N. De Kimpe

Investigation of the antimutagenic effects of selected South African medicinal plant extracts

Dichloromethane extracts from different parts of Rhamnus prinoides, Ornithogalum longibracteatum, Gardenia volkensii, Spirostachys africana, Diospyros whyteana, Syzigium cordatum and Prunus africana were investigated for mutagenic and antimutagenic effects in Salmonella/microsome and micronucleus tests. None of the extracts tested in the Ames test were found to induce mutations or to modify the effect of the mutagen 4-nitroquinoline-oxide (4NQO). In the micronucleus test, extracts from twigs/bark of R. prinoides, twigs of D. whyteana, P. africana and S. cordatum significantly lowered the effect of the mutagen mitomycin C (MMC). Extracts from twigs/bark of G. volkensii and S. africana were genotoxic in the micronucleus test, while extracts of O. longibracteatum leaves potentiated the genotoxicity of MMC. This preliminary investigation shows that plant extracts used in traditional medicine may have particular effects with regard to mutagenicity and antimutagenicity indicating careful use in some instances and the need to isolate their active principles for further research.

A Facile Synthesis of 1,2-Disubstituted Aziridines

Abstract In spite of the fact that a number of methods are available for the preparation of aziridines, general synthetic routes leading to 1,2-disubstituted aziridines remained laborious in most cases(2-6). A convenient and versatile synthesis is desirable in order to permit studies of this important biologically active heterocyclic system.

Hypoglycemic and hypolipidemic effects of the total triterpene acid fraction from Folium Eriobotryae.

For seeking the good natural material to develop new agent to treat diabetes, the total triterpene acid (TTA) fraction extracted from Folium Eriobotryae [leaves of Eriobotrya japonica (Thunb.) Lindl.] was evaluated for its hypoglycemic and hypolipidemic potential through normal, alloxan and streptozotocin-induced diabetic mice administered with graded oral doses (100, 200, 300 mg/(kg day)) for 7 or 14 days. The results showed that a dose of 300 mg/kg of TTA is the most effective dose to cause significant (p<0.01) hypoglycemic and/or hypolipidemic effects on normal, alloxan and streptozotocin-induced diabetic mice. This dose also significantly (p<0.01) lowered the glycosylated serum protein (GSP), total cholesterol (TC) and triglyceride (TG) level in severely diabetic mice. Furthermore, TTA increased the superoxide dismutase activity (SOD) and the serum insulin level of diabetic mice. These evidences indicated that the total triperpene acid fraction from Folium Eriobotryae has a high anti-diabetic potential along with a good hypolipidemic profile.

The use of plants in traditional medicine: potential genotoxic risks

Dichloromethane and 90% methanol extracts of different parts of Antidesma venosum, Balanites maughamii, Chaetacme aristata, Croton sylvaticus, Gardenia volkensii, Plumbago auriculata and Spirostachys africana which are commonly used in South African traditional medicine were evaluated for their mutagenic potential. The genotoxicity tests used were the Ames test, micronucleus test, comet assay and VITOTOX® test. All species showed mutagenicity or DNA damage in at least one test. The species, organ extracted, extraction solvent and the type of test used, (whether based on bacterial or human cells), could affect the induction of genotoxicity.

The favorskii rearrangement of dichlorinated methylketones

Abstract Twenty-two dichlorinated methylketones have been submitted to Favorskii rearrangement in NaOMeMeOH. Distribution of products is strongly dependent on substitution. Primary dichloromethyl-ketones (R2 = H) gave rise to Favorskii esters only. Results are explained by a cyclopropanone intermediate, which is formed stereospecifically by disrotative closure of a delocalized zwitter-ion. Opening of the cyclopropanone intermediate is affected by steric and electronic influences. On the contrary secondary dichloromethylketones (R2 ≠ H) afforded Favorskii esters next to methoxyketones derived from a solvolysis mechanism.

The hepatoprotective principle of Hypoestes triflora leaves

Hypoestes triflora is frequently used in Rwandese native medicine to treat hepatic diseases. Premedication with a water extract of the leaves prevented the prolongation of the barbiturate sleeping time associated with carbon tetrachloride-induced liver damage in mice. The compound responsible for this protective activity was benzoic acid. Mice previously treated with benzoic acid also showed a significant diminution of the increased GOT and GPT levels seen after carbon tetrachloride administration.

Untargeted screening of secondary metabolites in fungal cultures and samples from mouldy indoor environments by time-of-flight mass spectrometry

Nowadays, complaints about poor indoor air quality have become common. The variety of indoor air health problems include chronic fatigue, allergy, skin and eye irritation, and can be caused by several factors including fungi and their metabolites present in a building. The objective of this study was to establish a method for untargeted analysis of secondary fungal metabolites in indoor environments. As a detection technique, time-of-flight mass spectrometry was chosen, as it provided mass accuracy and higher sensitivity in full scan acquisition mode compared to tandem mass spectrometers. The method was first applied to fungal cultures, namely Penicillium brevicompactum and Chaetomium murorum, which were isolated from mouldy houses and grown on building materials under laboratory conditions for 7-21 days. Following the proposed strategy based on accurate mass measurement and post-acquisition data processing using principal component analysis, roquefortine C, brevianamide A and mycophenolic acid were ident...

Facile Synthesis of γ-Butyrolactones

Abstract During the course of our investigations concerning the synthesis of allylic bromides bearing two electron-Withdrawing groups, it has been observed that Knoevenagel condensation products derived from aliphatic aldehydes and active methylene functions showed a tendency to undergo ring closure.1

Enantioselective Synthesis of (-)-(6R,7S)-Nitramine

The spirocyclic (-)-(6R,7S)-nitramine was prepared in a straightforward way from an appropriately substituted chiral α-allylaldimine precursor involving an electrophile-induced cyclization as the key step.

X-ray crystallographic analysis of 2-acetylimino-3-isopropyl-5-methyl-4-phenyl-2,3-dihydro-1,3-thiazole

The crystal structure determination of C15H18N2OS allows the unambiguous identification of the reaction product of an alpha-bromoketimine with potassium thiocyanate.