Pierre Guissou

Quercetin inhibits a large panel of kinases implicated in cancer cell biology.

Flavonoids are polyphenolic secondary metabolites from plants that possess a common phenylbenzopyrone structure (C6-C3-C6). Depending upon variations in their heterocyclic C-ring, flavonoids are categorised into one of the following groups: flavones, flavonols, flavanones, flavanols, anthocyanidins, isoflavones or chalcones. Flavonols include, among others, the molecules quercetin, myricetin and kaempferol. The anticancer activity of flavonols was first attributed to their electron-donating ability, which comes from the presence of phenolic hydroxyl groups. However, an emerging view is that flavonoids, including quercetin, may also exert modulatory actions in cells by acting through the protein kinase and lipid kinase signalling pathways. Data from the current study showed that 2 μM quercetin, a low concentration that represents less than 10% of its IC50 growth-inhibitory concentration as calculated from the average of eight distinct cancer cell lines, decreased the activity of 16 kinases by more than 80%, including ABL1, Aurora-A, -B, -C, CLK1, FLT3, JAK3, MET, NEK4, NEK9, PAK3, PIM1, RET, FGF-R2, PDGF-Rα and -Rß. Many of these kinases are involved in the control of mitotic processes. Quantitative video microscopy analyses revealed that quercetin displayed strong anti-mitotic activity, leading to cell death. In conclusion, quercetin partly exerts its anticancer activity through the inhibition of the activity of a large set of kinases. Quercetin could be an interesting chemical scaffold from which to generate novel derivatives possessing various types of anti-kinase activities.

Protective effect of Moringa oleifera leaves against gentamicin-induced nephrotoxicity in rabbits.

Oxidative stress due to abnormal production of reactive oxygen species has been implicated in the nephrotoxicity induced by gentamicin. The nephroprotective effect of aqueous-ethanolic extract of Moringa oleifera leaves (150 and 300 mg/kg) was evaluated against gentamicin-induced (80 mg/kg) renal injury in rabbits. Serum urea and creatinine levels were evaluated as the markers of renal nephrotoxicity. At the end of the experiment, the kidneys of rabbits were excised for histological examinations and determination of lipid peroxidation levels. Serum urea and creatinine levels were reduced in the M. oleifera (150 and 300 mg/kg) plus gentamicin treated groups. On histological examinations, kidney of intoxicated rabbits groups which received M. oleifera extract showed reparative tendencies. A highly significant (p < 0.01) elevation was observed in lipid peroxidation (LPO) level in the kidneys of gentamicin-intoxicated rabbits whereas combined treatment of M. oleifera and gentamicin group showed a highly significant (p < 0.01) depletion in LPO. The present study indicates that aqueous-ethanolic extract of M. oleifera leaves attenuates renal injury in rabbits treated with gentamicin, possibly by inhibiting lipid peroxidation.

Cytotoxic pentacyclic triterpenes from Combretum nigricans.

A new pentacyclic triterpene, 11alpha-acetoxy-20,24-epoxy-25-hydroxy-dammar-3-one (1), has been isolated from the African tree Combretum nigricans, together with the known corresponding diol, 20,24-epoxy-11alpha, 25-dihydroxy-dammar-3-one (2). They are responsible, at least in part, for the cytotoxic activity of the methanolic extract of the plant.

Pilot study on agricultural pesticide poisoning in Burkina Faso

ABSTRACT Epidemiologic data related to agricultural pesticide poisoning cases in Burkina Faso were collected. The study was carried out using retrospective (from January 2002 to June 2010) surveys conducted among farmers and healthcare centers. One hundred and fiftythree (153) pest control products were recorded during the survey and 56 active ingredients were identified. Out of the 153 pest control products, 49 (i.e. 32%) were authorized for sale in Burkina Faso. The main risk factors are socio-demographic characteristics of farmers, their low education level, and some attitudes and practices on using agricultural pesticides. Pesticide poisonings are relatively frequent and their management was not always efficacious. Actions are needed to reduce pesticide poisoning as a global public health problem and to improve management of pesticide poisoning. To this purpose, advanced investigations should be carried out over a longer period of time to complement the present pilot study

