Effect of medium composition and light on root and rhinacanthin formation in Rhinacanthus nasutus cultures

Rhinacanthus nasutus (L.) Kurz (Acanthaceae) has long been used in Thai traditional medicine for treatment of tinea versicolor, ringworm, pruritic rash, and abscess. The active constituents are known as a group of naphthoquinone esters, rhinacanthins. This work focused on establishment of R. nasutus root cultures and determination of rhinacanthin production. Induction of R. nasutus root formation was accomplished on solid Gamborg’s B5 (B5) medium, supplied with 0.1?mg/L indole-3-butyric acid (IBA) and 20?g/L sucrose. The effects of explants (whole leaf explants and four-side excised leaf explants), light and medium composition on root and rhinacanthin formation were investigated. The root formation from the whole leaf explants was 10 times higher than that from the four-side excised leaf explants. In addition, light possessed an inhibitory effect on the root and rhinacanthin formation of R. nasutus. Medium manipulation found that Murashige and Skoog (MS) medium supplied with 3?mg/L IBA and 30?g/L sucrose was the most suitable for induction of the root formation. Unfortunately, the obtained root cultures produced only rhinacanthin-C in very low amount, 0.026?mg/g dry weight (DW), when they were transferred into the same MS liquid medium. With semisolid medium (4?g/L agar) of the same MS composition, however, the root cultures appeared to produce higher content of rhinacanthin-C, -D and -N (3.45, 0.07 and 0.07?mg/g DW, respectively). Our finding suggests that culturing in semisolid medium is capable of improving of rhinacanthin production in R. nasutus root cultures.     

Synthesis of new hetero- and carbocyclic aromatic amides of glycyrrhizic acid as potential anti-HIV agents

Members of a new group of di- and trisubstituted amides of glycyrrhizic acid (GA), the major component of licorice root extract, were synthesized; derivatives contained fragments of heterocyclic and aromatic amines (2-aminopyridine, 4-aminopyridine, 5-aminouracil, sulfadimezine, sulfapyridazine, and L-histidine methyl ester) using the dicyclohexylcarbodiimide method. Amides of GA containing 2-aminopyridine and 5-aminopurine residues had anti-HIV-1 activity in MT-4 cell cultures. The index of selectivity (IS) of the amide of GA with 5-aminouracil was, using various parameters, from 27.73 to 277.32, exceeding values for GA (from 4.45 to 24.0).     

Comparison of digoxin analysis by high-performance liquid chromatography/post-column derivatization and fluorescence polarization immunoassay

1. This study compared the analysis of digoxin using a high-performance liquid chromatographic post-column derivatization (HPLC-PC) assay and the TDx fluorescence polarization immunoassay (FPIA). 2. Serum obtained from 15 digitalized patients showed higher mean digoxin levels with the FPIA method as compared to the HPLC-PC procedure such that the mean HPLC-PC/FPIA ratio was 0.91 +/- 0.14 (mean +/- SD). Demonstrated cross-reactivity of digoxin metabolites with the FPIA is probably responsible for this observation. 3. Cross-reactivity of the immunoassay towards endogenous material present in serum samples from certain patient groups was an even greater problem, with apparent 'digoxin' serum concentrations in untreated hepatic failure patients being within the therapeutic range for digoxin. 4. The HPLC-PC method did not suffer from such interference and would therefore provide more accurate values for patients where high levels of interference could contribute to false digoxin levels.     

In vitro and in vivo inhibitory effects of glycyrrhetinic acid on cytochrome P450 3A activity

The liquorice plant has long been used in both Eastern and Western cultures. Glycyrrhizin is the major triterpenoid saponin in liquorice root, and glycyrrhetinic acid (GA) is its predominant metabolite and a pharmacologically active form of glycyrrhizin. We have assessed the ability of GA to inhibit the enzyme cytochrome P450 3A (CYP3A). A Lineweaver-Burk plot showed that GA was a mixed inhibitor of CYP3A, with an IC?? of 7.25 μmol/l, a K(m) of 4.3 μmol/l and a K(i) of 6.4 μmol/l by non-linear regression analysis. CYP3A activity was also affected by intragastric administration of GA, which resulted in increases in area under the plasma concentration-time curve (AUC)(?-t) and in apparent elimination half-time (t?/?) and significant decreases in body clearance, as well as in the formation of 1-hydroxy-midazolam after intragastric or intravenous administration of midazolam (p < 0.05). An increase in C(max) after intragastric administration (p < 0.05) was also observed. These results suggest the likelihood of an interaction between GA and CYP3A-metabolised drugs in humans and indicate that liquorice root should be used with caution when taken concomitantly with other drugs that interact with CYP3A.     

