Maurice Vanhaelen
Université libre de Bruxelles
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Featured researches published by Maurice Vanhaelen.
Phytochemistry | 1988
Mondher El Jaziri; Marc Legros; Jacques Homes; Maurice Vanhaelen
Abstract Hairy root were induced by inoculation of Agrobacterium rhizogenes in sterile seedlings of Datura stramonium and Hyoscyamus niger . The transformed roots cultures were established and subcultured on a Murashige and Skoog [1] hormone free medium. Several strains of hairy root were obtained from different genotypes of D. stramonium . Determination of hyoscyamine and scopolamine was performed by TLC-densitometry. A high variability of alkaloids production was observed between the different strains. Sucrose concentration as well as mineral composition of the culture medium influence the alkaloidal content of the transformed roots; scopolamine concentration expressed on a dry weight basis reached 0.56% in optimum conditions.
Plant Cell Tissue and Organ Culture | 1997
A.T. Bakkali; Mondher El Jaziri; A. Foriers; Y. Vander Heyden; Maurice Vanhaelen; Jacques Homes
The improvement of axillary shoot formation of Lawsonia inermis L. cultured in vitro depended on the iron concentration in the culture medium. Regenerated shoots were rooted on a hormone-free half-strength Murashige and Skoog medium (1/2 MS) before transfer to greenhouse conditions. Determination of lawsone in the plant material was investigated using a new HPLC method. The results showed that lawsone accumulation in vivo is restricted to the aerial part of the plant. In addition, the possibility of inducing lawsone biosynthesis in root cultures was studied. Hairy root cultures were established by a co-culture method using leaf segments of L. inermis and Agrobacterium rhizogenes NCIB 8196. Of several basal media tested, the production of lawsone (0.13% dry weight) was only observed in hairy roots tissues incubated in the dark and cultured in 1/2 MS or MS media.
Phytochemistry | 1993
Mondher El Jaziri; Bilo Diallo; Maurice Vanhaelen; Jacques Homes; Kayo Yoshimatsu; Koichiro Shimomura
Abstract A highly specific and sensitive ELISA method was developed for the detection and semi-quantitative determination of artemisinin and its structurally related compounds in crude extracts of Artemisia annua. The antibodies were raised in rabbits using a 10-succinyldihydroartemisinin-BSA conjugate as immunogen. The peroxide linkage in the artemisinin molecule was critical in determining the antibody specificity. The working range of the assay was from 0.02 to 10 ng per assay. The cross-reacting material in crude plant extracts was evaluated by chromatographic methods combined with the immunoassay method. The distribution of artemisinin equivalents in five-week-old A. annua plants cultivated in hydroponic conditions was investigated. The highest artemisinin equivalent content (1.12% dry wt) was found in the leaves of the upper parts of the plant.
Journal of Liquid Chromatography & Related Technologies | 1988
Maurice Vanhaelen; R. Vanhaelen-fastre
Abstract A procedure which combined countercurrent chromatography with gradient elution and preparative high-performance liquid chromatography was developed for the isolation and the purification of the seven predominant flavonol glycosides from Ginkgo biloba leaves.
Journal of Liquid Chromatography & Related Technologies | 1992
Renée Vanhaelen-Fastré; Bilo Diallo; Mondher El Jaziri; M.-L. Faes; Jacques Homes; Maurice Vanhaelen
Abstract Taxol and related taxane diterpenoids were isolated from pre-purified extracts of stem-barks of Taxus bacccata by HSCCC. The described method allowed to obtain a mixture of taxol and cephalomannine without any other interfering constituent and furthermore a partial separation of taxol (40 % of the total recovery) from cephalomannine. In addition, the HPLC and TLC separation conditions of these compounds for the semi-preparative and analytical purposes were improved. The proposed HSCCC method could be adapted to the scaling-up separation of taxol from vew material.
Plant Cell Tissue and Organ Culture | 1994
Abdesselam Zhiri; Mondher El Jaziri; Jacques Homes; Maurice Vanhaelen; Koichiro Shimomura
A simple and efficient in vitro method for breaking the dormancy of Taxus baccata L. cv. Stricta seeds was investigated. The highest rate of germination (100%) of embryos isolated from seeds, which had been washed with running tap water for 7 days, was obtained after 7 days of culture on modified Murashige and Skoog or Heller media. The taxol equivalent content in 2-month-old Taxus plantlets was investigated using anti-taxol polyclonal antibodies. The results showed that the taxol equivalent content varied, depending on Taxus species and on the individuals in the same taxon.
Journal of Ethnopharmacology | 1987
Bilo Diallo; Maurice Vanhaelen; Yoshinobu Kiso; Hiroshi Hikino
The antihepatotoxic activity of the rhizomes of Cochlospermum tinctorium was investigated using carbon tetrachloride- and galactosamine-induced cytotoxicity in primary cultured rat hepatocytes. Because the methanol and ethanol extracts of C. tinctorium rhizomes exhibited antihepatotoxic effects, the former was fractionated in order to elucidate the active constituents. Polyphenol compounds (gallic and ellagic acids) were detected in the active fractions and may account for much of the antihepatotoxic activity. Carotenoids could also be implicated in the activity of the total extracts.
Phytochemistry | 1987
Bilo Diallo; Maurice Vanhaelen
Abstract Seven carotenoids have been isolated from Cochlospermum tinctorium by means of countercurrent chromatography and HPLC. The two major constituents were identified by spectroscopic methods (UV-VIS, IR, 1 H NMR, 13 C NMR and EIMS) as 6-hydroxy-8′-apo-e-caroten-3-one-8′-oic acid (cochloxanthin) and 4,5-dihydro-6-hydroxy-8′-apo-e-caroten-
Phytochemistry | 1991
Bilo Diallo; Renée Vanhaelen-Fastré; Maurice Vanhaelen
Abstract The composition of the volatile fraction from Cochlospermum tinctorium rhizome was investigated by GC and GC-MS; among 11 constituents detected, eight were identified as straight chain ketonic compounds. In addition, five triacylbenzenes were isolated from a petrol extract of the rhizome, separated by HPLC and identified by their spectral data.
Journal of Liquid Chromatography & Related Technologies | 1988
Bilo Diallo; Maurice Vanhaelen
Abstract Carotenoids are well-known for their instability so as usual analytical methods such as HPLC or preparative TLC applied to the separation of the constituents of Cochlospermum tinctorium failed to the isolation of pure pigments for further chemical characterization. Thus high-speed CCC using a horizontal flow-through coil planet centrifuge was used to conveniently and efficiently achieve this separation for quantities up to 500mg of the crude plant extract.