Alassane Wele

Prof. Alassane Wele


Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 January 2017 in Molecules
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TYTINE Yoro
TINE Yoro
FRFranck Renucci
Franck Renucci
JCJean Costa
Jean Costa
AWAlassane Wele
Alassane Wele
JPJulien Paolini
Julien Paolini
The metabolites from the coumarin class, present in tissues of plants belonging mainly to the Rutaceae and Apiaceae families, included compounds with high chemical diversity such as simple coumarins and furocoumarins. These health-promoting components are recognized for their valuable biological activities in herbal preparations but also for their phototoxic effects. In this work, a targeted liquid chromatography (LC) coupled with tandem mass spectrometry (MS2) was developed for the screening of 39 reference standards of coumarins and furocoumarins in essential oils and plant extracts. Chromatographic separation was accomplished on reversed phase column using water/acetonitrile as the mobile phase and detection was performed on a hybrid QqQ/linear ion trap spectrometer fitted with an atmospheric pressure chemical ionization (APCI) source operating in positive ion mode. This analytical approach was applied to investigate the coumarin compositions of fruit essential oils and methanolic extracts obtained from separated parts (fruit, leaf, stem, trunk, and root) of Zanthoxylum zanthoxyloides. Ten coumarins and six furanocoumarins were reported in this species and data analyses were used to assess the suitability of these compounds to the metabolomics-based differentiation of plant organs. The quantification criteria of the metabolites in extract samples included linearity, limit of quantification, limit of detection, and matrix effect were validated. As reported for other species of the Rutaceae family, the concentration of coumarins was drastically higher in Z. zanthoxyloides fruits than in other plant organs.

1 December 2017 in Natural Product Communications
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TYTINE Yoro
TINE Yoro
YYYin Yang
Yin Yang
FRFranck Renucci
Franck Renucci
JCJean Costa
Jean Costa
AWAlassane Wele
Alassane Wele
JPJulien Paolini
Julien Paolini
Flavonoids are a large group of phenolic secondary metabolites having a wide range of biochemical and pharmacological effects. In this work, a targeted liquid chromatography (LC) coupled with tandem mass spectrometry (MS2) was used to characterize the flavonoid compositions of methanolic plant extracts from separated parts (fruits, leaves, stems, trunk barks, and root barks) of Zanthoxylum zanthoxyloides. Nine flavonoids were reported in this species, including three flavanones, five flavonols and one flavone. Quantitative analysis of flavonoid profiles from Z. zanthoxyloides extracts is useful to a better understanding of the pattern and distribution of metabolites in extract samples. The concentrations of two glycosylated flavanones (neohesperidin and hesperidin) and one flavonol (quercetin) were higher in root and trunk samples compared to fruit samples. These compounds were reported in small amounts in the stem and leaf samples. In contrast, four flavonols (hyperoside, quercetin-3- O-glucopyranoside, datiscin and quercitrin) were present in significant levels only in the leaf extracts. The presence of glycosylated flavanone (eriocitrin) has been reported only in fruit extract. The antioxidant properties of different extracts were tested regarding their scavenging activities on ABTS•+ radical. Leaf and trunk bark extracts exhibited antioxidant activities, while the extracts obtained from other organs (fruits, stems, and root barks) showed low antioxidant properties.

