[Leaf micro-morphology and features in adsorbing air suspended particulate matter and accumulating heavy metals in seven trees species]

The purpose of this study was to assess the relationship between tree leaf micro-morphology and features in adsorbing air suspended particulate matter and accumulating heavy metals. Seven tree species, including Ginkgo biloba, at heavy traffic density site in Huainan were selected to analyze the frequency of air particulate matter retained by leaves, the particle amount of different sizes per unit leaf area retained by leaves and its related micro-morphology structure, and the relationship between particle amount of different sizes per unit leaf area retained by leaves and its related accumulation of heavy metals. We found that the species characterized by small leaf area, special epidemis with abundant fax, and highly uneven cell wall, as well as big and dense stomata and without trichomes mainly absorbed fine particulate matter; while those species with many trichomes mainly retained coarse particulate matter. Accumulation of heavy metals in leaves of the seven species was significantly different except for Ph. Tree species with high capacities in heavy metal accumulation were Ginkgo biloba, Ligustrum lucidum, and Cinnamomum camphora. Accumulation of Cd, Cr, Ni, Zn, Cu and total heavy metal concentration for seven tree species was positively related to the amount of particulate matter absorbed. Correlation coefficients of d10 vs d2.5, d10 vs d1.0, d2.5 vs d1.0 were 0.987, 0.971, 0.996, respective, and the correlate level was significant. The ratios of d2.5/d10, d1.0/d10, d1.0/d2.5 were 0.844, 0.763, 0.822, indicating that the particulate matter from traffic was mainly fine particulates.

Expression patterns of an isoflavone reductase-like gene and its possible roles in secondary metabolism in Ginkgo biloba

Our results showed that GbIRL1 belongs to the PCBER protein family. Besides, IRL1 gene was a novel gene regulating lignin change and also effecting the accumulation of flavonoids in Ginkgo. A cDNA encoding the IFR-like protein was isolated from the leaves of Ginkgo biloba L., designated as GbIRL1 (Accession no. KC244282). The cDNA of GbIRL1 was 1,203 bp containing a 921 bp open reading frame encoding a polypeptide of 306 amino acids. Comparative and bioinformatic analyses revealed that GbIRL1 showed extensive homology with IFLs from other gymnosperm species. Phylogenetic tree analysis revealed that GbIRL1 shared the same ancestor in evolution with other PCBERs protein and had a further relationship with other gymnosperm species. The recombinant protein was successfully expressed in E. coli strain with pET-28a vector. The vitro enzyme activity assay by HPLC indicated that recombinant GbIRL1 protein could catalyze the formation the TDDC, IDDDC from DDDC, DDC. Tissue expression pattern analysis showed that GbIRL1 was constitutively expressed in stem and roots, especially in the parts of the pest and fungal infection, with the lower expression being found in 1- or 2-year old stem. The increased expression of GbIRL1 was detected when the seedlings were treated with Ultraviole-B, ALA, wounding and ethephon, abscisic acid, salicylic acid. Correlation analysis between GbIRL1 activity and flavonoid accumulation during Ginkgo leaf growth indicated that GbIRL1 might be the rate-limiting enzyme in the biosynthesis pathway of flavonoids in Ginkgo leaves. Results of RT-PCR analysis showed that the transcription level of change in GbIRL1 power correlated with flavonoid contents, suggesting IRL1 gene as a novel gene regulating lignin change and also effecting the accumulation of flavonoids in Ginkgo.

[Chlorophyll fluorescence transient kinetics of ginkgo leaves during expansion]

OBJECTIVE

To provide the theoretical basis for cultivating ginkgo (Ginkgo biloba).

METHODS

Changes of chlorophyll fluorescence transient kinetics in chloroplasts of 10-year-old seeded ginkgo leaves during expansion were studied in the field under natural environmental conditions.

RESULTS

W(k) peaked between 12: 00 - 15: 00, phiE(o) and psi(o) declined gradually between 8: 00 - 12: 00. ABS/ RC,TR(o)/RC and DI(o)/RC increased, while RC/CS decreased at noon. PI(abs) and F(v)/F(m) declined and reached its lowest value at 13:00, then increased, and the levels at 19:00 could restore to the levels at 7: 00.

CONCLUSION

The donor and acceptor sides of PS II are temporarily inhibited. The reaction centers of PS II are damaged, leading to the light energy transfer efficiency of PS II decrease and excess excitation energy increase at noon. The damage of reaction centers of PS II and inhibition of photosynthetic primary reaction are reversible inactivation not irreversible damaged.

Ginkgo biloba responds to herbivory by activating early signaling and direct defenses

Background

Ginkgo biloba (Ginkgoaceae) is one of the most ancient living seed plants and is regarded as a living fossil. G. biloba has a broad spectrum of resistance or tolerance to many pathogens and herbivores because of the presence of toxic leaf compounds. Little is known about early and late events occurring in G. biloba upon herbivory. The aim of this study was to assess whether herbivory by the generalist Spodoptera littoralis was able to induce early signaling and direct defense in G. biloba by evaluating early and late responses.

Methodology/Principal Findings

Early and late responses in mechanically wounded leaves and in leaves damaged by S. littoralis included plasma transmembrane potential (Vm) variations, time-course changes in both cytosolic calcium concentration ([Ca²⁺]_cyt) and H₂O₂ production, the regulation of genes correlated to terpenoid and flavonoid biosynthesis, the induction of direct defense compounds, and the release of volatile organic compounds (VOCs). The results show that G. biloba responded to hebivory with a significant Vm depolarization which was associated to significant increases in both [Ca²⁺]_cyt and H₂O₂. Several defense genes were regulated by herbivory, including those coding for ROS scavenging enzymes and the synthesis of terpenoids and flavonoids. Metabolomic analyses revealed the herbivore-induced production of several flavonoids and VOCs. Surprisingly, no significant induction by herbivory was found for two of the most characteristic G. biloba classes of bioactive compounds; ginkgolides and bilobalides.

Conclusions/Significance

By studying early and late responses of G. biloba to herbivory, we provided the first evidence that this “living fossil” plant responds to herbivory with the same defense mechanisms adopted by the most recent angiosperms.

Mutagenic and morphologic impacts of 1.8GHz radiofrequency radiation on human peripheral blood lymphocytes (hPBLs) and possible protective role of pre-treatment with Ginkgo biloba (EGb 761)

The mutagenic and morphologic effects of 1.8GHz Global System for Mobile Communications (GSM) modulated RF (radiofrequency) radiation alone and in combination with Ginkgo biloba (EGb 761) pre-treatment in human peripheral blood lymphocytes (hPBLs) were investigated in this study using Sister Chromatid Exchange (SCE) and electron microscopy. Cell viability was assessed with 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) reduction assay. The lymphocyte cultures were exposed to GSM modulated RF radiation at 1.8GHz for 6, 8, 24 and 48h with and without EGb 761. We observed morphological changes in pulse-modulated RF radiated lymphocytes. Longer exposure periods led to destruction of organelle and nucleus structures. Chromatin change and the loss of mitochondrial crista occurred in cells exposed to RF for 8h and 24h and were more pronounced in cells exposed for 48h. Cytoplasmic lysis and destruction of membrane integrity of cells and nuclei were also seen in 48h RF exposed cells. There was a significant increase (p<0.05) in SCE frequency in RF exposed lymphocytes compared to sham controls. EGb 761 pre-treatment significantly decreased SCE from RF radiation. RF radiation also inhibited cell viability in a time dependent manner. The inhibitory effects of RF radiation on the growth of lymphoctes were marked in longer exposure periods. EGb 761 pre-treatment significantly increased cell viability in RF+EGb 761 treated groups at 8 and 24h when compared to RF exposed groups alone. The results of our study showed that RF radiation affects cell morphology, increases SCE and inhibits cell proliferation. However, EGb 761 has a protective role against RF induced mutagenity. We concluded that RF radiation induces chromosomal damage in hPBLs but this damage may be reduced by EGb 761 pre-treatment.

