Salomé Kpoviessi

Chemical composition, cytotoxicity and in vitro antitrypanosomal and antiplasmodial activity of the essential oils of four Cymbopogon species from Benin.

ETHNOPHARMACOLOGICAL RELEVANCE Cymbopogon species are largely used in folk medicine for the treatment of many diseases some of which related to parasitical diseases as fevers and headaches. As part of our research on antiparasitic essential oils from Beninese plants, we decided to evaluate the in vitro antiplasmodial and antitrypanosomal activities of essential oils of four Cymbopogon species used in traditional medicine as well as their cytotoxicity. MATERIALS AND METHODS The essential oils of four Cymbopogon species Cymbopogon citratus (I), Cymbopogon giganteus (II), Cymbopogon nardus (III) and Cymbopogon schoenantus (IV) from Benin obtained by hydrodistillation were analysed by GC/MS and GC/FID and were tested in vitro against Trypanosoma brucei brucei and Plasmodium falciparum respectively for antitrypanosomal and antiplasmodial activities. Cytotoxicity was evaluated in vitro against Chinese Hamster Ovary (CHO) cells and the human non cancer fibroblast cell line (WI38) through MTT assay to evaluate the selectivity. RESULTS All tested oils showed a strong antitrypanosomal activity with a good selectivity. Sample II was the most active against Trypanosoma brucei brucei and could be considered as a good candidate. It was less active against Plasmodium falciparum. Samples II, III and IV had low or no cytotoxicity, but the essential oil of Cymbopogon citratus (I), was toxic against CHO cells and moderately toxic against WI38 cells and needs further toxicological studies. Sample I (29 compounds) was characterised by the presence as main constituents of geranial, neral, β-pinene and cis-geraniol; sample II (53 compounds) by trans-p-mentha-1(7),8-dien-2-ol, trans-carveol, trans-p-mentha-2,8-dienol, cis-p-mentha-2,8-dienol, cis-p-mentha-1(7),8-dien-2-ol, limonene, cis-carveol and cis-carvone; sample III (28 compounds) by β-citronellal, nerol, β-citronellol, elemol and limonene and sample IV (41 compounds) by piperitone, (+)-2-carene, limonene, elemol and β-eudesmol. CONCLUSIONS Our study shows that essential oils of Cymbopogon genus can be a good source of antitrypanosomal agents. This is the first report on the activity of these essential oils against Trypanosoma brucei brucei, Plasmodium falciparum and analysis of their cytotoxicity.

In vitro antitrypanosomal and antiplasmodial activities of crude extracts and essential oils of Ocimum gratissimum Linn from Benin and influence of vegetative stage

ETHNOPHARMACOLOGICAL RELEVANCE Different parts of Ocimum gratissimum Linn are largely used in folk medicine for the treatment of many diseases, some of which related to parasitical infections as fevers and headaches. In order to validate their use and to clarify the plant part which possesses the best antiparasitic properties, we decided to evaluate the in vitro antiplasmodial and antitrypanosomal activities of essential oils and crude extracts from leaves, stems and seeds of Ocimum gratissimum as well as their cytotoxicity. MATERIALS AND METHODS The essential oils and ethanol crude extracts of leaves and stems of Ocimum gratissimum from Benin, were obtained in pre and full flowering stages. Seeds obtained only in full flowering stage, were also extracted. The oils were isolated by hydrodistillation and analyzed by GC/MS and GC/FID. Extracts and essential oils were tested in vitro against Trypanosoma brucei brucei and Plasmodium falciparum. Cytotoxicity was evaluated in vitro against Chinese Hamster Ovary (CHO) cells and the human non cancer fibroblast cell line (WI38) through MTT assay to evaluate the selectivity and toxicity was assessed against Artemia salina Leach. RESULTS The essential oils and non-volatile crude extracts of Ocimum gratissimum were more active on Trypanosoma brucei brucei than on Plasmodium falciparum (3D7). This activity varies according to the vegetative stage (pre and full flowering) and the plant part (seeds, stems and leaves) extracted. The best growth inhibition of Trypanosoma brucei brucei was observed with ethanol crude extracts of leaves (IC50=1.66 ± 0.48 μg/mL) and seeds (IC50=1.29 ± 0.42 μg/mL) in full flowering stage with good selectivity (SI>10). The chemical composition of the essential oil from aerial parts (47 compounds), characterized by the presence as main constituents of p-cymene, thymol, γ-terpinene, β-myrcene and α-thujene, depends on the vegetative stage. The oil contained some minor compounds such as myrcene (IC50=2.24 ± 0.27μg/mL), citronellal (IC50=2.76 ± 1.55μg/mL), limonene (IC50=4.24 ± 2.27μg/mL), with good antitrypanosomal activities. These oils and crude extracts were not toxic against Artemia salina Leach and had a low cytotoxicity except leaves and seeds ethanol extracts obtained in full flowering which showed toxicity against CHO and WI38 cells. CONCLUSIONS Our study shows that ethanol crude extracts of leaves and seeds of Ocimum gratissimum in full flowering stage can be a good source of antitrypanosomal agents. This is the first report about the relation between the plant part extracted, the vegetative stage of the plant, the antitrypanosomal and antiplasmodial activities and the cytotoxicity of essential oils and non-volatile extracts of Ocimum gratissimum from Benin.

