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See detailValidation of a high-performance thin-layer chromatography/densitometry method for the quantitative determination of glucosamine in a herbal dietary supplement
Esters, Virginie ULg; Angenot, Luc ULg; Brandt, V. et al

in Journal of Chromatography. A (2006), 1112(1-2), 156-164

A quantitative densitometric high-performance thin-layer chromatography (HPTLC) method was developed for the determination of glucosamine in a dietary supplement containing dried extracts of the main ... [more ▼]

A quantitative densitometric high-performance thin-layer chromatography (HPTLC) method was developed for the determination of glucosamine in a dietary supplement containing dried extracts of the main plants traditionally used for rheumatic disorders. The HPTLC method was chosen in order to circumvent the tedious and time-consuming sample preparation steps necessarily performed before using HPLC methods when analysing complex matrixes. Glucosamine was separated from the plant extracts on a silica gel 60 F(254) HPTLC plate using a saturated mixture of 2-propanol-ethyl acetate-ammonia solution (8%) (10:10:10, v/v/v). The plates were developed vertically up to a distance of 80 mm. For visualization, the plate was dipped into a modified anisaldehyde reagent and heated at 120 degrees C for 30 min in a drying oven. Glucosamine appeared as brownish-red chromatographic zones on a colourless background. Densitometric quantification was performed at lambda = 415 nm by reflectance scanning. The HPTLC method was successfully validated by applying the novel validation protocol proposed by a commission of the "Societe Francaise des Sciences et Techniques Pharmaceutiques" (SFSTP). In the pre-validation phase, the appropriate response function was determined, while in the validation phase the method showed good performance thereby fulfilling its objective of quantifying accurately. The relative standard deviations for repeatability and intermediate precision were between 4.9 and 8.6%. Moreover, the method was found to be accurate, as the two-sided 95% beta-expectation tolerance interval did not exceed the acceptance limits of 85 and 115% on the whole analytical range (800-1,200 ng of glucosamine). [less ▲]

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See detail5',6'-Dehydroguiachrysine and 5',6'-Dehydroguiaflavine, Two Curarizing Quaternary Indole Alkaloids from the Stem Bark of Strychnos Guianensis
Penelle, J.; Christen, P.; Molgo, J. et al

in Phytochemistry (2001), 58(4), 619-26

Two new quaternary indole alkaloids 5',6'-dehydroguiachrysine (1) and 5',6'-dehydroguiaflavine (2) were isolated from Strychnos guianensis stem bark. Their structures were determined by analysis of ... [more ▼]

Two new quaternary indole alkaloids 5',6'-dehydroguiachrysine (1) and 5',6'-dehydroguiaflavine (2) were isolated from Strychnos guianensis stem bark. Their structures were determined by analysis of spectral data. Their inhibitory effects on neuromuscular transmission are also reported and compared to that of other quaternary alkaloids. [less ▲]

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See detailMain Glucosidase Conversion Products of the Gluco-Alkaloids Dolichantoside and Palicoside
Brandt, V.; Tits, Monique ULg; Penelle, J. et al

in Phytochemistry (2001), 57(5), 653-9

The enzymatic glucose cleavage of palicoside revealed the biosynthetic pathway to akagerine, whereas the conversion of dolichantoside led to a new quaternary heteroyohimbine alkaloid named N(b)-methyl-21 ... [more ▼]

The enzymatic glucose cleavage of palicoside revealed the biosynthetic pathway to akagerine, whereas the conversion of dolichantoside led to a new quaternary heteroyohimbine alkaloid named N(b)-methyl-21-beta-hydroxy-mayumbine. The hypothetical models of reactions occurring after the conversion of both substrates are proposed. Dolichantoside and palicoside, as well as Strychnos mellodora stem bark crude ethanol extract, exhibit significant antimycotic activity against human pathogens in presence of specific glucosidase. [less ▲]

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See detailStrychnogucines a and B, Two New Antiplasmodial Bisindole Alkaloids from Strychnos Icaja
Frederich, Michel ULg; Gillet, Marie-Claire ULg; Prosperi, Christelle ULg et al

in Journal of Natural Products (2001), 64(1), 12-16

A reinvestigation of Strychnos icaja roots has resulted in the isolation of two tertiary quasi-symmetric bisindole alkaloids named strychnogucines A (1) and B (2). Their structures were identified by ... [more ▼]

A reinvestigation of Strychnos icaja roots has resulted in the isolation of two tertiary quasi-symmetric bisindole alkaloids named strychnogucines A (1) and B (2). Their structures were identified by means of spectroscopic data interpretation. Compound 2 was highly active in vitro and compound 1 moderately active against four strains of Plasmodium falciparum. Strychnogucine B (2) was more active against a chloroquine-resistant strain than against a chloroquine-sensitive one (best CI(50), 80 nM against the W2 strain). In addition, this compound showed a selective antiplasmodial activity with 25-180 times greater toxicity toward P. falciparum, relative to cultured human cancer cells (KB) or human fibroblasts (WI38). [less ▲]

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See detailGuiaflavine, a New Bisindole Quaternary Alkaloid from the Stem Bark of Strychnos Guianensis
Penelle, J.; Tits, Monique ULg; Christen, P. et al

in Journal of Natural Products (1999), 62(6), 898-900

A reinvestigation of Strychnos guianensis resulted in the isolation of a colored quaternary bisindole alkaloid from the stem bark. The structure of this new substance, guiaflavine (1), was defined by ... [more ▼]

A reinvestigation of Strychnos guianensis resulted in the isolation of a colored quaternary bisindole alkaloid from the stem bark. The structure of this new substance, guiaflavine (1), was defined by detailed spectroscopic methods and comparison with model compounds. [less ▲]

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See detailbeta-carboline glucoalkaloids from Strychnos mellodora
Brandt, V.; Tits, Monique ULg; Geerlings, A. et al

in Phytochemistry (1999), 51(8), 1171-1176

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See detail3 ',4 ',5 ',6 ' tetradehydrolongicaudatine Y, an anhydronium base from Strychnos usambarensis
Frederich, Michel ULg; Quetin-Leclercq, J.; Biala, R. G. et al

in Phytochemistry (1998), 48(7), 1263-1266

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See detailGlucoindole alkaloids from stem bark of Strychnos mellodora
Brandt, V; Tits, Monique ULg; Angenot, Luc ULg

Poster (1996, February)

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See detailGlucoindole Alkaloids from Stem Bark of Strychnos Mellodora
Tits, Monique ULg; Brandt, V.; Wauters, Jean-Noël ULg et al

in Planta Medica (1996), 62(1), 73-4

Three glucoindole alkaloids, dolichantoside (1), strictosidine (2), and palicoside (3), have been identified in the stem bark of Strychnos mellodora (Loganiaceae), collected in Zimbabwe. The chiroptical ... [more ▼]

Three glucoindole alkaloids, dolichantoside (1), strictosidine (2), and palicoside (3), have been identified in the stem bark of Strychnos mellodora (Loganiaceae), collected in Zimbabwe. The chiroptical (CD) data are compared. [less ▲]

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