Diet and thrombosis risk: nutrients for prevention of thrombotic disease

An increased prothrombotic state is a major risk factor for the development of heart attacks, strokes, and venous thromboembolism. Platelet activation and aggregation play an important role in determining a prothrombotic state. Although pharmaceutical agents such as aspirin, heparin, and warfarin are able to reduce prothrombotic tendency, long-term drug treatment may produce a variety of side effects, including bleeding. Diet is generally recognized to be significantly involved in modifying the individual risk for the development of thrombotic diseases, although its influence during the treatment of these disorders is probably less important. Dietary intervention has proven effective in lowering serum lipid levels, which are otherwise essential elements in the pathogenesis of cardiovascular disease. Likewise, certain dietary components have also been proven effective in decreasing platelet activation through various mechanisms and therefore may contribute to attenuating the future risk of thrombosis. This article provides an up-to-date review of the role of nutrient and nonnutrient supplements on platelet aggregation and risk of thrombosis.

The extract of Ginkgo biloba EGb 761 reactivates a juvenile profile in the skeletal muscle of sarcopenic rats by transcriptional reprogramming

Background

Sarcopenia is a major public health problem in industrialized nations, placing an increasing burden on public healthcare systems because the loss of skeletal muscle mass and strength that characterizes this affection increases the dependence and the risk of injury caused by sudden falls in elderly people. Albeit exercise and caloric restriction improve sarcopenia-associated decline of the muscular performances, a more suitable and focused pharmacological treatment is still lacking.

Methodology/Principal Findings

In order to evaluate such a possible treatment, we investigated the effects of EGb 761, a Ginkgo biloba extract used in chronic age-dependent neurological disorders, on the function of the soleus muscle in aged rats. EGb 761 induced a gain in muscular mass that was associated with an improvement of the muscular performances as assessed by biochemical and electrophysiological tests. DNA microarray analysis shows that these modifications are accompanied by the transcriptional reprogramming of genes related to myogenesis through the TGFβ signaling pathway and to energy production via fatty acids and glucose oxidation. EGb 761 restored a more juvenile gene expression pattern by regenerating the aged muscle and reversing the age-related metabolic shift from lipids to glucose utilization.

Conclusions/Significance

Thus, EGb 761 may represent a novel treatment for sarcopenia both more manageable and less cumbersome than exercise and caloric restriction.

Fungal endophytes-induced abscisic acid is required for flavonoid accumulation in suspension cells of Ginkgo biloba

Treatment of suspension cells of Ginkgo biloba with fungal endophytes resulted in accumulation of flavonoids, increased abscisic acid (ABA) production and activation of phenylalanine ammonia-lyase (PAL). Fluridone, an inhibitor of ABA biosynthesis, was effective in inhibiting fungal endophytes-induced ABA biosynthesis, increase of PAL activity and flavonoids accumulation. Moreover, exogenous application of ABA enhanced PAL activity and increased accumulation of flavonoids in G. biloba cells with or without fungal endophytes elicitor. These finding suggest a causal relationship between ABA release and both PAL activity and flavonoid accumulation under fungal endophytes treatment and that ABA is involved in fungal endophytes-induced flavonoids accumulation in this plant.

Complementary action of jasmonic acid on salicylic acid in mediating fungal elicitor-induced flavonol glycoside accumulation of Ginkgo biloba cells

The antagonistic action between jasmonic acid (JA) and salicylic acid (SA) in plant defence responses has been well documented. However, their relationship in secondary metabolite production is largely unknown. Here, we report that PB90, a protein elicitor from Phytophthora boehmeriae, triggers JA generation, SA accumulation and flavonol glycoside production of Ginkgo biloba cells. JA inhibitors suppress not only PB90-triggered JA generation, but also the elicitor-induced flavonol glycoside production. However, the elicitor can still enhance flavonol glycoside production even though the JA generation is totally inhibited. Over-expression of SA hydrolase gene NahG not only abolishes SA accumulation, but also suppresses the elicitor-induced flavonol glycoside production when JA signalling is inhibited. Interestingly, expression of NahG does not inhibit the elicitor-induced flavonol glycoside accumulation in the absence of JA inhibitors. Moreover, JA levels are significantly enhanced when SA accumulation is impaired in the transgenic cells. Together, the data suggest that both JA and SA are involved in PB90-induced flavonol glycoside production. Furthermore, we demonstrate that JA signalling might be enhanced to substitute for SA to mediate the elicitor-induced flavonol glycoside accumulation when SA signalling is impaired, which reveals an unusual complementary relationship between JA and SA in mediating plant secondary metabolite production.

[Studies on dynamic change of total ginkgolic acids in Ginkgo biloba leaves of different aged trees and different collecting seasons]

OBJECTIVE

To study dynamic change of total ginkgolic acids in Ginkgo biloba leaves of the different aged trees and different collecting seasons.

METHOD

The content of total ginkgolic acids in G. biloba leaves was determined by HPLC. A Alltima C18 (4.6 mm x 250 mm, 5 microm) and the mobile phase of methanol and 1% acetic acid (90:10) were used, the flow rate was 1.0 mL x min(-1), and the wavelength was 310 nm. The content were calculated with external standard method.

RESULT

The content of total ginkgolic acids in G. biloba leaves was in the range of 0.48% to 2.51% in different collecting seasons. The content reached maximum at the end of May and the beginning of June, and then declined gradually. In different aged trees, the content in the older ages was lower than that in the younger ages.

CONCLUSION

The results provide scientific basis for the collecting season of G. biloba leaves.

Impact of elevated CO2 and O3 concentrations on biogenic volatile organic compounds emissions from Ginkgo biloba

In natural environment with ambient air, ginkgo trees emitted volatile organic compounds 0.18 microg g(-1) h(-1) in July, and 0.92 microg g(-1) h(-1) in September. Isoprene and limonene were the most abundant detected compounds. In September, alpha-pinene accounted for 22.5% of the total. Elevated CO(2) concentration in OTCs increased isoprene emission significantly in July (p<0.05) and September (p<0.05), while the total monoterpenes emission was enhanced in July and decreased in September by elevated CO(2). Exposed to elevated O(3) increased the isoprene and monoterpenes emissions in July and September, and the total volatile organic compounds emission rates were 0.48 microg g(-1) h(-1) (in July) and 2.24 microg g(-1) h(-1) (in September), respectively. The combination of elevated CO(2) and O(3) did not have any effect on biogenic volatile organic compounds emissions, except increases of isoprene and Delta3-carene in September.

[Effects of root-excision on trunk hydraulic traits and growth status of Ginkgo biloba]

The roots of 8-year-old Ginkgo biloba saplings were partially excised to three degrees to study the effects of root-excision on the trunk hydraulic traits and growth status of the saplings. The three degrees were severe, medium, and light (8:1, 10:1, and 12:1 of excised root diameter to base diameter of tree trunk, respectively). Physiological parameters including trunk ultrasound acoustic emission (UAE) signal, branch percentage loss of hydraulic conductance (PLC), sap flow flux, and leaf stomatal conductance, transpiration rate and water potential were measured periodically after root-excision. In all treatments, a great number of trunk UAE signal produced after a short time of root-excision, peaked at 6 h, and decreased gradually then. The intensity of the UAE signals increased with increasing root-excision degree. After root-excision, the branch PLC increased rapidly in the first 12 h but slowly after 24 h. The sap flow flux, leaf stomatal conductance, transpiration rate and water potential after root-excision decreased obviously, with significant differences among the three treatments. The cumulative number of UAE signals (cUAE) was significantly and positively correlated with branch embolism degree, while negatively correlated with sap flow flux and leaf water potential. The leaf area and new branch length of G. biloba in the next year after root-excision decreased significantly, and the decrement was increased with root-excision degree. Root-excision not only made the degrees of conduits cavitation and branch embolism increased, but also affected water transportation and leaf transpiration rate within a short period of time, which would in turn give an impact on G. biloba plant growth.

