Synthesis of vinca alkaloids and related compounds, Part XCVI. Nitration study of vinblastine-type bisindole alkaloids

The bisindole alkaloids vinblastine, vincristine, and N-formyl-leurosine were nitrated and subsequently converted to amino derivatives. In the case of compounds 5e and 5b cytotoxic activity has been found for non-small cell lung cancer and breast cancer in the concentration range tested (10(-5)-10(-9) M). 5b also showed potency in the screen for colon cancer and leukemia.

Synthesis and biological activity of the structural analogues of (-)-cabenegrin A-I

A series of phenylbutene and butanol derivatives (6a-j, 12, 13, 15, 17, 24b,c, 26, 27a,b) were prepared from the readily available resorcinol derivatives 2a-f and 7-hydroxy-chroman (18). The products were tested for inhibitory activity on the LPS-induced TNF-alpha production in the plasma in comparison with that of cabenegrin A-I (1a).

Role of sodium channel inhibition in neuroprotection: effect of vinpocetine

Vinpocetine (ethyl apovincaminate) discovered during the late 1960s has successfully been used in the treatment of central nervous system disorders of cerebrovascular origin for decades. The increase in the regional cerebral blood flow in response to vinpocetine administration is well established and strengthened by new diagnostical techniques (transcranial Doppler, near infrared spectroscopy, positron emission tomography). The latest in vitro studies have revealed the effect of the compound on Ca(2+)/calmodulin dependent cyclic guanosine monophosphate-phosphodiesterase 1, voltage-operated Ca(2+) channels, glutamate receptors and voltage dependent Na(+)-channels; the latest being especially relevant to the neuroprotective action of vinpocetine. The good brain penetration profile and heterogenous brain distribution pattern (mainly in the thalamus, basal ganglia and visual cortex) of labelled vinpocetin were demonstrated by positron emission tomography in primates and man. Multicentric, randomized, placebo-controlled clinical studies proved the efficacy of orally administered vinpocetin in patients with organic psychosyndrome. Recently positron emission tomography studies have proved that vinpocetine is able to redistribute regional cerebral blood flow and enhance glucose supply of brain tissue in ischemic post-stroke patients.

Intramolecular Mannich Reaction of 2-Oxotryptamines with Acetone Yielding Spiro[indole-3,3'-pyrrolidin]-2-ones

2-Oxotryptamines undergo intramolecular Mannich-type cyclization with acetone to give 2',2'-dimethylspiro[indole-3,3'-pyrrolidin]-2-ones. In presence of an alkylating reagent, this reaction gives the corresponding 1'-substituted products.

Analysis and implications of transition-band signals in high-resolution NMR

The problem of signals generated in and received from regions outside the active coil area is discussed in the context of using standard measurement techniques. Some of the conceptual and practical consequences of the existence of such transition-band signals are highlighted. Examples include radiation damping, pulse-width calibration, lineshape and radiofrequency homogeneity tests, improper saturation, and exchange- and relaxation-rate determinations. One interesting implication is that apparent sample-to-sample variations in the calibrated 90 degrees pulse width values are a function not only of probe tuning and bulk susceptibility effects, but also of the linewidths involved. A semi-quantitative treatment of the phenomenon is also given.

[New antitumor derivatives of vinblastine]

The alkaloids of Catharanthus roseus vincristine 1 and vinblastine 2 are widely used in the chemotherapy of cancer. Their nitro-derivatives have also antitumour activity [2]. The dinitro-derivatives 4, 6-9 were prepared for pharmacological investigation. Some new hydroxymethyl derivatives 12-14, 17-18, 23-24 of the antitumour indole-indoline alkaloids vinblastine 2 and leurosine 5 were synthetised in two different ways a) by the selective reduction of 2, 5 or deacetoxy-vinblastine 16, b) by the ferric chloride mediated coupling reaction of catharanthine 19 and the corresponding vindoline derivatives 21, 22. Synthetising 24 a new bisvindoline 25 was the main product. 13 and 14 showed cytotoxic activity for small cell lung cancer LXFS 650.

Inhibition of gamma-aminobutyric acid uptake by bicuculline analogues

Enantiomers of norbicuculline, (+)[1S,9R] and (-)[1R,9S]erythro-1-[1'-(4',5'-methylenedioxyphthalidyl)]-6,7-meth ylenedioxy-1,2,3,4-tetrahydroisoquinoline and of the N-methyl derivatives {(+)[1S,9R] and (-)[1R,9S]bicuculline} were found to inhibit the progress of the gamma-aminobutyric acid transporter-mediated uptake of 40 microM [14C]gamma-aminobutyric acid into native plasma membrane vesicles from the rat cerebral cortex at 30 degrees C. The values for the dissociation constants of the reversible inhibition, relative to (+)[1S,9R]bicuculline, in order of increasing inhibition, were: (-)[1R,9S]bicuculline, 3.3; (+)[1S,9R]-bicuculline, 1.0; (-)[1R,9S]norbicuculline, 0.4 approximately (+)[1S,9R]norbicuculline; guvacine, 0.02. The norbicucullines have higher potencies than (+)[1S,9R]bicuculline for the gamma-aminobutyric acid transporter, in contrast to the relative potencies of these inhibitors for the inhibition of function and gamma-aminobutyric acid binding of the gamma-aminobutyric acid type A receptor.