The effect of quercetin on pro-apoptotic activity of cisplatin in HeLa cells.

It is well known that some tumour cells are very resistant to chemotherapy-induced cell death which indicate poor prognosis for patients. Thus the aim of the present study was to investigate the effect of quercetin on pro-apoptotic activity of cisplatin in human cervix carcinoma cells (HeLa). Three variants of experiments were performed. In the first one cells were incubated with studied drugs separately for 8 and 24h. In the second, drugs were added to the culture medium simultaneously. In third cisplatin or quercetin addition was followed by subsequent quercetin or cisplatin treatment, respectively. We observed different apoptotic effects, dependent on the drug succession. Preincubation of cells with quercetin followed by cisplatin treatment appeared to be the most effective and was correlated with strong activation of caspase-3 and inhibition of both heat shock proteins (Hsp72) and multi-drug resistance proteins (MRP) levels. Our results indicate that quercetin pretreatment sensitizes HeLa cells to cisplatin-induced apoptosis in HeLa cells.

Detrimental effects of water extracts from surface and interior of Taxus baccata leaves on the two-spotted spider mite (Tetranychus urticae Koch).

Surface deposits on Taxus baccata needles removed by dipping in water of 96, 60 or 40 degrees C for 5 s caused changes in life history components of mites. Paclitaxel was among other peaks present in the removed fractions in concentrations between 0.017 and 0.170 microg/g of fresh weight (f.w.) increasing with temperature. Long extraction for 60 min at only 40 degrees C did not increase removable paclitaxel, but at 60 degrees C extraction rate was the highest (1.326 microg/g) suggesting that leakage from an interior of needles occurred. Mortality, developmental time, total fecundity, oviposition period and life history parameters of Tetranychus urticae Koch. were detrimentally affected.

Variation of free phenolic acids in medicinal plants belonging to the Lamiaceae family.

Ten species belonging to the family Lamiaceae and representing the most popular medicinal plants used in Polish phytotherapy were examined for the content of free phenolic acids (PhAs). Two depsides, rosmarinic and chlorogenic acids, as well as eight simple PhAs, protocatechuic, gentisic, p-hydroxybenzoic, caffeic, vanillic, syringic, p-coumaric and ferulic acids, in different qualitative and quantitative proportions depending on the plant examined were determined by the rapid, selective and accurate method combining solid-phase extraction and high-performance liquid chromatography.

Solid-phase extraction and simplified high-performance liquid chromatographic determination of 10-deacetylbaccatin III and related taxoids in yew species.

Solid-phase extraction was accomplished with specially prepared cartridges filled with silanised silica gel (RP-2) for the purpose of 10-deacetylbaccatin III (10-DAB III) and related taxoids extracts purification obtained from different yew materials. In the first method, the analysed taxoids eluted in 75% methanol, but in the second method, the preliminary elution with 30% methanol was made. DAB III and its six derivatives were separated from co-extractives in merely acetonitrile-water gradient mode during 25 min on Waters Symmetry C-18 column with photodiode array (PDA) detection. The total recoveries for 10-DAB III and paclitaxel in the first SPE method (all compounds were applied in amounts of 80 microg) were about 98 and 94%, respectively. Almost 100% recoveries for paclitaxel and baseline separation of 10-DAB III and co-extracted compounds were obtained when preliminary elution with 30% methanol was performed. This method can be applied as a routine, inexpensive and uncomplicated procedure for 10-DAB III and related taxoids determination in yew material.

The influence of ultraviolet radiation on the content of pharmacologically active taxoids in yew tissues.

The aim of the work was the investigation of the influence of UV radiation on the taxoids contents in yew tissues. The experiment was performed using Taxus baccata var. Aurea Corr. twigs irradiated with UV C (lambda = 254 nm) and UV A (lambda = 366 nm) in comparison to control samples. Multistep procedure of sample preparation was applied before the analysis of paclitaxel and 10-DAB III: SPE using alumina - for purification from the chlorophylles, waxes and polar balasts as well as zonal micropreparative TLC on silica - for isolation of partially separated fractions. The quantitation of some taxoids in the isolated fractions was performed using RP-HPLC procedure in system C18/acetonitrile + water. The experiments with UV-A and especially UV-C radiation showed changes in concentrations of paclitaxel and its precursor-10-deacetylbaccatin III. The results can be utilized to increase the yield of the taxoids isolated for medicinal and practical purposes.