Comparison of digoxin versus low-dose amiodarone for ventricular rate control in patients with chronic atrial fibrillation

1. Rapid ventricular rate (VR) and rhythm irregularity during atrial fibrillation (AF) impair cardiac performance. Although digoxin has been widely used in patients with AF, its efficacy for the control of VR and rhythm irregularity is unsatisfactory. Whether low-dose amiodarone is more effective remains unclear. 2. We randomized 16 patients (13 male, three female; mean (+/-SD) age 63 +/- 9 years) with chronic AF to receive either digoxin or amiodarone for 24 weeks. At baseline and at 12 and 24 weeks follow up, Holter monitor recording and cardiopulmonary exercise test were performed to assess VR and rhythm irregularity control and exercise capacity. 3. Seven and nine patients received digoxin and amiodarone, respectively. After 12 and 24 weeks treatment, both digoxin and amiodarone significantly decreased the mean ambulatory VR and the VR during peak exercise compared with baseline (all P < 0.05). At 24 weeks, there were no significant differences between digoxin and amiodarone in the percentage reduction in VR during ambulatory (27 +/- 13 vs. 25 +/- 12%, respectively; P = 0.8) and peak exercise (13 +/- 12 vs. 12 +/- 10%%, respectively; P = 0.6). 4. The rhythm irregularity, as measured by SD of RR intervals and the root mean square of the SD of RR intervals, and the exercise capacity, as measured by exercise workload, maximal oxygen consumption (VO2), minute ventilation, ventilatory equivalent and oxygen pulse, were not significantly changed after treatment with digoxin or amiodarone (all P > 0.05). 5. Quality of life, determined by SF-36 questionnaire, and AF symptomatology, as measured by the AF Symptom Checklist, were also not significantly changed after treatment with digoxin or amiodarone (all P > 0.05). 6. In conclusion, digoxin and low-dose amiodarone had similar efficacy in the control of VR during ambulatory activity and exercise. However, both were less efficacious during exercise and did not significantly affect rhythm irregularity, exercise capacity, quality of life and AF symptomatology in patients with chronic AF.     

Comparative in vivo evaluation of a radioimmunoassay and a chromatographic assay for the measurement of digoxin in biological fluids

The concentrations of digoxin in plasma and urine samples obtained from three healthy male volunteers, who received 1.2 mg of labeled digoxin perorally and intravenously, were simultaneously measured by a commercially available radioimmunoassay (RIA) and by a combined column thin-layer chromatographic assay (CA). The CA method, previously shown to assay digoxin specifically, was also used to monitor the individual digoxin metabolites. The results of this investigation showed that digoxin was significantly metabolized, particularly after peroral administration. The lower level of sensitivity of the RIA in plasma was 0.4 ng/mL. There were highly significant positive linear correlations between the values of the following parameters of digoxin as obtained by the RIA and CA methods: the concentrations in plasma and urine, the AUCs, and the cumulatively excreted amounts in urine. The two assays did not give completely identical results either with plasma or urine; the slopes of the regression lines deviated from unity in a significant number of cases. However, there was no relationship between the magnitude of the slopes of the regression lines and the extent of metabolism. It was concluded that the commercially available RIA evaluated was specific for digoxin and that the presence of digoxin metabolites did not affect the determinations.     

Specific and sensitive determination of digoxin and metabolites in human serum by high performance liquid chromatography with cyclodextrin solid-phase extraction and precolumn fluorescence derivatization

A precolumn fluorescence derivatization high performance liquid chromatographic method has been developed for the simultaneous determination of digoxin and its metabolites digoxigenin bisdigitoxoside, digoxigenin monodigitoxoside digoxigenin, and dihydrodigoxin (20-R and 20-S epimers) in human serum. Digoxin and its metabolites were extracted from serum samples (containing digitoxin as internal standard) with a cyclodextrin solid-phase extraction (SPE) column. Fluorescent derivatives were formed by reaction of the analytes with 1-naphthoyl chloride in the presence of 4-dimethylaminopyridine under a nitrogen atmosphere in a glove box with controlled relative humidity (26% r.h. or less). The derivatives were isolated using cyclodextrin and Cl SPE columns sequentially, and determined by HPLC using silica column separation and fluorescence detection. Calibration curves were linear over the concentration range from 0.25 to 4.0 ng ml⁻¹. Recoveries of digoxin and its metabolites from serum ranged from 62 to 86%, and coefficients of variation from repetitive analyses ranged from 6.9 to 20.9% and from 5.8 to 12.2% at 0.5 ng ml⁻¹ and 2.0 ng ml⁻¹, respectively. This method has been shown capable of specifically determining digoxin and its major metabolites in serum, and has been successfully used in the determination of digoxin and its metabolites in serum samples collected from patients undergoing digoxin therapy. This method thus permits the investigation of digoxin metabolism and pharmacokinetics after the administration of commercial dosage forms.     

