Discovery of podophyllotoxins.

This review deals with the historical discovery of particularly important lignan derivatives used in cancer chemotherapy. From isolation of the naturally occurring podophyllotoxin, an inhibitor of microtubule assembly, to hemisynthesis of the clinically important anticancer drugs etoposide and teniposide, it will be demonstrated how the activities and the ability of this class of compounds to inhibit topoisomerase II were discovered by different research teams. By virtue of these discoveries, new hemisynthetic derivatives, with different mechanisms of action, are bringing improvements in the ability to treat cancer.

Synthesis and antitumor activity of new glycosides of epipodophyllotoxin, analogues of etoposide, and NK 611.

A series of 3-amino- and 3-alkylamino-2-deoxy-beta-D-ribo- and beta-D-arabino-glycosides of 4'-demethylepipodophyllotoxin have been synthesized by means of an improved trimethylsilyliodide procedure for the podophyllotoxin-4'-demethylepipodophyllotoxin conversion, an efficient and high yielding synthesis of silyl glycoside donors of 3-azido-2,3-dideoxy-beta-D-ribo- and beta-D-arabino-hexopyranosides and stereoselective glycosylations. In vitro evaluation of cytotoxic effects against murine L1210 leukemia critically demonstrates the essential role played by a 4,6-acetal for biological activity. Among the most cytotoxic compounds, 3-amino-2,3-dideoxy- and 3-N, N-(dimethylamino)-2,3-dideoxy etoposide analogues, 17 and 27-29 are at least as potent as etoposide on the in vivo P388 (iv/ip) murine leukemia models. However, surprisingly enough, none of these compounds inhibits the human DNA topoisomerases I or II or binds to tubulin to prevent its polymerization and microtubule assembly. Therefore, their mechanism of action remains to be cleared up.

New substituted 1-(2,3-dihydrobenzo[1, 4]dioxin-2-ylmethyl)piperidin-4-yl derivatives with alpha(2)-adrenoceptor antagonist activity.

The emergence of a novel theory concerning the role of noradrenaline in the progression and the treatment of neurodegenerative diseases such as Parkinson's and Alzheimer's diseases has provided a new impetus toward the discovery of novel compounds acting at alpha(2)-adrenoceptors. A series of substituted 1-(2, 3-dihydrobenzo[1,4]dioxin-2-ylmethyl)piperidin-4-yl derivatives bearing an amide, urea, or imidazolidinone moiety was studied. Some members of this series of compounds proved to be potent alpha(2)-adrenoceptor antagonists with good selectivity versus alpha(1)-adrenergic and D(2)-dopamine receptors. Particular emphasis is given to compound 33g which displays potent alpha(2)-adrenoceptor binding affinity in vitro and central effects in vivo following oral administration.

F 11782, a novel epipodophylloid non-intercalating dual catalytic inhibitor of topoisomerases I and II with an original mechanism of action.

F 11782, a novel epipodophylloid, proved a potent inhibitor of the catalytic activities of both topoisomerases I and II. Unlike classical inhibitors such as camptothecin or etoposide, F 11782 did not stabilise cleavable complexes induced by either topoisomerases I or II nor did it preferentially inhibit the religation step of the catalytic cycle of either enzyme. F 11782 neither intercalated DNA nor bound in its minor groove, and showed only weak inhibition of the ATPase activity associated with topoisomerase II. F 11782 appeared to act by inhibiting the binding of topoisomerases I and II to DNA in a manner dependent both on drug and enzyme concentrations, via a mechanism not previously described or shared by other known topoisomerase 'poisons' or inhibitors. In contrast, F 11782 had only a weak effect or none at all on various other DNA-interacting enzymes. In conclusion, F 11782, as a non-intercalating, specific catalytic inhibitor of both topoisomerases I and II with an original mechanism of action, may be considered to represent the first of a new class of topoisomerase-interacting agents.

alpha2-Adrenoreceptor antagonists.

A review of the literature relating to the therapeutic potential of alpha2-adrenoceptor antagonists published between 1990 and 2000 is presented. Although extensively studied since the early 1970s in a wide spectrum of therapeutic applications, the distinction of alpha2-adrenoceptor subtypes and some emerging evidence concerning new applications in neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases, obesity and schizophrenia, have refreshed an interest in this class of agents.

A fluorescent biomarker of the polyamine transport system to select patients with AML for F14512 treatment.

The polyamine transport system (PTS), hyperactive in cancer cells, can constitute a gate to deliver F14512, a novel spermine epipodophyllotoxin conjugate recently selected for clinical development in AML phase I. We investigated in vitro the high antiproliferative effect of F14512 against 13 leukemia cell lines, and demonstrated a statistically significant correlation with the level of PTS activity, using a novel fluorescent marker F96982. This labelling protocol was then adapted for clinical applications for blood, bone marrow and AML samples with CD45 gating. Within the patient samples, the PTS activity varied significantly in AML cells, as compared to normal lymphocytes. In conclusion, the identification of PTS-positive AML with F98982 probe offers new perspectives to select patients prone to respond to F14512.