21 August 2024 in Journal of Fungi
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SSSAFIETOU SABALY
SAFIETOU SABALY
TYTINE Yoro
TINE Yoro
ADAlioune cheikh anta diop Diallo
Alioune cheikh anta diop Diallo
AFAbdoulaye Faye
Abdoulaye Faye
MCMouhamed CISSÉ
Mouhamed CISSÉ
SNSaliou Ngom
Saliou Ngom
Aspergillus flavus is a cosmopolitan saprophytic fungus that infests several foodstuffs and is associated with adverse effects in humans. In Senegal, significant losses of groundnut production are mainly due to contamination caused by this species. This study evaluated in vitro antifungal activities of Cyperus articulatus, Cyperus rotundus and Lippia alba essential oils against A. flavus isolated from peanut seeds. Essential oils obtained by hydrodistillation of rhizomes of the two Cyperus species and leaves of L. alba were analyzed with GC-DIF and GC-MS. The essential oil yields from C. articulatus, C. rotundus and L. alba were 1.1%, 1.3% and 1.7%, respectively. These three samples had the following chemotypes: (i) mustakone (21.4%)/eudesma-4(15)-7-dien-1β-ol (8.8%)/caryophyllene oxide (5.9%), (ii) caryophyllene oxide (25.2%)/humulene epoxyde 2 (35.0%) and (iii) geranial (46.6%)/neral (34.6%). The three oils tested inhibited the growth of A. flavus at concentrations between 100 and 1000 ppm. The L. alba oil was the most effective with total clearance of A. flavus on PDA. For the essential oils of C. rotundus (93.65%) and C. articulatus (78.11%), the highest inhibition rates were obtained with a 1000 ppm dose. Thus, L. alba oil could be used safely as an effective protector of groundnuts against A. flavus.

13 February 2020 in International Journal of Biological and Chemical Sciences
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TYTINE Yoro
TINE Yoro
MDMoussa Diop
Moussa Diop
INIdrissa Ndoye
Idrissa Ndoye
ADAlioune Badara Diallo
Alioune Badara Diallo
AWAlassane Wele
Alassane Wele
Cette étude avait pour objectif de faire le point sur la composition chimique et les activités biologiques de G. senegalensis, une plante médicinale largement utilisée en Afrique par les guérisseurs traditionnels pour le traitement de divers troubles. La plupart de ces études chimiques ont porté sur le criblage phytochimique des extraits de feuilles, de racines, de tiges et de galles. Elles ont montré la présence d'hydrates de carbone, de stéroïdes, de saponines, de flavonoïdes, d’alcaloïdes, de tanins, de saponines, de glycosides cardiaques, de coumarines, d’anthraquinones, d’acide ascorbique, d’hétérosides cardiotoniques, de cyanogènes et de terpénoïdes. Les potentialités thérapeutiques des extraits de G.  senegalensis rapportées dans plusieurs travaux scientifiques ont porté sur les activités antibactériennes, antitussives, antidiarrhéiques, cytotoxiques, anti-inflammatoires antipaludiques, antitrypanosomiques, antihelminthiques, antivirales et antioxydantes. Des études de toxicité sur ces extraits ont été aussi réalisées. Ainsi, des études de caractérisation chimique (variabilité chimique), de formulation galénique et aussi de toxicité clinique sur G. senegalensis doivent être menées afin de mettre en place des produits de phytothérapie moderne. Mots clés: Phytochimie, pharmacologie, feuilles, Guiera senegalensis. English Title: Review on the chemical composition and biological activities of Guiera senegalensis J.F. Gmel. (Combretaceae) The aim of this study was to review the chemical composition and biological activities of G. senegalensis, a medicinal plant widely used in Africa by traditional healers for the treatment of various disorders. Most of these chemical studies have focused on the phytochemical screening of leaf, root, stem and gall extracts. They showed the presence of carbohydrate, steroids, saponins, flavonoids, alkaloids, tannins, saponins, cardiac glycosides, coumarins, anthraquinones, ascorbic acid, cardiotonic glycosides, cyanogens and terpenoids. The therapeutic potentialities of extracts of G. senegalensis reported in several scientific studies have focused on antibacterial, antitussive, antidiarrheal, cytotoxic, anti-inflammatory, antimicrobial, antitrypanosomal, anthelmintic, antiviral and antioxidant activities. Toxicity studies on these extracts have also been carried out. Thus, chemical characterization studies (chemical variability), galenic formulation and clinical toxicity studies on G. senegalensis must be carried out in order to implement modern phytotherapy products. Keywords: Phytochemistry, pharmacology, leaves, Guiera senegalensis.

