Podophyllotoxin Derivatives Research Articles

4′-Demethylepipodophyllotoxin-β-D-Glucoside: A New Podophyllotoxin Derivative With VM-26-Like and VP-16-213-Like Activities<xref ref-type="fn" rid="FN2">2</xref>

Mutants of Chinese hamster ovary (CHO) cells independently selected for resistance to the anticancer drug 4'-demethylepipodophyllotoxin thenylidene-beta-D-glucoside (VM-26) and the microtubule inhibitor podophyllotoxin exhibit mutually an exclusive cross-resistance pattern toward various podophyllotoxin derivatives that possess either VM-26-like or podophyllotoxin-like activities, respectively. The cross-resistance studies with these mutants have led to the identification of a new podophyllotoxin derivative, 4'-demethylepipodophyllotoxin-beta-D-glucoside (compound No. 13), which possesses VM-26-like and 4'-demethylepipodophyllotoxin ethylidene-beta-D-glucoside (VP-16-213)-like activity. This inference is strongly supported by our observation that, like VM-26 and VP-16-213, compound No. 13 showed no antimitotic activity (as seen by the effect on the mitotic index) but was highly active in inducing DNA strand breaks, sister chromatid exchanges, and mutations at the hypoxanthine-guanine phosphoribosyl transferase and adenosine kinase loci in CHO cells. On the basis of structure-activity data of various podophyllotoxin derivatives, three structural features have been identified that appear essential for VM-26-like activity. These are: 1) the presence of an hydroxyl group at the 4'-carbon, 2) an epi-configuration at the C-4 position, and 3) the presence of a glycoside moiety on the hydroxyl group at the C-4 position. In addition, the nature of the glycoside substituents at the C-4 position greatly affects the relative VM-26-like activity of various compounds.

Podophyllotoxin and VP-16-213: a review of their divergent mechanisms of action

VP-16-213 (Etoposide), a semi-synthetic derivative of podophyllotoxin, has been shown to be an effective antitumor agent in the treatment of lung cancer, a variety of leukemias, and other solid tumors. Although VP-16-213 and podophyllotoxin possess similar chemical structures, each drug expresses different biological properties. Structure-activity relationship studies have identified some of the chemical sites responsible for each of their biological properties and has offered insights into their respective mechanisms of action.

High-performance liquid chromatography of aryltet-rahydronaphthalene lignans

The retention behaviour of some aryltetrahydronaphthalene lignans is studied. Adsorption chromatography on silica eluted with n-heptane dichloromethane-meth- anol (90:10:4) and reversed-phase chromatography on a C C18 column with methanol- water (45:55) as mobile phase are effective for the resolution of the seven known diastereoisomers of podophyllotoxin. Methanol is essential for the separation of the diastereoisomers by reversed-phase chromatography, but is less useful for the separation of the functional-group derivatives of podophyllotoxin. Acetonitrile and/or di-methyl sulphoxide are superior for the resolution of functional derivatives, but are unable to separate the diastereoisomers. A ternary mobile phase of acetonitrile- methanol -water (22.5:22.5:55), dimethyl sulphoxide-methanol-water (10:25:35) or a quaternary solvent mixture of acetonitrile-dimethyl sulphoxide-methanol-water (20:20:10:50) is required for the separation of a mixture containing diastereoisomers and functional-group derivatives. The relative retention of the lignans can be explained by the relative ability of a lignan to interact with the adsorption site or by its relative hydrophobicity in reversed-phase chromatography.

Immune Hemolytic Anemia and Renal Failure Due to Teniposide

TENIPOSIDE (VM 26) is a semisynthetic derivative of podophyllotoxin (molecular weight, 657 daltons) that has been used for a decade in cancer chemotherapy, especially in lymphoma and brain tumors. The drug has been reported to cause anaphylactic reactions of unknown origin.1 This paper describes clinical and immunohematologic features of an antibody to teniposide that causes acute hemolysis and renal failure. Case History Teniposide therapy was initiated in a 47-year-old man who had a relapse a few months after removal of a brain tumor. The drug was given monthly at a dose of 100 mg per day on Days 1 and . . .

Phase II study of VP16-213 (etoposide) in refractory metastatic breast carcinoma.

