Biomedical subjects
Publications and source records attributed to L Angenot.
Several indole alkaloids were tested by the agar dilution technique on a panel of human pathogenic fungi, yeasts, and dermatophytes. Our results indicate that the most active compounds possess a beta-carboline skeleton and that the presence of a 3-4 double bond enhances the activity. Our results also show that antifungal activities are not linked to the cytotoxic, antimicrobial or antiparasitic properties.
In this work, we have analysed the effects of alpha-hederin, a monodesmosidic triterpenoid saponin isolated from Hedera helix, on mouse B16 melanoma cells and non-cancer mouse 3T3 fibroblasts cultured in vitro. Our results indicate that, in a serum-free medium, alpha-hederin is cytotoxic and inhibits proliferation in both cell lines at rather low concentrations (< 5 micrograms/ml) after only 8 hours of treatment. Its cytotoxicity decreases in the presence of serum in which BSA seems to be able to bind the saponin. alpha-Hederin also induces vacuolization of the cytoplasm and membrane alterations leading to cell death.
We analysed the effects of strychnopentamine, an alkaloid isolated from Strychnos usambarensis, on an Ehrlich ascites tumor growing in the mouse after inoculation. Four subcutaneous injections of 1.5 mg strychnopentamine (1 per day) induce a significant decrease of the number of tumor cells and a significant increase of the survival of the treated mice. Observed side effects are partial haemolysis and some liver damage.
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This paper describes the powerful cytotoxic action exerted by strychnopentamine (SP), a dimeric indole alkaloid extracted from Strychnos usambarensis Gilg, on B16 melanoma cells and on non-cancer human fibroblasts cultured in vitro. SP strongly inhibits cell proliferation and induces cell death at a relatively low concentration (less than 1 microgram/ml) after 72 h of treatment in the two lines. Incorporation of [3H]thymidine and [3H]leucine by B16 cells significantly decreases after only 1 h of treatment at 0.5 microgram/ml. SP induces the formation of dense lamellar bodies and vacuolization in the cytoplasm, intense blebbing at the cell surface and various cytological alterations leading to cell death.
Strychnos henningsii Gilg is used in African traditional medicine for the treatment of various ailments, including rheumatism, gastrointestinal complaints and snake bites. Different preliminary pharmacological experiments are described. The results show that some of the reported folk medicinal applications of S. henningsii can be at least partially explained by the presence of retuline-like alkaloids, whose use could lead to new antinociceptive (antiinflammatory and analgesic) and antispasmodic drugs.
Seven alkaloids isolated from Strychnos usambarensis have been assessed for in vitro activities against Entamoeba histolytica and Plasmodium falciparum and for in vivo activity against Plasmodium berghei in mice. Strychnopentamine and 3',4'-dihydrousambarensine were highly active against P. falciparum in vitro, but were inactive and non-toxic against P. berghei in vivo. Usambarensine, usambarine, and 18,19-dihydrousambarine were highly active against E. histolytica in vitro, but were less active against P. falciparum in vitro. Nb-Methylusambarensine was less active against both protozoa than was usambarensine, and akagerine possessed little antiprotozoal activity. Structure-activity relationships are discussed in the context of the reported cytotoxic and pharmacological properties of these alkaloids.
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The ethnobotanical uses of South American species of Strychnos L. (Loganiaceae) are reviewed, with the exception of their major rôle in the preparation of curare, which will be dealt with in detail elsewhere. Medicinal uses are less common than is the case with the African and Asian species of the genus. About 140 samples, mostly of leaves, belonging to 53 species, have been screened for alkaloids. As with species from other parts of the world, the stem bark and root bark tend to be a richer source than leaves. Nor-harman is present in extracts from S. barnhartiana leaves. Pyridino-indolo-quinolizidinone (angustine-type) bases are also found in several species. The occurrence and pharmacology of the (non-curarizing) alkaloids known to be present in South American Strychnos species is reviewed.
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The potential cytotoxic activities of 46 alkaloids isolated from different Strychnos species were tested on different cancer or normal cells cultured in vitro. The authors used a relatively simple microtest which gives good reproducibility. Most of the active compounds belong to the usambarane skeleton but other structure-activity relationships are being discussed.
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Strychnopentamine has been tested for its cytotoxic and antitumor activities and compared with two other bisindolic alkaloids that possess an usambarane skeleton. The presence of a N-methylpyrrolidine group increases the antimitotic activity of this type of alkaloids.
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