To compare the efficacy and safety of nifedipine sustained release with Ginkgo biloba extract to treat patients with primary Raynaud's phenomenon in South Korea; Korean Raynaud study (KOARA study)

This study examined the efficacy and safety of nifedipine sustained release (nifedipine SR) compared with Ginkgo biloba extract as treatment for primary Raynaud's phenomenon (RP) in Korea. Primary RP were screened and assigned to either the nifedipine SR group (Group N) or the Ginkgo biloba extract group (Group G) in the ratio of 2:1. After a run-in period of 2 weeks, patients received treatment for 8 weeks. We observed the percent improvement of the RP attack rate between before and after the 8-week treatment. Ninety-three subjects were randomly assigned. The percent improvement in Group N was 50.1% at 8 weeks after treatment, while it was 31.0% in Group G (p = 0.03). No serious adverse events occurred, and almost adverse events were mild and improved without specific treatment. nifedipine SR was more effective than Ginkgo biloba extract for treatment of primary RP in Korean patients. Both drugs were tolerable with primary RP patients.

Changes of main secondary metabolites in leaves of Ginkgo biloba in response to ozone fumigation

To investigate the effect of elevated O3 on the accumulation of main secondary metabolites in leaves of Ginkgo biloba L., four-year-old trees were exposed in open-top chambers with ambient air and the air with twice ambient O3 concentration in Shenyang in 2006. Elevated O3 increased the concentrations of terpenes, but decreased the concentrations of phenolics in G. biloba leaves. The results showed that secondary compounds from G. biloba leaves responded to the elevated O3 exposure in a different way when compared to previous studies which showed elevated O3 increased the concentrations of phenolics but had no effect on the terpenes in leaves of other deciduous trees. Furthermore, reduced synthesis of phenolics may decrease the resistance of G. biloba to O3 and other environmental factors. On the other hand, the induced synthesis of terpenes may enhance the antioxidant abilities in G. biloba leaves at the end of O3 fumigation.

Light and temperature regulation of greening in dark-grown ginkgo (Ginkgo biloba)

The last steps of chlorophyll (Chl) biosynthesis were studied at different light intensities and temperatures in dark-germinated ginkgo (Ginkgo biloba L.) seedlings. Pigment contents and 77 K fluorescence emission spectra were measured and the plastid ultrastructure was analysed. All dark-grown organs contained protochlorophyllide (Pchlide) forms with similar spectral properties to those of dark-grown angiosperm seedlings, but the ratios of these forms to each other were different. The short-wavelength, monomeric Pchlide forms were always dominating. Etioplasts with small prolamellar bodies (PLBs) and few prothylakoids (PTs) differentiated in the dark-grown stems. Upon illumination with high light intensities (800 micromol m(-2) s(-1) photon flux density, PFD), photo-oxidation and bleaching occurred in the stems and the presence of (1)O(2) was detected. When Chl accumulated in plants illuminated with 15 micromol m(-2) s(-1) PFD it was significantly slower at 10 degrees C than at 20 degrees C. At room temperature, the transformation of etioplasts into young chloroplasts was observed at low light, while it was delayed at 10 degrees C. Grana did not appear in the plastids even after 48 h of greening at 20 degrees C. Reaccumulation of Pchlide forms and re-formation of PLBs occurred when etiolated samples were illuminated with 200 micromol m(-2) s(-1) PFD at room temperature for 24 h and were then re-etiolated for 5 days. The Pchlide forms appeared during re-etiolation had similar spectral properties to those of etiolated seedlings. These results show that ginkgo seedlings are very sensitive to temperature and light conditions during their greening, a fact that should be considered for ginkgo cultivation.

Influence of elevated carbon dioxide and ozone on the foliar nonvolatile terpenoids in ginkgo biloba

The aim of this study was to determine the effects of elevated O(3) and elevated CO(2,) singly and in combination, on the contents of nonvolatile terpenoids in leaves of Ginkgo Biloba. The results showed that elevated CO(2), alone and in combination with elevated O(3) increased concentrations of all the determined terpenoids, while elevated O(3) alone only increased concentration of bilobalide. These results demonstrated that the metabolism of terpenoids in ginkgo leaves was more sensitive to elevated CO(2) than elevated O(3).

Two copies of 4-(cytidine 5'-diphospho)-2-C-methyl-D-erythritol kinase (CMK) gene in Ginkgo biloba: molecular cloning and functional characterization

4-(Cytidine 5'-diphospho)-2-C-methyl-D-erythritol kinase (CMK or YchB), the fourth enzyme of the 2-C-methyl-D-erythritol 4-phosphate pathway, phosphorylates the 2-hydroxyl group of 4-(cytidine 5'-diphospho)-2-C-methyl-D-erythritol in the presence of ATP. Two isogenes encoding CMK (GbCMK1 and GbCMK2) were cloned and characterized from Ginkgo biloba. The activities of both isozymes were confirmed by complementation assay using Escherichia coli NMW29, a ychB knock-out mutant. The transcript profiles of GbCMKs in the radicles and the cotyledons of the cultured Ginkgo biloba embryos demonstrated that the transcript levels of GbCMK1 were similar in both organs, whereas that of GbCMK2 was predominantly high in the ginkgolide-synthesizing radicles. Selective increases in the transcript abundance of GbCMK2 in the radicles, induced by light and methyl jasmonate treatments, were observed. These differential induction patterns of the transcripts imply GbCMK1 and GbCMK2 respectively have high correlations with the primary and the secondary metabolisms. The transit peptides of both isozymes delivered the fused green fluorescent protein (GFP) into the chloroplast in the Arabidopsis and the Nicotiana transient expression systems; interestingly, the transit peptide of GbCMK1 delivered the GFP protein into the cytosol and the nucleus in addition to the chloroplasts.

Purified polysaccharide from Ginkgo biloba leaves inhibits P-selectin-mediated leucocyte adhesion and inflammation

AIM

To investigate the anti-inflammatory mechanism of the polysaccharides of Ginkgo biloba leaves (PGBL) by inhibiting leucocyte adhesion.

METHODS

The rough PGBL were isolated and purified. The anti-inflammatory effects of purified PGBL (p-PGBL) were assayed by ear edema induced by xylol and the acute peritonitis model in mice. The effect of p-PGBL on inhibiting the interaction between P-selectin and its ligands was investigated by flow cytometry and flow chamber.

RESULTS

p-PGBL could effectively inhibit the acute inflammation in mice and interfere with the adhesion of HL-60 cells, a human leukaemia cell line, or neutrophils to P-selectin in static conditions, as well as the adhesion of neutrophils to Chinese hamster ovary cells expressing human P-selectin and human umbilical vein endothelial cells in flow conditions in a dose-dependant manner.

CONCLUSIONS

p-PGBL can inhibit the inflammatory process through interfering with the interaction between P-selectin and its ligands.

[Effects of elevated O3 on the volatile organic compounds emit from Ginkgo biloba and Pinus tabulaeformis]

To study the impact of elevated tropospheric O3 concentrations on BVOCs emissions by Pinus tabulaeformis and Ginkgo biloba in urban area, the trees were exposed in open-top chambers. Two ozone treatments were established: ambient air (approximately 30 nmol x mol(-1) ) (CK) and elevated O3 concentrations (80 nmol x mol(-1) ) (O3 ). Elevated O3 concentrations significantly induced isoprene to emit for Pinus tabulaeformis and Ginkgo biloba (p < 0.05), and delta3-carene for Ginkgo biloba (p < 0.05). The emission rates were increased to 1.96, 9.71 and 0.09 microg/(g x h) (-1), respectively. There were no significant differences between ozone fumigation treatments for the other monoterpenes. At the same time, the relative abundances of the monoterpenes and isoprene were to be different between tree species and effect by O3 exposure. In CK chambers, the dominate BVOCs emitted by Ginkgo biloba was isoprene, and a-pinene for Pinus tabulaeformis. In the elevated O3 chambers, the isoprene accounted for 64.73% of Pinus tabulaeformis BVOCs. To sum up, the BVOCs emitting patterns were influenced by elevated O3 significantly.