Chemical composition and antimicrobial activity of essential oils of Ocimum basilicum, Ocimum canum and Ocimum gratissimum in function of harvesting time

Abstract The chemical composition of essential oils obtained by hydrodistillation from aerial parts of Ocimum basilicum, Ocimum canum and Ocimum gratissimum from Benin as affected by harvesting time, were analyzed by GC-FID (Gas chromatography-Flame ionization detector) and GC-MS (Gas chromatography-Mass spectrometry). Based on the composition analysis, major components were as follows: estragol (43.0–44.7%) and linalool (24.6–29.8%) in O. basilicum oils; carvacrol (12.0–30.8%) and p-cymene (19.5–26.2%) in O. canum oils; thymol (28.3–37.7%) and γ-terpinene (12.5–19.3%) in O. gratissimum oils. Disc diffusion and broth microdilution assays were used to evaluate the antibacterial activity of essential oils and their main components against two foodborne bacteria, Listeria monocytogenes and Salmonella enterica serotype Typhimurium. The tested oils and their components exhibited notable antimicrobial activities against L. monocytogenes and S. Typhimurium. The O. canum and O. gratissimum oils collected at 7h and 19h showed significant higher activities against L. monocytogenes and S. Typhimurium (MICs and MBCs 0.34–2.5 μL/ mL) (p < 0.05), whereas O. basilicum showed lower activity (MICs and MBCs 2.0–8.0 μL/mL) at any daytime of harvest, the weakest being at 19h (MIC and MBC 12.0–32.0 μL/mL). The daytime of harvest can influence the composition of oils and their activities on bacteria.

Synthesis and trypanocidal activity of salicylhydrazones and p-tosylhydrazones of S-(+)-carvone and arylketones on African trypanosomiasis.

Hydrazones are nowadays considered to be good candidates for various pharmaceutical applications. Here, we have synthesized two series of hydrazones: salicylhydrazones (GS1-4) and p-tosylhydrazones (GT1-4) from S-(+)-carvone and three aryketones with good yields (57-91%). Molecules were characterized by elemental analyses; TLC, NMR 1H, NMR 13C and MS. Submitted, in vitro, to their antiparasitic testing on Trypanosoma brucei brucei, and toxicity on Artemia salina Leach, all compounds except GT2 showed significant antitrypanosomal activity IC50 ranging from 1 to 34 micromolar (µM). Among them, 2-acetynaphthalene salicylhydrazone GS4 (IC50 = 1.97 ± 0.42 µM) and 7-methoxy-1-tetralone p-tosylhydrazone GT3 (IC50 =7.98 ± 1.65 µM) exhibited good trypanocidal activity and the other are moderates on parasite; when the compounds GS1, GT3 and GT4 presented toxic activity on larvae. In agreement to their selectivity index, which is greater than 1 (SI > 1), products turn out quite selective on the parasite: a series of salicylhydrazones revealed more selective (SI ≥ 11), especially GS4 (SI = 157) than the series of p-tosylhydrazones showed 1 ≤ SI ≤ 22. The synthesized compounds clearly displayed significant selective pharmaceutical activities on the parasite tested. Compounds developing could open promising route to news drug-candidates.

Adsorption kinetics of 2-chloroacétophénone and 4- bromoacétophénone thiosemicarbazone on Oueme Valley clays (R. Benin)

Laboratoire National de Pharmacognosie, Centre Beninois de la Recherche Scientifique et Technique (CBRST), BP 06 Oganla, Porto-Novo, Benin. Laboratory of Physic and Synthesis Organic Chemistry (LaCOPS), University of Abomey-Calavi, Faculty of Sciences and Technics (FAST),BP: 4521 Cotonou, Benin. Laboratory of Physical Chemistry, University of Abomey-Calavi (UAC), Faculty of Sciences and Technics (FAST), Cotonou, Benin. Louvain Drug Research Institute (LDRI), School of Pharmacy, Université catholique de Louvain, B1 7203 Avenue Emmanuel Mounier 72, B-1200 Brussels, Belgium.

