Biomedical subjects
Publications and source records attributed to H P Husson.
A non-rigid cyclopropane-containing diamine analogue of CP-99,994 was synthesised and was found to have only moderate NK1 receptor binding affinity. Molecular dynamics calculations of the conformational space of the former compound gave good correlation between observed activity and a recently published pharmacophore model, lending predictive value to the latter.
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Various oxazolidines prepared in two steps from (R)-phenylglycinol react at 0 degrees C with dialkylalkynylalane-triethylamine complexes in the presence of trimethylaluminum in high yield and diastereoselectivity. Enantiomerically pure primary alpha-substituted propargylamines can be easily obtained in two steps after removal of ferrocenylmethyl protective group under smooth acidic conditions and oxidative cleavage of the chiral appendage.
A rapid, sensitive and specific high-performance liquid chromatographic method for the quantification of acrolein (1), one of the toxic metabolites of oxazaphosphorine alkylating agents (cyclophosphamide and ifosfamide) was developed. Condensation of acrolein with Luminarin 3 afforded a fluorescent derivative that could be specifically detected and quantified. Chromatographic conditions involved a C18 RP column Uptisphere and a gradient elution system to optimize resolution and time analysis. The method showed high sensitivity with a limit of detection of 100 pmol/ml and a limit of quantification of 300 pmol/ml. This technique is particularly suitable for pharmacokinetic studies on plasma of oxazaphosphorine-receiving patients.
One unsubstituted and one stereoselectively prepared 3-(S)-substituted-2-oxopiperazine have been used as dipeptide templates to generate tetrapeptide analogues. NMR analysis shows that these tetrapeptide analogues present an inverse gamma-turn conformation in chloroform.
Following a brief historical review of the notion of chirality, the importance of the relationship between pharmacological activity and the enantiomeric forms of drugs is indicated. Different approaches for the preparation of optically-pure molecules are discussed, and an original strategy, known as the "CN(R,S) method", is described. To conclude, an application of this method in the synthesis of a pharmacologically-active molecule is presented.
Five alkaloids have been isolated from a New Caledonian sponge Xestospongia sp. These include three known xestospongin derivatives, the new demethylxestospongin B (1) and a tetrahydrocarboline derivative 5. The structures of the new compounds 1 and 5 have been established by nmr studies and comparison with previously described products.
The MDR P-glycoprotein has been described as a major factor of multidrug resistance. This transmembrane glycoprotein acts like an energy dependent efflux pump which possesses a broad specificity. It seems to be acting as a pump requiring drug fixation prior to extrusion. With the aim of investigating which parameters influence the recognition of drugs by the MDR system, we have determined the toxicities of different drugs on human and murine sensitive and resistant cell lines. For this purpose we have isolated and characterized a human adriamycin-resistant cell line, CEM/Adr, which presents an MDR phenotype. The tested drugs were ellipticine and olivacine derivatives which differ through discrete lateral chain substitutions. The influence of lateral chain lipophilicity and nitrogen quaternarization on drug recognition was studied. Small modifications in the chemical structure of the drugs have induced large changes in their toxicities and in the cross-resistance levels of the MDR cells to the tested compounds. The cross-resistances of the murine and human cells to the various compounds were strikingly different. The validity of murine screening models in the selection of anti-tumor drugs for human therapy must therefore be questioned.
The chemical synthesis of 9-hydroxyolivacine and 7-hydroxyolivacine based on a biomimetic approach is described. These two hydroxylated derivatives have been found as main in vitro metabolites of olivacine after incubation with rat hepatic microsomes. The pretreatment of animals with benzo[a]pyrene caused a large increase in both microsomal hydroxylations, whereas the pretreatment with phenobarbital caused a weak increase, with a preservation of 9-hydroxylation/7-hydroxylation ratio greater than 1 in both cases. The two hydroxyolivacines have been also found as principal in vivo metabolites of olivacine in rat bile as glucuronide and sulfate conjugates. The pretreatment of animals with benzo[a]pyrene reverses the 9-hydroxyolivacine/7-hydroxyolivacine ratio excretion in bile to a value that is less than 1. In both in vitro and in vivo experiments, the free metabolites were identified by HPLC and UV-visible, MS, and 1H NMR spectra. Hydroxylation at position 9 increases the in vitro cytotoxicity against leukemia L1210 cells (ID50 = 0.06 microM compared to 2.03 microM for olivacine) and an opposite effect is observed for hydroxylation at position 7 (ID50 = 12.8 microM). On the other hand, hydroxylation at position 9 has no effect on the in vivo antitumor activity against L1210. This might be related to the oxidative and conjugative metabolic pathways that play an important role in antitumor activity and deactivation of olivacine and its hydroxy metabolites.
Platelets of reserpinized rabbits, incubated in buffer containing tritiated 5-hydroxytryptamine (3H-5HT), have the ability to convert 3H-5HT into labeled compound(s) extractable with alkaline-chloroform. The bulk of the chloroform-extractable radioactivity showed a Rf value similar to authentic melatonin on silicagel thin-layer chromatography. The labelled product eluted with ethanol from the silicagel area where melatonin was suspected to reside was identified as melatonin by mass spectrometry and radioimmunoassay. Our in vitro experiments demonstrate that rabbit platelets are capable of converting 5-HT into melatonin apparently because they possess the enzymatic equipment necessary for this biosynthesis i.e. serotonin N-acetyltransferase and hydroxyindole-O-methyltransferase.
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A structural immunochemical study has shown that fixation of melatonin on bovine serum albumin by formaldehyde occurs via reaction of both an indole NH group and the side chain, allowing extremely specific antibody production. Isotopic in vitro investigations and radioimmunological estimation of this hormone in man and in the rat shows that it is transported by plasmatic albumin in a 1/10(6) ratio and is eliminated in the urine as native material, 6-hydroxy melatonin and as an as yet unidentified metabolite.
The sites of fixation to bovine serum albumin of melatonin and of mono- and dimethylated melatonin identified by mass spectrometry and nuclear magnetic resonance, have been determined. The binding sites appear to be important in the conservation of the structural features necessary for the antigenicity of the molecule.
A total alkaloid and two purified alkaloid extracts of Alangium vitiense were found to be oncostatic for L1210 leukemia; the total alkaloid exerted a noticeable activity, and the purified extracts exerted a borderline activity. These two purified extracts are noticeably oncostatic for two other lymphoid neoplasias in mice, P388 leukemia and Gardner lymphosarcoma. These compounds are not active on Warner myelomonocytic leukemia WEH13 or on B16 melanoma.
A total alkaloid and two purified alkaloid extracts of Alangium Vitiense were revealed by our experimental screening to be oncostatic on L1210 leukemia and two other lymphoid neoplasias in Mice. They are not active on myelomonocytoid leukemia WEHI3 nor on B16 melanoma.
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