Screening for pharmaceutically important taxoids in Taxus baccata var. Aurea corr. with CC/SPE/HPLC-PDA procedure.

Needles of 'the golden yew' Taxus baccata var. Aurea Corr. were extracted with methanol followed by pre-purification of the crude extract and column chromatographic (CC) separation on florisil in gradient mode (an increasing concentration of acetone in dichloromethane). The obtained fractions were concentrated and purified on silanized silica gel SPE cartridges and taxoids eluted with 75% methanol were analysed by HPLC-PDA procedure using Waters Symmetry C(18) column with gradient elution. The applied method enabled not only determination of four taxoids commonly occurring in yew extracts (10-deacetylbaccatin III, baccatin III, paclitaxel and cephalomannine), but also, on the basis of chromatographic behaviour and UV spectrum, 10-deacetylated taxoids (10-deacetylpaclitaxel, 10-deacetylcephalomannine, 7-xyloside-10-deacetylpaclitaxel and 10-deacetyltaxol C) could be detected together with 7-epi-10-deacetylpaclitaxel. From the needles of Taxus baccata var. Aurea Corr. the largest amounts isolated were of 10-deacetylbaccatin III, then 10-deacetylpaclitaxel and 7-xyloside-10-deacetylpaclitaxel, all compounds considered to be paclitaxel precursors in semisynthesis. The efficient mechanism of the separation of 10-acetylated taxoids from their 10-deacetylated derivatives on florisil on the basis of electron acceptor-electron donor interactions is discussed.

Qualitative and quantitative analysis of phenolic acids in Asclepias syriaca L.

TLC and HPLC was applied to qualitative and quantitative determination of phenolic acids free and liberated by acid and alkaline hydrolysis in common milkweed. The presence of phenolic acids, namely p-hydroxybenzoic, p-coumaric, protocatechuic and caffeic acids, was confirmed in the leaves and flowers. Moreover, the flowers contained gallic acid, and the leaves contained alpha-resorcylic, vanilic and chlorogenic acids. Conjugated forms of phenolic acids predominate in the plant. They hydrolyse mainly to coffeic, p-coumaric, ferulic and p-hydroxybenzoic acids.

Isolation And Structure Elucidation Of 5,7-disubstituted Simple Coumarins In The Fruits Of Heracleum Mantegazzianum.

In addition to bergapten ( 1 ), xanthotoxin ( 2 ), isopimpinellin ( 3 ), imperatorin ( 4 ), and pimpinellin ( 5 ), for the first time 5,7-disubstituted simple coumarins, limettin (5,7-dimethoxycoumarin) ( 6 ) and a new compound 5-methoxy-7-(3,3-dimethylalliloxy)-coumarin ( 7 ), have been isolated from the fruits of Heracleum mantegazzianum Somm. et Lev. The new compound 7 is a derivative of anisocoumarin B. The structures of 6 and 7 were determined on the basis of 1D and 2D NMR spectra.

Seasonal changes in the concentrations of four taxoids in Taxus baccata L. during the autumn-spring period.

The concentrations of four common taxoids: baccatin III, paclitaxel, cephalomannine and 10-deacetylbaccatin III (10-DAB III) were measured in fresh needles and stems of Taxus baccata L. during the late autumn-spring period (November'96-April'97) which has not been investigated to date in this species. Baccatin III, paclitaxel and 10-DAB III were present on the surface of the twigs in concentrations of 8-26 micrograms/1000 g (fresh weight). Changes in the levels of baccatin III and paclitaxel inside the needles and stems showed similar trends over the investigated period. From November to March the total level of taxoids differed between the needles and stems, and were the same only in April. Total levels in fresh needles were stable from December to March. The highest concentrations of 10-DAB III in the whole analysed period in fresh stems were measured, as well as in the fresh needles except for samples collected in November and December when the levels of cephalomannine were higher. The concentrations of paclitaxel were usually the lowest. These results confirm that epigenetic factors--date of collection (and thus phyllogenesis) and kind of plant tissue--determine taxoid levels during the late autumn-spring period in T. baccata. The opposite patterns of changes for 10-DAB III and cephalomannine, especially in the fresh needles, suggest a possible role for 10-DAB III in the biosynthetic pathway to cephalomannine, a less polar taxoid with a side-chain at position C-13. As well, owing to the thermolability of taxoids, the influence of low temperatures in December and January could explain the highest observed concentrations of 10-DAB III in the fresh stems and needles, respectively.