Formation of [20R]-dihydrodigoxin from digoxin in humans

The objective of this research was to determine the stereochemical identity of dihydrodigoxin (DHD3), a metabolite of digoxin excreted in urine after digoxin administration in man. Separation of the individual epimers in reference DHD3 was effected by a chemical derivatization-HPLC procedure. Comparison of individual derivatized epimers of DHD3 with the known 20R and 20S epimers of derivatized dihydrodigoxigenin using chromatographic data and NMR spectroscopy permitted identification of the 20R and 20S epimers in reference DHD3. Material corresponding chromatographically to R-DHD3 was isolated from urine of a volunteer taking oral digoxin daily. The NMR spectrum of the chromatographically pure, derivatized urinary isolate was identical to the NMR spectrum of derivatized R-DHD3. Urine samples from 20 patients on chronic digoxin therapy and from two volunteers were surveyed for chromatographic evidence of R- or S-DHD3 using HPLC of a fluorescent derivative as well as HPLC of a UV-absorbing derivative. The more sensitive fluorescence procedure yielded evidence for R-DHD3 in eight patients and both volunteers. There was a sufficient concentration in four patients and both volunteers for independent evidence of R-DHD3 using the UV-absorbing derivative. Chromatographic evidence (fluorescent derivative) for S-DHD3 was found in urine from three patients. However, this evidence for S-DHD3 was demonstrated to be an artifact by the absence of the peak expected for S-DHD3 in the chromatogram of the UV-absorbing derivative as well as by the inability of fecal incubates to convert digoxin to S-DHD3. The results of the investigation indicate that the DHD3 metabolite formed in humans is the 20R epimer.     

Activated charcoal is effective but equilibrium dialysis is ineffective in removing oleander leaf extract and oleandrin from human serum: monitoring the effect by measuring apparent digoxin concentration

Accidental poisoning from oleander leaf or oleander tea can be life threatening. The authors studied the effectiveness of activated charcoal and equilibrium dialysis in removing oleander leaf extract and commercially available oleandrin as well as oleandrigenin, the active components of oleander plant, from human serum. Oleander leaf extract was prepared in distilled water and drug-free serum was supplemented with the extract. Then serum was treated with activated charcoal at room temperature and an aliquot was removed at 0 minutes, 10 minutes, 20 minutes, and finally 30 minutes to study the presence of oleander extract by measuring the apparent digoxin concentration using the FPIA for digoxin. The authors observed effective removal of oleander extract by activated charcoal. When the authors supplemented other drug-free serum pools with pure oleandrin or oleandrigenin and then subsequently treated them with activated charcoal, the authors observed complete removal of digoxin-like immunoreactivity at the end of 30 minutes' treatment. When drug-free serum pool supplemented with either oleander leaf extract, oleandrin, or oleandrigenin was passed through a small column packed with activated charcoal, the authors observed almost no apparent digoxin concentration following the passage through the column indicating that activated charcoal is very effective in removing oleander from human serum in vitro. In contrast, when serum pools containing either oleander leaf extract or oleandrin were subjected to equilibrium dialysis against phosphate buffer at pH 7.4, the authors observed no significant reduction in apparent digoxin concentration even after 24 hours. The authors conclude that activated charcoal is effective but equilibrium dialysis is ineffective in removing oleander leaf extract from human serum.     