A new efficient synthesis of efaroxan.

The key step of the synthesis of efaroxan was the dihydrobenzofuran ring formation involving an intramolecular cyclization of the tertiary alcohol intermediate with the fluoroaromatic moiety in basic medium. This carbinol was prepared according to two routes, either from reaction of a benzyl Grignard reagent with an alpha-ketoester, or from a Darzens condensation.

Preclinical antitumour activity of F 11782, a novel dual catalytic inhibitor of topoisomerases.

F 11782 is a novel inhibitor of topoisomerases I and II, with an original mechanism of action (Perrin et al, 2000). This study, aimed to define its anticancer efficacy against a series of murine and human tumour models, has provided evidence of major antitumour activity for F 11782. This was demonstrated as a high level of activity against the P388 leukaemia, as reflected by increased survival of 143-457%, when administered i.p., p.o. or i.v. as single or multiple doses, and proved consistently superior to etoposide or camptothecin tested concurrently. Single or multiple i.p. doses of F 11782 also proved highly active against the s.c. grafted B16 melanoma, significantly increasing survival (P < 0.001) and inhibiting tumour growth (T/C of 0.3%), again superior to etoposide tested concurrently. Furthermore, F 11782 inhibited the number of pulmonary metastatic foci of the B16F10 melanoma by 99%. In human tumour xenograft studies, multiple i.p. doses of F 11782 resulted in major inhibitory activity against MX-1 (breast) tumours (T/C of 0.1%), as well as causing definite tumour regressions, whereas none resulted from similar experimental treatments with etoposide. Significant activity was also recorded with F 11782 against the relatively refractory LX-1 (lung) xenografts, with an optimal T/C value of 19%. It was notable that the antitumour activity of F 11782 was consistently demonstrated over a wide range of 2-6 dose levels, providing evidence of its good overall tolerance. In conclusion, these results emphasize the preclinical interest of this novel molecule and support its further preclinical development.

CRE 10904 [2-(p-fluorophenoxy), 1-(o-hydroxyphenyl)-ethane]: a new diuretic and antihypertensive drug acting by in vivo sulfation.

CRE 10904 [2-(p-fluorophenoxy), 1-(o-hydroxyphenyl)-ethane, the leading compound of a new family of loop diuretic and antihypertensive agents: 1-aryl, 2-aryloxy-ethanes] induced high-ceiling natriuretic action in dogs and rats, but was completely inactive in pigs. High-performance liquid chromatography determinations revealed that all CRE 10904 (p.o. or i.v. administered) was rapidly sulfo-conjugated in dogs and rats, and glucurono-conjugated in pigs. The (O-sulfonyl)-CRE10904 metabolite (or simply CRE 11296) rapidly appeared in plasma, reached a concentration peak at about 40 min and disappeared with a half-life time of about 3 hr. The urinary excretion of CRE 11296 was correlated with the natriuretic activity of CRE 10904. Moreover, CRE 11296 was a powerful natriuretic compound in rats and dogs and, even in pigs, i.v. CRE 11296 induced transient natriuresis (just before its rapid hydrolysis and glucurono-conjugation). Studies in human red blood cells revealed that: 1) CRE 11296 was a potent inhibitor of the [Na+,K+,Cl-]-cotransport system (IC50 of 1.5 +/- 0.3 x 10(-5) M; mean +/- S.E.M. of 5 experiments), slightly more powerful than furosemide (IC50 of 2 x 10(-5) M), 2) it was the only diuretic drug potently inhibiting the [K+,Cl-]-cotransport system (IC50 of 2.1 +/- 0.6 x 10(-5) M; N = 3) and the [Cl/HCO3-] exchanger (IC50 of 4.5 +/- 1.0 x 10(-5) M; N = 3) and 3) CRE 10904 and its glucuronide were much less potent Cl- transport inhibitors.(ABSTRACT TRUNCATED AT 250 WORDS)

Requirements for P-glycoprotein recognition based on structure-activity relationships in the podophyllotoxin series.

Podophyllotoxin and epipodophyllotoxin react with tubulin at the same binding site as colchicine, but in contrast to colchicine, do not appear to exert their cytotoxicities by mechanisms dependent on P-glycoprotein (Pgp) expression. To investigate structural requirements for Pgp recognition a series of podophyllotoxin and epipodophyllotoxin derivatives have been synthesized. Their interactions with the multidrug resistance-related protein Pgp have been studied by evaluating their relative cytotoxicities versus P388-sensitive murine leukemic cells and a classic multidrug-resistant (MDR) Pgp-overexpressing subline (P388/ADR), and their relative tubulin polymerization inhibitory activities against microtubular proteins have been determined. Based on tridimensional structure-activity relationships within this series of compounds, structural requirements for Pgp recognition have been identified. Moreover, proposals are made for extending these criteria to other chemical classes of anticancer drugs.