Effect of Ginkgo biloba extract on lopinavir, midazolam and fexofenadine pharmacokinetics in healthy subjects

OBJECTIVE

Animal and in vitro data suggest that Ginkgo biloba extract (GBE) may modulate CYP3A4 activity. As such, GBE may alter the exposure of HIV protease inhibitors metabolized by CYP3A4. It is also possible that GBE could alter protease inhibitor pharmacokinetics (PK) secondary to modulation of P-glycoprotein (P-gp). The primary objective of the study was to evaluate the effect of GBE on the exposure of lopinavir in healthy volunteers administered lopinavir/ritonavir. Secondary objectives were to compare ritonavir exposure pre- and post-GBE, and assess the effect of GBE on single doses of probe drugs midazolam and fexofenadine.

METHODS

This open-label study evaluated the effect of 2 weeks of standardized GBE administration on the steady-state exposure of lopinavir and ritonavir in 14 healthy volunteers administered lopinavir/ritonavir to steady-state. In addition, single oral doses of probe drugs midazolam and fexofenadine were administered prior to and after 4 weeks of GBE (following washout of lopinavir/ritonavir) to assess the influence of GBE on CYP3A and P-gp activity, respectively.

RESULTS

Lopinavir, ritonavir and fexofenadine exposures were not significantly affected by GBE administration. However, GBE decreased midazolam AUC(0-infinity) and C(max) by 34% (p = 0.03) and 31% (p = 0.03), respectively, relative to baseline. In general, lopinavir/ritonavir and GBE were well tolerated. Abnormal laboratory results included mild elevations in hepatic enzymes, cholesterol and triglycerides, and mild-to-moderate increases in total bilirubin.

CONCLUSIONS

Our results suggest that GBE induces CYP3A metabolism, as assessed by a decrease in midazolam concentrations. However, there was no change in the exposure of lopinavir, likely due to ritonavir's potent inhibition of CYP3A4. Thus, GBE appears unlikely to reduce the exposure of ritonavir-boosted protease inhibitors, while concentrations of unboosted protease inhibitors may be affected. Limitations to our study include the single sequence design and the evaluation of a ritonavir-boosted protease inhibitor exclusively.

[Exogenous nitric oxide accelerates soluble sugar, proline and secondary metabolite synthesis in Ginkgo biloba under drought stress]

The effects of exogenous nitric oxide donor sodium nitroprusside (SNP) on substance metabolism of Ginkgo biloba leaves under drought stress were studied. The results showed that 250 micromol/L SNP (Fig.2) treatment under 35% relative soil water content (RSWC) stress (Fig.1) raised remarkably soluble sugar content (Fig.3), proline content (Fig.4), phenylalanine ammonia lyase (PAL) activity (Fig.5), flavonoids (Fig.6) and ginkgolides content (Fig.7) of G. biloba leaves. Hemoglobin, used as NO scavenger, counteracted the effects of SNP in raising the soluble sugar (Fig.3), proline (Fig.4), flavonoid (Fig.6), ginkgolide content (Fig.7) and PAL activities (Fig.5), which indicates that the effects of sodium nitroprusside were through the nitric oxide released from sodium nitroprusside. We propose from these results that the roles of flavonoids and ginkgolides are the same as those of soluble sugars and proline under drought stress. NO may alleviate the damage caused by drought stress through raising soluble sugar, proline, flavonoid and ginkgolide content.

Analysis of flavonol aglycones and terpenelactones in Ginkgo biloba extract: A comparison of high-performance thin-layer chromatography and column high-performance liquid chromatography

Advancements in automated high-performance thin-layer chromatography (HPTLC) have made it feasible to assess its use for the quantitative analysis of marker compounds in botanical preparations. We report here the findings of method comparisons for the terpenelactones and flavonol aglycones by column high-performance liquid chromatography (HPLC) with evaporative light scattering and UV detection, and HPTLC with a scanning densitometer. For the HPTLC assay of terpenelactones, total bilobalide, ginkgolide A, and ginkgolide B consistently achieved <70% of the total determined using HPLC, regardless of variations to postchromatographic derivatization time and temperature. Accuracy testing showed the possibility of a matrix interference. In contrast, a good relationship (95%) was determined between HPTLC and HPLC for determination of total flavonol glycosides (calculated from combined quercetin, kaempferol, and isorhamnetin) from an acid-hydrolyzed Ginkgo biloba L. (GBE) sample. The HPTLC flavonol aglycone method also performed well in terms of accuracy (overall average of 96% recovery for the 3 aglycones) and consecutive plate repeatability (overall percent relative standard deviation of 4.4). It is demonstrated that HPTLC can be a time-saving complement to HPLC for routine analysis of the flavonol glycosides in GBE.

Hydraulic design of leaves: insights from rehydration kinetics

We examined the leaf hydraulic design in 10 species based on their rehydration kinetics. In all cases, a biphasic response described the temporal pattern of water uptake, with time constants of approximately 30 to 800 s and approximately 800 to 8000 s. The time constants of the fast phase were significantly shorter in the six angiosperms (30 to 110 s) compared with the two single-veined conifer species (>400 s) examined, while the two multi-veined gymnosperm species, Gnetum gnemon and Ginkgo biloba, had time constants for the fast phase of approximately 150 s. Among angiosperm species, the fast phase constituted 50-90% of the total water absorbed, whereas in gymnosperms 70-90% of the water uptake could be assigned to the slow phase. In the four gymnosperms, the relative water uptake corresponding to the fast phase matched to a good degree the relative volume of the venation and bundle sheath extension; whereas in the angiosperm species, the relatively larger water influx during the fast phase was similar in relative volume to the combined venation, bundle sheath extension, epidermis and (in four species) the spongy mesophyll. This suggests a general trend from a design in which the epidermis is weakly connected to the veins (all four gymnosperms), to a design with good hydraulic connection between epidermis and veins that largely bypasses the mesophyll (four of six angiosperms), to a design in which almost the entire leaf appears to function as a single pool.

[Effects of elevated atmospheric CO2 concentration on endogenous hormones in gingko leaves]

With top-opened chamber system, this paper studied the responses of endogenous hormones abscisic acid (ABA), indoleacetic acid (IAA), zeatin riboside (ZR) and gibberellins (GA3) in gingko leaves to elevated atmospheric CO2 concentration (ambient + 350 micromol x mol(-1), EC). The results showed that EC could decrease the ABA content. After treated with EC for 120 days, the ABA content could be decreased by 63.0%, in comparing with the control. EC could also decrease the contents of IAA and ZR, and the decrement could reach significant with the extension of the treatment. The IAA content was 2 times higher after 100 days treatment, and ZR content was 2.5 times higher after 80 days treatment than those of CK. Under EC, the peak of GA3 appeared earlier. The (IAA + GA3 + ZR)/ABA ratio decreased gradually with the growth of gingko, and was obviously higher than the control at later stage (after 40-60 days treatment), indicating that elevated atmospheric CO2 concentration could promote the growth and development of gingko.

Differences in photosynthetic activity, chlorophyll and carotenoid levels, and in chlorophyll fluorescence parameters in green sun and shade leaves of Ginkgo and Fagus

The differences in pigment levels and photosynthetic activity of green sun and shade leaves of ginkgo (Ginkgo biloba L.) and beech (Fagus sylvatica L.) are described. Sun leaves of both tree species possessed higher levels in chlorophylls (Chl) and carotenoids on a leaf area basis, higher values for the ratio Chl a/b and lower values for the ratio Chl/carotenoids (a+b)/(x+c) in comparison to shade leaves. The higher photosynthetic rates P(N) of sun leaves (ginkgo 5.4+/-0.9 and beech 8.5+/-2.1 micromol m(-2)s(-1)) were also reflected by higher values for the Chl fluorescence decrease ratios R(F)(d) 690 and R(F)(d) 735. In contrast, the shade leaves had lower P(N) rates (ginkgo 2.4+/-0.3 and beech 1.8+/-1.2 micromol m(-2)s(-1)). In both tree species the stomatal conductance G(s) was significantly higher in sun (range: 70-19 1 mmol m(-2)s(-1)) as compared to shade leaves (range: 5-55 mmol m(-2)s(-1)). In fact, at saturating light conditions there existed a close correlation between G(s) values and P(N) rates. Differences between sun and shade leaves also existed in several other Chl fluorescence ratios (F(v)/F(m), F(v)/F(o), and the stress adaptation index Ap). The results clearly demonstrate that the fan-shaped gymnosperm ginkgo leaves show the same high and low irradiance adaptation response as the angiosperm beech leaves.

