A novel benzofuro-(2, 3-c)-7'-chromene from Cassia sieberiana.

The stem bark of Cassia sieberiana was extracted with methanol and the methanol extract partitioned with chloroform. Column chromatography of the chloroform fraction over silica gel yielded a novel benzofurochromene [2-(4-hydroxylphenyl)-7'-1, 2-dihydroxy-1-phenylpropyl)-4', 6'-dihydroxy [1] phenylbenzofuro (2, 3-c)-7'-chromene], lupeol and epiafzelechin. Their structures determined by Nuclear Magnetic resonance and mass spectrometry.[Figure: see text].

Bioassay-guided isolation of active principles from Nigerian medicinal plants identifies new trypanocides with low toxicity and no cross-resistance to diamidines and arsenicals.

ETHNOPHARMACOLOGICAL RELEVANCE: Leaves from the plant species studied herein are traditionally used in northern Nigeria against various protozoan infections. However, none of these herbal preparations have been standardized, nor have their toxicity to mammalian cells been investigated. In search of improved and non-toxic active antiprotozoal principles that are not cross-resistant with current anti-parasitics, we here report the results of the in vitro screening of extracts from seven selected medicinal plant species (Centrosema pubescens, Moringa oleifera, Tridax procumbens, Polyalthia longifolia, Newbouldia laevis, Eucalyptus maculate, Jathropha tanjorensis), used traditionally to treat kinetoplastid infections in Nigeria, and the isolation of their bioactive principles. AIM OF THE STUDY: To investigate the efficacies of medicinal plant extracts, and of compounds isolated therefrom, against kinetoplastid parasites, assess cross-resistance to existing chemotherapy, and assay their toxicity against mammalian cells in vitro. MATERIAL AND METHODS: Plants were extracted with hexane, ethyl acetate and methanol. Active principles were isolated by bioassay-led fractionation, testing for trypanocidal activity, and identified using NMR and mass spectrometry. EC50 values for their activity against wild-type and multi-drug resistant Trypanosoma brucei were obtained using the viability indicator dye resazurin. RESULTS: Seven medicinal plants were evaluated for activity against selected kinetoplastid parasites. The result shows that crude extracts and isolated active compounds from Polyalthia longifolia and Eucalyptus maculata, in particular, display promising activity against drug-sensitive and multi-drug resistant Trypanosoma brucei. The EC50 value of a clerodane (16α-hydroxy-cleroda-3,13(14)-Z-dien-15,16-olide) isolated from Polyalthia longifolia was as low as 0.38µg/mL, while a triterpenoid (3ß,13ß-dihydroxy-urs-11-en-28-oic acid) isolated from Eucalyptus maculata displayed an EC50 of 1.58µg/mL. None of the isolated compounds displayed toxicity towards Human Embryonic Kidney cells at concentrations up to 400µg/mL. In addition, the isolated compounds were active against Leishmania mexicana, as well as against T. congolense. CONCLUSION: We have isolated a clerodane compound from Polyalthia longifolia that shows low toxicity, no cross-resistance with current treatments, and promising activity against both human-infective and veterinary Trypanosoma species.

Antitrypanosomal activity & docking studies of isolated constituents from the lichen Cetraria islandica: possibly multifunctional scaffolds.

Chemical investigation of the lichen Cetraria islandica has led to the isolation of four compounds identified as protolichesterinic acid, lichesterinic acid, protocetraric acid and fumarprotocetraric acid. Their structures were characterized using their physical and spectroscopic data. Using an Alamarblue™ 96 well microplate assay, these compounds were tested to evaluate their trypanocidal activity against Trypanosoma brucei brucei. Protolichesterinic acid (MIC = 6.30 µM) and lichesterinic acid (MIC = 12.5 µM) showed very significant activity against the test organism. Docking studies (GRIP technique) of these molecules revealed their strong affinity towards possible targets of Trypanosoma brucei such as riboflavin kinase, sterol-14α-demethylase (CYP51), rohedsain and glutathione synthetase. Hydrophobicity played a significant role in their antitrypanosomal activity.

Antitrypanosomal activity & docking studies of components of Crateva adansonii DC leaves: novel multifunctional scaffolds.

Chemical investigation of Crateva adansonii DC has led to the isolation of aurantiamide acetate, a novel ethyl pyropheophorbide A, purpurin-18 ethyl ester and pyropheophorbide A. Their structures were elucidated using extensive spectral data. These metabolites were then evaluated for their in vitro bioactivity against the African trypanosome Trypanosoma brucei brucei (S427) blood stream forms. Anti-trypanosomal activity decreased with aurantiamide acetate (MIC 25µM), while it increased with the pheopytins (MIC 6.25µM), when compared to the standard drug Suramin. Using the Vlife MDS 4.3 - GRIP docking, these phytoconstituents were then tested to identify the proteins targeted and the mode of activity employed. Their affinity towards the receptor sites of trypanothione reductase, riboflavin kinase, rohedsain, glutathione synthetase & sterol-14α-demethylase (CYP51) of Trypanosoma brucei were evaluated according to the resulting docking energies.