR-spectroscopy and FAB-MS. The substances were identified as scilliroside (1), 12ß-hydroxyscillirosidin (2), 12ß-hydroxyscilliroside (3), hellebrigenin-3-0-ß-glucoside (4), 16ß-hydroxyhellebrigenin (5), 16ß-hydroxyhellebrigenin-3-O-ß-glucoside (6) and 5ß,16ß-dihydroxybufalin-3-O-ß-glucoside (7).

New bufadienolides from Urginea maritima sensu strictu

Two new bufadienolides, 11 alpha-acetylgamabufotalin 3-O-(4-O-beta-D-glucosyl)-alpha-L-rhamnoside (1) and 11 alpha-hydroxyscilliglaucoside (2), were isolated from bulbs of hexaploid Urginea maritima and identified by means of FAB-MS, (1)H-NMR and (13)C-NMR studies.

Bufadienolides from Urginea maritima from Egypt

Forty-one bufadienolides were isolated from the bulbs of Urginea maritima agg. from Egypt; 26 of them are new natural compounds. Structure elucidation was performed by comparison with authentic substances or by means of 1H, 13C NMR and FAB mass spectroscopy. Sixteen of the glycosides derive from nine structurally new aglycones: 16 beta-hydroxy-scillarenin, 16 beta-O-acetyl- scillarenin, 12 beta-hydroxy-5 alpha-4,5-dihydro-scillirosidin, 16 beta- hydroxy-5 alpha-4,5-dihydro-scillirosidin, 16 beta-O-acetyl-5 alpha-4,5- dihydro-scillirosidin, 12 beta-hydroxy-scillirubrosidin, 16 beta-O-acetyl- scillirubrosidin, 9-hydroxy-scilliphaeosidine and 12 beta-hydroxy-desacetyl- scillirosidine.

About the bufadienolide complex of "red" squill

Red coloured bulbs of plants of the URGINEA MARITIMA aggregate from the northern and southern Mediterranean area were shown to exhibit different bufadienolide compositions. Therefore, the bufadienolide complex of "red squill" samples from Tunesia and from Sardegna was investigated. Twelve bufadienolides were isolated from bulbs of tetraploid squill from Tunesia, sixteen from tetraploid samples from Sardegna. The Compounds were identified by means of FAB-MS, (1)H-NMR, and (13)C-NMR studies or comparison with authentic substances. Both of the samples contained scilliroside ( 14), scillarenin 3- O-beta- D-glucoside ( 2), proscillaridin A (1), scilliphaeosidin 3- O-beta- D-glucoside ( 5), scilliglaucoside ( 17), scilliphaeoside ( 4), and 12- EPI-scilliphaeoside ( 7); the bulbs from Tunesia contained additionally glucoscilliphaeoside ( 6) and the four new bufadienolides 12- EPI-glucoscilliphaeoside ( 10), 12beta-hydroxyscilliglaucosidin 3- O-beta- D-glucoside ( 21), 12- EPI-scilliphaeosidin 3- O-beta- D-glucoside ( 8), and 12- EPI-scilliphaeosidin 3- O-alpha- L-rhamnosido-alpha- L-rhamnoside ( 9). In the bulbs from Sardegna scülaren A ( 3), gamabufotalin 3- O-alpha- L-rhamnoside ( 20), scilliglaucoside ( 17), scillirubrosidin 3- O-alpha- L-rhamnoside ( 11), scillirubroside ( 12), 12beta-hydroxyscilliroside ( 15), 5alpha-4,5-dihydroscillirosidin 3- O-alpha- L-thevetosido-beta- D-glucoside ( 19), and deacetyl-scilliroside ( 8) besides the new Compounds 10-carb-oxy-5beta,14beta-dihydroxybufa-3,20,22-trienolide 5- O-beta- D-glucoside ( 18) and scilliglaucogenin ( 16) were found in addition. Not only quantitative but even qualitative differences in the bufadienolide pattern between the samples of the northern and the southern Mediterranean area were proved. By now it is not clear whether the investigated samples belong to different chemodemes of URGINEA NUMIDICA or are two different species of the URGINEA MARITIMA aggregate.

Bufadienolides from Urginea maritima sensu strictu

Fourteen bufadienolides were isolated from bulbs of hexaploid URGINEA MARITIMA (L.) Baker SENSU STRICTU. The compounds were identified by means of FAB-MS, (1)-NMR and (13)C-NMR studies or comparison with authentic substances. Besides the already known proscillaridin A, scillaren A, glucoscillaren A, scilliphaeoside, glucoscilliphaeoside, 12- EPI-scilliphaeoside, gamabufotalin-3- O-alpha- L-rhamnoside, 16beta- O-acetyl-gamabufotalin-3- O-alpha- L-rhamnoside, scilliglaucoside, and scillicyanoside, four new bufadienolides were isolated: 5alpha-4,5-dihydroproscillaridin A, 5alpha-4,5-dihydroglucoscillaren A, gamabufotalin-3- O-alpha- L-rhamnosido-beta- D-glucoside, and 19-oxo-5alpha-4,5-dihydro-proscillaridin A.

Bufadienolides from Urginea hesperia

For the first time the composition of the bufadienolide complex in URGINEA HESPERIA Webb & Berth. has been investigated. From an extract of lyophilized plants, thirteen bufadienolides were isolated. By means of FAB-MS, (1)H-NMR, and (13)C-NMR studies the compounds were structurally elucidated as scillarenin, scilliphaeosidin, scillarenin-3- O-alpha- L-rhamnoside, scilliphaeosidin-3- O-alpha- L-rhamnoside, gamabufotalin-3- O-alpha- L-rhamnoside, 11alpha-hydroxyscilliglaucosidin-3- O-alpha- L-rhamnoside, scillarenin-3- O-alpha- L-2',3'-diacetylrhamnosido-4'-beta- D-glucoside, scillarenin-3- O-alpha- L-rhamnosido-4'-beta- D-glucosido-3''-beta- D-glucoside, scillarenin-3- O-alpha- L-rhamnosido-4'-beta- D-glucosido-4''-beta- D-glucoside, scillarenin-3- O-alpha- L-2',3'-diacetylrhamnosido-4'-beta- D-glucosido-3''-beta- D-glucoside, scillarenin-3- O-alpha- L-2',3'-diacetylrhamnosido-4'-beta- D-glucosido-4''-beta- D-glucoside, scilliphaeosidin-3- O-alpha- L-rhamnosido-4'-beta- D-glucosido-3''-beta- D-glucoside, and scilliphaeosidin-3- O-alpha- L-rhamnosido-4'-beta- D-glucosido-4''-beta- D-glucoside.