Single-laboratory validation for the determination of terpene lactones in Ginkgo biloba dietary supplement crude materials and finished products by high-performance liquid chromatography with evaporative light-scattering detection

A single-laboratory validation was completed for a method to determine total terpene lactones in Ginkgo biloba products. The method determines terpene lactones on the basis of the main terpene lactones (Bilobalide, Ginkgolide A, Ginkgolide B, Ginkgolide C, and Ginkgolide J) by high-performance liquid chromatography with evaporative light-scattering detection after extraction. Nine matrixes were chosen for study, including crude leaf material, standardized dry powder extract, single- and multiple-entity finished products, and alcohol and glycerin tinctures. The sample purification with prepacked columns allows selective extraction of the terpene lactones with no interferences from any matrix under study. A Youden ruggedness trial testing 7 instrumental and preparation factors with the potential to affect quantitative results showed that 2 factors (volume of the column elution solvent and pH of the diluent) were the most important parameters to control during sample preparation. The method performed well in terms of precision; 4 matrixes tested in triplicate over a 3-day period showed an overall repeatability relative standard deviation (RSD) of about 3%. HorRat values were within the limits for performance acceptability, ranging from 0.5 to 1.0. Analysis of variance testing at a = 0.05 showed no significant differences among the within-or between-group sources of variation, although comparison of within-day, between-day, and total precision showed that most of the RSD came from within-day determinations except those for the Ginkgo dry extract (Gb-SLV-2). Accuracy testing at 4 concentration levels of terpene lactones obtained by spiking a negative control matrix at approximately 300, 750, 1500, and 2250 microg/mL gave recoveries of about 91% for the 300 microg/mL level, about 98% for the 750 microg/mL level, about 99% for the 1500 microg/mL level, and 97% for the 2250 microg/mL level with an overall recovery of 96% and an RSD of 3.2%.

Distinct developmental mechanisms reflect the independent origins of leaves in vascular plants

Vascular plants diverged more than 400 million years ago into two lineages, the lycophytes and the euphyllophytes . Leaf-like organs evolved independently in these two groups . Microphylls in lycophytes are hypothesized to have originated as lateral outgrowths of tissue that later became vascularized (the enation theory) or through the sterilization of sporangia (the sterilization hypothesis) . Megaphylls in euphyllophytes are thought to represent modified lateral branches . The fossil record also indicates that the seed plant megaphyll evolved uniquely in the ancestor of seed plants, independent of megaphylls in ferns, because seed plants evolved from leafless progymnosperm ancestors . Surprisingly, a recent study of KNOX and ARP gene expression in a lycophyte was reported to indicate recruitment of a similar mechanism for determinacy in both types of leaves . We examined the expression of Class III HD-Zip genes in the lycophyte Selaginella kraussiana and in two gymnosperms, Ginkgo and Pseudotsuga. Our data indicate that mechanisms promoting leaf initiation, vascularization, and polarity are quite different in lycophytes and seed plants, consistent with the hypotheses that megaphylls originated as lateral branches whereas microphylls originated as tissue outgrowths.

Effect of supplementing terpenoid biosynthetic precursors on the accumulation of bilobalide and ginkgolides in Ginkgo biloba cell cultures

The effect of precursor feeding on the production of bilobalide and ginkgolides was studied with suspension cell cultures of Ginkgo biloba. The precursors greatly influenced the productivity of bilobalide and ginkgolides. Precursor supplementation increased the accumulation of both bilobalide and ginkgolides, and with positive effect on cell growth. The GA accumulation by cell cultures was influenced by precursors upstream in the metabolism, whereas the BB accumulation was under the influence of downstream precursors of the terpenoid biosynthetic pathway. Furthermore, precursor feeding modified the ratios of the BB, GA and GB in cells and cell cultures of G. biloba. The studies also aid in understanding effect of precursor feeding on the bilobalide and ginkgolides biosynthetic pathway.

Determination of terpene trilactones in Ginkgo biloba solid oral dosage forms using HPLC with evaporative light scattering detection

A reversed phase high performance liquid chromatographic method with evaporative light scattering detection (RP-HPLC-ELSD) was developed for the quantitative determination of the terpene trilactones, ginkgolide A, B, C and J and the sesquiterpene, bilobalide in Ginkgo biloba solid oral dosage forms. Separation was achieved using a minibore Phenomenex Luna (5 microm) C18 column with dimensions 250 mm x 2.00 mm maintained at a temperature of 45 degrees C. A simple gradient method using a mobile phase of methanol:water and a flow rate of 350 microl/min facilitated baseline separation of the selected marker compounds within 14 min. The ELSD parameters affecting the detector response were optimized prior to the validation. The limits of detection and quantification were 31.25 and 62.50 ng, respectively. The percentage relative errors of the recovery ranged between -3.16 and +1.88 and both intra-day and inter-day percentage standard deviations were all better than 6%. This method was used to assay commercially available Ginkgo biloba products and proved to be suitable for the routine analysis of such products for quality control purposes.

Molecular cloning and expression profile analysis of Ginkgo biloba DXS gene encoding 1-deoxy-D-xylulose 5-phosphate synthase, the first committed enzyme of the 2-C-methyl-D-erythritol 4-phosphate pathway

Plant diterpenes such as ginkgolides are biosynthesized via the recently discovered 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. The initial step of the MEP pathway is the formation of 1-deoxy-D-xylulose 5-phosphate (DXP) catalyzed by 1-deoxy-D-xylulose 5-phosphate synthase (DXS, EC: 4.1.3.37), which may thus be considered the first committed step of the MEP pathway for ginkgolides biosynthesis. The full-length cDNA of DXS was isolated and characterized from the gymnosperm plant species, Ginkgo biloba. The full-length cDNA of GbDXS was 2795 bp containing a 2154 bp open reading frame (ORF) encoding 717 amino acids. Comparative and bioinformatic analyses revealed that GbDXS has extensive homology with DXSs from other plant species and, like these, contains a conserved transit peptide for plastid import, histidine residue, a putative thiamine diphosphate-binding site and a transketolase motif. Phylogenetic analysis indicates that GbDXS belongs to the plant DXS1 cluster and suggests it to be more ancient than other plant DXSs. GbDXS was found to be expressed in all tested tissues including roots, stems, leaves, pericarps and seeds. Expression profiling analyses revealed that GbDXS expression was induced by exogenous elicitors including methyl jasmonate, arachidonic acid, acetylsalicylic acid and ceric ammonium sulfate, and showed that the transcription levels were correlated with ginkgolide accumulation, suggesting that DXS might play a regulatory role in ginkgolide biosynthesis in cell culture of G. biloba at the transcriptional level.

Identification of class 2 1-deoxy-D-xylulose 5-phosphate synthase and 1-deoxy-D-xylulose 5-phosphate reductoisomerase genes from Ginkgo biloba and their transcription in embryo culture with respect to ginkgolide biosynthesis

Diterpenoid ginkgolides having potent platelet-activating factor antagonist activity are major active ingredients of ginkgo extract. Class 2-type 1-deoxy-D-xylulose 5-phosphate synthase (GbDXS2) and 1-deoxy-D-xylulose 5-phosphate reductoisomerase (GbDXR), the first two enzymes in 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway, operating in the earlier step of ginkgolide biosynthesis, were cloned from embryonic roots of Ginkgo biloba through a homology-based polymerase chain reaction for role assessment of the enzymes. Plasmids harboring each gene rescued the respective knockout E. coli mutants. The levopimaradiene synthase gene (LPS), responsible for the first committed step in ginkgolide biosynthesis, and GbDXS2 were transcribed exclusively in embryonic root, suggesting a specific role of GbDXS2 in ginkgolide biosynthesis. GbDXR retained a higher transcription level in roots than in leaves, whereas class 1 DXS (GbDXS1) showed 30 to 50 % higher level in leaves. Ginkgolides and bilobalide were found both in leaves and roots from an earlier stage of the embryo culture. Exclusive transcription of ginkgolide biosynthesis-specific LPS and GbDXS2 in roots and the appearance of ginkgolides in leaves was consistent with translocation of the compounds from roots to leaves.