VP16-213 is a semi-synthetic derivative of podophyllotoxin. Preclinical trials have indicated a marked schedule dependency in the L1210 system suggestive of an advantage to short-cycle times and divided dose regimens. Seventy-seven patients with advanced breast carcinoma were studied. All patients had failed conventional combination chemotherapy (median prior chemotherapy: 23 months). All had prior Adriamycin and more than half had prior exposure to vinca alkaloids. The patients were randomly allocated to either: 1) intermittent bolus —50–70 mg/m2/day over 1 h daily for 5 days (39 patients), or 2) infusion — 50–70 mg/m2/day as a continuous infusion for 5 days (38 patients). In the intermittent group, three patients were inevaluable (early death) and one was lost to follow-up. In the infusion group, four patients were inevaluable (early death), two were lost to follow-up and one refused further treatment. In the intermittent group of 35 evaluable patients, five (14%) achieved partial remission, three (9%) had responses less than partial, six (17%) had stable disease, and 21 (60%) had progressive disease. In the infusion group of 31 evaluable patients, one (3%) achieved complete remission, three (10%) achieved partial remission, three (10%) had responses less than partial, five (16%) had stable disease and 19 (61%) had progressive disease. Principle toxicity observed was myelosuppression, which was severe (granulocytes <1,000) in approximately 50% with nadirs occuring at about day 12. Recovery was rarely prolonged beyond day 20. Nausea and vomiting were moderate with the intermittent schedule and almost absent with the infusion schedule. One patient in the intermittent group developed an anaphylactoid reaction requiring discontinuation of the drug. Congestive heart failure was precipitated by the fluid load in five patients on the infusion schedule. VP16-213 has significant antitumor activity in refractory breastcarcinoma and merits further evaluation. The infusion schedule showed no advantage over the intermittent schedule of this study.

VP16-213 and podophyllotoxin. A study on the relationship between chemical structure and biological activity.

VP16-213, a semi-synthetic derivative of podophyllotoxin, is an effective antitumor agent in the treatment of a variety of leukemias and solid tumors. A comparison of the mechanism of action of VP16-213 and podophyllotoxin has revealed that although both drugs inhibit the uptake of nucleosides into HeLa cells, they exhibit other biological properties which are quite distinct. Podophyllotoxin is a potent inhibitor of microtubule assembly in vitro, while VP16-213 has no effect in this system. VP16-213 induces single stranded breaks in HeLa cells DNA, an effect which may be related to its antitumor activity. In contrast to VP16-213 treated cells, podophyllotoxin-treated cells maintain DNA integrity. Structure-activity relationship studies have identified some of chemical sites of VP16-213 and podophyllotoxin responsible for each of their biological properties. These studies illustrate that chemical modification of podophyllotoxin can generate derivatives which possess new and unique biological properties.

VP16-213 (etoposide). A critical review of its activity.

VP16-213 is a new semisynthetic podophyllotoxin derivative, which appears to have a unique mode of action. Early suggestive data of activity in small cell lung cancer [21, 25] have ben confirmed and the single-agent response rate remains at over 40% with well more than 200 patients studied. It also shows a pronounced antitumor activity in the treatment of testicular cancer, monocytic or myelomonocytic leukemia, non-Hodgkin's lymphomas and hepatocellular carcinoma. Its role in some other neoplasms, like non-small cell lung cancer and breast cancer, has still to be ascertained.

Current development of podophyllotoxins.

The unique biological properties and therapeutic efficacy of the podophyllotoxin derivatives, Vumon (VM26, teniposide) and Vepesid (VP16-213, etoposide), are stimulating the interest of both laboratory and clinical researchers. Investigations on new pharmaceutical formulations, pharmacokinetics and metabolism are providing more appropriate information in drug administration; experimental chemotherapy indicates that, among others, cytosine arabinoside and cisplatin are highly synergistic with podophyllotoxins; single agent and combination treatment clinical trials are defining the respective role of Vumon and Vepesid in cancer chemotherapy.

Resistance to the microtubule inhibitor podophyllotoxin: selection and partial characterization of mutants in CHO cells.

Stable mutants two- to fourfold more resistant to the microtubule inhibitor podophyllotoxin (PodRI) have been selected in a single step in Chinese hamster ovary (CHO) cells. Mutants showing higher levels of resistance to the drug can be obtained in a second-step selection using the PodRI mutants (PodRII class). Prior treatment of cells with the mutagen ethylmethane sulfonate markedly enhanced the frequency of both PodRI and PodRII mutants in culture. The spontaneous rate of mutation of PodRI as determined by fluctuation analysis was found to be 1 - 2 x 10(-5) and 4 x 10(-7) mutations/cell/generation at 20 and 30 ng/ml podophyllotoxin, respectively. Somatic cell hybrids between PodRI x PodS and PodRII x PodS showed intermediate levels of resistance to the drug, indicating that the PodR phenotype behaves codominantly under these conditions. Cross-resistance studies with various PodRI and PodRII mutants show that they are not cross-resistant to other microtubule inhibitors, e.g., colchicine, colcemid, griseofulvin, vinblastin, that have been examined, or to a compound such as VP16-213, which is a podophyllotoxin derivative which lacks microtubule inhibitory activity. These results indicate that the lesion in PodR mutants is highly specific and probably does not involve a permeability alteration.