30 September 2018 in European Journal of Chemistry
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MBMamadou Balde
Mamadou Balde
SESaid Ennahar
Said Ennahar
SDStephanie Dal
Stephanie Dal
SSSeverine Sigrist
Severine Sigrist
AWAlassane Wele
Alassane Wele
DJDiane JULIEN-DAVID
Diane JULIEN-DAVID
The extraction of bioactive compounds from medicinal plants requires methods which are as diverse as the chemical nature of the compounds themselves. In this study, a 96-well microplate was used where solvent mixtures spanning wide ranges of selectivity and polarity were tested with the objective of extracting a broad range bioactive compounds from plant material. Microplate wells were filled with plant material and the solvents and their mixtures were added. The obtained extracts were assessed in terms of their total antioxidant activity, oxygen radical absorbance capacity and effects on cell viability. An aqueous extract, generally used by traditional therapists, was also included in the study. The results showed that the extracts using methanol with acetic acid (0.1%, v:v), chloroform/ethanol, butanol/DMF, butanol/acetonitrile, ethylene glycol with acetic acid (0.1%, v:v), MTBE/DMSO, ethylene glycol, pentane/ethanol (v:v), ethanol, DMF, DMF with acetic acid (0.1%, v:v), DMSO, DMSO with acetic acid (0.1%, v:v) and THF had a higher antioxidant activity than the aqueous extract. Extracts with greater antioxidant activity than the aqueous extract were obtained largely from solvent mixtures with the exception of ethanol, DMF, DMSO and THF. The antioxidant activity obtained in TEAC varied between 1474.1±4.4 and 3183.0±16.0 μmol TE/g dry extract respectively for aqueous and THF extracts; in ORAC between 1727.7±8.4 and 2683.5±11.7 μmol TE/g dry extract for aqueous and DMSO acetic acid 1%, respectively, with mean ±SEM. In TEAC the THF extract had the highest antioxidant potential with 3183.0±16.0 μmol TE / g dry extract. The DMSO acetic acid (0.1%, v:v) extract had the highest antioxidant potential in ORAC with 2683.5±11.7 μmol TE / g dry extract. Cell viability test using β-pancreatic cells showed that only the acidified methanol extract was toxic after one hour of incubation. After 24 hours, cell viability was less than 70% for extracts using butanol/acetonitrile, MTBE/DMF, acidified methanol, pentane/ethanol and acidified DMF.

15 October 2022 in Journal of Drug Delivery and Therapeutics
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ODOusmane Dembele
Ousmane Dembele
MHMahamane Haidara
Mahamane Haidara
ANAwa Ndong
Awa Ndong
FBFirmin Barbosa
Firmin Barbosa
GSGuata Yoro Sy
Guata Yoro Sy
AWAlassane Wele
Alassane Wele
Objectives:  Pain management is provided by analgesics. While considerable progress has been made in recent years due to better knowledge of the pathophysiology and mechanism of pain, the search for new, more effective analgesics with fewer side effects remains relevant. Previous work carried out at the pharmacology laboratory of the Faculty of Medicine, Pharmacy and Odontology of UCAD (Senegal) had shown an anti-inflammatory activity of the ether extract, as well as that of the methanolic fraction and of ethyl acetate from Annona senegalensis leaves. This study concerns the fractionation of the total methanolic and ethyl acetate fractions by chromatography on a Sephadex column. A phytochemical characterization of the fractions obtained, followed by the study of the analgesic activity of the derivative fractions of the methanolic and ethyl acetate extracts carried out in mice. Methods: Sephadex gel fractionation yielded ten fractions. Characterization tests were carried out on the total extracts and the different derivatives fractions. Results: Phytochemical characterization of the fractions revealed the presence of tannins, alkaloids, flavonoids, sterols and triterpenes. The F4 and F'4 fractions, rich in sterols and triterpenes, significantly reduced the number of cramps at low doses (1 mg/kg and 3 mg/kg). Conclusion: The presence of sterols and triterpenes in the methanolic F4 fraction of the leaves of Annona senegalensis could be the cause of the analgesic activity of the plant. Keywords: Annona senegalensis, phytochemistry, sterols and triterpenes, analgesic.