Biomedical subjects
Publications and source records attributed to R Vanhaelen-Fastré.
A new alkaloid, named gasabiimine (1), together with four known bisbenzyltetrahydroisoquinoline alkaloids (phaeanthine, 1,2-dehydroapateline, N-methylapateline, O-methylcocsoline) has been isolated from the roots of Triclisia sacleuxii. The structure of the new alkaloid was elucidated by spectroscopic data analysis.
Several triterpenes isolated from Leptadenia hastata latex were tested for their anti-inflammatory activity. Lupeol (1), its acetate (2) and palmitate (3) esters were found to be the main antiinflammatory constituents in the croton oil-induced ear oedema test. Furthermore, lupeol hemisuccinate (4), synthesized from lupeol, exhibited a higher activity than lupeol in the test. These results prove that the triterpenes play a pivotal role in the topical antiinflammatory effect of this latex. In addition, an in vitro model of human skin keratinocytes (epidermal explants) cultured at an air-liquid interface on a de-epidermized human dermis (DED) was used to investigate the effects of lupeol esters on skin repair in vitro. Compared with the control, compounds 2 and 3 improved keratinocyte proliferation at a concentration of 5 microM in the culture medium; however, they remained less active than compounds 1 and 4. In contrast to compound 1, all the lupeol esters (2-4), and particularly compound 4, induced a good differentiation of keratinocytes with a well-formed stratum corneum without parakeratosis. These results substantiate the topical use of Leptadenia hastata latex in traditional medicine and showed that both antiinflammatory activity and the effect on keratinocyte proliferation of compound 1 could be improved by its hemisuccinylation; on the contrary, esterification by acetylation or palmitoylation decreased these activities.
Two groups of patients with sickle-cell disease were given a single dose of sodium cromoglicate by inhalation or nasal route. The striking decrease in sickle cells after treatment by both routes lends support to the role of sodium cromoglicate in sickle-cell disease treatment.
We previously observed that aqueous extracts of the stem bark and leaves of Khaya senegalensis exhibited a strong antisickling activity. These results prompted us to find out the constituent(s) responsible for these properties using an in vitro bio-guided fractionation. The bioassay was based on sickle cells countings, before and after deoxygenation, in blood samples taken from patients with severe sickle cell anemia and pre-incubated with the drugs to be tested. The main active constituent was identified as a rearranged limonoid whose structure was recently elucidated. In comparison with pentoxifylline used as standard, the in vitro antisickling activity of this limonoid was much higher at any concentrations and incubation conditions. In addition, it did not alter significantly the corpuscular indices.
The improvement in sickle cell disease (SCD) children receiving cromolyn sodium therapy prompted us to investigate its antisickling activity in vitro. The number of sickle cells was determined in deoxygenated blood samples from 15 children with severe SCD. At the eight concentrations tested, cromolyn sodium exhibited a significantly higher activity than pentoxifylline, the standard compound. Therefore cromolyn sodium would appear to be an interesting candidate for SCD therapy and deserves further in vivo investigations.
Polyclonal antibodies raised against 2'-succinyltaxol-bovine serum albumin (BSA) conjugate were used for the immunodetection of bioactive taxoids in chromatographic fractions of the stem bark extract of Taxus baccata. In addition to taxol, cephalomannine, and baccatin III, two taxoids were isolated and their structures were elucidated as 4 alpha,7 beta-diacetoxy-2 alpha,9 alpha-dibenzoxy-5 beta,20-epoxy-10 beta, 13 alpha, 15-trihydroxy-11(15-->1)-abeo-tax-11-ene[5] and taxol C [6] using spectroscopic methods.
Two new taxoids, 13-deoxo-13 alpha-acetyloxy-7 beta,9 alpha-diacetyl-1,2-dideoxytaxine B[1] and 7 beta-xylosyl-10-deacetyltaxol D [7], were isolated from the stem bark of Taxus baccata cv. stricta. Their structures were elucidated using spectroscopic methods and their bioactivity was evaluated using an in vitro microtubule assembly assay.
Callus cultures of Taxus baccata L. cv. stricta were induced from hypocotyl and leaf explants on Woody Plant medium (hormone-free or additionated with phytohormones). Under continuous dark condition, adventitious roots were regenerated from hypocotyl- and leaf-derived callus cultures. Antibodies raised in rabbits against 10-succinyl-10-deacetylbaccatin III were used for the detection and the semi-quantitative determination of 10-deacetylbaccatin III in Taxus cultures. The presence of 10-deacetylbaccatin III in callus extracts was confirmed by TLC, HPLC using a photodiode array detector and mass spectrometry (CI-MS). The highest equivalent content of the taxoid derivatives (7.83 mg/100 g dry wt.) was detected in an extract from leaf-derived callus.
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The determination of potential vitamin D concentrations in raw materials and in multivitamin formulations by high-performance liquid chromatography is reported. Simple experimental conditions allow the rapid separation of the vitamins from their respective pro- and pre-vitamins, from their irradiation side-products and from some of their overirradiation products. Vitamin extraction is performed directly from dry concentrates, tablets and capsules, without saponification; all procedures are carried out at room temperature so as to preserve the ratio of vitamin D and pre-vitamin D present in the prepatation. The relative standard deviation is less than 1.5%.
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The volatile materials emitted by Trichothecium roseum (Fungi Imperfecti) at a very low concentration are strong attractants for Tyrophagus putrescentiae (Schrank, 1781) (Acarina, Acardae). The identification of cis- and trans-octa-1,5-dien-3-ol, the main attractant constituents of these volatile materials, was performed by spectroscopic methods (GC/MS and NMR) on a microsample (less than 100 micrograms) isolated by a new pre-concentration method. Although this unsaturated alcohol has only been found in Trichothecium roseum and in a Rhodophyta, it may be present in other microfungi and in fungi and may be implicated in the ecological process.
The metabolism of clocoumarol, 3-[1-[P-(2-chlorethyl)phenyl]butyl]-4-hydroxycoumarin, by rat liver microsomes was investigated. The chemical structure of the main metabolite is 6-[1-hydroxy-2-oxo-3-[p-(2-chloro