Simultaneous quantification of terpenelactones and flavonol aglycones in hydrolyzed ginkgo biloba extract by liquid chromatography with inline ultraviolet and evaporative light scattering detection

We report here a liquid chromatography (LC) method with inline ultraviolet/evaporative light scattering (UV/ELS) detection for the simultaneous quantification of the terpenelactones and flavonol aglycones in a single sample of hydrolyzed Ginkgo biloba extract (GBE). The sample is hydrolyzed by a rapid and convenient oven heating method for 1 h at 90 degrees C with 10% hydrochloric acid. The 1 h hydrolysis was found to be equivalent to the 2.25 h reflux treatment for dry powder extract, where total flavonol glycosides were 28.4 and 28.1%, respectively. Acceptable precision was achieved for total terpenelactones [relative standard deviation (RSD) = 4.8%] by ELS detection, and total flavonol aglycones (RSD = 2.3%) by UV detection. The analytical range was 1.5 to 7.3% (w/w) for the individual terpenelactones (ELS) and 2.5 to 15.0% (w/w) for the individual glycosides (UV) calculated from the aglycones quercetin, kaempferol, and isorhamnetin. This improved method allows for the first time high throughput sample preparation coupled with the quantification of the predominant compounds generally used for quality control of GBE in a single assay.

EST analysis in Ginkgo biloba: an assessment of conserved developmental regulators and gymnosperm specific genes

Background

Ginkgo biloba L. is the only surviving member of one of the oldest living seed plant groups with medicinal, spiritual and horticultural importance worldwide. As an evolutionary relic, it displays many characters found in the early, extinct seed plants and extant cycads. To establish a molecular base to understand the evolution of seeds and pollen, we created a cDNA library and EST dataset from the reproductive structures of male (microsporangiate), female (megasporangiate), and vegetative organs (leaves) of Ginkgo biloba.

Results

RNA from newly emerged male and female reproductive organs and immature leaves was used to create three distinct cDNA libraries from which 6,434 ESTs were generated. These 6,434 ESTs from Ginkgo biloba were clustered into 3,830 unigenes. A comparison of our Ginkgo unigene set against the fully annotated genomes of rice and Arabidopsis, and all available ESTs in Genbank revealed that 256 Ginkgo unigenes match only genes among the gymnosperms and non-seed plants – many with multiple matches to genes in non-angiosperm plants. Conversely, another group of unigenes in Gingko had highly significant homology to transcription factors in angiosperms involved in development, including MADS box genes as well as post-transcriptional regulators. Several of the conserved developmental genes found in Ginkgo had top BLAST homology to cycad genes. We also note here the presence of ESTs in G. biloba similar to genes that to date have only been found in gymnosperms and an additional 22 Ginkgo genes common only to genes from cycads.

Conclusion

Our analysis of an EST dataset from G. biloba revealed genes potentially unique to gymnosperms. Many of these genes showed homology to fully sequenced clones from our cycad EST dataset found in common only with gymnosperms. Other Ginkgo ESTs are similar to developmental regulators in higher plants. This work sets the stage for future studies on Ginkgo to better understand seed and pollen evolution, and to resolve the ambiguous phylogenetic relationship of G. biloba among the gymnosperms.

Unexpected behavior of coniferin in lignin biosynthesis of Ginkgo biloba L

To gain insight into the behavior of monolignol glucoside in Ginkgo biloba L., we examined glucosides potentially involved in lignin biosynthetic pathway. Coniferin (coniferyl alcohol 4O-beta-D-glucoside) is a strong candidate for the storage form of monolignol. Coniferaldehyde glucoside may also have a role in lignin biosynthesis; this was examined with tracer experiments using labeled glucosides fed to stem segments. A series of tracer experiments showed that coniferin and coniferaldehyde glucoside were modified into coniferyl alcohol and then efficiently incorporated into lignin under the experimental conditions used. Interestingly, more than half of the administered coniferin underwent an oxidation to the aldehyde form before its aglycone; coniferyl alcohol was polymerized into lignin. This suggests that there is an alternative pathway for coniferin to enter the monolignol biosynthetic pathway, in addition to the direct pathway beginning with the deglucosylation of coniferin catalyzed by beta-glucosidase. Enzymatic assays revealed that coniferaldehyde glucoside was produced enzymatically from coniferin, and that coniferaldehyde glucoside can be deglucosylated to yield coniferaldehyde, which could be fated to become coniferyl alcohol . Albeit the findings cannot be taken as proof for the in-planta functioning, these results present a possibility for the existence of alternative pathway in which some of the stored coniferin is oxidized to coniferaldehyde glucoside, which is deglucosylated to generate coniferaldehyde that joins the monolignol biosynthesis pathway.

Biotransformation of α-Santonin by Cell Suspension Cultures of Five Plants

Cell suspension cultures of five plants (Catharanthus roseus, Ginkgo biloba, Platycodon grandiflorum, Taxus cuspidata, Phytolacca asinosa) were employed to bioconvert the eudesmanolide compound, alpha-santonin. Reactions occurring were hydroxylation (C-1, C-11 and C-15), reduction of the double bond [1(2) or 3(4)], rearrangment of the eudesmanolide skeleton to a guaianolide skeleton and lactone-ring hydrolysis. Four new compounds were identified.

Analysis of the Inhibitory Potential ofGinkgo biloba,Echinacea purpurea, andSerenoa repenson the Metabolic Activity of Cytochrome P450 3A4, 2D6, and 2C9

OBJECTIVE

To study the potential of three top-selling herbal products, Ginkgo biloba, Echinacea purpurea, and Serenoa repens to inhibit the in vitro enzymatic activity of three of the most important drug metabolizing enzymes, cytochrome P450 (CYP) 3A4, 2D6, and 2C9.

METHODS

High throughput CYP inhibition screening was used to test the inhibitory capacity of extracts of commercially available herbal medications on the metabolism of CYP enzyme substrates.

RESULTS

S. repens showed potent inhibition of the metabolic activity of all three CYPs tested. The effects of G. biloba and E. purpurea varied. E. purpurea demonstrated mild inhibition of CYP3A4 activity with 7- benzyloxy-4-trifluoromethylcoumarin (BFC) as the model substrate, but mild inducing effects in the presence of the model substrate resorufin benzyl ether (BzRes). Little effect on CYP2D6 and moderate inhibition of CYP2C9 was seen with both E. purpurea and G. biloba. G. biloba also showed mild-to-moderate inhibition of CYP3A4 depending on the model substrate.

CONCLUSIONS

The inhibitory capacity of herbal products varies depending on the concentrations of the model substrate and the herbal extract, as well as the identity of the model substrate, as demonstrated by the varied effects of CYP3A4 enzymatic activity with different model substrates. The potential for strong adverse interactions exists for Serenoa repens, which was a potent inhibitor of all three CYPs examined. Physicians are encouraged to advise patients of the risks of combining herbal products with prescription medications.

Molecular cloning and sequence analysis of a novel chalcone synthase cDNA from Ginkgo biloba

A chalcone synthase (CHS) gene was cloned from Ginkgo biloba for the first time and it was also the first cloned gene involved in flavonoids metabolic pathway in G. biloba. The full-length cDNA of G. biloba CHS (designated as Gbchs) was 1608bp with poly(A) tailing and it contained a 1173bp open reading frame (ORF) encoding a 391 amino acid protein. Gbchs was found to have extensive homology with those of other plant chs genes via multiple alignments. The active sites of the CoA binding, coumaroyl pocket and cyclization pocket in CHS protein of Medicago sativa were also found in GbCHS. Molecular modeling of GbCHS indicated that the three-dimensional structure of GbCHS strongly resembled that of M. sativa (MsCHS2), implying GbCHS may have similar functions with MsCHS2. Phylogenetic tree analysis revealed that GbCHS had closer relationship with CHSs from gymnosperm plants than from other plants. Gbchs is a useful tool to study the regulation of flavonoids metabolism in G. biloba.