Synthesis, Characterization and Antimicrobial Properties of Some 1,3,4-Thiadiazolines

Through The literature, there is little information about the antibacterial activity of 1,3,4-thiadiazoles. In order to verify if drugs based on this family of compounds could constitute an alternative to the antibiotics usually used in the antimicrobial fight, the aim of this work was to synthesize, to confirm the structures and then to test some 1,3,4-thiadiazolines for their antimicrobial activity against microbes. Twelve 1,3,4- thiadiazolines were synthesized with yields going from 27 to 95%. The products purity was confirmed by mass spectrometry coupled with high-performance liquid chromatography (LC/MS) and there were characterized using spectrometry IR, NMR 1 H and 13 C (nuclear magnetic resonance). The synthesized compounds were tested on strains of Escherichia coli ATCC 25922 and Salmonella typhimurium R 30951401 according to the macro-dilution method in liquid environment for a comparison of their antibacterial activity. Thiadiazoline 1 has been shown to be more active than other products. The most antibacterial thiadiazolines are those having para-electro attractor groups and also alkyl groups at R2. It could be a good drug candidate against these microbes.

Fats of Pig and Beef from Benin: Purification, Stability Study, Chemical and Nutritional Composition

Animal fats, are used in several western countries in industrial sectors as energy, oleochemistry, animal and human feed but stay under-utilized through Africa. The aim of the present study was to purify and stabilize fats of Bos taurus Linnaeus (BTL) and Sus scrofa domesticus Erxleben (SSDE) from Benin for various uses. Fats from BTL and SSDE were purified using local reagents, for the first time in Benin. The physicochemical properties, nutritional composition and the fatty acid profile were determined, with also, their preserving times. The GC/FID analyzes shown that 100 g of purified BTL fat contained 65.76% of saturated fatty acids (SFA), 31.83% of monounsaturated fatty acids (MUFA) and 2.41% of polyunsaturated fatty acids (PUFA). In the SSDE fat, 48.57% of SFA, 38.59% of MUFA and 12.84% of PUFA were obtained. The studied fats were rich in unsaturated fatty acids (UFA) such as oleic acid (34% and 26% and for SSDE and BTL respectively) and linoleic acid (11% and 1% for SSDE and BTL respectively). Their major saturated acids were palmitic and stearic acids, with respectively 25% and 35% for BTL fat and 25% and 21% for SSDE fat. The physicochemical parameters such as acid, peroxide, iodine and saponification indexes of the two fats were in agreement with the Codex Stan 211 (1999) recommendations, during all the conservation time. The preserving times of the two purified fats varied according to the temperature of conservation. These purified fats, with interesting physicochemical properties, could be used in agri-food, energy, oleochemistry, cosmetology.

Willgerodt-Kindler ReactionâÂÂs Microwave-Enhanced Synthesis ofThiobenzamides Derivatives in Heterogeneous Acid Catalysis withMontmorillonite K-10

The Willgerodt-Kindler (WK) reaction of is one of most synthesis methods used to access the thioamides. The known to thioamides have made this reaction more attractive in catalytic synthesis methods. Heterogeneous catalysis acid with the montmorillonite K-10 applied to this reaction under activation microwave for the synthesis of phenyl (morpholino) methanethiones derivatives shows that the mixture (aldehyde, sulfur, morpholine and K-10) is not only appropriate, but optimizes the reaction. This solid catalyst was easily separated from the reaction mixture and was recycled at least twice (02) without any loss of activity. Operational simplicity, short reaction times, excellent yields and benign environmental conditions are other advantages of this protocol, thus respecting the principles of green chemistry. Among the thioamides synthesized, 4-(morpholine-4-carbonothioyl)benzoic acid (h) is a novel molecule which to our knowledge has never before been synthesized. We obtained it with a yield of 68%. In summary, we can be concluded that the heterogeneous catalysis acid conditions with the montmorillonite K - 10 favourable to the Willgerodt-Kindler reaction for carbonyl compounds. The structures of thioamides synthesized were characterized and confirmed by highresolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) 1D and 2D (COSY, HSQC, HMBC).