Enhanced bioavailability of digoxin from silica matrix formulations (author's transl)]

The bioavailability of digoxin from 3 silica matrix formulations was assessed in single-dose crossover studies in 12 healthy human volunteers: digoxin/silica matrix tablets (I, Digacin), digoxin/silica matrix in capsule form (II) and digoxin/silica matrix dragées, protected against gastrict juice by film coating (III). Urinary glycoside excretion for 6 days after 0.5 mg doses were measured by radioimmunoasay. Referring to an intravenous injection the bioavailability of digoxin from Digacin tablets is 82%, from the encapsulated matrix 69%, and from the dragées 54%. In comparison with corresponding results from other investigators Digacin tablets havet the same high bioavailability as digoxin solutions. In vitro liberations of digoxin from the silica matrix formulations (94% in 90 s) is significantly better than from conventional tablets produces from a digoxin-lactose trituration (61% in 90 s).     

The new enzyme-linked immunosorbent digoxin assay on the ADVIA Integrated Modular System is virtually free from oleander interference

Despite known toxicity of oleander, this product is used in herbal preparations. Oleander interferes with various digoxin immunoassays. It is possible that a person taking digoxin also may take oleander-containing herbal products, and digoxin immunoassays interfering with oleander cannot be used for therapeutic monitoring of digoxin. Recently, Bayer Diagnostics introduced a new enzyme-linked chemiluminescent immunosorbent digoxin assay for application on the ADVIA IMS System (ECLIA-digoxin). We studied potential interference of oleander with this new digoxin assay and found that this assay is virtually free from oleander interference. When aliquots of drug-free serum pools were supplemented with ethyl alcohol extract of oleander leaf or pure oleandrin standard, we observed significant apparent digoxin concentration when measured by the fluorescence polarization immunoassay (FPIA) but minimal digoxin-like immunoreactivity using the ECLIA digoxin assay. Because cross-reactivity should be studied in the presence of primary analyte, we prepared 2 serum pools using sera from patients receiving digoxin. Then aliquots of first digoxin pool were supplemented with oleandrin standard and aliquots of second digoxin pool with oleander extract. We observed significant increases in apparent digoxin concentration in the presence of both oleandrin and oleander extract using the FPIA. However, we observed no statistically significant change in digoxin concentration when ECLIA digoxin assay was used, indicating that this assay is virtually free from oleander interference.     

Guaiazulene in health care products: determination by GC-MS and HPLC-DAD and photostability test

A liquid chromatographic method with UV detection (HPLC-DAD) and a gas chromatographic method coupled with mass spectrometry (GC-MS) have been developed for the determination of guaiazulene (GA) in complex matrices such as creams and toothpastes. A solid phase extraction (SPE) sample pre-treatment on a polymeric sorbent (Strata-X polymer) was applied before the HPLC analyses, which were performed on a XTerra C8 stationary phase, using a mobile phase consisting of acetonitrile-water 50:50 (v/v). For GC-MS analyses, solid-liquid extraction (creams) and SPE (toothpastes) were applied. The proposed methods, based on techniques with different selectivity, were validated and both proved to be suitable to obtain an unambiguous identification and reliable determination of GA in commercial health care products (creams and toothpastes), giving concordant results. Moreover, the described methods can offer a useful analytical support for photostability studies of GA, a photolabile natural compound, in creams.     

Digoxin pharmacokinetics and spirapril, a new ace inhibitor

As concurrent use of digoxin with the novel ACE inhibitor spirapril should be common, potential for spirapril to affect steady-state digoxin kinetics was studied. Fifteen healthy white male volunteers aged 22-42 and weighing 135-225 lbs took digoxin tablets 0.25 mg every 12 hours for 5 weeks. In crossover design, each also received spirapril or matching placebo capsules during weeks 1 and 2, or 4 and 5. Dosage of spirapril was increased from 12 mg to 48 mg once daily. Spirapril produced no significant effect on mean (+/- SD) serum digoxin concentration in the steady state, area under curve for 12 hours, peak digoxin level, time to peak, or urinary digoxin excretion over 12 hours. No change in renal or whole body digoxin clearance was seen. Unlike some other cardiovascular drugs, spirapril does not alter steady-state digoxin kinetics in healthy adults.     