Cytotoxic lignans from Podophyllum, and the nomenclature of aryltetralin lignans

Roots of Podophyllum hexandrum and P. peltatum both contain (1 R,2 R,3 R)-desoxypodophyllotoxin [(1α,2α,3β)- desoxypodophyllotoxin] and the previously unreported (1 R,2 R,3 R)-podophyllotoxone [(1α,2α,3α)-podophyllotoxone]. Thermal isomerization of (loc,2ct,3fl)-podophyllotoxone readily occurs to yield (1α,2α,3α)-podophyllotoxone (isopicropodophyllone) with traces of (1α,2β,3β)-podophyllotoxone (picropodophyllone). Small amounts of (1α,2α,3α)-podophyllotoxone were also present in dried roots of P. hexandrum and P. peltatum. A more systematic nomenclature for podophyllotoxin derivatives and other aryltetralin lignans using α,β conventions is proposed.

Analysis of the anticancer drugs VP 16-213 and VM 26 and their metabolites by high-performance liquid chromatography.

A rapid and convenient high-performance liquid chromatographic procedure for the analysis of the clinically useful anticancer agents VP 16-213 and VM 26 is described. The drugs, which are semi-synthetic derivatives of the natural product podophyllotoxin, are extracted from plasma with chloroform. The extracts are evaporated to dryness, reconstituted in methanol, and chromatographed on a reversed-phase microparticle C18 column using isocratic elution with a mixture of methanol--water (60:40). Each drug is used as the internal standard for the other. Quantitation to 500 ng/ml (0.85 nmole/ml) plasma is based on peak height ratios using UV detection at 254 nm. Patient plasma concentration versus time data agree well with previously published data obtained using radiolabelled drug. Investigations into the nature of the hydroxy acid metabolite of VP 16-213, carried out using paired-ion chromatography with tetrabutylammonium bromide and fluorescence detection, are described. Also, a unique separation of VP 16-213 and a possible metabolite, the isomer, picro VP 16-213, is described.

Anthracycline cardiomyopathy in childrenReport of two cases

Two children with leukemia are presented, each demonstrating an unusual aspect of anthracycline-induced cardiomyopathy. In the first patient (a 7-month-old female with acute monocytic leukemia) extremely young age and previous chemotherapy with a podophyllotoxin derivative, VP-16, may have prediposed the patient to fatal congestive heart failure at a total Daunorubicin dose of only 225 mg/m2. In the second patient, a delay of 4 1/2 years was not sufficient in preventing congestive heart failure resulting from the administration of additional anthracycline chemotherapy. We conclude that extremely young age and, possibly, prior therapy with VP-16 may be addition risk factors in the development of anthracycline cardiomyopathy. Also, we suggest that once an anthracycline agent has reached a toxic threshold for the myocardium, the heart may always be at risk to injury from additional Adriamycin or Daunorubicin therapy.

A quantitative microdensitometric and autoradiographic study of the effect of 4?-demethyl-epipodophyllotoxin-?-D-thenylidene glucoside (VM-26) on the cell cycle of cultured fibroblasts

The effect of 4'-demethyl-epipodophyllotoxin-beta-D-thenylidene glucoside (VM-26) , a semi-synthetic derivative of podophyllotoxin, on the cell cycle was studied with chick embryo fibroblasts cultivated in vitro. DNA, RNA and protein content, as well as NADH-diaphorase activity were determined by quantitative microdensitometry and cytofluorometry. The incorporation of [3H]thymidine and [3H]leucine into DNA and proteins were analysed by autoradiography. These metabolic data correlated with morphological observation showed that VM-26 blocks the cell cycle at different moments of its kinetics depending on both the dose and the time exposure. NADH-diaphorase activity is the first to be affected, then biochemical changes (involving the metabolism of RNA and proteins) and morphological alterations (especially of mitochondria) follow. This suggests that VM-26 may act primarily upon the mechanism of respiration of the cell.

Podophyllotoxin derivative VP 16-213

VP 16-213, a derivative of podophyllotoxin, is currently entering phase-III studies. Its mode of action is incompletely understood, but differs markedly from that of its parent compound. The greatest lethal damage is experienced by cells in the late S and G2 phases. In the L 1210 system the drug shows marked schedule dependency: prolonged administration may be more effective than single bolus administration. As a single agent, VP 16-213 is the most active compound yet tested against small-cell bronchial carcinoma. It may also prove to be a useful agent in patients with other types of lung tumour, testicular teratomas, and some types of leukaemia. No long-term or cumulative toxicity has been reported. Most side effects are predictable and reproducible.