Isolation of RNA of high quality and yield from Ginkgo biloba leaves

An improved protocol was developed to isolate total RNA in good yield and integrity from Ginkgo biloba leaves containing high levels of flavonoid glycosides, terpene lactones, carbohydrates and polyphenolic secondary metabolites. Polyvinylpolypyrrolidone at 2% and beta-mercaptoethanol at 4% were added to the standard CTAB extraction buffer and, after chloroform and phenol extraction, the pellet obtained by ethanol/acetate precipitation was washed and a second phenol/chloroform extraction was introduced to remove co-precipitated polysaccharides. Both A(260)/A(230) and A(260)/A(280) absorbancy ratios of isolated RNA were around 2 and the yield was about 0.4 mg g(--1) fresh weight. At least seven distinct rRNA bands were detected by denaturing gel electrophoresis. Sharp hybridization signals were obtained from Northern blots with both nuclear and plastid gene probes. Two gene fragments: nuclear-encoded cab and chloroplast encoded rbcL were successfully amplified by RT-PCR, suggesting the integrity of isolated RNA. The total RNA isolated by this protocol is of sufficient quality for subsequent molecular applications.

Multiresidue determination of organophosphorus pesticides in ginkgo leaves by accelerated solvent extraction and gas chromatography with flame photometric detection

A rapid and simple method using accelerated solvent extraction and solid-phase extraction cleanup was developed and validated for the determination of 15 organophosphorus pesticides in ginkgo leaves by capillary gas chromatography with flame photometric detection. The pesticides were extracted at 100 degrees C under 1500 psi pressure in <20 min. The average recovery from 10 g ginkgo leaves, fortified at 3 levels ranging from 0.05 to 1.00 mg/kg, was 95.2% with a relative standard deviation of 4.6%. The limits of detection ranged from 1.11 x 10(-3) mg/kg (dimethoate) to 4.44 x 10(-3) mg/kg (dichlorvos). The proposed method showed acceptable accuracy and precision while minimizing environmental concerns, time, and labor. Furthermore, the method could be easily applied to the monitoring of these 15 organophosphorus pesticides in ginkgo leaves.

Effect of ginkgo and ginger on the pharmacokinetics and pharmacodynamics of warfarin in healthy subjects

AIM

The aim of this study was to investigate the effect of two common herbal medicines, ginkgo and ginger, on the pharmacokinetics and pharmacodynamics of warfarin and the independent effect of these herbs on clotting status.

METHODS

This was an open label, three-way crossover randomized study in 12 healthy male subjects, who received a single 25 mg dose of warfarin alone or after 7 days pretreatment with recommended doses of ginkgo or ginger from herbal medicine products of known quality. Dosing with ginkgo or ginger was continued for 7 days after administration of the warfarin dose. Platelet aggregation, international normalized ratio (INR) of prothrombin time, warfarin enantiomer protein binding, warfarin enantiomer concentrations in plasma and S-7-hydroxywarfarin concentration in urine were measured. Statistical comparisons were made using anova and the 90% confidence intervals (CIs) of the ratio of log transformed parameters are reported.

RESULTS

INR and platelet aggregation were not affected by administration of ginkgo or ginger alone. The mean (95% CI) apparent clearances of S-warfarin after warfarin alone, with ginkgo or ginger were 189 (167-210) ml h(-1), 200 (173-227) ml h(-1) and 201 (171-231) ml h(-1), respectively. The respective apparent clearances of R-warfarin were 127 (106-149) ml h(-1), 126 (111-141) ml h(-1) and 131 (106-156) ml h(-1). The mean ratio (90% CI) of apparent clearance for S-warfarin was 1.05 (0.98-1.21) and for R-warfarin was 1.00 (0.93-1.08) when coadministered with ginkgo. The mean ratio (90% CI) of AUC(0-168) of INR was 0.93 (0.81-1.05) when coadministered with ginkgo. The mean ratio (90% CI) of apparent clearance for S-warfarin was 1.05 (0.97-1.13) and for R-warfarin was 1.02 (0.95-1.10) when coadministered with ginger. The mean ratio (90% CI) of AUC(0-168) of INR was 1.01 (0.93-1.15) when coadministered with ginger. The mean ratio (90% CI) for S-7-hydroxywarfarin urinary excretion rate was 1.07 (0.85-1.32) for ginkgo treatment, and 1.00 (0.81-1.23) for ginger coadministration suggesting these herbs did not affect CYP2C9 activity. Ginkgo and ginger did not affect the apparent volumes of distribution or protein binding of either S-warfarin or R-warfarin.

CONCLUSIONS

Ginkgo and ginger at recommended doses do not significantly affect clotting status, the pharmacokinetics or pharmacodynamics of warfarin in healthy subjects.

Dietary rescue of fumble--a Drosophila model for pantothenate-kinase-associated neurodegeneration

Hallervorden-Spatz syndrome (HSS) is a devastating neurological disease, characterized by iron accumulation in the globus pallidus in the basal ganglia. Most HSS cases are caused by mutations in one of the four human pantothenate kinases (PANK2). This PANK2-caused subgroup of HSS is sometimes referred as PKAN (pantothenate-kinase-associated neurodegeneration). No effective treatment for PKAN or HSS is currently available. fumble, a Drosophila mutant that carries a mutation in Drosophila Pank, has many features similar to those of PKAN patients. In this study, we used fumble as a model to evaluate various compounds or nutritional products for their possible therapeutic efficacy. While no product was found to dramatically improve the symptoms, GKE (containing Ginkgo biloba extract and flavone) and vitamin E showed statistically significant beneficial effects. Our studies indicate that pantothenate is of limited value in alleviating fumble phenotypes and also suggest that some compounds might have deleterious effects.

Determination of flavonol aglycones in Ginkgo biloba dietary supplement crude materials and finished products by high-performance liquid chromatography: single laboratory validation

A single laboratory validation (SLV) was completed for a method to determine the flavonol aglycones quercetin, kaempferol, and isorhamnetin in Ginkgo biloba products. The method calculates total glycosides based on these aglycones formed following acid hydrolysis. Nine matrixes were chosen for the study, including crude leaf material, standardized dry powder extract, single and multiple entity finished products, and ethanol and glycerol tinctures. For the 9 matrixes evaluated as part of this SLV, the method appeared to be selective and specific, with no observed interferences. The simplified 60 min oven heating hydrolysis procedure was effective for each of the matrixes studied, with no apparent or consistent differences between 60, 75, and 90 min at 90 degrees C. A Youden ruggedness trial testing 7 factors with the potential to affect quantitative results showed that 2 factors (volume hydrolyzed and test sample extraction/hydrolysis weight) were the most important parameters for control during sample preparation. The method performed well in terms of precision, with 4 matrixes tested in triplicate over a 3-day period showing an overall repeatability (relative standard deviation, RSD) of 2.3%. Analysis of variance testing at alpha = 0.05 showed no significant differences among the within- or between-group sources of variation, although comparisons of within-day (Sw), between-day (Sb), and total (St) precision showed that a majority of the standard deviation came from within-day determinations for all matrixes. Accuracy testing at 2 levels (approximately 30 and 90% of the determined concentrations in standardized dry powder extract) from 2 complex negative control matrixes showed an overall 96% recovery and RSD of 1.0% for the high spike, and 94% recovery and RSD of 2.5% for the low spike. HorRat scores were within the limits for performance acceptability, ranging from 0.4 to 1.3. Based on the performance results presented herein, it is recommended that this method progress to the collaborative laboratory trial.