Effect of Baccharis dracunculifolia D.C. (Asteraceae) extracts and its isolated compounds on macrophage activation

Baccharis dracunculifolia D.C. (Asteraceae), a shrub which grows wild in Brazil, is the main botanical source of Brazilian green propolis. Since Brazilian propolis shows an immunomodulatory activity, the goal of this work was to evaluate the action of B. dracunculifolia extracts and some of its isolated compounds on reactive oxygen intermediate (H(2)O(2)) production by macrophages obtained from male BALB/c mice. The results showed that the leaf (Bd-L) (25, 50, and 100 microg mL(-1)), leaf rinse (Bd-LR) (25 microg mL(-1)), and the root (Bd-R) (25 microg mL(-1)) extracts enhanced H2O2 release by macrophages. A phytochemical study of the root and leaves of B. dracunculifolia was carried out. The chromatographic fractionation of Bd-R, using several techniques, afforded the isolation of baccharis oxide (1), friedelanol (2), viscidone (11), 11-hydroxy-10,11-dihydro-euparin (12), and 6hydroxy-tremetona (13), while Bd-LR gave the following isolated compounds: baccharis oxide (1), friedelanol (2), isosakuranetin (3), aromadendrin-4'-methyl ether (4), dihydrocumaric acid (5), baccharin (6), hautriwaic acid lactone (7), hautriwaic acid acetate (8), drupanin (9), and cumaric acid (10). Among the isolated compounds, baccharis oxide (1) and friedelanol (2) increased H2O2 production at a concentration of 100 microM. This is the first time that the presence of compounds 7, 8, 12, and 13 in B. dracunculifolia has been reported. Based on these results it is suggested that the crude extracts and some isolated compounds from B. dracunculifolia display an immunomodulatory action.     

The comparative bioavailability of Lanoxin tablets and Lanoxicaps with and without sorbitol

Summary (1) The mean cumulative urinary digoxin excretion over 8 days was compared in 8 healthy volunteers after single doses of digoxin administered as 3 Lanoxin tablets of 0.25 mg, 3 digoxin tablets of 0.2 mg, 12 Lanoxicaps without sorbitol of 0.05 mg, 6 Lanoxicaps without sorbitol of 0.1 mg digoxin, 3 Lanoxicaps without sorbitol of 0.2 mg and 3 Lanoxicaps with sorbitol of 0.2 mg. (2) There was no significant difference between the 8 day cumulative urinary excretion for any of the Lanoxicaps treatments. (3) Cumulative urinary excretion after 3 digoxin tablets of 0.2 mg was significantly (P<0.05) lower than after all other treatments. (4) Cumulative urinary excretion after 3 Lanoxin tablets of 0.25 mg was not significantly different from that after any of the Lanoxicaps treatments except 0.1 mg Lanoxicaps without sorbitol, it was significantly (P<0.05) lower after the latter. (5) Mean urinary excretion of digoxin was 60% of ingested dose for all Lanoxicaps treatments and was significantly (P<0.05) higher than the mean value of 50% for both tablet treatments. (6) Enhanced absorption of digoxin from Lanoxicaps was confirmed and shown to be unrelated to the sorbitol content of the capsule shell.Trade marks     

Chemical characteristics for different parts of Panax notoginseng using pressurized liquid extraction and HPLC-ELSD

The chemical characteristics for different parts of Panax notoginseng, including root, fibre root, rhizome, stem, leaf, flower and seed, were determined using high performance liquid chromatography-evaporative light scattering detection (HPLC-ELSD) and pressurized liquid extraction (PLE). Eight major saponins, namely notoginsenoside R1, ginsenosides Rg1, Re, Rb1, Rc, Rb2, Rb3 and Rd were also quantitatively compared among the different parts of P. notoginseng. The chromatograms showed that there was significant difference between underground (root, fibre root, rhizome) and aerial (leaf and flower) parts from P. notoginseng, though the similarities of entire chromatographic patterns among tested samples from underground (0.965 ± 0.029, n = 12) and aerial parts (0.987 ± 0.014, n = 5) were similar, respectively. Especially, no saponin was detected in the seed of P. notoginseng. Hierarchical clustering analysis based on eight investigated saponins or the ratios of contents for ginsenoside Rg1/Rb1 and ginsenoside Rb3/Rb1 showed that the samples from different parts of P. notoginseng were divided into three main clusters. One cluster was underground parts, which contained rich protopanaxatriol and protopanaxadiol types saponins. The leaf and flower were in the same cluster, which contained protopanaxadiol type saponins only. Especially, ginsenoside Rc, Rb2 and Rb3, rare in the underground parts, were rich in aerial parts of P. notoginseng. The stem of P. notoginseng was another cluster. Based on the cluster analysis, the chemical characteristics for different parts of P. notoginseng were revealed. They are composite cluster (underground parts), protopanaxadiol cluster (aerial parts) and interim (stem) cluster, which was the one between the two typical clusters, respectively. The result shows that chemical characteristics of underground parts and aerial parts from P. notoginseng are obviously different, which is helpful for pharmacological evaluation and quality control of P. notoginseng.     