Determination of furanochromones and pyranocoumarins in drugs and Ammi visnaga fruits by combined solid-phase extraction-high-performance liquid chromatography and thin-layer chromatography-high-performance liquid chromatography.

A new, simple and rapid solid-phase extraction method for the determination of furanochromones and pyranocoumarins in Ammi visnaga L. fruits and pharmaceuticals by reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The isolation of compounds examined was carried out on octadecyl BakerBond SPE columns using various concentrations of methanol, acetonitrile and tetrahydrofuran in water. High and reproducible recoveries were obtained. To compare the results of quantitative analysis a preparative TLC procedure was also elaborated and carried out.

Sample preparation for taxol and cephalomannine determination in various organs of Taxus sp.

Solid-phase extraction and preparative thin-layer chromatography were applied as sample preparation techniques for the purification of crude extracts from twigs and needles of various Taxus species as well as for the isolation of taxol and cephalomannine for further reversed phase high performance liquid chromatography analysis. Significant differences in the contents of taxanes examined were found. The preparative chromatographic methods used were compared and evaluated as routine and reproducible procedures for the rapid isolation and determination of taxol and cephalomannine in plant extracts.

Taxol on the surface of leaves and inside the needles of three species and two varieties of Taxus.

Leaves of three outside-growing Taxus species (Taxus baccata L.; T. baccava var. elegantissima; T cuspidata Sieb, et Zucc; T. media var. Hatfieldii; T media var. Hickii) and two varieties contained 26-890 µg/g of taxol (paclitaxel®), thus are substantial renewable resources for obtaining this drug. Taxol® was deposited on the surface of these needles in 0.1-1.29 µg/g which was removed with brief dipping in hot water amounting up to 0.58% of total concentration. Two other taxanes were identified (7-epi-10-deacetyltaxol; cephalomannine) but still many await identification. Thus, renewable resources of taxol were found both within and on the leaf surface of different Taxus species. The highest taxol concentrations were found to be in the T. media hybrids, higher than in the case of both original species.

Increased proliferation of phytohaemagglutinin (PHA)-stimulated human leucocytes after 8-methoxypsoralen treatment.

The effect of 8-methoxypsoralen on human blood mononuclear cells cultured in darkness has been examined. 8-Methoxypsoralen (1 microgram mL-1, 4.6 microM) added to (phytohaemagglutinin-stimulated cells induced a two-fold increase in the number of mitoses. The number of blastic cells also increased. There was no effect on the formation of micronuclei and there was no chromosomal breakage.

[Hydrophobic parameters of certain coumarins in studies of structure-activity relationship]. / Parametry hydrofobowosci niektórych kumaryn w badaniach zaleznosci struktura-aktywnosc.

The hydrophobic nature of drugs, very important feature in determination of biological activity, is in Hansch's approach characterized by the logarithm of partition coefficient (log P) determined in n-octanol -water system, or calculated from hydrophobic constants pi (Hansch) or f (Rekker). Those as well as other parameters of hydrophobicity (log k'w, RMw or chi-connectivity index) were correlated with the spasmolytic and cytostatic activity of some coumarins.

Effects of modifier and molecular structure of some coumarins on retention in reversed-phase high-performance thin-layer and column chromatography.

Coumarins, furocoumarins and pyranocoumarins (29 compounds) were investigated in silanized silica (HPTLC RP-2 and RP-18 and HPLC RP-18)-water organic modifier (methanol, acetonitrile, dioxane, tetrahydrofuran and methanol containing acetic acid) systems. The physico-chemical properties of these compounds were characterized by their hydrophobicity parameters (RMw), determined by extrapolation of the linear relationships for retention data in binary solvent systems [RM = f(phi)] to pure water. The effect of individual substituents on retention was quantified by using the group contribution parameter delta RM or delta log k'.