In vitro impact of five pesticides alone or in combination on human intestinal cell line Caco-2

In Burkina Faso, as in most Sahelian countries, the failure to follow good agricultural practices coupled with poor soil and climate conditions in the locust control context lead to high environmental contaminations with pesticide residues. Thus, consumers being orally exposed to a combination of multiple pesticide residues through food and water intake, the digestive tract is a tissue susceptible to be directly exposed to these food contaminants. The aim of our work was to compare in vitro the impact of five desert locust control pesticides (Deltamethrin DTM, Fenitrothion FNT, Fipronil FPN, Lambda-cyalothrine LCT, and Teflubenzuron TBZ) alone and in combination on the human intestinal Caco-2 cells viability and function. Cells were exposed to 0.1–100 μM pesticides for 10 days alone or in mixture (MIX). Our results showed a cytotoxic effect of DTM, FNT, FPN, LCT, and TBZ alone or in combination in human intestinal Caco-2 cells. The most efficient were shown to be FPN and FNT impacting the cell layer integrity and/or barrier function, ALP activity, antioxidant enzyme activity, lipid peroxidation, Akt activation, and apoptosis. The presence of antioxidant reduced lipid peroxidation level and attenuated the pesticides-induced cell toxicity, suggesting that key mechanism of pesticides cytotoxicity may be linked to their pro-oxidative potential. A comparative analysis with the predicted cytotoxic effect of pesticides mixture using mathematical modeling shown that the combination of these pesticides led to synergistic effects rather than to a simple independent or dose addition effect.

Biological alterations and self-reported symptoms among insecticides-exposed workers in Burkina Faso

Biological alterations and self-reported symptoms among insecticides-exposed workers in Burkina Faso Occupationally exposed workers, farm workers and plant protection agents in the Sahel region of Burkina Faso were interviewed to assess adverse health effects of insecticides. The subjects were also examined for changes in both hematological and biochemical parameters. The prevalence of liver and kidney dysfunction was found to be quite high among insecticide applicators, especially among plant protection agents. The prevalence of biochemical alterations seems to be correlated to the frequency of insecticide use. However, no significant differences were found between the hematological parameters among farm workers and plant protection agents. The hematological parameters of all the insecticide applicators were normal. The great majority of insecticide applicators (85%) reported symptoms related to insecticide exposure. The use of insecticides in the agriculture of Burkina Faso is threatening to human health.

Ethnobotany and preliminary bioactivity investigation on hepatoprotective medicinal plants from the Mouhoun Region of Burkina Faso

An ethnobotanical survey of medicinal plants used to treat hepatitis in the Mouhoun region of Burkina Faso was undertaken. The extracts of the most quoted species were then evaluated for their phytochemistry and their antioxidant activity The anti-radical activity (by the method of the discoloration of the ABTS cation radical) and that of the antioxidant (by the method of the reduction of the iron ion, FRAP) were evaluated. Then the phenolic content of the aqueous extracts was determined and a correlation was studied between these two parameters. The antioxidant tests showed that the plants counted have a good antioxidant power. The three most active extracts are those of the trunk and root bark of Pseudocedrela kostchyi , and the trunk bark of Sterculia setigera . The extract of the bark of the trunk of Sterculia setigera showed the highest total tannin and phenolic content, while that of the leaves of Piliostigma reticulatum showed the highest content of flavonoids. The analyses showed that there is a relationship between the total phenolic contents and the antioxidant capacities of all the extracts (R2 = 0.82). The extracts of the trunk and root barks of Pseudocedrela kostchyi , and that of the trunk bark of Sterculia setigera showed the best antioxidant properties. They could be good candidates for the search for liver protective molecules.