Effect of two different doses of nitrendipine on steady-state plasma digoxin level and systolic time intervals

Summary The effect of two different doses of nitrendipine on plasma digoxin levels, urinary recovery and systolic time intervals was investigated in 8 healthy volunteers. Following a loading dose, digoxin 0.25 mg b.d. p.o. was given alone for 2 weeks. Then 0.25 mg digoxin b.d. was administered for two 1-week periods combined with nitrendipine 10 mg or 20 mg once daily. The study was completed with another digoxin monotherapy phase lasting 7 days. Nitrendipine 20 mg daily led to a significant increase in plasma digoxin levels and in its area under the plasma concentration-time curve AUC (0–12) compared to digoxin monotherapy. The AUC (0–12) was 9.7 ng ml^–1h when digoxin alone was given and 11.2 ng ml^–1h on co-administration of the calcium antagonist. Urinary recovery and renal clearance of digoxin were slightly but not significantly increased by nitrendipine. Nitrendipine 10 mg once daily caused a small, insignificant tendency to elevate the plasma digoxin level. Nitrendipine co-administration (10 and 20 mg once daily) did not significantly alter systolic time intervals, as non-invasively measured haemodynamic parameters, compared to digoxin treatment alone. Thus, nitrendipine 20 mg daily caused a significant increase in plasma digoxin concentrations and in its AUC, which would rarely be of clinical relevance.     

Effect of cyclodextrins on the acid hydrolysis of digoxin

The effects of three cyclodextrins (alpha-, beta-, gamma-CyD) on the acid hydrolysis of digoxin were examined. From the high performance liquid chromatographic tracing of each of the four components (digoxin, bisdigitoxoside, monodigitoxoside, digoxigenin) in reaction mixtures, the individual rate constants (K1-K6) were determined by analogue computer simulation. The hydrolysis was suppressed by CyDs in the order of beta-great than gamma-greater than alpha-greater than-CyD, where beta-CyD inhibited the appearance rates of digoxigenin (k3, K5, and K6) significantly. In the dissolution study of digoxin tablets, the increase in dissolution rate and decrease in acid hydrolysis were attained by inclusion complexation. The data are presented suggesting that CyDs are useful for improving the oral bioavailability of digoxin.     

Kinetics of digoxin and anti-digoxin antibody fragments during treatment of digoxin toxicity.

Anti-digoxin antibody fragments (ADAF, 80 mg) were infused intravenously to successfully treat severe digoxin toxicity in an 82 year old woman. During treatment, total and free digoxin were determined using an Abbot TDX analyser and an ultrafiltration technique. ADAF were measured by an enzyme-linked immunosorbent assay. By 1 h after ADAF, total serum digoxin concentrations had risen 12-fold from a pretreatment level of 15.4 nmol l-1 but free digoxin fell from 10 to 0.1 nmol l-1, indicating greater than 99.9% digoxin binding to ADAF. However, the low free levels had rebounded to 7.7 nmol l-1 by 12 h, but despite this rise the patient's condition had improved. A serum ADAF/digoxin molar ratio of around five was associated with the low concentration of free digoxin at 1 h, while at later times with ratios roughly between 3 and 4, the free digoxin concentrations ranged between 2.0 and 7.7 nmol l-1. ADAF were mainly confined to the plasma during the first hour, but subsequently distributed into an apparent volume of 193 ml kg-1. The elimination half-lives of ADAF and total digoxin were 96 and 55 h, respectively. More than 50% of the estimated digoxin load had been excreted in the urine by 5 days; for ADAF the equivalent figure was only about 3%. Renal and/or bacterial degradation may have contributed to the low detection of urinary ADAF.     

Ascorbic acid induces furanocoumarin production in organ cultures of Glehnia littoralis

Exogenously supplied ascorbic acid (AsA) strongly induced furanocoumarin production in leaf and root cultures of GLEHNIA LITTORALIS, but not in cell suspension cultures, after 24 h of treatment. The dose dependency showed that both organ tissues responded well to AsA supplied at concentrations of 10 - 40 mM. For induction of furanocoumarin production, roots required contact with AsA for at least 6 h and productivity markedly increased after 8 h of treatment. This is the first report of the induction of furanocoumarin biosynthesis by AsA alone and of the detection of furanocoumarin biosynthesis in a root culture system.