Analysis of polymorphonuclear leukocyte (PMN) migration by the leading-front technique: Random locomotion and chemotaxis

The present study was designed to elucidate the contribution of non-stimulated random movement, stimulated random movement, antitubulin-resistant chemotaxis and antitubulin-sensitive chemotaxis to the casein-induced PMN migration into a micropore filter, evaluated by the leading-front technique. This analysis was conducted by a simplified test design including PMN migration, ( a) without casein; ( b) in a gradient of casein; and ( c) in casein without gradient. Treatment with the antitubulin SPI (a podophyllotoxin derivative) inhibited PMN migration within a casein gradient down to the level of the stimulated PMN random movement induced by casein. The casein-induced PMN chemotaxis measured by the leading-front technique is thus composed of stimulated random movement and antitubulin-sensitive chemotaxis without evidence of antitubulin-resistant chemotaxis. It is suggested that the anti-inflammatory effects of the antitubulins (colchicine, podophyllotoxin, Vinca alcaloids, griseofulvin) are due to an inhibition of the antitubulin-sensitive chemotaxis.

Additions and Corrections - Nonenolizable Podophyllotoxin Derivatives.

Additions and Corrections - Nonenolizable Podophyllotoxin Derivatives.

Podophyllotoxin derivatives. 3. The remaining diastereomeric C-4 alcohols and ketone of the L series.

Podophyllotoxin derivatives. 3. The remaining diastereomeric C-4 alcohols and ketone of the L series.

Microtubule assembly and function in Chlamydomonas: inhibition of growth and flagellar regeneration by antitubulins and other drugs and isolation of resistant mutants.

The distribution of microtubules in Chlamydomonas reinhardtii suggests that they are involved in mitosis, cell and nuclear cleavage, and generation of flagella. Vinblastine, colchicine, and podophyllotoxin bind to the protein building block of microtubules (tubulin) and prevent normal assembly. Mutants resistant to these "antitubulin" drugs are candidates to have alterations in tubulin primary structure. We report the ability to inhibit growth, and flagellar regeneration after amputation, of: vinblastine, several colchicine derivatives, two water-soluble derivatives of podophyllotoxin (succinylpodophyllotoxin and epipodophyllotoxin thiuronium bromide), and other substances which may interfere with flagellar assembly or motility (isopropyl N-phenyl carbamate, 2-methoxy-5-nitrotropone, chloral hydrate, caffeine, and nickel acetate). The ability of each drug to inhibit binding of labeled colchicine or podophyllotoxin to mammalian brain tubulin was also determined. The results suggest that only in the cases of colchicine, colcemide, and epipodophyllotoxin thiruonium bromide was the toxicity to Chlamydomonas mediated by inhibition of tubulin assembly. The requirement for high concentrations of colchicine may be due to permeability barriers, since colchicine toxicity was potentiated by deoxycholate. Mutants resistant to antitubulins were isolated after treatment with methyl methanesulfonate. The results with vinblastine were equivocal. Of three mutants resistant to inhibition of growth and flagellar regeneration by colchicine, one was also cross-resistant to epipodophyllotoxin thiuronium bromide.

Experience with 4′-demethylepipodophyllotoxin 9-(4,6- o-2-thenylidene-beta- D-glucopyranoside); VM-26; NSC-122819 in the treatment of malignant lymphosis

Twenty-three patients, 16 with Hodgkin's Disease, 6 with lymphosarcoma and one with reticulum cell sarcoma were treated with the podophyllotoxin derivative 4′-demethylepipodophyllotoxin 9-( 4,6-o- 2-thenylidene-beta- d -glucopyranoside); (VM- 26; NSC- 122819). All patients had far advanced, stage IIIB or IV disease. With the exception of 4 patients, all had received prior therapy. An initial dosage schedule of 40 mg/M 2 three times weekly was reduced to 50 mg/M 2 twice weekly in the last 17 patients. The overall objective tumor response rate was 57%. In the patients with Hodgkin's Disease it was 69% including 2 complete remissions. The median remission duration for Hodgkin's Disease was 128 days ( 26 to 516+ days). The non-Hodgkin lymphoma remissions were shorter with a median of 33 days. The major toxic effect encountered was leukopenia with a lesser degree of thrombocytopenia. This was seen in all but 3 patients. It occurred rapidly, but was also quickly reversible. Over half the patients experienced nausea and vomiting. This limited treatment in only one patient. The value of this compound as monotherapy in malignant lymphomas has been proven. A trial of its use in combination chemotherapy is recommended.

Lignans and related phenols. Part XIII. Halogenated derivatives of podophyllotoxin

Replacement of the alcoholic hydroxy-group by halogen in podophyllotoxin on treatment with phosphorus pentahalides is followed by halogenation of the pendant aryl substituent; this occurs either by substitution of a hydrogen atom or by displacement of a methoxy-group. The sequence ends with the halogenation of the methylene-dioxy-residue. The orientation and stereochemistry of the inserted halogen atoms have been largely assigned by n.m.r. spectroscopy.