Improved extraction of ginkgotoxin (4'-O-methylpyridoxine) from Ginkgo biloba products

A simple extraction procedure was applied to the analysis of canned/packaged white nuts and Ginkgo biloba extracts. Extraction by shaking with water at room temperature was more convenient to use than a previously published Soxhlet procedure for analysis of packaged Ginkgo biloba seeds (white nuts) for ginkgotoxin; recoveries from spiked dried seeds by the simple extraction procedure averaged 76%. Determination was by liquid chromatography with UV or fluorescence detection. Recoveries of ginkgotoxin from a spiked and unspiked natural health product (powder from Ginkgo biloba capsules) were equivalent by both procedures; recovery from spiked powder by the simple extraction procedure was 81%. Application of this extraction procedure in the analysis of 6 samples of white nuts (vacuum packaged and canned products) showed that free ginkgotoxin was present in 5 samples at concentrations up to 25 microg/g dry weight. Total ginkgotoxin was determined after hydrolysis with beta-glucosidase of sample extracts in which a peak corresponding to the 5'-O-glucoside was detected. Ginkgotoxin was determined in 10 Ginkgo biloba natural health products by the same method at levels up to 181 microg/g.

Testing the amyloid toxicity hypothesis of Alzheimer's disease in transgenic Caenorhabditis elegans model

Alzheimer's disease (AD) is affecting more people every year due to the increase in elderly population. This disease is characterized by senior plaques, containing aggregated amyloid beta peptide (A beta), and neurofibrillary tangles in the AD brains. The A beta depositions are thought to increase in cellular oxidative stress, which subsequently produces neuronal cell death in the patient s brain, causing loss of memory and, in the latter stages, dementia. Diverse models have been established to test this, "Amyloid Toxicity Hypothesis of AD". Among these, the use of the nematode Caenorhabditis elegans has some advantages. This invertebrate has its entire genome known, as well as numerous gene homologues to those seen in humans. In relationship with the cell model, the nematode gives the benefit of an organismal view of the disease. The nematode's short life span proves useful, when compared with that of mice, allowing mechanistic studies of the disease and pharmacological treatments. Alongside with other laboratories, we have used this in vivo model to correlate the Abeta expression with its toxicity through the observance of the organism's behavior to provide a better understanding of the cellular processes underlining AD.

Ginkgo biloba and neurodegenerative disorders

The Gingko biloba extract EGb 761 has been the subject of many studies which confirm its usefulness for the prevention and treatment of neurodegenerative pathologies. These studies have focused on: a) the probable mechanisms of action that are involved in these disorders (including non-specific mechanisms implicated in diverse neurodegenerative disorders, particularly oxidative stress, or specific mechanisms such as those associated with beta-amyloid in Alzheimer's disease) and the processes of neuronal death; b) available animal models, and c) healthy individuals or those suffering from mild cognitive impairment or Alzheimer's disease. This data must be completed, particularly with regard to new knowledge about the pathogenesis of these disorders. Ambitious interventional studies are underway and may provide new evidence regarding the effect of EGb 761 in preventing Alzheimer's disease in humans. Positive findings would be particularly interesting since this drug is very safe to use.

[Studies on the cell growth, differentiation and terpene lactone accumulation in Ginkgo biloba cell suspension cultures]

To provide supports for Ginkgo biloba cell engineering for production of Terpene lactones (Ginkgolides and bilobalide), the cell suspension were established from calli induced from zygote embryos and stems of 30-day-old seedlings respectively. The relationship between cell growth, differentiation and the terpene lactone accumulation in these suspension cultures were investigated. HPLC determination indicated that, the ginkgolide B was found in the embryo derived cell suspension cultures at 0.044% of cell dry weight, and this result was the first time reported in this study. The accumulation of terpene lactone in the suspension cultures derived from both the embryo and seedling stems are effected by the level of the cell differentiation. The ginkgolide B was only found in small cell aggregates in the size smaller than 2mm, and the highest level of ginkgolide B was accumulated in cell aggregates in the size smaller than 1mm; however, the cell aggregates in the size bigger than 3mm could only produced bilobalide and ginkgolide A. In the same size aggregates of the suspension cultures the terpene lactone accumulation is strongly effected by the source of the explant. When the size of cell aggregates was in less than 1mm, the concentration of bilobalide, ginkgolide A and B in the cell suspension cultures derived from the embryos was 2, 1.4 and 0.56-fold, respectively, higher than that of cell cultures derived from seedling stems.

Natural antioxidants and neurodegenerative diseases

Neurodegenerative diseases such as Alzheimer's (AD) and Parkinson's (PD) diseases are defined by a progressive neuronal dysfunction and an ensuing behavioral dysfunction. Although protein aggregation (i.e beta-amyloid and alpha-synuclein) plays a pivotal role in both AD and PD, there is increasing evidence that excessive accumulation of reactive oxygen species (ROS) that occurs during normal and pathological brain aging contributes to neuronal losses and dysfunction. Based on these observations, it has been hypothesized that natural antioxidants derived from food, beverages and natural extracts may be beneficial to prevent or delay the occurrence of age-related cognitive deficits and neurodegenerative diseases. We will summarize in this review the role of oxidative stress in pathological brain aging, and provide evidence for a role for antioxidant molecules as therapeutic agents. We will also focus on the various mechanisms underlying their neuroprotective effects in in vivo and in vitro models of neurotoxicity.

Predicting pharmacokinetic herb-drug interactions

In vitro and in vivo studies have indicated that the induction or inhibition of cytochrome P450 (CYP) is one of the major mechanisms for some clinically important pharmacokinetic herb-drug interactions. Thus, an attempt was made to predict pharmacokinetic herb-drug interactions using the pharmacokinetic principles that are used for predicting drug-drug interactions. The expected AUC ratio was mainly dependent on unbound herbal inhibitor concentration ([I]) and inhibition constant (Ki), hepatic fraction (fh), number of inhibitory herbal constituents (n) and metabolic pathway fraction in hepatic metabolism (fm). Herb-drug interactions would be with low risk if sigma(i=1)n [[Ii]/Ki(i)] is less than 0.1, medium risk if it is between 0.1 and 1.0, and high risk if it is greater than 1. For high clearance drugs, the change of fh x fm had minor influence on AUC ratio when sigma(i=1)n [[Ii]/Ki(i)] values were fixed. Similarly, fm did not affect the AUC ratio for low clearance drugs. It appeared likely to predict a herb-drug metabolic interaction when [I], Ki, fh, fm and n could be determined. However, many herb- and drug-related factors may cause difficulties with the prediction, and well-designed human studies are always necessary.

Enteric Disposition and Recycling of Flavonoids and Ginkgo Flavonoids

OBJECTIVE

The objective of this study was to determine the intestinal and microbial disposition of flavonoids and how these disposition processes affect their enteric recycling.

DESIGN

Studies were performed using a perfused rat intestinal model or using enrichment cultures and a pure isolate of Enterococcus avium (LY1).

RESULTS

In the rat intestine, aglycones, such as quercetin and apigenin, were as permeable (P*(eff) > or = 2) as compounds such as propranolol (100% absorption). However, a significant portion of the absorbed aglycones was conjugated and the metabolites were excreted into the lumen. Flavonoid glycosides, such as isoquercitrin and apigenin-7-O-glucoside, also had high apparent P*(eff) values (> or = 2) in the upper small intestine because of rapid hydrolysis. However, isoquercitrin was absorbed much slower (P*(eff) < or = 0.7, p < 0.05) when hydrolysis was absent or inhibited by 20 mmol gluconolactone. Absorption of other intact glycosides was similar to intact isoquercitrin and was much slower than the corresponding aglycones (P*(eff) < or = 0.7, p < 0.05). Intestinal bacteria, such as LY1, hydrolyzed the flavonoid glycosides used in the study. Excreted glycosidases were involved in the hydrolysis of glycosides because glycosides were poorly taken up by LY1. In conclusion, glycosidase-catalyzed hydrolysis is a critical first step in the intestinal and microbial disposition of flavonoid glycosides. Aglycones were not only rapidly absorbed, but also rapidly metabolized into phase II conjugates, which were then excreted back into the lumen. Therefore, intestinal and microbial glycosidases and intestinal phase II enzymes make a significant contribution to the disposition of flavonoids via the proposed enteric and enterohepatic recycling scheme.